Science for South Africa ISSN 1729-830X
A school project & environmental education Radio astronomy spreads across Africa
Volume 10 | Number 2 | 2014
Climate change and the Southern Ocean Concrete & sustainability
Unique pollinators in the fynbos Stingrays: a forgotten species Acad e my O f Sci e n ce O f South Afri ca
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ontents Volume 10 | Number 2 | 2014
Cover Stories 3 Rural effluent disposal:
A case for environmental education
Lesley van Heerden and her team from Albert College, Prince Albert, show how we can all make a difference
10 Africa prepares for SKA:
the African VLBI Network
Anita Loots and Mike Gaylard explain how Africa is becoming part of the global radio astronomy network
16 How are Antarctica and the Southern Ocean responding to climate change?
Mike Lucas, Kirti Gihwala and Michal Viskich explain how the Southern Ocean is Earth’s ‘freezer’
24 The unique pollinators of the Cape Floral Kingdom
Chris Johnson explains how an unlikely small mammal is vital to the health of the fynbos
26 The importance of the overlooked: the story of stingrays
Chantel Elston describes the biology of this little-known species
28 Concrete and environmental sustainability
Olukayode Alao shows that concrete structures do not have to add to carbon emissions
Features 20 Reframing climate change
Wiida Fourie-Basson shows how climate change is a social science issue
30 A skin photosensitivity atlas for South Africa
Caradee Wright looks at our sensitivity to the sun
32 News from the University of Pretoria
Beefing up efforts to breed with cattle • Study asks for ban on 4x4s in protected areas • Ostriches can’t choke or taste • New technique finds anti-HIV compounds in indigenous plant species • Haviside’s dolphins on the West Coast are related • Images of long bones used to identify children • Decoding of Eucalyptus tree genome unlocks new possibilities for renewable fibre, fuel and biomaterials
20 26 24
Regulars 23 Fact file
Climate change: what can you do? • Tipping points: The case of the West Antarctic ice sheet
Collecting samples down to 500 m under the sea
38 Books 41 News
Algoa Bay’s underwater ‘chemical warfare’
42 Subscription 43 News
Declining numbers of seabirds at Marion Island
44 Back page science • Mathematics puzzle
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Science for South AfricA iSSn 1729-830X
A school project & environmental education Radio astronomy spreads across Africa
Volume 10 | Number 2 | 2014
Climate change and the Southern Ocean Concrete & sustainability
Unique pollinators in the fynbos Stingrays: a forgotten species AcAd e my o f Sci e n ce o f South Afri cA
Images: Albert College, Mike Lucas, NASA, Rainer von Brandis/D’Arros Research Centre, SKA
Editor Dr Bridget Farham Editorial Board Roseanne Diab (EO: ASSAf) (Chair) John Butler-Adam (South African Journal of Science) Anusuya Chinsamy-Turan (University of Cape Town) Neil Eddy (Wynberg Boys High School) George Ellis (University of Cape Town) Kevin Govender (SAAO) Himla Soodyall (University of Witwatersrand) Penny Vinjevold (Western Cape Education Department) Correspondence and enquiries The Editor PO Box 663, Noordhoek 7979 Tel.: (021) 789 2331 Fax: 0866 718022 e-mail: firstname.lastname@example.org Advertising enquiries Barbara Spence Avenue Advertising PO Box 71308 Bryanston 2021 Tel.: (011) 463 7940 Fax: (011) 463 7939 Cell: 082 881 3454 e-mail: email@example.com Subscription enquiries and back issues Phathu Nemushungwa Tel.: (012) 349 6624 e-mail: firstname.lastname@example.org Copyright © 2014 Academy of Science of South Africa
Published by the Academy of Science of South Africa (ASSAf) PO Box 72135, Lynnwood Ridge 0040, South Africa
Permissions Fax: 0866 718022 e-mail: email@example.com Subscription rates (4 issues and postage) (For other countries, see subscription form) Individuals/Institutions – R100.00 Students/schoolgoers – R50.00 Design and layout Creating Ripples Graphic Design Illustrations James Whitelaw Printing Seriti Printing Pty Ltd
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Our environment –
he opening article in this edition of Quest is all about understanding our environment and trying to make a difference. Two of the subsequent articles discuss climate change and its effects. The world around us is all we have and it may appear that we are not doing a very good job of conserving it – or even of making it a good place for those of us who live here right now. Humans have only been part of the Earth’s history for the equivalent of a few seconds. Modern humans first began to evolve around 200 000 years ago. These early modern humans started moving out of Africa between 125 000 and 60 000 years ago. We started as hunter-gatherers, with a pretty small impact on the world around us. But around 11 000 years ago there was a shift from the hunter-gatherer lifestyle to farming and with it the start of the massive changes in our environment that have come from agriculture, increasing human population and technology. These very recent changes have had an enormous impact on the very structure of our environment. Since the Industrial Revolution, which lasted from around 1760 to sometime between 1820 and 1840, human impact on the environment has been significant and damaging. The evidence that humans are responsible for the climate change that we are all experiencing now is unequivocal – man-made carbon emissions have already tipped us past a point of no return and in our lifetimes (and those of your children and grandchildren) there will be major changes in the seasons and what those seasons bring. What can we do about this? On a global scale nations must come together to agree on policies that will make a difference to carbon emissions and other industrial activities such as mining that are causing irreparable damage. But it is possible to make a difference on a very small scale, as the opening article in this issue of Quest shows us. A small school in a tiny Karoo town has spent time and energy investigating a seemingly small environmental problem – effluent run-off from the local sewage works and its effects on the indigenous vegetation in the area. All that this required was a group of enthusiastic teachers, dedicated students and the cooperation of the local environmental agencies. This small study (while contributing to the students’ knowledge of Life Sciences) has produced concrete results that have been translated into practical recommendations for change in the way that Prince Albert manages water and waste for its growing population. This is an example to us all – we can all contribute and any contribution, however small, will make a difference.
Bridget Farham Editor – QUEST: Science for South Africa Quest would like to apologise for the incorrect spelling of Madiba’s Xhosa name in the last issue. The correct spelling is Rholihlahla.
All material is strictly copyright and all rights are reserved. Reproduction without permission is forbidden. Every care is taken in compiling the contents of this publication, but we assume no responsibility for effects arising therefrom. The views expressed in this magazine are not necessarily those of the publisher.
❚❚❚❙❙❙❘❘❘ Citizen science The stream, overflow from the sewage works, that flows through the Wolwekraal Nature Reserve. Image: Albert College
One school in Prince Albert, in the Cape, decided to take action to improve their local environment and learn about ecology research at the same time. By Lesley van Heerden and her team.
RURAL EFFLUENT DISPOSAL:
A case for environmental education
he current Life Sciences curriculum from Grades 10 to 12 covers environmental science in some detail and includes a major fieldwork project, offering an opportunity to learn ecological research techniques in detail. Students and staff at Albert College, Prince Albert – a small town in the little Karoo – used this opportunity to look at the environmental effects of the local sewage disposal system and, by doing so, contributed to environmental conservation in their area. Effluent disposal – the pitfalls Small Karoo towns manage their effluent or sewage in a number of ways. In Prince Albert 63% of sewage is water borne. The effluent reaches the sewage works by pipeline or is collected by pump trucks and pumped into two of six sewage pans. The raw sewage is not chemically treated and the solid sludge sinks and settles, while the liquid evaporates. The six pans are arranged in a grid, which is linked by a series of pipes, which provide gravity flow. Gravity
flow ensures that the top pans contain mostly solid waste while the bottom two pans hold mostly liquid. However, Prince Albert is growing and with its population growth so too is there an increase in waste, which includes sewage. According to the 2014 Integrated Development Plan, Prince Albert produces 1 063 kilolitres of wastewater per day, which exceeds the capacity of the sewer dams that were designed to treat 623 kl/day. This has resulted in overflow, seen as a perennial run-off stream from the bottom two pans, flowing for approximately 0.9 km through the Wolwekraal Nature Reserve (WKNR), which borders the municipal waste disposal site. Students from the school noticed a change in the vegetation close to the stream and decided to investigate the effects of the effluent stream on both the soil and the indigenous vegetation. Investigating the effects Our work took place in the Wolwekraal Nature Reserve which is approximately 2 km NNW of Prince Albert.
An aerial view of the Wolwekraal Nature Reserve and the sewage works. Image: Google Maps
Prince Albert, although falling into a summer rainfall area, does not have strongly seasonal rainfall. Precipitation is on average about 175 mm/year and the area is prone to droughts when rainfall is 60% of the average or less. Average midday temperatures range from about 17°C in winter to 32°C in summer. The soil is shallow and stony and the veld type is mostly shrub and grass species with succulents. Thornveld is found in the stream and river beds. 10| 2 2014
Data were collected along five transects, 50 m apart and perpendicular to the effluent stream, the first being approximately 150 m from the ‘treated’ sewage effluent outlet, as seen in the diagram. The group chose to work only on the western side of the stream because the conditions and vegetation on the west mirrored that of the east. Sampling and testing Soil
The sampling area with details of the transects from which samples were taken.
A 100 ml auger was used to collect five random soil samples from each transect block, which was then mixed to get a representative sample – providing one mixed, representative sample from each transect block. Each of these mixed samples was carefully labelled to show which transect and block it had been collected from. A third of each of these samples was kept for testing soil moisture while two thirds was sent to Labserve, a laboratory that tests soil chemistry. Soil moisture
Each sample was weighed and its mass recorded before being dried to a constant mass at 50°C in a drying oven. The dry mass was then recorded. We calculated the percentage soil moisture as follows: mass of dry soil (g) % dry soil = mass of wet soil (g) % moisture = 100% (wet mass) – % dry soil Soil chemistry
A broad view of the sampling area, approximately 35 m from the effluent stream. A reed bed can be seen in the background. Image: Albert College
Thornveld is a type of veld that is characterised by grassland that contains thorny Acacia species and other species of thorny bushes.
Students from Albert College, who were guided and mentored by Dr Sue Milton of Wolwekraal Conservation and Research Organisation (WCRO), investigated the effects of the stream on the local environment, looking specifically at: n The vegetation – health and cover n The soil – its chemistry and moisture. The equipment used to plot transects and grids. Image: Albert College
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The project Sampling was carried out between July and September 2013.
Samples were sent to Labserve, who kindly sponsored the soil chemistry testing, because the school laboratory did not have full sampling facilities. Broad tests, including the soil pH and conductivity, were requested. The concentrations of various ions found in the samples were also recorded. pH and soil conductivity are two measures of the ‘health’ of a soil. pH is a good indicator of the balance of available nutrients in the soil. The electrical conductivity of the soil gives an idea of the quantity of the available nutrients in soil. Remember that only nutrients that are dissolved in water are available for plants to take in.
Sampling vegetation The team looked at the amount of cover provided by the vegetation and the health of the vegetation. Again, they used
Taking vegetation samples. Image: Albert College Right: A group sampling at the edge of the effluent stream. Image: Albert College
The equipment used to measure out the 30 cm distances along the transect lines. Image: Albert College
These graphs show the relationship between the distance down the stream and the health of the plants and their cover.
the transect grid used in soil sampling. The team stretched a tape measure out along each transect from 0 - 30 m. At 10 cm intervals they looked at what plants were present. The plants were categorised into four broad categories – herbaceous, woody, grass and succulents. At the same time they made an approximate assessment of the state of health of the plants in each transect by using this scale: 1 = almost dead (0 - 25%) 2 = very unhealthy (25 - 50%) 3 = slightly unhealthy (50 - 75%) 4 = healthy (75 - 100%) All the data collected were then analysed to look for the effects of the effluent stream on the vegetation and soil in the WKNR.
What they found Vegetation
Some very clear trends were seen. Herbaceous plants (mostly soft, weedy plants that need continuously moist soil to survive and grow) are healthiest near the effluent stream and nearest the source of the effluent (upstream). They also cover more of the ground within 15 m of the stream than they do 25 - 50 m from the stream. Total vegetation canopy cover decreases with distance from the effluent stream. The normal vegetation cover in this part of the Karoo with rainfall of less than 170 mm/year is about 35%. Therefore the extra moisture provided by the stream has led to a substantial increase in
Healthy vygie plant growing over 40 m from the effluent stream. Image: Albert College
vegetation cover within the first 15 m from the stream. Woody cover has increased within 10 m of the steam. Most woody cover near the stream is sweet thorn (Acacia karoo) and gannabos (Salsola aphylla), 10| 2 2014
These graphs show the relationship between average plant health and distance from the stream.
likely to be a complex mixture of factors including competition for light (from the woody plants that are favoured in these conditions), waterlogging and grazing.
An unhealthy specimen of gannabos at the edge of the effluent stream. Image: Albert College
These photographs show salt damage to plants at the edge of the effluent stream and salt leaching to the surface of the soil near the stream. Image: Albert College
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while further from the stream woody cover largely comprises kriedoring (Lycium spp.) Despite the increase in woody cover near the effluent stream, the health status of many of the woody plants is worse near the stream and near the source of the effluent. The cause of the poor health is probably a combination of excess water causing waterlogging, increased salinity and increased grazing on the plants by rodents. The health and cover of grasses and succulents increases with distance from the stream and with distance from the effluent source. Again, causes of poor health for these groups are
The relationship between soil moisture and distance from and down the effluent stream, for each transect and as an average.
There is a clear decrease in soil moisture content relative to distance from the effluent stream over all five transects.
The relationship between distance from the stream and the phosphorus content of the soil.
Levels of phosphorus closer to the stream are abnormally high – 300 mg/kg against an average of 144 mg/kg. Phosphorus is one of the chemicals used in soaps and it remains in the water, significantly affecting the soil chemistry. Moving away from the stream, around 50 m away, normal levels of phosphorus were found.
Soil pH in the Karoo is basic and this is reflected in the graphs. However, the pH in the soil closest to the effluent source is acidic. This is in sharp contrast to that of the soil further from the source. The acidity could be as a result of high organic matter level and bacteria or as a result of the initial pH of the water which comes from the water courses of the Zwartberg Mountains.
The relationship between the magnesium in the soil and distance from the stream.
There is a clear decrease in the magnesium content of the soil relative to distance from the effluent stream.
There is a strong relationship between the conductivity of the soil and the concentration of sodium ions [Na+].
There is a clear relationship between conductivity and the concentration of sodium cations ([Na+ ]). Conductivity is related to the movement of charged particles, in this case the sodium cations, so this relationship is to be expected in a soil that is ‘salty’. When concentration of cations increases, so does conductivity. This reading is similar to the data collected from a sample of borehole water from the borehole closest to the stream (419 mS/m – irrigation).
The relationship between soil pH in each transect and distance from and down stream and the relationship between average pH and distance from the stream.
The relationship between calcium in the soil and distance from the stream.
Calcium levels fluctuate, but the trend is to decrease slightly with distance from the stream. In 2004, average soil calcium levels in the area were 250.4 mg/kg. The current average is four times this value, showing that the soil has become limed. In limed soils calcium may immobilise iron. This may prevent plants from absorbing iron, even when plenty of iron is present in the soil. Potassium content drops steeply from about 550 mg/kg at 5 m to about 220 mg/kg at 25 m and then increases slightly before levelling out at approximately 220 mg/kg. Average soil potassium in 2004 was 250 mg/kg.
The relationship between the potassium content of the soil and the distance from the stream.
The Succulent Karoo, including the area around Prince Albert is known worldwide for its high diversity of specialised plants known as succulents. These plants, including hundreds of kinds of vygies, plakkies and ghaap, survive desert conditions by storing water in their leaves or stems. Constant wetting of the soil by the effluent stream rots their roots and leaves. When they die, their place on the wet soil is taken by alien vegetation introduced from other countries. Clearly, the effluent stream has changed the indigenous vegetation and the nature of the soil. Where to now? The point of this type of ecological study of the environment is to find out whether or not an intervention by people, in this case the effluent run-off from Prince Albert’s growing volume of sewage, has affected the environment and how. It is apparent that the stream resulting from the sewage overflow has had adverse effects by changing the nature of the soil and the plants growing around the stream. How can people in this community lessen these effects? The first approach would be to try to improve the quality of the effluent. There are several possible ways that this could be done: n Recycle water in grey water systems using less detergent and/or biofriendly cleaning detergents so there is less water reaching the sewage works n Use water-saving toilet cisterns so that less water reaches the sewage works and less effluent runs into the natural environment n Use reed beds to filter the water after the initial settling process in the sewage works, so that any effluent would be less polluted. What clearly came out of this study is that people in the community need to be exposed to the problem and sustainable and cost-effective ways to deal with it – constructive environmental education is needed. How can this be done? Ideas include: n The three schools in the village should work together with the Life Science teachers. This project could be the foundation of a joint project undertaken to understand our responsibility and very real role in 10| 2 2014
The team Jean Windvogel (AC), Lesley van Heerden (AC, Biology), Dr Richard Dean (WCRO), Ken Auerswald (Labserve), Willem Zietsman (AC), Rebekah Swanepoel (AC), Dr Sue Milton (WCRO), André Goosen (AC, Natural Sciences). Image: Albert College Photography: Rebekah Swanepoel
Dr Judie Maguire (WCRO). Image: Albert College
managing water before it becomes part of the effluent. n There are more than 60 guest houses and a hotel in Prince Albert, essential for the socioeconomic development of the region, but part of the reason for the growing numbers of people in the community, all of whom need to be aware of the problems of sewage disposal in a small, rural town. People who run the guest
References Labserve Analytical Sevices. Test report# 14-01238: Soil Analysis Prince Albert Municipality 2014. Draft Revisions to the Integrated Development Plan (IDP) for 2012-2017 (p33-35) http://www.lenntech.com/periodic/water/calcium/calcium-andwater.htm#ixzz31yLYe9ps Shearing, D and Van Heerden, K. Karoo Southern African Wild Flower Guide 6. 1994. Botanical Society of South Africa, Cape Town. South Africa. Van Breda, PAB and Barnard, SA. Veld Plants of the Winter Rainfall Region. Department of Agricultural Development. 1991. Pretoria
Dr Zola Urgessa, a post-doctoral physics student at Nelson Mandela Metropolitan University, conducts research using the university’s new scanning probe microscope. Image: NMMU
Nelson Mandela Metropolitan University’s Prof. JR Botha inspects the university’s R7.5 million scanning probe microscope, which will be used for a broad range of research, including work on cancer and diabetes.
atom – but it is also allowing researchers from NMMU and other institutions throughout the Eastern Cape to probe solids, polymers (plastics and resins) and biological material for their structural, electrical and mechanical properties. ‘It is the fastest instrument available on the market today, with the ability to obtain high resolution morphological (structural) images on a time scale of one second, which will have a tremendous impact on NMMU’s research on dynamic processes in cancer and insulin resistant cells,’ said professor of physics JR Botha, who holds a research chair in nanophotonics. It will be used to study a diverse range of material, including advanced semiconductors being developed at NMMU, Walter Sisulu University and Fort Hare University, as well as fibers and polymers in bio-composites being studied
houses and hotels and their visitors need to understand the problem, which will require a campaign, publicising the results of this study and helping them to reduce the damage to the environment by: n Reducing the volume of water used for bathing and laundry n Using biodegradable detergents to improve the quality of the waste water. Q
Futuristic instruments for NMMU Imagine being able to place a threedimensional cancer cell specimen under a powerful microscope that has a tiny probe to stimulate the specimen from all angles, providing scientists with a clearer perspective of its properties. It sounds futuristic, but it is happening right now in Nelson Mandela Metropolitan University’s (NMMU) physics department, which recently received a state-of-the-art scanning probe microscope valued at R7.5 million. It is one of two new leadingedge instruments the university has acquired though the National Research Foundation’s competitive National Equipment Programme (NEP) and National Nanotechnology Equipment Programme (NNEP) – which awards two-thirds funding to enable South African universities to buy world-class research equipment. The second instrument, worth R5.4 million, is a three-dimensional optical profiler, which will broaden the scope of NMMU’s research in the area of optical component manufacturing (e.g. pertaining to mirrors and lenses) in the aerospace and automotive industry. The scanning probe microscope not only enables research on the nano scale – which is almost down to the miniscule level of the
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t the Centre for Scientific and Industrial Research (CSIR). NMMU will also use it for battery electrode research. The second instrument, the threedimensional optical profiler, is the latest addition to NMMU’s Ultra-High Precision Manufacturing Centre, which produces advanced optical components usually found in applications in the aerospace and automotive industries. ‘The new instrument has been designed to address the increasing demand by the optics industry to characterise the profiles and surfaces of freeform and complex optical components, such as aspheric (deviating slightly from a perfectly spherical shape) and diffractive (enabling the bending of light) mirrors and lenses,’ said manufacturing engineering expert Prof. Khaled Abou-El Hossein.
Africa prepares for SKA: the African VLBI Network
Selection of receiver systems for first light operations of the AVN telescopes was informed by those most frequently used by the EVN. Image: Dr Mike Gaylard, original from Prof Huib van Langevelde (JIVE, Netherlands)
Global radio astronomy VLBI arrays. Note the ‘gap’ between Europe and Africa. Image: Dr Mike Gaylard
A map of Africa showing redundant 32m large telecommunications antennas (white dots), highlighting the Ghana antenna and the HartRAO observatory in yellow. Image: Googlemaps, image courtesy Dr Mike Gaylard
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During May 2012, an international panel awarded the hosting privileges of the international Square Kilometre Array (SKA) telescope jointly to Africa and Australia. When the SKA is completed during 2023, Africa will be the home of several radio telescope arrays in stations across nine African countries (Botswana, Ghana, Kenya, Madagascar, Mauritius, Mozambique, Namibia, South Africa, Zambia). Anita Loots with contributions from Mike Gaylard.
adio astronomy in South Africa is growing – and the successful outcome of the South African-led African bid to host the Square Kilometre Array (SKA) telescope has had a major influence. Significant investments over the past decade have established and grown globally competitive engineering, technology and science capacity in South Africa. Beyond South Africa, the other eight African SKA partner countries are also preparing to become significant contributors to the SKA and beneficiaries of its opportunities. Activities have kicked off in most partner countries to establish dynamic radio astronomy research communities, acquire the skills to mine data from archives to conduct publishable science and to develop core teams with appropriate skills to engage in the engineering and technology development related to radio astronomy instrumentation. The data transport networks connecting all the instruments of the SKA telescope will be by far the fastest in the world, creating significant opportunities for groundbreaking science from the huge data repositories in the data archives of the SKA. VLBI stands for very long baseline interferometry. Read ‘From theory to practice’, Quest 8(3) 2012 to find out more about interferometry and ‘‘Seeing” radio waves’ Quest 9(2) 2013 to find out more about the nuts and bolts of radio astronomy.
❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘❘ The opportunities Single dish research and training opportunities for young African scientists include spectroscopy (with a narrowband multi-channel spectrometer), (e.g. for periodic variations of methanol masers at 6668MHz in star-forming regions), ground state hydroxyl at 1612, 1665, 1667 and 1720 MHz, observing pulsars with a wideband multi-channel pulsar timer, monitoring of pulsars for glitches and long-term behaviour, searching for/monitoring of intermittent pulsars, transients (RRATs) and fast radio bursts (FRBs), radio continuum flux measurement with a wideband multi-channel radiometer, daily calibration of the telescope receivers using standard radio astronomy calibration sources, monitoring of radio emission from Gamma-ray flare sources. All of these research areas are highly competitive research domains.
The African VLBI Network (AVN) of telescopes is one of the most significant vehicles through which capacity development for SKA participation will be realised. It is a forerunner to the long baseline Phase 2 component of the mid-frequency SKA and will ensure that Africa can participate optimally in SKA activities during and after deployment of SKA Phase 2. The AVN project is a partnership between the National Research Foundation – through the office of the SKA in South Africa – and new institutions being established in the SKA Africa partner countries. South African funding for the AVN is from the African Renaissance Fund (ARF) – within the Department of International Relations and Cooperation (DIRCO) – and the Department of Science and Technology (DST). The importance of very long baseline interferometry (VLBI) science VLBI is used to observe radio-bright sources of small angular size. Large objects physically meet this requirement if they are far enough away from us. Active galactic nuclei and radio-bright supernovae in external galaxies are examples of objects whose evolution can be studied with VLBI. Masers in star-forming regions in the Milky Way are examples of nearby bright, compact sources. Methanol masers at 6.668 GHz and 12.178 GHz are currently of particular interest to scientists. Measurement of their annual parallaxes by repeated VLBI observations allows their distances to be determined, and thus also the locations of the spiral arms in the Milky Way. The same technique can be used to measure pulsar distances. The objects described above are all within the Milky Way. The puzzling transient radio sources and gamma-ray bursters are both potential classes of target objects beyond the Milky Way. A maser in astrophysics is a naturally occuring emission from the electromagnetic spectrum that is stimulated by atomic activity. This emission may be found in molecular clouds, comets, planetary atmospheres, stellar atmospheres and various other conditions in interstellar space.
Who is who in the SKA in Ghana In Ghana, the Ghana Space Science and Technology Institute (GSSTI) is the home of radio astronomy and the custodian of the AVN radio observatory under development. This new AVN radio observatory is being developed by converting the 32m telecommunications antenna at Kutunse, north of Accra, into a VLBI-capable radio telescope. The GSSTI was established
The 32m telecommunications antenna at Kutunse, Ghana that is under conversion into a VLBI-capable radio telescope. Image: SKA
The GSSTI team posing in front of the Kutunse antenna with members of the AVN team in South Africa (January 2014) during a technical visit as part of the engineering programme to convert the 32m antenna system into a VLBIcapable radio telescope. Image: SKA
in 2012 as an institute within the Ghana Atomic Energy Commission (GAEC). Besides the 26m HartRAO telescope in South Africa, Ghana is expected to be the first to establish a VLBI-capable telescope for the AVN project. This Ghana telescope will be well placed to fill the gap between Europe and Africa for VLBI with the EVN. Capacity building to run an observatory includes establishing competent core, essential observatory staff teams in partner 10| 2 2014
The team carefully checks the jacks and lifting fixtures prior to antenna lift (January 2014). Image: SKA
GSSTI team members and the AVN project team discuss the challenges for structural and mechanical modifications to the 32m diameter antenna at Kutunse, Ghana. (Left to right: Felix Madjitey, Eric Aggrey, Japie Ludick, Christian Rhoe Quaye, Joyce Koranteng-Acquah (standing at the back). Image: SKA
The GSSTI trainees from Ghana in Cape Town with the AVN Small Training Telescope: Emmanuel Proven Adzri, Theophilus Ansah-Narh, Felix Madjitey, Emmanuel Kodwo Mornoh, Joseph AK Nsor, Severin Azankpo, Anita Loots (SKA SA), Joyce Koranteng-Acquah. Image: SKA
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Final arrangements for lifting and centering of the 240-ton antenna structure in Ghana in January 2014. Image: SKA
countries that can train larger teams in science, engineering and technology issues and collaborate with the broader global science community to develop new African radio astronomy science communities. A team of physicists and engineers from the GSSTI completed a high-intensity six-month training programme in South Africa on 29 May 2014. This team forms the core observatory essential staff in Ghana and is equipped to train others at the GSSTI, especially during the telescope engineering activities currently under way. Establishing a radio astronomy observatory through the re-use of suitable telecommunications systems is a cost-effective entry strategy for radio astronomy. The engineering programme to do so is underway in Ghana. Equipment needed for a typical VLBI radio telescope consists of a receiver covering at least one standard VLBI band, a hydrogen maser frequency standard providing frequency standard and reference frequencies for the receiver/signal chain, a GPS receiver providing time standard for recording systems and an internet connection (10 Mbps minimum bandwidth). A 10 Mbps internet connection is required for receiving VLBI test and science schedules, liaising with operators at other telescopes in the schedule and at the correlator that is processing the data and sending VLBI test data samples to the correlator. A wideband internet connection (128 Mbps minimum bandwidth) enables real-time e-VLBI transmission of VLBI science data by e-shipment to the correlator, narrowband spectroscopy data to the correlator and real-time e-VLBI transmission of wideband continuum and pulsar data to the correlator (1 Gbps = 1024 Mbps minimum bandwidth). Radio astronomers from around the world are likely to pursue collaborative projects with Ghanaian scientists on single-dish research, student projects and practicals as well as multi-dish VLBI observations for high angular resolution imaging. Countries with VLBI-capable radio telescopes are a source of knowledge. European countries such as the UK, Italy, the Netherlands, Poland and Spain are members of the EVN and could provide expertise and training. In addition several other countries have already independently converted satellite antennas to radio telescopes or are doing so now. These countries include Australia, Japan, New Zealand, UK, Peru (with Japanese assistance). They also have experience that can be shared. Several Ghanaian scientists are studying towards postgraduate qualifications in radio astronomy through SKA SA bursaries and other funding. These scientists will become the pioneers in a scientific domain not previously well
Engineers from GSSTI, South African AVN team and the original equipment manufacturer on the 32m diameter reflector surface to discuss critical repair to the quadrapod legs during a site visit in January 2014. Image: SKA
known in Ghana. The Royal Society in the UK awarded a grant to develop a radio astronomy community of methanol maser researchers over a period of three years using the Kutunse radio telescope, starting in March 2015. This project aims to train 60 students in maser monitoring techniques and telescope operations. Preparations are under way for this project and, during July 2013, a meeting was held with heads of departments of physics from universities in Ghana to explore ways to introduce radio astronomy or astrophysics into their curricula. The research comprises a systematic search of the Milky Way for new massive binary star systems in the process of formation. Monitoring of the strong interstellar maser emission from the methanol molecule can reveal periodic flaring of the emission as the two young stars approach each other on their elliptical orbits. A thousand such maser sources are now known thanks to a recent survey of the Galaxy and the time is right for a concerted monitoring effort. This project will be carried out in collaboration with similar efforts in South Africa where such studies were pioneered and in the UK where a similar dish conversion project is underway at Goonhilly. A census and detailed follow-up of such objects will help us to understand how all stars are formed. This project involving astrophysics from several countries will inspire new generations of Ghanaians to take up science and technology. As part of this project, additional training in the commercial opportunities afforded by knowledge of radio astronomy techniques will be provided by an experienced entrepreneur from a satellite communications business in the UK. Training will consist of eight weeks of lectures, workshops and hands-on sessions together with five weeks of observing using the Kutunse telescope, spread over the academic year. The top two trainees as judged by the training team will be given the opportunity to visit the UK or South Africa for two weeks to gain additional observing experience and to visit universities that are potential PhD destinations. The SKA, the AVN and work and science in Ghana Following the successful completion of the engineering programme to establish the Ghana AVN VLBI telescope, the operations team staff will consist of an AVN VLBI science
Intense concentration by Rhoe Quaye (GSSTI) to monitor the movement of the antenna in Ghana during the centering activities in January 2014. Image: SKA
and operations leader, operations and support scientist(s) and engineering support staff in all the relevant disciplines. The scientists will be able to spend about 50% of their time on their own research interests and 50% on facility support for radio astronomy and VLBI. Technical development and support for radio telescopes happen continuously during the operational lifetime of the instrument. The required skills include computer (hardware) engineers and technicians, software engineers, radio frequency engineers and technicians, structural and mechanical engineers and technicians. Telescopes developed for the AVN will initially join other networks for VLBI. When at least four VLBI-capable telescopes are operational on the continent, it will be possible to initiate stand-alone AVN VLBI. In addition, each country where an AVN telescope becomes operational will have its own single-dish observing programme. The number of staff needed at the observatories, in national institutes and in the academic community will depend on how many hours per year the AVN does VLBI as a stand-alone network and how enthusiastically each country pursues radio astronomy as part of its national science agenda. 10| 2 2014
(rotation measure). Other studies will involve resolving active galactic nuclei (AGN) and star formation in galaxies, radio studies of high-redshift AGN jets, transients (long baselines provide discrimination against radio frequency interference (RFI)), binary supermassive black holes, X-ray binary systems and relativistic jets. Other SKA science that can only be pursued once the full SKA has been deployed include strong field test of gravity (timing relativistic binary systems), monitoring an array of millisecond pulsars to detect gravitational waves with nanoHertz frequencies, imaging protoplanetary disks at centimetre wavelengths, the first generation of AGN jets, and CO studies of high-redshift AGN jets. Q
Professor Melvin Hoare from Leeds University (UK) explains the focus of the Royal Society-funded research programme for maser monitoring using the Kutunse telescope in Ghana. Image: SKA
Local youth involvement in the project During their training in South Africa, the Ghanaians built a small radio telescope with all the engineering features of a much larger instrument. This will be used for outreach activities in Ghana to encourage young people to pursue careers in science, technology and engineering. Several outreach and community information activities are planned. During their training in South Africa, the Ghanaian team participated in a number of outreach activities to help them develop a suitable programme for Ghana. How this part of the SKA links in with South Africa and Australia VLBI-capable telescope in SKA partner countries such as Ghana, Kenya and Zambia will be readily accepted into the European VLBI Network (EVN) and there will be at least the same demand for these as there is for the 26m HartRAO telescope in South Africa. They will be equivalent to HartRAO in terms of the system equivalent flux density (SEFD) (or system sensitivity), a metric used by the VLBI community. The African VLBI network needs four or more antennas for an independent imaging capability. The baseline to Mauritius or Madagascar is important for science and the dynamic science community in Mauritius is currently investigating possible funding sources to build a new telescope with VLBI capability. The AVN will be important to study equatorial sources, i.e. sources between +20 and -20 degrees declination. Other global arrays that will have an interest in collaborating with the AVN include the Global Array (EVN+ US VLBA), the Australia Telescope Long-baseline Array (AT-LBA), MeerKAT, SKA and possible the Astrometry and Geodesy Network (IVS). Although some topics for the long-baseline science for SKA cannot be pursued by current VLBI or future AVN networks due to instrument limitations, some can be explored. These early investigations could inform the design of future experiments and surveys using the far more sensitive SKA. SKA science topics that are therefore likely to be possible with current VLBI and AVN networks of telescopes include the determination of accurate pulsar distances from trigonometric parallax measurements (as well as pulsar proper motions), modelling of the large-scale galactic magnetic field using pulsars 14
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Anita Loots is a professional engineer. She graduated in South Africa and worked as a structural design engineer and specialist in construction materials in the private sector and the Council for Scientific and Industrial Research (CSIR) in South Africa. She is contracted as Associate Director and she has handled various portfolios within the SKA SA since 2004. She is currently responsible for the African VLBI Network (AVN) (to engage all African SKA partner countries through capacity building programmes, establishment of VLBI-capable telescope systems, enabling institutional and governance programs for SKA readiness on the continent), the C-Bass telescope project and the PAPER/HERA projects. She is a ‘student for life’ and part-time researcher in engineering (working towards her PhD in Engineering Management of Mega-projects), is passionate about development of young people and is an outdoors and sports enthusiast. She is a member of the Engineering Council of South Africa, and the South African Institute for Civil Engineers and serves on the Science Advisory Committee (SAC) for ASTRON in the Netherlands. Michael Gaylard did a BSc (Hons) in 1973 at the then University of Rhodesia, majoring in Physics and Chemistry. He obtained his MSc from Rhodes University in Grahamstown on the performance of a 22 GHz radio telescope in 1976, after which he was appointed to the Hartebeesthoek Radio Astronomy Observatory (HartRAO) near Johannesburg, then newly formed from the decommissioned NASA Deep Space Station 51, where he established spectroscopic research with the 26m radio telescope. He used this opportunity to obtain his PhD, on radio studies of ionised hydrogen in the Milky Way, again through Rhodes University, completed in 1989. His research interests including molecular clouds and lines; star-forming regions and interstellar masers; the structure of the Milky Way; and active galactic nuclei. He has authored or co-authored 69 publications in astronomy journals and conference proceedings. He is now the Managing Director of HartRAO and in addition to overseeing the operations of HartRAO, he leads the facility’s radio astronomy programme, supervises undergraduate and postgraduate research projects in radio astronomy and manages the observatory’s science awareness outreach programme aimed primarily at learners and educators. He was involved in the early development of the Karoo Array Telescope (KAT), leading to the construction of the 15m eXperimental Development Model radio telescope at HartRAO in 2007 as the first KAT prototype. He is involved in the establishment of radio astronomy facilities in other African countries to create an African VLBI Network in the lead-up to the SKA.
Join Hannah and our young astronomer, Naledi, as they N discover more about the SKA project in the Karoo in the next edition of HAN our cartoon series: Mission MeerKAT. In this, the fourth edition of Mission MeerKAT, Naledi and Hannah explain the relationship between SKA South Africa and SKA Australia, and how important this partnership is to uncovering the secrets of the universe.
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If you missed the previous issues, you can find them on http://www. ska.ac.za/education/index.php.
Mission MeerKAT: Working Together is available online at http://www.ska.ac.za/download/ mission_meerkat4_eng.pdf.
LD, ONE S KY
Is discovering the universe for you? If Mathematics and Natural Science are subjects that excite you, why not look to the stars for a career in engineering, technology or astrophysics? The SKA SA Project invests in developing skills for MeerKAT and the SKA through its dedicated Human Capacity Development Programme. Already, close to 500 people, ranging from artisans to postgraduate students and postdoctoral fellows, have already received bursaries and grants. Find out more at www.ska.ac.za/students
COOL FACTS ABOUT THE SKA The data collected by the SKA in a 24-hour period, would take nearly two million years to play back on an iPod. The SKA will generate enough raw data every day to fill 15 million 64GB iPods. The SKA central computer will have the processing power of about one hundred million PCs. The SKA will use enough optical fibre to wrap twice around the Earth. The dishes of the SKA will produce 10 times the current global internet traffic. The aperture arrays will produce more than 100 times the current global internet traffic.
Photo credit PHOTOWISE
The SKA super-computer will perform 1018 (1 000 000 000 000 000 000) operations per second â€“ equivalent to the number of stars in three million Milky Way-size galaxies. This is needed to process all the data that the SKA will produce. (source: www.skatelescope.org)
Keep up to date with the latest news and views from the SKA SA. Follow us on Facebook â€“ www. facebook.com/SKASOUTHAFRICA
Department: Science and Technology REPUBLIC OF SOUTH AFRICA
How are Antarctica and the Southern Ocean responding to climate change? Antarctica and the Southern Ocean – Earth’s ‘freezer’. By Mike Lucas, Kirti Gihwala and Michal Viskich
T The Southern Ocean connects with the Atlantic, Pacific and Indian Oceans through both horizontal and vertical (overturning) circulation that is part of the deep and very slow moving global ‘conveyor belt’ circulation. Physical oceanographers recognise different water masses (e.g. Antarctic Bottom Water, AABW) on the basis of characteristic temperature and salinity properties – their ‘finger-print’, which is unique to each different water mass. Image: Courtesy of the Southern Ocean Observing System (SOOS) Science Plan, 2013 (www.soos.aq)
Major ocean currents and oceanic fronts (boundaries) around Antarctica. The light blue shaded area is the Antarctic Circumpolar Current (ACC), bounded to the north by the Antarctic Front, also known as the Antarctic Polar Front (APF). The darker blue region is the sub-Antarctic, which lies between the sub-Antarctic and the APF. Image: www.theenergylibrary.com
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he continent of Antarctica, covered by its vast 4 km thick freshwater ice sheet, is the coldest and windiest place on Earth, where winter temperatures can plummet to below -40°C. It’s ice sheet continuously flows slowly and inexorably towards the sea, where at the ice shelf, icebergs split off and drift northwards, taking six months or more to melt. Surprisingly perhaps, Antarctica is a cold desert region because it experiences so little rainfall as snow. During winter, 24 hours of darkness envelops the continent for six months until the sun re-appears in spring, once again bathing this white desert in 24 hours of sunlight during summer. Antarctica is completely encircled by the cold and tempestuous Southern Ocean, which averages just 2-4°C in temperature. This unique easterly-flowing ocean has a major influence on global ocean circulation and extends from about 35°S to the Antarctic continent. In the austral winter, frozen 1-2m thick sea ice covers 20 million km2 of the ocean’s surface, but in summer when the sea ice melts, this cover shrinks to just 2 million km2. In the early years of polar exploration, ships trapped in the sea ice were often crushed and sank – giving rise to epic tales of hardship, courage, leadership and survival, as epitomised by Ernest Shackleton and his crew on his ill-fated ship, Endurance. But that is another story for another time! Both Antarctica and the Southern Ocean are closely coupled to global climate by inter-ocean and oceanatmosphere linkages, making this region a very important component of Earth’s climate system – helping to cool our planet. Drake’s Passage, the narrow ocean between South America and the Antarctic Peninsula (56-62°S), allows the Antarctic Circumpolar Current (ACC) to flow continuously eastwards around Antarctica, driven by prevailing westerly winds – the roaring forties and furious fifties. These winds drove the great three-masted sailing ships of the 18th century eastwards from the Pacific Ocean into the South Atlantic, bound for Europe with their cargos of grain, rice and tea. The ACC is the largest current in the world, dominated south of the Antarctic Polar Front (APF) at about 50°S by water of just 2°C or less. Seawater freezes at about -1.89°C instead of 0°C because of its dissolved salts, which lower the freezing point of water, and when it does so in winter, sea ice is formed.
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By connecting with the Atlantic, Pacific and Indian oceans through wind and density-driven overturning circulation – see the diagram – the Southern Ocean has the capacity to store and transport heat, salt and dissolved inorganic carbon (i.e. CO2 from the atmosphere) throughout these major oceans in a way that significantly influences global climate. The Southern Ocean captures and stores about 40% of total CO2 emissions and delivers enough nutrients to other oceans to support 75% of the global ocean productivity north of 30°S. About 70% of the excess heat added to the Earth-atmosphere system by human activities is stored in the Southern Ocean. Global climate and sea level rise are strongly influenced by ocean/sea ice and atmosphere feedbacks. Changes in sea ice extent and continental ice volume alter Earth’s albedo (reflectivity), the inter-ocean exchanges of water and nutrients, as well as affecting oceanatmosphere exchanges of CO2 and other greenhouse gases. For example, reductions in sea ice extent reflect less heat back into space, creating a positive feedback of further warming. Similarly, models suggest that the Southern Ocean’s capacity to take up CO2 is weakening, so providing another positive feedback of further warming. Climate change – what is happening? The Scientific Committee of Antarctic Research (SCAR) Antarctic Climate Change and the Environment Report (2013), summarises what climate-driven changes are taking place. Changes in sea ice, ocean warming and rising air temperatures along the western Antarctic Peninsula mean that marine ecosystems here are experiencing the most rapid warming of any marine system on Earth. Marine species here such as penguins and seals are typically well adapted to cope with low temperatures, but poorly adapted to cope with warming temperatures. However, the Antarctic Peninsula has exhibited the fastest regional warming on Earth, of 0.55°C per decade over the past 50 years, relative to a mean global warming 0.11°C per decade over the same period. Winter warming on the west side of the Antarctic Peninsula has been linked to the loss of sea ice on the western side of the Peninsula in the AmundsenBellingshausen Sea. On the main part of the continent, West Antarctic warming exceeds 0.1°C per decade in winter and spring, but East Antarctica is cooling. Overall however, the warming trend is positive, and if greenhouse gas concentrations double over the next century, Antarctica could warm by 3°C. Even so, just +2°C warming (in 50-100 years) is considered a threshold where serious ecosystem effects will be felt. In the Southern Ocean, the ACC flow has strengthened and shifted southwards by 50-70 km since the 1950s.
Antarctic krill, Euphausia superba (right), form vast swarms of millions of individuals in open water in summer, feeding on phytoplankton, but in winter they feed on ice algae that grow on the underside of the sea-ice (left). Krill are a ‘key-stone’ species in the Southern Ocean that support almost the entire Southern Ocean food-web. Image: Wikimedia Commons
The collapse of the ‘Larsen B’ ice shelf in February 2002, an area the size of Rhode Island in the USA. Image: NASA
Warming and cooling of different regions of Antarctica and the Southern Ocean. Note that the Antarctic Peninsula is warming, while East Antarctica is cooling. Image: Courtesy of the Southern Ocean Observing System (SOOS) Science Plan, 2013 (www.soos.aq)
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Gentoo (left) and Adelie (right) penguins. Images: Wikimedia Commons
A much smaller female elephant seal on Crozet Island shares its beach with King penguins. Image: Mike Lucas Emperor penguins depend on ‘fast ice’ to breed. The female lays a single egg in the autumn and then promptly passes it to the male before heading off to sea to feed. The male incubates the egg all winter long on his feet, keeping the egg warm in a brood pouch. He and other males in the colony huddle together for warmth, enduring darkness for six months at temperatures of -40°C, and losing 25% of their body weight before they are relieved by the returning females. Tough love! Image: Mike Lucas
Four-ton elephant seals breed on sub-Antarctic islands, such as Marion Island (above), but feed on fish close to the Antarctic continent. To do so, they can dive as deep as 1 000 m and hold their breath for 45 minutes in pursuit of their prey. Image: Mike Lucas
Increased heat flux into the ocean has warmed near-surface waters by about 1°C since the 1930s (at 0.1°C per decade), but measurable warming extends down to 1 000 m. As a result, the Southern Ocean has captured and stored more heat than any other ocean. The Southern Ocean is also becoming slightly fresher, particularly in the Ross Sea, reflecting glacial ice melt at the continental margins and increased rainfall. As a result, 18
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Antarctic Bottom Water formation in the Indian and Pacific sectors has become fresher and less dense, which has the potential to change the deep ocean ‘conveyor belt’ circulation. Satellite-derived measurements reveal that ice shelves are thinning along the margins of the East Antarctic Ice Sheet, but especially so along the West Antarctic Ice Sheet. Total ice-shelf loss on both sides of the Antarctic Peninsula over the last 50 years has been about 28 000 km2, resulting in a global sea level rise of about 0.2 mm per year relative to Greenland ice-sheet melt of 0.39 mm per year. Shelf-ice loss is not due to atmospheric warming, but due to warming from below by warm water inflow that has its origins in the tropical Pacific Ocean, pointing to climate-linked changes in broad global ocean circulation patterns. From 1979 to 2010, sea ice cover over the Southern Ocean as a whole has increased by 1.3% per decade, reaching a record extent of over 20 million km2 in 2012. Even so, substantial decreases in sea ice extent around the Antarctic Peninsula have resulted in an 80% decline in regional Antarctic krill density between 1976 and 2004. This is because krill feed on algae that grow on the underside of the ice in winter, so as sea ice disappears, so does their food. Declining krill populations have negative knock-on impacts on penguin, seal and whale consumers of krill. At Palmer Station, on the western Antarctic Peninsula, ice-dependent Adelie penguin populations are rapidly declining, but are being replaced by sub-polar Gentoo penguins. Emperor penguins in East Antarctica now exhibit low breeding success because of the lack of krill and reduced sea ice extent. Changing ocean circulation, ice cover and the scarcity of fish to eat have also caused a southerly shift in elephant seal populations. Deeper wind-driven mixing in the higher latitudes of the Southern Ocean has increased ocean-atmosphere
❚❚❚❙❙❙❘❘❘ Climate change Did you know? At the South Pole, Antarctica is the most southern of all continents, covering an area of about 14 million km2. It is covered by a permanent freshwater ice sheet that is over 4.5 km thick in places, divided into the West Antarctic Ice Sheet and the East Antarctic Ice Sheet, separated by the 3 400 km long Transantarctic Mountains. The highest peak is the Vinson Massif, rising to 5 140 m. Antarctica’s height is three times that of any other continent, averaging 2 300 m of elevation. The weight of ice is so heavy that it depresses the Earth’s crust into the shape of a bowl. Because of its position at the ‘bottom of the world’, Antarctica escaped human discovery for over 2 000 years. It was not discovered until barely 150 years ago, when Terra Australis Incognita was sighted for the first time. Scientists worry that the West Antarctic Ice Sheet is becoming unstable in the face of global warming and may melt, as it is doing in some places along the Antarctic Peninsula. By contrast, the East Antarctic Ice Sheet is cooling. Together with the Greenland Ice Sheet in the northern hemisphere, these two ice sheets lock up about 90% of Earth’s freshwater in the form of ice. By contrast, the Artic region covering the North Pole is not a land mass at all. Instead it is an ocean – the Arctic Ocean – which is covered by floating sea ice 1-2 m in thickness that seasonally increases in extent during winter, but melts and retreats during summer. However, serious changes are underway. Changing Arctic sea-ice cover is recognised as one of the four major or indices of climate change by the International Geosphere-Biosphere Programme (IGPB), an organisation that monitors and engages in research on global change. The loss of Arctic sea ice due to global warming and melting over the past few decades has been faster than even the most pessimistic of future predictions. The northern hemisphere summer sea ice minimum has shrunk from nearly 8 million km2 in 1980 to just a little over 4 million km2 in 2007 – a loss of nearly 50% in just 27 years. Maximum winter sea ice extent has declined
by about 1.5% per decade since the 1980s, while multi-year (or permanent) sea ice cover has declined by about 10% per decade over the same period. Ice thickness is also declining and because more open water is appearing, ice drift is increasing, which fragments the area covered by ice. Current rates of sea-ice melt and retreat may have passed a ‘tipping point’, where recovery in the near future is unlikely and if so, sea ice loss will accelerate. Some models predict that summer sea-ice will vanish by 2085 – perhaps even as soon as 2050. Why is this happening when Antarctic sea ice extent is mostly stable? There are several reasons for this. Firstly, northern hemisphere temperatures are rising faster and to higher levels than southern hemisphere temperatures. Secondly, the Arctic Ocean is not as isolated or as large as the circumpolar Southern Ocean, which, together with the vast size of Antarctica, exerts a very much stronger cooling influence. Instead, the Arctic Ocean is connected via several ocean currents with the warmer North Atlantic and North Pacific oceans, which
A map of Antarctica. Image: NASA
gaseous exchanges, including that of CO2. Ocean uptake of CO2 is causing ‘ocean acidification’, which is felt most acutely in cold polar oceans, with adverse consequences for some phytoplankton species and important components of the food web, such as pteropods (sea butterflies) and krill. Deeper mixing has also resulted in a 30% decline in phytoplankton production over the last 25 years, which has altered phytoplankton community structure from larger to smaller species. This again has a negative impact on krill and consequently alters the Southern Ocean food-web structure, making it less efficient and more vulnerable to change. Why are these impacts felt so strongly in the Southern Ocean? Many of the physical, chemical and biological changes in the Southern Ocean can be linked to the increasing wind strength of the circumpolar westerly winds. But what has caused this? Since about 1980, the ozone hole has had a major impact on the climate of high southern latitudes, increasing westerly wind
Arctic sea ice coverage as of 2007 compared to 2005 and compared to 1979–2000 average. Image: NASA
results in heat exchange between these ocean basins. In short, the Arctic is more vulnerable to warming, so sea ice there is melting faster. One consequence of Arctic sea ice loss includes changes in the ability of the Earth to reflect excess heat back into space – called the albedo effect. While snow-covered ice strongly reflects solar radiation, exposed and much darker water has a very low albedo effect. This creates a positive feed-back loop leading to further warming. Sea ice is also a major habitat for a number of important marine mammals, including the ringed seal (Phoca hispida), the most numerous seal in the Arctic, as well as the larger bearded seal (Erignathus barbatus). Both seals rely on sea ice to reproduce and moult, and neither species is found where sea ice is absent. This is bad news for Polar bears, which feed extensively on these seals. Polar bears themselves use sea ice as a habitat, and as this disappears, it is likely to endanger their populations and survival. Just how polar bears will fare in the future is a matter of considerable concern and debate. It is hard to imagine that the iconic whiteness of the Arctic may give way to an entirely blue ocean in summer by the end of the century, but that is almost certainly where it is heading.
strengths over the Southern Ocean by 15-20%. This has caused the deeper ocean mixing and also slightly cooled the continental interior, as well as decreasing the growth rate of both terrestrial and marine plants. However, ozone hole recovery is on the way. Ozone-depleting chlorofluorocarbons (CFCs) in the stratosphere are decreasing by about 1% per year, so by the end of the 21st century, ozone concentrations will have almost completely recovered. Q Associate Professor Mike Lucas is employed within Biogical Sciences, University of Cape Town and is an Honorary Research Associate at the National Oceanography Centre (NOC) in Southampton, UK. He conducts much of his research in the North and South Atlantic, as well as in the Southern Ocean and in the Benguela upwelling system. Kirti Gihwala and Michal Viskich are honours students in Biological Sciences at the University of Cape Town who are working with Mike Lucas on the effects of climate change in the Southern Ocean. 10| 2 2014
Reframing climate change
For too long the field of climate and global change has been dominated by the natural sciences, states the 2013 World Social Science Report. Wiida Fourie-Basson looks at the social aspects of climate change.
he challenge is twofold, the argument goes: no single discipline or scientific domain is able to understand, let alone address, the complexity of the interconnected environmental and sustainability challenges that society faces. Since the 1980s, thousands of scientists have been working to establish a sound physical science basis for the phenomenon of global and environmental change. This year will see the fifth assessment report on the state of our knowledge of global warming, and evidence for concern is only increasing. Working Group 1’s report, issued on 23 September 2013, states that: ‘Cumulative emissions of CO2 largely determine global mean surface warming by the late 21st century and beyond. Most aspects of climate change will persist for many centuries even if emissions of CO2 are stopped. This represents a substantial multi-century climate change commitment created by past, present and future emissions of CO2.’ Translated into simple English, this means that some parts of the Earth may become uninhabitable for future generations. Essentially, we are already beyond the tipping point. So what are you and I doing about this? How do the average man and woman in the street react to these kinds of messages? According the 2013 World Social Science Report, we might be missing an opportunity to get the message out to those who need it the most. If we continue to confront global The sociologist, Anthony Giddens. Image: Newstyle Magazine
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environmental change through a natural sciences lens – as particles, physics and species – we’re losing the general public. Society urgently needs to change the way we do things in order to ensure a liveable planet for our children. Literally thousands of experts and established researchers are telling us to adapt, mitigate or die. But why are we seemingly reacting so slowly, if at all? Giddens’s paradox and manufacturing controversies where none exist Our slow reaction, writes the British sociologist Anthony Giddens, is because there’s ‘a life to be lived within the constraints of the here-and-now’. In this way, after reading the morning’s newspaper headlines or listening to the radio news, it’s off to work we go. All risk, that of climate change included, constitutes only one set of worries among a range of others. Calling it the ‘Giddens’s paradox’, Giddens argues that ‘since the dangers posed by global warming aren’t tangible, immediate or visible in the course of day-to-day life, however awesome they appear, many will sit on their hands and do nothing of a concrete nature about them. Yet waiting until they become visible and acute before being stirred to serious action will, by definition, be too late’. If we do want to make a difference, however, all of society needs to be on board. Giddens’s paradox is aggravated by another phenomenon specific to the social sciences in general and the mass media in particular. In 2008 Leah Ceccarelli, a communication scholar from the US, wrote a blog on ‘Manufactroversy’, or the art of creating controversy where none exists. A typical example of manufactured controversy is global warming denialism, where the (scientific) uncertainty surrounding a scientific truth claim is magnified in order to delay the
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as a social problem
Opposite page: A view of part of the coast on the West Antarctic. Image: NASA The lone polar bear in melting ice – the icon of climate change in the media. Image: www.skiigreen.com
adoption of policy. The tobacco industry deployed this 2 500-year-old rhetorical device when scientists blew the whistle on the industry’s cover-up of research showing that smoking causes cancer. In 1969, the Brown and Williamson Tobacco Corporation countered the scientific evidence with the now infamous ‘Doubt is our product’ approach. Quoting from the 1969 confidential report: ‘Doubt is our product since it is the best means of competing with the “body of fact” that exists in the mind of the general public. It is also the means of establishing a controversy…’ In the 5th century BC, sophists like Gorgias boasted that he could persuade a lay audience to ignore the expert and listen to him instead. A sophist was a particular type of teacher in ancient Greece and in the Roman Empire. These teachers used philosophy and rhetoric in their teaching. Rhetoric is the art of discourse, which aims to improve the ability of writers or speakers to inform, persuade or motivate particular audiences in particular situations. Source: Wikipedia
Another sophist, Protagoras, claimed that there are always two sides to a case and it’s the sophist’s job to make the worst case appear the stronger. In our post-modern, information society, some of the fiercest battles in the so-called climate change debate are being played out in the mass media. The mass media play an important role in shaping people’s perception of their environment. Very few of us will ever have the chance to visit the North Pole or see a polar bear in real life. Yet, thanks to the mass media, the images of melting icecaps and lone polar bears are deeply embedded in our collective consciousness. We must thus ask what the public is supposed to believe when media coverage of global environmental change too often drowns in a twittery flurry of name-calling. Would you like to be called a ‘so-called peer-reviewed scientist…
peddling embarrassing tripe about the so-called melting of glaciers’. Or would you like your work described as ‘a hoax, perpetrated by governments that are addicted to taxes’, or as ‘an excuse to extort ever-increasing amounts of taxes based on voodoo “science” and downright fraud’? This kind of verbal abuse recently took place on the online pages of one of South Africa’s leading business dailies. It was in reaction to an article headlined ‘Denialists’s disdain for climate change is a vital human rights issue’, with the opening paragraph: ‘The public debate about climate change is an aberration because we do not have debates in newspapers about the validity of medical science, physics, aeronautics, geology or genetics. So what is different about climate science?’ This phenomenon is not specific to South Africa. Remember Climategate? And more recently, a row in Britain about the fact that the BBC spent thousands of pounds over six years to ‘cover up’ a climate change seminar credited with shaping its coverage of the environment. In October 2013, however, the very same BBC was taken to task for favouring climate sceptics in its coverage. Deeply ingrained in the journalistic ethos is the concept of balance, of providing both sides of the story, of giving everyone a voice, of holding those with power and responsibility to account. Because of these deeply embedded journalistic norms, the mass media stand accused of contributing to society’s inertia by giving the climate denialists a platform to question the science, by creating the illusion that there exists scientific uncertainty about climate change. In 2007, the BBC Trust, in a report on safeguarding impartiality in the 21st century, described their position in regard to covering climate change as follows: ‘The BBC has held a high-level seminar with some of the best scientific experts, and has come to the view that the weight of evidence no longer justifies equal space being given to the opponents of the consensus. But these dissenters (or even sceptics) will still be heard, as they 10| 2 2014
Tipping point A climate tipping point is not a well-defined concept. However, essentially it is thought of as a point where global climate changes from one stable state to another stable state. Think of a wine glass tipping over – the wine remains, but it is no longer contained within the glass. After the tipping point has been reached, there is a transition to a new state. This tipping point may be irreversible. Global warming is being brought about by changes in the composition of gases in the Earth’s atmosphere and oceans by the emission of greenhouse gases such as carbon dioxide and methane. As this warming proceeds, it brings about changes to the natural environment that may result in other changes. For example, warming may begin to melt the Greenland Ice Sheet and/or the West Antarctic Ice Sheet. At some level of temperature rise, the melt of the entire ice sheet will become inevitable, but the ice sheet may remain for many millions of years. A tipping point may be passed without any immediately obvious consequences or any acceleration in the warming process. Carbon dioxide as of May 2012 makes up 396.18 ppm of Earth’s atmosphere and monitoring stations in the Arctic spring of 2012 measured more than 400 ppm (parts per million) of the heat-trapping gas in the atmosphere. Scientist James E Hansen said that this tipping point had already been reached in April 2008, when the carbon dioxide level was 385 ppm. (Hansen states 350 ppm as the upper limit.) ‘Further global warming of 1°C defines a critical threshold. Beyond that we will likely see changes that make Earth a different planet than the one we know.’ He has further suggested potential projections of runaway climate change on Earth creating more Venus-like conditions in his book Storms of My Grandchildren. Source: http://en.wikipedia.org/wiki/Tipping_point_(climatology)
The climate change in the Arctic image above shows where average air temperatures (October 2010-September 2011) were up to 3°C above (red) or below (blue) the long-term average (1981-2010). Image: Wikimedia Commons
The rate of change of the Greenland ice cap (cm/year). Image: Wikimedia Commons
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should, because it is not the BBC’s role to close down this debate (author’s emphasis). They cannot be simply dismissed as “flat-earthers” or “deniers”, who “should not be given a platform” by the BBC. Impartiality always requires a breadth of view: for as long as minority opinions are coherently and honestly expressed, the BBC must give them appropriate space. “Bias by elimination” is even more offensive today than it was in 1926. The BBC has many public purposes of both ambition and merit – but joining campaigns to save the planet is not one of them. The BBC’s best contribution is to increase public awareness of the issues and possible solutions through impartial and accurate programming.’ How does one then reconcile these two worlds, each with its own ethos and traditions and important roles in society? In response to the sophists of ancient Greece, Aristotle arranged the art of rhetoric into a series of rules so that experts, if they should study rhetoric, can stand against those who try to mislead public audiences. Using this approach, Ceccarelli says that the stronger argument should appear stronger in front of an audience of non-experts. This approach would place the onus on the experts to communicate more effectively. But is that sufficient? Reframing climate change as a social problem What if we changed lenses, and started looking at climate and environmental change as a social problem? According to the 2013 World Social Science Report there can be a multitude of framings: ‘Climate change might be framed, for example, as a symptom of a dysfunctional society; global environmental change as the unprecedented rise of a single species affecting the entire planet; biodiversity loss and resource depletion as a market failure … and global change as an opportunity for fundamental transformation and creative innovation.’ And many scientists and journalists are already doing precisely that. The report issues an ‘urgent and decisive appeal to the social sciences to research more effectively the human causes, vulnerabilities and impacts of environmental change, and thus to inform societal responses to the sustainability challenges that society now faces.’ It goes further and urges scientists to work across the natural, physical, engineering, health and human sciences to deliver credible and legitimate knowledge for real-world problem solving. Thinking out of the box, and talking to each other, might help ‘unblock the inherent limitations of our current thinking and language about global change … and identify opportunities for new and more effective solutions’. Reframing climate change as a social problem might work, or not. In Giddens’s words: ‘No quick fix is available to deal with the problems we face – it’s going to be a slog, even with the breakthroughs we need, and in fact must have.’ q Wiida Fourie-Basson is media officer for the Faculty of Science at Stellenbosch University. She writes this article in her personal capacity as someone interested in the role of the mass media in society, as well as working towards bridging the divide between the social and the natural sciences. She’s a former journalism lecturer and holds an MA in Communication from UNISA.
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CLIMATE CHANGE: WHAT CAN YOU DO? Do you read the newspaper or listen to the news – or check your favourite social media site – and then simply forget about the big issues that face us, like climate change? Have a look at the picture on the right to see some of the ways that you can be part of the solution.
Tipping points: The case of the West Antarctic ice sheet On 12 May 2014 two reports were issued in the journals Science and Geophysical Research Letters showing that the West Antarctic glaciers have retreated far enough to cause instability in the Antarctic ice sheet – an instability that has been feared for decades by scientists. A large section of the West Antarctic ice sheet has already begun to fall apart and continued melting now seems to be unstoppable, according to these two groups of scientists. This melting could destabilise neighbouring parts of the ice sheet and cause a rise in sea level of more than 3 m over the coming centuries. Although still relatively slow in our current century, the rate of melting could accelerate in the more distant future, potentially causing a crisis as sea levels rise. The West Antarctic ice sheet sits in a bowl-shaped depression in the Earth and its base is below sea level. Warm ocean water is causing the ice along the edge of the rim of the bowl to thin and retreat. As the front edge of the ice pulls away from the rim and enters deeper water, it can retreat even faster. The new finding appears to be the fulfillment of a prediction made in 1978 by an eminent glaciologist, John H Mercer of the Ohio State University. He outlined the vulnerable nature of the West Antarctic ice sheet and warned that the rapid human-driven release of greenhouse gases posed ‘a threat of disaster’. He was ridiculed at the time, but in recent years, scientists have been
You can make a difference. Image: www.myseek.org
watching with growing concern as events have unfolded in much the way Dr Mercer predicted. He died in 1987. The ice sheet is not melting as a result of warmer air temperatures, but because of warmer water from deep in the ocean being pulled to the surface because the powerful winds that blow around the Antarctic have become far more intense over the past few decades. Human-induced global warming is thought to be one of the reasons that these winds have become stronger. These winds help to isolate Antarctica and keep it cold at the surface, but as global warming proceeds there will be more of a temperature difference between the Antarctic and the rest of the surface of the Earth. This temperature difference will provide further energy for the winds, which in turn stir up the ocean waters. The global sea level has been rising since the 19th century, but so far Antarctica has only played a small part in this. Until now, the biggest factor is that seawater expands as it warms up.
Sources BBC Trust, 2007. From seesaw to wagon wheel. Safeguarding impartiality in the 21st century. BBC. http://www.bbc.co.uk/bbctrust/assets/files/pdf/review_report_research/ impartiality_21century/report.pdf Ceccarelli, L. April 11, 2008. Manufactroversy. In: Artice, Science & Society. Science Progress. URL: http://www.scienceprogress.org/2008/04/manufactroversy. Accessed 2 February 2014. Giddens, A. 2009. The Politics of Climate Change. Cambridge: Polity Press. Hackmann, H and Moser, S. 2013. Social sciences in a changing global environment: General Introduction, In ISSC/UNESCO, World Social Science Report 2013: Changing Global Environments, OECD Publishing and Unesco Publishing. http://dx.doi. org/10.1787/9789264203419-5-en Harvey, F. 1 October 2013. BBC coverage of IPCC climate report criticised for sceptics’ airtime. The Guardian. Http://www.theguardian.com/media/2013/oct/01/bbc-coverage-climate-reportipcc-sceptics
West Antarctica. Image: Wikimedia Commons
International Social Sciences Council (ISSC). May 2012. Transformative Cornerstones of Social Science Research for Global Change. Le Page, D. 14 January 2014. Denialists’ disdain for science is a vital human rights issue. Business Day. Http://www.bdlive.co.za/opinion/2014/01/14/denialists-disdain-for-science-is-avital-human-rights-issue.
About the International Social Science Council The ISSC is the primary body representing the social, behavioural and economic sciences at an international level. Established by UNESCO in 1952, the ISSC today is an independent, non-governmental organisation, with members that include international professional associations and unions, regional and national social science academies and research councils, and other organisations with major interest in the social sciences. www.worldsocialscience.org
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The unique pollinators of the Cape Floral kingdom The Redelinghuys pincushion has evolved remarkable adaptations to allow it to be pollinated by rodents. Chris Johnson explains.
Leucospermum arenarium in the field and one of its pollinators, Gerbillurus paeba, feeding on flowers. (A) Pollen presenter contact on G. paeba. (B) G. paeba foraging on L. arenarium. (C) Flowering L. arenarium with dense, mat-forming inflorescences. (D) Geoflorous inflorescences. (E) Pendulous inflorescences above ground level. Image: Chris Johnson
Gerbillurus paeba, feeding on flowers. Image: Chris Johnson
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he Cape Floristic Region is the smallest of the world’s six floral kingdoms. In spite of this, the level of plant diversity within the region is high. But alongside the large number of different plant species there are relatively few species that pollinate these plants. This imbalance between the numbers of plant species and the numbers of pollinator species has lead many plants to adapt to unique pollinators. One plant species that has done this is the Redelinghuys pincushion Leucospermum arenarium, which utilises the hairy-footed gerbil Gerbillurus paeba and striped field mouse Rhabdomys pumilio to fertilise its flowers. The Redelinghuys pincushion is listed by the Red Data Book as endangered and is restricted to the west coast sandveld region between the towns of Redelinghuys and Aurora. Its isolation has caused it to be ignored by researchers, who assumed that it was pollinated by insects, which is how its closest relatives are pollinated. But, on looking closely at the species, I and my co-workers noticed that the way that the flowers of this pincushion species are formed – its floral morphology – was quite different from its related species. The Redelinghuys pincushion displays many features, called ‘syndromes’, that are common in other species that are pollinated by rodents. The most obvious of these features are highly curved or ‘hooked’ flowers that are a dull colour, which produce large volumes of concentrated nectar at ground level. Presenting the nectar at ground level is called geoflory. Through a combination of collecting pollen samples from captured rodents and experiments in which we stopped other possible pollinators from getting access to the flowers, we determined that rodents were the primary pollinators. Rodents as pollinators No species that acts as a plant pollinator does so in order to pollinate the plant. The pollinator is after the nectar that the plant produces and picks up pollen incidentally. Rodents are notorious for destroying flowers in their quest for the sweet nectar, so if flowers hope to use their pollinator services they must evolve mechanisms that prevent this destruction. This often means that rodent-pollinated plants do not have nectar tubes. In the Redelinghuys pincushion, however, long, narrow nectar tubes are present. So how do the rodents remove the nectar without damaging flowers? To find this out we looked at the flowers under the microscope and also at the composition of the nectar.
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The amount of pollen transferred to recipient flowers with increasing time spent grooming between pollen uptake and deposition. The solid line represents the model prediction.
We found that the nectar is produced deep within the nectar tube, but is then transported through capillary action to a cup-shaped structure that is made up of fused petals. The nectar that the Redelinghuys pincushion produces is particularly sticky and settles in this ‘cup’, where the rodents can lick it up without damaging the flowers. No other pincushion species has this way of transporting nectar, so the Redelinghuys pincushion shows remarkable adaptation to rodent pollination. What happens to the pollen? A broad area interest in pollination biology is the study of what happens to the pollen – where is pollen lost to in the process of being transferred between flowers? This issue has been studied in great detail and it is generally concluded that most pollen must be lost when the pollinator grooms, but this idea has never been tested. Rodents are relatively easy to watch constantly, so we were able to look at the impact of grooming on pollen loss. To do this we brought rodents back to the lab and exposed them to manipulated flowers in a terrarium. We first exposed them to a ‘male phase’ flower that was loaded with pollen. Once the rodents had visited the male phase flower it was removed and replaced with a ‘female phase’ flower, which was similar to the male phase flower except that all pollen was manually removed and we fixed a piece of double-sided tape to the stigma. Once the rodent had visited the female phase flower, we removed the tape and counted pollen grains under a compound microscope. Between the male phase and female phase treatments we recorded the overall length of time between visits as well as how much time the individual rodent spent grooming. This allowed us to work out if pollen is lost primarily from active grooming or from simply falling off fur. We found that pollinator grooming exponentially diminishes the amount of pollen being transferred. So if rodents groom so effectively that they lose most of the pollen they have picked up why would flowers evolve to use them as pollinators? One possible explanation would be that other more typical pollinators, such as birds and bees, are already heavily used in the local community. If the harmful effects of competition for these more heavily used pollinators outweigh the ineffectiveness of less typical pollinators, natural selection would favour adaptation to the less typical pollinator. When this happens we are left with curious flowers that have a distinctive evolutionary history,
The odd nectar secretion of Leucospermum arenarium. (A) Nectar near the end of the petals. (B) Nectar accumulation on L. arenarium inflorescence. (C) Single L. arenarium flower with nectar present. (D) Leucospermum arenarium inflorescence. Image: Chris Johnson
Dissections and scanning electron micrograph depicting the capillary channels for nectar transport. (A) Capillary channel shown in a longitudinal section of an L. arenarium perianth. (B) Site of nectar accumulation in L. arenarium imaged with a dissecting microscope. (C) Electron microscope scan showing capillary channel formed from fused perianth segments. Image: Chris Johnson
and we now need to work out what lead to the evolution of these ‘curious flowers’. Adaptation to unique pollinators, or adaptation to typical pollinators in unique ways, is characteristic of the South African flora and is one of the main contributors to the vast floral diversity and astounding interactions we see throughout the different floral kingdoms across the country. Q Chris Johnson’s research interests are general themes in ecology and evolution applied to plant-pollinator interactions as well as the mechanical ‘fit’ between flowers and pollinators. He focuses on the pincushion proteas (Leucospermum spp.). He is currently in the final year of his doctoral research at Stellenbosch University, hoping to graduate in December. He has a BSc in Biology with a focus of Environmental Science from Syracuse University, Syracuse, New York, USA. 10| 2 2014
A feathertail stingray in St. Joseph Atoll. Image: Chantel Elston
Stingrays are not cute and cuddly and many people fear them. But they are interesting and important members of the marine environment. By Chantel Elston.
The importance of the overlooked:
the story of stingrays
he infamous stingray is probably best known for the unfortunate incident that resulted in television personality Steve Irwin’s death. Despite the publicity that surrounded this event, stingrays have been largely overlooked, especially by the scientific community. Most people are more interested in their larger and more charismatic relatives, the sharks. As a result most scientific endeavours have focused on sharks, while stingrays have lurked in the scientific background. The knowledge gap Even though there has been a dramatic increase in scientific interest over recent years, painfully little is known about stingrays. Simple biological measures such as their maximum size or the age at which they reach sexual maturity are missing for many species. Knowledge of more complex phenomena such as their foraging or movement ecology is even more limited. A group of marine biologists is trying to address this knowledge gap by studying a stingray population in a tiny paradise in the Indian Ocean. The St. Joseph Atoll, Republic of Seychelles, was chosen as the study site because it could very well be given the nickname of ‘Stingray City’. The shallow sandflats surrounding the central turquoise blue lagoon teem with the distinctive shapes of stingrays, making it a perfect location to gather more information about these important animals. The fieldwork Funded by the Save Our Seas Foundation (SOSF), and using the facilities of the SOSF D’Arros Research Centre, Masters
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student, Chantel Elston, and her two supervisors, Dr Paul Cowley and Dr Rainer von Brandis, have started a study focusing on the movement patterns and diets of the stingray population in the St. Joseph Atoll. These scientists are using acoustic transmitter tags to understand how the stingrays move in the lagoon. The tags can be attached externally or surgically implanted into the animal and they give off signals at pre-determined intervals. These signals are recorded by a receiver every time a ‘tagged’ animal swims past it. This allows the scientists to know exactly where an animal is and using this information they can work out home ranges, areas of preference of the animal, etc. Catching a stingray is no easy task, but using the expertise of Dr Cowley, these marine biologists managed to catch 30 stingrays using a combination of foul-hooking (casting a line directly in the path of an animal to hook it on purpose), cast-netting, and even simply sneaking up and catching the stingray by hand. Once caught, the stingrays are placed upside down, causing them to fall into tonic immobility, i.e. it was impossible for the stingrays to move. When a stingray has been immobilised, scientists can surgically implant implant the acoustic transmitter tags into its abdomen. The next step requires patience and waiting. Only after a year will the scientists download the data from the network of receivers in the lagoon so that they will pick up any differences in movement patterns between different seasons. The scientists will use these data to interpret the movement patterns of the stingrays, which are vitally important to understanding how these animals live.
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The next phase of the project is to determine the stingray's diet. Stingrays sense their prey with electroreceptors located on their underside, but no-one is quite sure what their prey is. To find out, the scientists will capture stingrays and flush out their stomachs with water, which makes them vomit up their stomach contents. The stomach contents are then analysed to determine exactly what these animals eat. Why are stingrays important? Overlooking stingrays has been an unfortunate mistake as they are important both ecologically and commercially. They are generally abundant in shallow, coastal, sandy habitats and are vital to the functioning of these ecosystems. They fall right in the middle of the food chain, feeding on smaller invertebrates and fish while themselves being eaten by larger animals such as sharks and dolphins. They are the link between these different trophic levels and without their presence the food chain would collapse. They are also ecologically important because they shift large quantities of sand when searching for prey and thus alter the underwater landscape – a phenomenon called bioturbation. In the commercial world they are caught in targeted fisheries because their meat and skin is valuable. Many communities use their meat for food and their skin for making exotic boots, jackets, wallets, and other goods. In other fishing industries they are often caught as by-catch, which means they are caught unintentionally. They also play an important part in ecotourism activities in many areas of the world and generate a lot of income. For example, snorkelers pay to feed stingrays by hand in the Cayman Islands and in Tahiti. Stingrays in danger Unfortunately, despite the importance of stingrays, there has been a global decline in their populations with some species being listed as vulnerable, endangered and data deficient by the International Union for the Conservation of Nature (IUCN). One of the contributing factors to this decline is their vulnerability to over-exploitation by the fishing industry. The species is particularly vulnerable to overfishing because they produce very few offspring, they grow slowly, only reach sexual maturity at a late age, and they have a long gestation period. However there is hope, as studies like ours are adding to knowledge of these animals. Stingrays are widely distributed across ocean basins so knowledge gained locally can be applied to many different areas. Hopefully this knowledge will be incorporated into management strategies and further population declines can be prevented. Q Chantel Elston completed her BSc and Honours at the University of Cape Town, specialising in marine biology. She is currently studying for an MSc at Rhodes University. Her main research interests are in the ecology of skates and rays. Because of their charismatic nature, very little research has been done on these animals. They could potentially be the least studied group of vertebrates in the world. Chantel believes that we need to work towards a better understanding of skates and rays so that we can produce effective conservation efforts.
Chantel Elston and team with a mangrove stingray that has just been implanted with an acoustic transmitter tag. Image: Rainer von Brandis/D’Arros Research Centre
Surgically implanting a transmitter. Image: Rainer von Brandis/D’Arros Research Centre
A mangrove stingray feeding. Image: Rainer von Brandis/D’Arros Research Centre
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& environmental sustainability Concrete
Reinforced concrete is one of the most commonly used building materials around the world. Olukayode Alao explains how making these structures more durable increases their environmental sustainability.
E Figure 1: The concept of sustainability and interactions (adapted from Cement and Concrete Institute).
Figure 2: Concrete spalling due to steel corrosion. Image: Olukayode Alao
Figure 3: World cement production. Image: Adapted from Uwasu et al. 2014
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nvironmental sustainability is the new buzzword in materials and engineering science – and something that is becoming ever more important with a rising world population and increasing urbanisation. The inter-relationship between these issues is shown in Figure 1. Urbanisation needs infrastructure, leading to an upsurge in construction of houses, hospitals, roads, bridges and public buildings such as sports stadiums. Many of these are built from reinforced concrete (RC) – traditionally Portland cement (PC). The challenge is to make these RC structures both environmentally friendly and sustainable – requiring increased service life and better durability. Traditional PC does not meet all these requirements and materials scientists are looking at what are called supplementary cementitious materials (SCMs), particularly ones that are the by-products of industrial processes. These by-products would include the waste from blast furnaces such as fly ash, slag and silica fume – using recycled materials in place of natural resources. Building in concrete Reinforced concrete is one of the most commonly used materials in the construction industry globally. So buildings made from concrete are subjected to just about every environmental condition that there is. Let’s take marine and coastal environments as an example. Typically, the atmosphere in marine environments is full of salts, released into the atmosphere by the waves in the sea. These salts are rich in chloride ions, which cause major corrosion of the steel in RC structures. The chloride ions are transported onto land by offshore winds and their concentration in a particular location may vary depending on factors such as relative humidity, precipitation, temperature and topography. Chloride ions enter the concrete through different processes such as permeation, diffusion and capillary absorption. As the chloride ions cause corrosion they produce oxides of iron that are three times the volume of the steel within the RC. This causes a process called spalling, in which flakes of the concrete are broken off over the steel, which you can see in Figure 2. This exposes the steel reinforcement, which then needs to be ‘patched’ with more concrete. Portland cement production and concrete use Portland cement (PC) is the major component in concrete and the component that gives it the ability to bind with the aggregates. As the world become more urbanised and industrial, cement production is increasing annually. China is the leading cement producer (see Figure 3). In 2008 China alone produced 51% of the world’s cement, which made it the largest emitter of CO2 in 2008. This sudden surge
❚❚❚❙❙❙❘❘❘ Materials science References Huntzinger, DN and Eatmon, TD. A life-cycle assessment of Portland cement manufacturing: comparing the traditional process with alternative technologies. 2009. Journal of Cleaner Production, 17(7), pp.668–675. Available at: http://www.sciencedirect. com/science/article/pii/S0959652608000826 [Accessed March 19, 2014]. Kjellsen, K, Guimaraes, M and Nilsson, A. The CO2 balance of concrete in a life cycle perspective. 2005. Nordic Innovation Centre, …, (December). Available at: http://www. nordicinnovation.org/Global/_Publications/Reports/2005/CO2 uptake during the concrete lifecycle.pdf [Accessed April 23, 2014]. Meyer, C. The greening of the concrete industry. 2009. Cement and Concrete Composites, 31(8), pp.601–605. Available at: http://www.sciencedirect.com/science/ article/pii/S0958946509000031 [Accessed March 19, 2014]. SANRAL, 2013. The South African National Roads Agency SOC Limited – Annual Report 2013, Pretoria. SANS, 1992. SANS 10100-2 – The structural use of concrete part 2: Materiala and execution of work, Pretoria, South Africa: South African Bureau of Standards (SABS). Tanaka, Y, et al. Study on Cover Depth for Prestressed Concrete Bridges in AirborneChloride Environments. 2006. PCI journal. Available at: http://cat.inist.fr/?aModele=affich eN&cpsidt=17558520 [Accessed March 27, 2014]. Uwasu, M, Hara, K and Yabar, H. World cement production and environmental implications. 2014. Environmental Development, 10, pp.36–47. Available at: http://www. sciencedirect.com/science/article/pii/S2211464514000256 [Accessed April 8, 2014].
can be attributed to the increasing population and rate of infrastructure development in China. PC production is estimated to contribute 5 - 7% of carbon dioxide emissions globally. About half of this production of carbon dioxide is caused by the calcination of limestone (CaCO3) to form clinker (CaO). The rest of the carbon dioxide emission is generated from energy used during cement production. This implies that reducing cement and concrete production will greatly decrease the carbon footprint of the construction industry. The process of hardening of concrete involves an exothermic chemical reaction (heat of hydration). Therefore, it is also a cause for concern in terms of global warming and climate change. However, we now know that between 33 - 57% of CO2 is reabsorbed by concrete through a chemical reaction called carbonation over a lifecycle of 100 years. Recycling in concrete production Modern concrete production techniques now use recycled materials – the SCMs mentioned earlier. These can replace between 6 - 50% of the PC normally used in concrete production. This not only reduces the carbon footprint of concrete production, but also improves the durability of structures build with this type of concrete. Examples of SCMs are slag, silica fume and fly ash. These SCMs are all by-products of industrial processes such as iron-ore refining and electricity production, so their use is economical and environmentally friendly. Using SCMs in concrete also decreases the heat of hydration (except in the case of silica fume) and its pore structure permeability. Less porous concrete allows fewer chloride ions into the RC structure and the embedded steel reinforcement is protected. Conclusion In conclusion, the design of durable concrete for a sustainable environment must encompass the use of recycled and by-product materials, a low energy requirement and low maintenance costs. The recent development of 0% cement concrete (geopolymer concrete) by Murray & Roberts in 2013 indicates that the construction industry in South Africa and the world at large is looking for ways to cut down carbon dioxide emissions. Innovative research and development will go a long way to enhancing environmental sustainability. RC structures with longer service life will ensure a reduced
Concrete’s carbon footprint is fairly large due to two factors: the energy used to heat limestone (CaCO3) in kilns to form CaO, one of the major components in concrete, and the large quantities of CO2 released as the conversion of limestone to CaO proceeds. However, a recent study has shown that over time, five percent, or more, of the lost CO2 reabsorbs back into the concrete, thereby reducing the ultimate carbon footprint. Image: Zina Deretsky, National Science Foundation
carbon footprint from cement production and its use for construction, repair and rehabilitation, improving sustainability of the environment. Q Olukayode Alao is currently a Master's student with the Concrete Materials and Structural Integrity Research Unit (CoMSIRU) at the University of Cape Town. He has a Bachelor's degree from the Federal University of Technology, Akure in Nigeria. His research interests are in structural engineering, specifically: concrete materials, durability and sustainability.
Design codes and concrete construction Table 1: Classification of marine exposure categories for South Africa (SANS 10100-2, 1992) MARINE EXPOSURE TIDAL AND SPLASH CATEGORY ZONES
Exposed to seawater, Not applicable heavy wave action
Exposed to seawater, Within 500 m of shore sheltered location in an exposed location
Near shore (1 – 15 km) in an exposed location
Anywhere else > 15 km from the coast
For construction with concrete, most African countries use European design codes although their prevailing weather conditions are different from those in Europe. In order to implement sustainable concrete technologies, practical African design codes must be developed. RC structures in the marine zone are usually categorised as shown in Table 1. The different marine exposure categories have different minimum concrete cover to steel, compressive strength and water/binder ratio (w/b) prescribed for them in the South African design codes. This approach is referred to as the prescriptive design method. Researchers are constantly evaluating whether the prescriptive method is the best design used to achieve durable concrete structures. As the distance of RC structures from coastline increases, the prescribed design compressive strength, cover and w/b decreases. In 2013, the South African National Roads Agency (SANRAL) reported that it currently monitors and manages 8 246 major bridges and culverts and it spent an estimated R11.8 billion on repair and maintenance of its roads. The continuously growing number of RC structures makes it very important for durable structures to be constructed as long as this directly influences the yearly expenditure on maintenance.
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A skin photosensitivity atlas FOR SOUTH AFRICA Caradee Wright and a team of collaborators have embarked on a study to produce a South African atlas of our nation’s skin sensitivity towards the sun.
7 Skin colour chart: 1 very fair, 2 fair, 3 medium, 4 olive, 5 dark, 6 very dark and 7 black. Image: Reeder and Jopson, 2004, University of Otago
Five different techniques to measure skin colour and photosensitivity 1. A self-report questionnaire: questions that ask what colour your skin is and how your skin reacts to sunlight during the middle of the day in summer. 2. The Munsell Colour Atlas Visual Standard: a paper-based manual of colour chips. 3. The Minolta CECF-9 Colour Reader: an electronic colour fan that identifies and searches for the closest colour from more than 5 000 options. 4. The Photo Research PR715 Spectroradiometer: measures intensity and colour. 5. Diffuse Reflectance Probe: used to measure reflectance properties of the skin which is determined by, among other factors, the melanin content of the skin.
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ince 1994, South Africa has been called ‘the rainbow nation’, a term reflecting the multi-cultural, cosmopolitan make-up of our population. Statistics South Africa asks people to describe themselves in the national census in terms of five racial groups: Black African, White, Coloured, Indian or Asian, and other/ unspecified. People sometimes think of South African ethnic groups in terms of skin colour. However, there is a wide range of skin colours among South Africans. There is usually a large range in skin colour, and therefore skin photosensitivity (or your skin’s sensitivity towards the sun) within a group of people who collectively belong to the same ethnic group. A team of researchers at the CSIR are interested in understanding the range of skin colours among all South Africans for the benefit of public health. There is a wellestablished link between skin colour or pigmentation and health outcomes associated with solar ultraviolet radiation (UVR) exposure. Generally, populations with light skin colour are at greater risk of skin cancers due to excess sun exposure. For individuals with dark skin, which has a high melanin content, i.e. the dark pigment in the skin, it can sometimes be difficult to get sufficient sunlight exposure for the body to make vitamin D and this can put them at greater risk of diseases related to vitamin D deficiency. For sun awareness and prevention of adverse health effects, a valid and reliable assessment of skin colour is needed. For population-based studies of large samples, skin biopsy is not a practical option. Self-reported skin colour using a survey questionnaire has been identified as an unreliable measure of skin colour. People sometimes overestimate how dark their skin colour is. To accurately define skin colour, you need to assess the colour of the skin on the inner, upper arm – skin that is generally not regularly exposed to the sun and therefore in its most natural, unexposed form. Given this context, this research will look for evidence of validity and test-retest reliability of skin colour using five different techniques (Box 1) currently used to categorise skin photosensitivity in population studies. There are six skin phototypes (Box 2). These were defined by Professor TB Fitzpatrick in the 1970s.
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The range of skin colours found in our country. Image: Linda Godfrey
The information collected in the study will also be used to form a database of skin colour among South Africans. We will be able to compare self-reported skin colour to the instrument-measured skin colour to determine whether South Africans overestimate their skin colour, as has been found among populations in other countries. We will also be able to more accurately define an individual’s skin photosensitivity – and this information can be used by the individual to protect them, using a form of sun protection such as shade or sunscreen, from adverse health risks associated with excess solar UVR exposure. Planning for this study began in 2013. Fieldwork will run between July and September 2014 and 1 000 South Africans will have their skin colour and photosensitivity measured. The database that we form will then be the very first atlas of skin colour for South Africa. It will be a valuable resource for epidemiological studies aimed at understanding diseases, for guiding health promotion programmes and developing tailored public health awareness messages. Q Caradee Wright is a Principal Scientist in the CSIR Climate Studies, Modelling and Environmental Health Research Group where she leads the environmental health team. Caradee is a member of the South African Young Academy of Science, council member of the National Association for Clean Air, founder of the Environmental Health Research Network and Principal Investigator of the SunSmart Research Programme and Lab in South Africa.
Suggestions for online reading: Diseases and conditions: Sunburn risk factors: http://www.mayoclinic.org/diseases-conditions/sunburn/basics/riskfactors/con-20031065 Sunburn and other sun reactions of the skin: http://www.webmd.com/allergies/guide/sun-reactions Skin cancer and skin of colour: http://www.skincancer.org/prevention/skin-cancer-and-skin-of-color Take the quiz – where does your skin fit in? http://www.skincancer.org/prevention/are-you-at-risk/fitzpatrick-skin-quiz
Six skin phototypes Skin type Description of typical skin type and phenotypic characteristics
Solar UVR exposure that will lead to sunburn if skin is unprotected (SED: Standard erythemal dose unit) 1 SED = 100 Jm-2
Brown or black skin, dark hair, brown eyes, rarely burns
Light brown skin, brown eyes, burns rarely
White or light brown skin, brown hair, may burn
Fair skin, fair/red hair, freckles, burns very readily
Fair skin, fair/red hair, light eyes, freckles, always burns on minimal sun exposure
10| 2 2014
Beefing up efforts to breed with cattle
A demonstration of how the Rice pelvimeter is used to measure internal pelvis width (transverse diameter) and pelvis height (vertical diameter). These measurements are taken trans-rectally by a veterinarian during prebreeding examination of heifers. Image: Dietmar Holm
A group of Bovelder heifers synchronised for artificial insemination during the research performed by Dr Dietmar Holm at Johannesburg Northern Farm. Image: Dietmar Holm
Beef cattle farmers will be able to fine-tune their selection and breeding programmes even further thanks to the research efforts of veterinarian Dr Dietmar Holm of the University of Pretoria. He has introduced the use of ultrasound and new criteria to measure the pelvis area of heifers to optimise pre-breeding examination systems. His research is likely to have a significant impact on the beef cattle breeding industry by adding value to selection programmes and improving productivity of beef cattle operations. Dr Holm recently received his doctoral degree in veterinary science from the University of Pretoria. His findings take into account observations he made over the course of seven years of a Bovelder herd at Johannesburg Water’s Northern Farm. Some of the results have already been published in the international Journal of Animal Science. Dr Holm has shown that heifers with relatively low reproductive potential in seasonal breeding systems can be identified before the first breeding season and before reproductive failure occurs. This means that animals with inferior potential can be removed to optimise productivity of a farm. His methods also help to prevent calving difficulties, without changing the frame size of the cattle herd. ‘The cost effectiveness of synchronisation programmes for individual animals within a herd can be improved by doing ultrasound examinations of heifers’ reproductive tracts and pelvis areas, or by using reproductive tract scoring by rectal palpation,’ says Dr Holm, who believes that measurements of the internal pelvic area are especially important to prevent dystocia or obstructed labour. ‘When ultrasonography is not available, the accuracy of reproductive tract scoring by transrectal palpation can be improved by repeating it in low scoring animals after seven days.’ Dr Holm says that reproductive tract scoring as a culling tool to predict heifer fertility compares well with other traits that are commonly used for heifer selection, such as Kleiber ratio. It is therefore useful as a pre-breeding examination method to identify beef cows with lower potential to reproduce successfully over the long term in a restricted breeding system. According to Dr Holm his research confirms the fact that reproductive traits have more impact on production in beef cattle than growth traits. Dr Holm, who lectures in veterinary reproduction in UP’s Faculty of Veterinary Science at Onderstepoort, says he is already applying the outcomes of these studies through consultations with veterinarians who collect heifer pre-breeding data from beef clients. Ultimately, he hopes these formulas will help improve selection tools that are part of the computer models of SA Studbook and Breedplan, the two major service providers to the cattle breeding industry.
Study asks for ban on 4x4s in protected areas Soil damage caused by 4x4 vehicles is underestimated, can last for between 5 and 1 000 years and is mostly irreversible. Due to their negative environmental impact, vehicles should not be allowed to do offroad driving in protected areas. Strict legal measures should be applied to regulate
A game drive vehicle loaded with 10 sand bags, each weighing 70 kg, was used to ‘simulate’ conditions in which a vehicle fully laden with tourists (weighing about 3 795 kg) will drive in different conditions. Image: Gerhard Nortjé
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4x4 use in such areas, while very sensitive areas such as wetland areas should be classified as absolute no-go areas. So says Dr Gerhard Nortjé, based on findings from his doctoral research in wildlife management, which he did through the University of Pretoria’s Centre for Wildlife Management. This soil scientist received his PhD on 15 April 2014. ‘While it may not seem that off-road driving has negative impacts on the environment, especially on the soil and vegetation, the risk of damage is real,’ says Dr. Nortjé. ‘It is not an ecologically sustainable practice and should therefore not be allowed.’ Dr Nortjé says increased soil erosion, damage to vegetation and habitat destruction are just some of the visible negative impacts of this popular so-called ‘eco-tourism’ activity.
New guidelines needed Dr Nortjé, who focused his research in the Makuleke Contractual Park in the northern
Pafuri section of the Kruger National Park (KNP), argues that SANParks should reconsider its management strategies for off-road driving in protected areas altogether. SANPark´s best practice guidelines currently recognise the potential of offroad driving to negatively affect natural resources, but do not explicitly refer to soil damage. Some of the current off-road driving guidelines have, up until Dr Nortjé’s study, never been tested or scientifically validated. One guideline, for instance, states that vehicles may not drive in each other’s tracks when going off-road. This is exactly the opposite of what Dr Nortjé’s research has shown, namely that up to 90% of damage is caused the first time a vehicle passes over an area, irrespective of soil type or tyre pressure. Driving on the same tracks a few times is therefore much less damaging than driving only once on different tracks. Some of his other findings include: Wet soils are more prone to off-road
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vehicle damage than dry soils, although both are affected. Off-road driving causes three forms of soil degradation: the dense compacting of the subsurface layer because of wheel traffic; the formation of a dense, thin soil crust under tracks; and soil erosion caused by increased runoff from the hardened soil crust. Soil compaction due to off-road driving can be up to 60 cm deep in places. It causes soil to be dry, because of poor water infiltration and high run-off. The soils are also poorly aerated, which further hampers seed germination and root development and functioning. In all, soil crusting makes plants more vulnerable to drought and influences their ability to absorb water due to shallower and poorly developed root systems. Plants in these disturbed areas are often nutrient deficient and poor growers, the research
shows. The effects are not just confined to strips under the wheel tracks – the so-called wheel pan. It also has a much wider lateral effect on both sides of the vehicle tracks. Even lower tyre pressures cause damage and degradation, although less soil compaction occurs than with higher tyre pressures. Off-road driving has negative impacts on vegetation recovery, soil resilience and root density distribution. Vegetation degradation worsens over time due to predisposition to further damage. Vehicle tracks acts as rill into which water is channeled, therefore predisposing the soil to erosion
Word of advice The results indicate a need for improved visitor education on the possible negative impacts of off-road driving, as well as the
rigorous enforcement of legal, scientifically based measures to control this practice. ‘Vehicles should be driven in the same tracks when driving off-road as a form of traffic control, and lower tyre pressures should be used,’ advises Dr Nortjé. Dr Nortjé says that in game reserves off-road driving is often done on virgin, undisturbed soils. Wild animals tend to concentrate in areas with the most nutritious and palatable vegetation. Consequently these are also the areas where predators are most likely to be found, and the areas with the highest frequencies of off-road driving to bring tourists close to wildlife. ‘Tourists’ ignorance and little consideration for the environment or the soil for that matter, combined with operators’ and land owners’ need to make money is normally the reason for allowing off-road driving,’ says Dr Nortjé.
Ostriches can’t choke or taste An ostrich can’t taste a thing and it won’t choke easily either, because of a pocket in its tongue. These are among the interesting findings that Dr Martina Crole has made while investigating the upper digestive tract of the world’s largest bird. Dr Crole received her doctorate in veterinary science from the University of Pretoria (UP) on Friday 11 April, 2014. She is a lecturer in veterinary anatomy in the Faculty of Veterinary Science at UP’s Onderstepoort campus. Dr Crole spent many hours in the field and laboratory using forceps and her fingers to manipulate and study fresh specimens that were still flexible. She wanted to find out exactly how it is possible for an ostrich not to choke even though it doesn’t have an epiglottis. The epiglottis is the flap of tissue that prevents food or water going into the oesophagus (wind pipe) in mammals. The ostrich also has quite a wide glottis or opening to the oesphagus that needs to be closed during swallowing to prevent choking. She worked out that when an ostrich’s glottis is closed and the body of its tongue moves backwards, the smooth root of the tongue folds. In the process of folding, the pocket in the base of the body of the tongue also folds around the front portion of the larynx (the laryngeal mound) – the breathing tube – with the closed glottis. To make sure that this pocket remains stable, the two projections at the base of the tongue (called the lingual papillae) hook over the closed laryngeal mound. Dr Crole has given this unique anatomical mechanism its own name: the linguo-laryngeal apparatus. Over the past 200 years, a few other researchers have noticed the pocket in the tongue body of the ostrich, but so far no one could quite work out why it was there. ‘They possibly didn’t realise its function because they did not use fresh specimens, but rather opted for material preserved in formalin or alcohol, which hardens the tissue and makes it rather inflexible,’ says Dr Crole. Dr Crole has also discovered that the emu – another large, flightless bird – can taste. In the process, she has become the first researcher to confirm a sense of taste in any ratite species. Ratites are a group of large, flightless birds that include the emu and the ostrich. However, she could not find any trace of taste buds in ostriches. This might help to explain why, in general, ostriches are not fussy eaters. ‘I simply couldn’t find any taste buds’ explains Dr Crole, who carefully dissected, removed and prepared samples for microscopy from the heads of ten ostriches and ten emus as part of her research. It will only be possible to be 100% certain that ostriches do not possess taste buds once genetic testing is done. Dr Crole also found that both ostriches and emus have very sensitive bills with which they can touch and inspect objects. She believes an ostrich’s very well-developed sense of smell, touch and sight helps it to discriminate its food in the absence of taste.
Dr Martina Crole and her promotor and colleague, Prof John Soley, both from the University of Pretoria, Onderstepoort campus. Image: University of Pretoria
‘A good sense of smell is characteristic of the ratites, with kiwis having the best smell of all,’ she says. ‘An ostrich’s eye is larger than its brain, and therefore its vision is well developed.’ Her guess is that ostriches have no need for taste buds because of the way in which they eat. ‘They throw it [the food] to the back of their mouths, which doesn’t really give them an opportunity to do any tasting,’ she speculates. ‘It could also be nature’s way of making it easier for them to eat so-called “bad tasting” food.’ ‘These findings strengthen the idea that ratite species should actually be seen as a unique group of birds that are very separate from flying bird species,’ she adds.
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New technique finds anti-HIV compounds in indigenous plant species
Helichrysum populifolium, known locally as poplar helichrysum. Image: University of Pretoria
An indigenous grey-leaved shrub with clusters of tiny honey-scented flowers has been used by University of Pretoria researcher Dr Heino Heyman to show that nuclear magnetic resonance (NMR)-based techniques can speed up testing of various compounds to see which can be used best to develop HIV medicines. Dr Heyman received his doctorate in medical plant science on 9 April 2014 from the University of Pretoria for the work he has done to show how NMR-based metabolomics techniques can be used to speed up the drug discovery process. His doctoral research is an extension of the work he did in 2009 as part of his MSc degree, in which he started to use NMRbased metabolomics techniques to test for the anti-HIV properties of Helichrysum species. ‘The drug discovery process for antiviral constituents is very tedious, time consuming and also expensive,’ Heyman says. ‘We therefore need a method with which to perform the fractionation, purification and isolation of compounds more effeciently.’ To this end, Dr Heyman turned his attention to securing a fast and effective technique that can help other researchers in this screening process.
Use of NMR techniques
Dr Heino Heyman working in the laboratory, making plant extracts. Image: University of Pretoria
He focused on using NMR techniques to identify specific metabolites. NMR spectrometers can detemine the specific characteristic of individual molecules. Metabolites are the chemical substances that are produced during the metabolic processes that take place in a cell and can be involved in, for example, producing energy or cell structures, or in providing defence mechanisms for a cell. All metabolites have their own unique sets of ‘fingerprints’ based on the chemicals from which they are built up. These all radiate
energy at a specific, unique and therefore identifiable frequency when investigated with NMR spectrometers. Heyman found that NMR-based metabolomics and multivariate data analysis can be successfully combined to compare the chemistry of numerous samples based on their specific activity against HIV. ‘These can be used to determine the differences and similarities between various samples based on their specific activity against HIV,’ he says. The common chemical factor or fingerprint of various samples that have high activity against HIV was succesfully determined. Dr Heyman then used this fingerprint to see if his method could quickly and effectively work to identify virus-fighting compounds among selected South African indigenous plants.
Local plants Members of the Helichrysum genus of plants are often used as traditional remedies to treat coughs, colds, fever, infection, headaches, and menstrual pain. The plants are also sometimes used as wound dressing because of their potential antibacterial properties. Previous studies have shown that Helichrysum aureonitens has anti-virus properties that can be used to fight the herpes virus, while other Helichrysum species could have an effect on HIV. After testing 30 species he discovered anti-HIV compounds for the first time in Helichrysum populifolium. This shrub of up to 2 m tall is called the poplar helichrysum because its grey leaves resemble that of poplar trees. ‘With only 30 of the 245 Helichrysum species in South Africa having been investigated, there is still enormous potential for discovering other potential medicinal uses for these plants,’ says Dr Heyman.
Haviside’s dolphins on the West Coast are related All Haviside’s dolphins found along southern Africa’s West Coast are related, and belong to one of two major populations. This
Haviside’s dolphins are endemic to the southern African coastline, and is only found from Table Bay to southern Angola. Image: Ryan Reisigner
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is one of the findings of the first in-depth genetic study of this endemic dolphin species, found only from Table Bay in the Western Cape to southern Angola. The species may be sensitive to overharvesting by the hake fishing industry. The study was conducted by conservation geneticist and Capetonian Dr Keshni Gopal as part of her doctoral research in zoology. She received her PhD degree from the University of Pretoria on 9 April 2014. She conducted various sensitivity analyses to look at how how changes in life history traits or environmental variations can influence the resilience of the populations. These techniques were also used to test the effect of different management approaches. In the process, her research revealed that if as few as 15 individuals are removed from a small population of 10 000 members, it can have a major effect on the overall population size of Haviside’s dolphins (Cephalorhynchus heavisidii). By determining the genetic relationship between the different populations Dr Gopal has helped to identify smaller population units. Knowledge of such units is vital to ensure effective conservation management strategies. Her data will also go a long way to update the species’ conservation status. Haviside’s dolphins are currently classified as Data Deficient by the International Union for the Conservation of Nature (IUCN) Red
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Dr Keshini Gopal in the field. Image: University of Pretoria
List of Threatened Species, because so little is known about their population size and life history traits, including direct and indirect threats that may lead to their extinction. ‘What is currently known about its biology and behaviour comes from opportunistic research rather than long term studies,’ explains Dr Gopal. ‘Hopefully the results of this study can be incorporated into risk assessments and much-needed conservation management and monitoring strategies for this species, and help towards its long-term survival.’ ‘I’ve always had a great passion for the marine world, and using dolphins as my study subject to conduct genetic analyses was a dream come true,’ says Dr Gopal, who has done similar studies on rock lobsters in the past. The sight of an albino Haviside’s dolphin off Hondeklipbaai
during one of her sampling trips is one that she will always treasure. Hondeklipbaai is one of seven coastal areas along the West Coast that she visited regularly during the course of four hot summers. She collected biopsy tissue samples from 395 dolphins living in Table Bay, St Helena Bay, Lambert’s Bay, Hondeklipbaai, and Port Nolloth, as well as near Luderitz and Walvis Bay in Namibia. Dr Gopal did her genetic analyses in Leslie Hill Molecular Laboratory of the South African National Biodiversity Institute in Cape Town, where she works. ‘An unexpected but positive experience was the opportunity to share information about my research with local fishermen in some of the fishing villages along the West Coast.’ Dr Gopal remembers the opportunities she had to convey valuable information about marine conservation. ‘The fishing communities in these areas have adopted the dolphins as their own, as I still often receive messages from them informing me about “their dolphins” and of new additions to their area.’ Conservation genetics is a discipline within science that uses genetic techniques to assess specific population characteristics of a particular species, such as genetic structure, connectivity and gene flow. Its techniques are often used to provide critical insights into the conservation problems of poorly researched species, many of which are at risk because of human impacts on the environment.
Images of long bones used to identify children Forensic anthropologist Dr Kyra Stull has developed a reliable tool that police, forensic pathologists and anthropologists can use to age and sex the remains of unidentified missing children. In the process, she has also compiled the world’s largest known sample of children’s long bone images. Dr Stull developed the tool as part of her doctoral research in anatomy at the University of Pretoria. Her PhD was one of eight conferred by the Faculty of Health Sciences during its Autumn Graduation Ceremony. A total of 214 new doctors and 42 dentists also graduated. Her study is the first to successfully estimate the age and sex of sub-adult children (younger than 12 years old) using an extensive number of measurements and multivariate statistical methods. As a next step, a computer software program will be developed that forensic anthropologists and other forensic practitioners can use. Scientists generally argue that difference between boys and girls are not fully established in their skeletons until they reach adolescence. Dr Stull has, however, shown that it is indeed possible to accurately and reliably estimate the sex of sub-adult children (younger than 12 years) using a large number of measurements from their long bones (including the humerus and femur). She applied statistical models that have yet to be used in anthropology for this purpose. She obtained skeletal information from 1 380 children from Cape Town’s Salt River Forensic Pathology Service and Red Cross War Memorial Children’s Hospital. Dr Stull analysed Lodox Statscan radiographic images captured from this group of children. The Lodox Statscan is a fullbody, low-dosage radiographic machine and is used in trauma units or in forensic laboratories during post-mortem examinations. ‘The machine was originally designed in
South Africa for the diamond mining industry but has since been used in hospitals and morgues worldwide,’ explains Dr Stull. Her sample is reflective of the South African population, and has led to the development of the first accurate, reliable, and applicable technique in the world to estimate the age and sex of children. Historically, forensic anthropologists could only compare data to antiquated growth studies from North America and Europe.
Unravelling skeletal clues ‘Estimating age from the skeletal components of a living child is complex,’ Dr Stull explains. ‘It is even more difficult when the child is dead and unknown. The main goal of a forensic anthropological analysis is to establish an accurate biological profile consisting of estimations of sex, age, ancestry and stature of unidentified human remains,’ she explains. ‘The biological profile is then used by the police to narrow down the list of missing individuals to ultimately identify the person. Homicide involving children is ubiquitous in all countries and dire improvements are needed to address the accuracy of methods routinely used in forensic anthropology, forensic pathology, and other related fields,’ she believes. Images such as those obtained through Lodox Statscan are proving to be invaluable, as researchers do not have to rely on actual collected bone samples to build biological profiles. Anthropologists and other practitioners have long used skeletal collections as the primary data source for their research but find it difficult to create or validate the techniques they develop for children because only a few documented skeletal collections of children’s bones exist. Further, the available material is often either too limited or old to apply to modern
Dr Kyra Stull measuring a femur that is part of the Pretoria Bone Collection at the University of Pretoria. Image: Jolandie Myburgh
populations. Children, for instance, are now taller than they were 100 years ago and experience maturation at earlier ages. Additionally, genetic differences, environmental influences, nutrition, and lifestyle also cause variation among populations (with regard to size, proportions and growth trajectories for instance). A Lodox Statscan radiographic image of a child around four years of age. Image: Red Cross War Memorial Children’s Hospital
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Decoding of Eucalyptus tree genome unlocks new possibilities for renewable fibre, fuel and biomaterials A researcher at the University of Pretoria (UP), South Africa – Professor Zander Myburg – was the lead investigator in a global project to unravel the genetic blueprint of Eucalyptus grandis, a species from a genus of fastgrowing trees commonly known as ‘gum trees’ (‘bloekoms’ in Afrikaans) in South Africa. The successful sequencing of this genome will be published in the prestigious journal Nature.
A fine example of Eucalyptus grandis – bloekomboom. Image: University of Pretoria
A gum tree plantation. Image: University of Pretoria
‘Now that we understand which genes determine specific characteristics in these trees, we can breed trees that grow faster, have higher quality wood, use water more efficiently and will cope better with climate change,’ Prof. Myburg explains the significance of this major scientific milestone. ‘Even more, we can turn well-managed Eucalyptus plantations into biofactories to produce specific kinds of sought-after materials and chemicals.’ ‘And, with this new knowledge about the molecular basis for superior growth and specific adaptations in plants, we can apply the same techniques to other woody plants that can be used as feedstock in the bioeconomy of the future.’ Gum trees are highly adaptable and grow exceptionally fast. While native to Australia, these trees are planted worldwide, mainly for timber, pulp and paper production, but increasingly also for ‘chemical cellulose’ – a form of pure cellulose that is used in a wide variety of industrial products from textiles to pharmaceuticals. The project to sequence the Eucalyptus grandis genome involved 80 researchers from 30 institutions across 18 countries. It took them five years to sequence and analyse the 640 million base pair genome. Combing through the more than 36 000 genes found in Eucalyptus, the researchers homed in on those that may be able to boost the economic value of the trees by influencing the production of cellulosic raw material that can be processed for pulp, paper, biomaterials and bioenergy applications. ‘As one of the lead organisations, the University of Pretoria is delighted with the positive outcomes of the project and the exciting new opportunities for our genomic research programmes,’ says Prof. Anton Ströh, Dean of the Faculty of Natural and Agricultural Sciences at UP. Prominent co-leaders on the project include Prof. Dario Grattapaglia of the Brazilian Agricultural Research Corporation (EMBRAPA) and Catholic University of Brasilia; Dr Gerald Tuskan of the Oak Ridge National Laboratory (ORNL) and the BioEnergy Science Center (BESC) and US Department of Energy Joint Genome Institute (DOE JGI); Prof. Dan Rokhsar of the DOE JGI and Dr Jeremy Schmutz of the DOE JGI and the HudsonAlpha Institute for Biotechnology. The US Department of Energy was a major funder via its Joint Genome Institute in Walnut Creek, California, where most of the DNA sequencing was done. South Africa’s Department of Science and Technology (DST), together with forestry companies Sappi and Mondi, supported Prof. Myburg and his team by funding the construction of the genome map used as a scaffold for genome assembly, as well as
the sequencing of expressed genes used for annotation of the genome. ‘The development of new knowledge and skills in tree genomics, and the application of that knowledge to enhance industry competitiveness, is directly aligned with the DST’s vision of a bio-economy’, says Dr Phil Mjwara, Director General of the Department of Science and Technology. ‘This is a superb example of full value-chain thinking, and thus an important investment for the Department.’ Prof. Myburg’s research team identified genes encoding 18 final enzymatic steps for the production of cellulose and the hemicellulose xylan, both carbohydrates that are enriched in wood fibre cells and can be used for biofuel production. ‘By tracing their evolutionary lineages and expression in woody tissues we defined a core set of genes for biopolymer production that are highly expressed in the development of xylem—the woody tissue that helps channel water throughout the plant and strengthens the tree,’ he explains. Team members Dr Carsten Külheim and Prof. Bill Foley at the Australian National University (ANU) also found that among sequenced plants to date, Eucalyptus showed the highest diversity of genes for specialised metabolites such as terpenes. These hydrocarbons serve as chemical self-defences against pests, as well as providing the familiar aromatic essential oils used in medicinal cough drops and in industrial processes. Among the family of terpene compounds naturally produced in plants and in particularly high abundance in Eucalyptus trees, derivatives of sesquiterpenes that contain 15-carbon atoms (diesel fuel typically contains 10 - 24 carbon atoms) may be promising alternatives for petroleum-based fuels. Researchers have already made important breakthroughs in engineering aspects of terpene biosynthesis into microbes such as bacteria and yeast. ‘This means that in future we could use specially selected Eucalyptus genes in bacteria and yeasts, turning them into bio-factories to manufacture advanced biofuels on a large scale,’ Myburg says. ‘In future, jumbo jets may take off powered by renewable, Eucalyptus-based fuel.’ More information about novel biofuels: High-performance aviation fuels from terpenes (http://arpa-e.energy. gov/?q=arpa-e-projects/high-performance-aviation-fuels-terpenes) New Biofuel Could Replace Today’s Standard Fuel for Diesel Engines (http://oilprice.com/Alternative-Energy/Biofuels/New-BiofuelCould-Replace-Todays-Standard-Fuel-For-Diesel-Engines.html) Joint BioEnergy Institute Scientists Identify New Microbe-Produced Advanced Biofuel as an Alternative to Diesel Fuel (http://newscenter.lbl.gov/news-releases/2011/09/27/jbei-scientists-identifybisabolane-as-an-alternative-to-diesel-fuel/)
Did you know?
Wood from Eucalyptus grandis. Image: University of Pretoria
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Eucalyptus species are commonly known as gum trees, but in South Africa the wood is often sold as ‘saligna’ due to the early (decades ago) misidentification of eucalypt trees in South Africa as the sister species Eucalyptus saligna. The well-known ‘blue gum’ is a different species, Eucalyptus globulus. More than 500 000 hectares of Eucalyptus plantations are cultivated as timber and fibre crops in South Africa – accounting for about 40% of the country’s forestry plantations. The rest is pine and wattle. Although eucalypts cover only 40% of the plantation land, they grow much faster and produce more than 50% of the wood products including pulp and paper. Forestry products contribute about R21 billion per year to South Africa’s GDP, of which R15 billion is from exports. Around 165 000 people are directly or indirectly employed in South Africa’s forestry sector (data source: http://www. forestry.co.za/statistical-data/).
down to 500 m under the sea Doctoral student’s pioneering research of sea-floor ecosystems along South Africa’s industry-rich west coast will help inform conservation decision makers, writes Nicky Willemse.
he west coast of South Africa is a key area for mining, trawling and the oil and gas industry, yet very little is known about the thousands of animals living in the sand at the bottom of the ocean, which could potentially be affected by these activities. Over the past five years, Cape Town’s Natasha Karenyi has been exploring these sandy ecosystems in selected areas stretching from the Namibian border to Cape Point, and in parts of the ocean as far out to sea as 160 km and as deep as 500 m. This ambitious large-scale project – the first of its kind along the west coast – formed the basis of her doctoral research at Nelson Mandela Metropolitan University in Port Elizabeth. She also drafted the country’s first conservation plan for the submerged sea floor sediment ecosystems in this area, taking into account selected priority areas and the industries that operate in these areas. Her work will feed into the South African National Biodiversity Institute’s (SANBI’s) next national biodiversity assessment. ‘One of the major issues with studying these ecosystems is that we are limited in terms of our understanding by the accessibility of the ecosystems – the deeper we go, the less we know. You need to go out on ships to get the deepest samples.’ Karenyi embarked on nine trips out to sea ranging from three days to two weeks, where she could gather samples from the far-off continental shelf. It was an impressive feat for the PhD student – one of a handful of benthic (bottom of the ocean) ecologists in South Africa – who has ‘no sea legs’ and was plagued by continual bouts of sea sickness. With a limited budget, she hitched rides on research vessels belonging to the Department of Environmental Affairs (DEA) and the Department of Agriculture, Forestry and Fisheries (DAFF). ‘Collaborations with colleagues and institutions are imperative for attaining research goals … I had to build working relationships with colleagues from different disciplines to get the study done.’ On board the research ships, she deployed an instrument called a grab. ‘It’s like a jaw you can send down and when it
Digging in the deep … Natasha Karenyi, who recently completed her PhD studies on west coast seafloor ecosystems through Nelson Mandela Metropolitan University in Port Elizabeth, had to work on research vessels to collect the samples she needed from the continental shelf.
hits the bottom, it takes a bite out of the sea floor.’ She also collected samples from the beach, and used divers to collect samples from shallow areas. In all, she collected more than 44 000 sand-dwelling animals representing over 450 species from 200 samples collected at 48 different sites during the course of her research. Her collection will be sent to a museum to identify any new species. ‘I looked at animals bigger than 1 mm that live in the sediment. These were mostly polychaetes (marine worms) and crustaceans (e.g. prawns and crabs). There were also some anemones and a few other organisms, like starfish and sea urchins.’ Karenyi is hoping that similar large-scale research studies currently underway or in the pipeline will produce comparable information for South Africa’s other coastlines. This will provide national scale data essential for the conservation and management of these ecosystems. ‘Marine unconsolidated sediments [the sandy sea floor] constitute the largest sea
floor ecosystem on Earth. Because it’s such a large ecosystem, you can’t sample the whole thing. Most people focus on a particular area – a bay or a harbour – and work on that. A large-scale study requires lots of resources and is very difficult to do.’ Karenyi’s study was funded by the National Research Foundation (NRF) and the Andrew Mellon Foundation in the United States. Although she completed her BSc, honour’s and master’s degrees at the University of Cape Town, she opted to complete her PhD through NMMU so that she could be supervised by Dr Ronel Nel, a leading expert in marine sandy ecosystems. Her co-supervisor was SANBI’s Dr Kerry Sink, who led the development of the South African national marine and coastal habitat classification. ‘I enjoyed learning about a system that very few people actually know about … I know my research will be used in future which gives me a sense of accomplishment – it’s a great feeling.’
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More on mammals A photographic guide to mammals of southern, Central and East Africa. By Chris and Mathilde Stuart. (Cape Town. Struik Nature. 2014.) As the introduction to this pocket guide says, mammals, particularly game species, are one of the main attractions of southern, Central and East Africa, often in impressively large herds. There are more than 1 000 species of mammals in Africa south of the Sahara Desert and most of these are found in the area covered by this book, which covers 152 species of mammal. The book provides excellent photographs, descriptions and distribution maps for nearly all of the larger and more obvious species, as well as a few of the more unusual species such as the pangolin, aardvark and porcupine. There are also representatives from the different families and genera of bat, shrew, elephant shrew, golden mole and many of the smaller rodents. The guide is too small to include all the small mammals, but will allow the user to work out the difference between, for example, a horseshoe bat from a free-tailed bat. The guide has been put together in a way that allows easy identification of the larger and more obvious mammals in the region covered, as well as some of the smaller species. Italic type has been used for key points of identification. Where there are differences between the sexes the photographs will show this, as well as the young when they are significantly different from adults. There is a brief description of each species along with a distribution map. Size has been shown using three different measurements: total length (nose-tip to tail-tip) for smaller species, shoulder height for larger mammals and wingspan for bats. Information on habitat is also provided. A thumbnail sketch at the beginning of the book will help you to determine to which group of mammals a species belongs. There is also a habitat map of Africa that shows the main vegetation types on the continent. This is an ideal pocket travel companion for anyone travelling in these regions of Africa.
Garden paradise Gardening for birds: planting and projects to entice birds to your garden. By Tracey Hawthorne. (Cape Town. Struik Nature. 2014.) This delightful little book provides all the information you need to make not only a beautiful indigenous garden, but one that will also attract local birds, which can only add to the enjoyment of the garden. Most people who want to garden to attract birds are likely to already be interested in watching birds, but just in case you are a beginner, there 38
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is an introductory section on bird watching. You are then taken on a tour of South African bird habitats and the regional climates. Now into planning your garden. Do you have a large lawn? This will only attract species such as hadedas, guineafowl and the Cape wagtails. Reduce the area of the lawn by planting shrubs or make sure you have well-planted border beds to provide cover, food and shelter for birds. Organic and indigenous gardens are best – and the birds you attract will help to control any ‘pests’ as well. In the ‘high traffic’ areas of your garden (pool and braai areas) plant tall trees such as fruit trees to attract birds and use a creeper over a pergola. Ground covers also attract birds and you can make an artificial wetland area as well, particularly if you already have a pond in your garden. The book covers composting, mulching, pest control, problem birds and problem plants and so provides excellent general gardening advice as well. There is a checklist of garden birds, covering the species likely to be seen across South Africa, as well as a list of the national botanical gardens, useful web sites and further reading. An added bonus are the lovely illustrations – I particularly like the Cape robin complete with neck scarf and leg warmers!
Exploring Kruger Kruger National Park Questions & Answers: Everything you ever wanted to know. By PF Fourie, updated by Chris van der Linde. (Cape Town. Struik Nature. 2014.) The Kruger National Park is arguably our most well-known wildlife sanctuary. It is certainly the largest of our national parks. The park covers an area of around 20 000 km2. During the 2011/12 year more than one million guests entered the park. Day visitors are allowed, but numbers are restricted during the peak season, which is the mid-year winter school holiday period. This book is a must for anyone planning a visit to this wonderful park. It starts with a brief history of the park and an overview of nature activities and the behaviour of the park animals. There are then separate
sections on primates, carnivores, herbivores, the smaller mammals, reptiles and larger birds. These sections provide a good overview of the biology of each of the groups. A comprehensive appendix provides information on the general code of conduct and the ecology of the park, including that of the rivers. Poaching is covered – unfortunately the rhino poaching numbers are already out of date. There is also a section on malaria – important as the park is in a malaria-endemic area. An excellent book to complement your trip to the Kruger National Park.
Interesting behaviour Wildways: Field companion to the behaviour of southern African mammals. By Peter Apps. (Cape Town. Struik Nature. 2014.) There are many field guides to African mammals and there are also extensive, academic volumes that cover this interesting group of animals. But this short, accessible book complements them all as a text that is easy for the amateur to understand and also as a quick reference for the professional. Essentially this is a field guide to the behaviour of southern Africa’s mammals and should be used in conjunction with an identification guide by those who want to do more than just watch. This is for people who are interested in understanding what the animals they are watching are doing – and why. It provides the reader with descriptions and explanations of the fascinating habits of southern Africa’s mammals. Of course, the amount of detail for the different species varies enormously, depending on the extent of research that has been done on the different animals. The author has concentrated on providing information on those animals that an amateur is likely to see – as well as some behaviours that are rare or particularly interesting. There is a good list of further reading for those who would like to follow up in more detail. The book starts with a look at some examples of unexpected or unusual behaviours that have lead to many misunderstandings of the animal’s motivation – such as the apparent unique concept of death among elephants. The author gives good scientific explanations for this type of behaviour, which in fact is not unique to elephants. The science of animal behaviour is called ethnology and there is a simple and concise account of this, concentrating on the causes of a particular type of behaviour, how it developed, what its function is and how it evolved. This guides the reader through the accounts of the different behaviours of the species covered in the book.
Before starting the individual species accounts, the author outlines the specifics of mammal behaviour such as reproduciton, social life, sexual behaviour, territoriality and learning and play. The species accounts are comprehensive and drawn from the latest research, illustrated with black and white photographs and line drawings. The book will contribute to a greater understanding of our rich mammal life and how important it is to conserve it.
Under the sea The Reef Guide: Fishes, corals, nudibranchs and other invertebrates, East and South Coasts of Southern Africa. By Dennis King and Valda Fraser. (Cape Town. Struik Nature. 2014.) This is one of those wonderfully colourful books that immediately makes you want to get your snorkel and mask out and head for tropical coasts. Although, the area covered includes the Cape coast, which is far from tropical. Because we cannot easily see our coastal life it is easy to forget the enormous wealth of sea life that surrounds our shores, and this book fills that gap. There is a simple explanation of how to use the book, which starts with the identification guide to the fishes – both cartilaginous and bony. Diagrams show the external features of the two types of fish and then outlines of the different fish groups as identification groups and a pictorial guide to fish families, with page references, acting as a table of contents for the different groups. The fish are followed by sea anenomes and corals, shrimps, lobsters and crabs and then the molluscs. The final and smallest group are the starfish, sea urchins and sea cucumbers. There is also a comprehensive glossary of terms. It is a book to study in depth before going on a trip that includes snorkelling or diving off our coasts and, as the authors say, it is surprisingly easy to learn to recognise these creatures if you have spent time going through the book.
Scientific names Latin for Birdwatchers: Over 3 000 Scientific Bird Names Explored and Explained. By Roger Lederer and Carol Burr. (Cape Town. Struik Nature. 2014.) This is a book for those who love finding out about more than the ordinary. Birdwatchers are generally happy to simply identify birds in the field, with the common name given more weight than the scientific name, which appears in italics next to this. Birders also tend to group birds by 10 |2 2014
behaviour or context – raptors covers all large predatory birds, dabblers and divers, the diving ducks, for example. The scientific names – binomials – are used by scientists to define the exact evolutionary relationships of birds and are standard across the world. Although the names are derived from Greek or Latin, they are descriptive and if you take the time to look at these names, you can see interesting patterns and find relationships between birds that you might not have known about before. Latin for Birdwatchers is not only about the origin of scientific names. It is also about how and why birds are named and also adds bits and pieces of information about the birds themselves. The book is organised into an alphabetical listing, with the scientific name and which bird or group of birds this describes. Latin in action boxes connect the history of scientific names to individual birds or groups of birds. Genus profile pages are dotted through the book looking at the particular characteristics of different bird genera. There are also accounts of famous birders, as well as bird themes, which examine the physical attributes and behaviour of certain birds in depth,
International Conference coming to South Africa! Minerals as Mines of Information
21st General Meeting of the International Mineralogical Association 1 - 5 September 2014
Sandton Convention Centre, Gauteng, South Africa Hosted by:
Geological Society of South Africa
MINERALS AS MINES OF INFORMATION
The IMA 2014 Organising Committee invites you to participate in the 21st General Meeting of the International Mineralogical Association. This is the first time that this quadrennial conference will take place in Africa, with South Africa being the proud hosts. The overall theme of the conference is “Minerals as Mines of Information”, in recognition of South Africa’s resource wealth and mining heritage. IMA 2014 promises to be an exciting experience, in bringing the world’s leading mineralogists to Africa and exposing mineralogists from around the world to the latest research in various fields. We look forward to welcoming everyone to South Africa in September! Dr Sabine Verryn (Chairperson) Dr Desh Chetty (Scientific Programme Chair) Dr Craig Smith (Finance Chair)
For more information visit: www.ima2014.co.za Email: firstname.lastname@example.org • Tel: +27 11 463 5085 10 |2 2014
looking at any relationship between these and the scientific names. There is also a short history of binomials – useful as an adjunct to the Life Sciences curriculum which now covers this in some depth.
Silent voices Engraved Landscape: Biesje Poort, Many Voices. By Mary E Lange, Liana Müller Jansen, Roger C Fisher, Kenyan G Tomaselli and David Morris. (Jeffreys Bay. Tormentoso. 2013.) This lovely book was published with funding from the National Heritage Council of South Africa, who regarded the Biesje Poort rock art as an important part of our national heritage. The landscape of Biesje Poort is graphically shown with beautiful photographs of the area, setting the scene for the exploration of the area’s rock art. Rock art is seen as an important part of our indigenous knowledge systems and is a living reminder of things past. This book provides an account of the valuable record of important pre-historic and historic remains that most of us will never see. It also shows new ways of doing research in this type of environment. The various contributors to the book use the rock engravings as a way to probe questions about the nature of heritage and our links to the land. This is more than a coffee table book – it is one that invites the reader to probe more deeply into our fascinating roots.
The world’s oldest vertebrate In 2012 fossil finds in southwestern Canada started to give us new insights into the evolution of vertebrates and their jaws in particular. The creature, called Metaspriggina walcotti was previously known from two very small fossil fragments found almost 100 years ago, and was first described in 1933. Now, scientists have found larger specimens, the largest about 6 cm long and the best preserved and most complete fossils include impressions of eyes, muscle groups and support for the gills. The creature swam actively, had large, prominent eyes – with a lens – and a curved, paired structure supporting the gills. It is the arrangement of these paired structures that suggests an early step in the evolution of jaws. Detailed analysis places Metaspriggina near the base of the vertebrate family tree and certainly among the earliest fish. An artist’s impression of Metaspriggina walcotti. Image: Science Direct
Prof. Mike Davies-Coleman, Dean of Natural Sciences at the University of the Western Cape, is an expert on the chemical interactions among Algoa Bay’s reef inhabitants. Image: Mike Davies-Coleman
Algoa Bay’s underwater ‘chemical warfare’ Under the waves of Algoa Bay, there is daily ‘chemical warfare’ between reef-dwellers like sponges, soft corals and sea slugs, who protect themselves from fishy predators with toxic organic chemical compounds. Studies of these organic compounds – called marine natural products – have captured the imagination of scientists the world over, particularly as some have been found to have anti-cancer properties. Prof. Mike Davies-Coleman, long-time researcher in the waters of Algoa Bay and Dean of Natural Sciences at the University of the Western Cape, recently spoke about this underwater world in a public lecture at Nelson Mandela Metropolitan University, entitled ‘Molecules and marine life in Algoa Bay – a journey of discovery’. The main reason for this talk was to promote Algoa Bay as one of the world’s ‘Hope Spots’ – an initiative championed by Mission Blue, a global initiative of the Sylvia Earle Alliance, and supported in South Africa by the Sustainable Sea Trust, to set up formally-protected conservation areas to keep the ocean healthy. Dr Earle, a renowned ocean researcher who last year received an honorary doctorate from NMMU, will be launching South Africa’s first five Hope Spots in December 2014. Davies-Coleman – a trained organic chemist who spent 28 years at Rhodes University and has also worked at the Scripps Institution of Oceanography (SIO) at the University of California, San Diego – has spent his career studying the chemistry of the compounds produced by marine cyanobacteria, plants and invertebrates in the Eastern Cape. ‘The marine organisms that produce these compounds do so for a purpose we don’t know unless we see the consequences in action and can then work out who the players are in this fascinating chemical ecology that is very common on marine reefs. ‘In Algoa Bay, there are some sea slugs that don’t make the compounds themselves. Instead, they will eat a sponge and then make use of the sponge’s toxic chemicals, storing it in special glands in their skin to deter predators. The first clue we have that a sea slug is carrying a chemical arsenal is its bright colouration. Bright colours clearly say “don’t eat me” in the marine world.’ Davies-Coleman said by sheer luck, scientists had found that some marine compounds had anti-cancer properties. ‘They have the ability not only to deter predators but also serendipitously to kill cancer cells.’ In Algoa Bay, the National Cancer Institute in the United States in collaboration with researchers at Rhodes University and the University of Cape Town, have conducted extensive cancer research on marine natural products. ‘We’ve found a number of molecules that kill cancer cells. The problem is they kill other normal cells too.’ However, the research has not been in vain as they have been able to study how some of these molecules kill cancer cells, which has assisted in the understanding of the biology of cancer cells, opening new avenues for anti-cancer drug development in the laboratory. Davies-Coleman said research by his team on a sponge collected from Aliwal Shoal, north of Algoa Bay, had also revealed a marine natural product that potentially could kill antibiotic-resistant bacteria that are causing increasing numbers of fatalities in hospitals around the world.
Some of the exquisite sea squirts inhabiting the reefs of Algoa Bay. Images: Shirley Parker-Nance
He said the semi-pristine reefs off Algoa Bay were quite spectacular – especially compared with other reefs off industrial cities. ‘In particular, there is an amazing and unique diversity of sea squirts. What’s special about these particular marine invertebrates is that many not only produce toxic natural products, but they also accumulate metal ions.’ Along with other reef-dwellers like sponges, they act as filters, taking in the toxic heavy metals potentially polluting the ocean. ‘A 1 kg sponge, which can fit into a shopping packet, filters the equivalent of an Olympic-sized swimming pool every day. ‘If you took out all the sponges, sea squirts and soft corals, Algoa Bay would be a cess pool. They do an amazing job.’
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Science Science for for South South AfricA AfricA
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Probing our cosmic past
Science for South AfricA
Volume 10 | Number 1 | 2014
Antibodies and HIV vaccines Rising sea temperatures and coral reefs Gliders in the ocean: a dual robotics platform
The search for Earth-like planets
Volume 9 | Number 4 | 2013
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DNA: The code of life The human genome: first in Africa Where do chameleons come from?
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Velvet worms: DNA and conservation The oldest scorpion Short tails key to modern birds Nantechnology in space
Clouds: the enigma in our skies
ISSN 1729-830X ISSN 1729-830X
The electromagnetic spectrum: key to understanding our Universe Time machines and the accelerating Universe
The SK A: Answering questions about the cosmos Shedding light on Dark Matter A. sediba: A curious mosaic
Citizen science makes a difference to Leopard Toads
The Age of the Anthropocene: climate change
Volume 9 • Number 2 • 2013 Volume 3 • Number 2 • 2007 r20
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History and ichthyology in South Africa
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Declining numbers of seabirds at Marion Island By Nicky Willemse A team from Nelson Mandela Metropolitan University (NMMU) returned in May 2014 from a five-week research trip to Marion Island. The island is expriencing decreasing numbers of several of the seabird species that breed on the island. It was the second relief trip to Marion Island for the newly built SA Agulhas II research vessel, to pick up the over-wintering research team and to drop off a new team with new supplies. NMMU students form part of these teams. Master's student Tegan Carpenter-King has been studying the foraging distribution, diet and breeding success of gentoo penguins while honours student Makabongwe Sigqala has been studying burrowing seabirds. Included in the new team is MSc graduate David Green, who will be monitoring and studying various seabird species over the next 12 months. NMMU zoology senior lecturer Dr Pierre Pistorius said, ‘The most likely explanation for the declining numbers of several of the seabirds breeding on the island is that oceanographic conditions are changing and sea temperatures are rising. The Antarctic Polar Front, an important foraging area, is moving further south and away from the island due to ocean warming and this places greater energy demands on foraging seabirds commuting back and forth to provide food for their chicks. ‘Over the past few years, there has been a substantial drop in the “arrival weight” of macaroni and southern rockhopper penguins [they return to the island to breed after long periods at sea], clearly indicating that food is limited, which results in poor breeding success.’ Inshore-foraging gentoo penguins and cormorants (crozet shags) have both experienced a similar decline in numbers and Pistorius said this was probably associated with the virtual disappearance of a species of krill (Notocaris) endemic to Marion Island that once formed a major part of their diet. ‘There are big changes to both the inshore and offshore environment around Marion Island.’ Over the last 20 years, macaroni penguins have decreased by 30% and southern rockhopper penguins by 70%. There are currently 290 000 breeding pairs of macaroni penguins and 40 000 breeding pairs of rockhopper penguins. ‘Inadequate breeding success has influenced the decrease of macaroni and rockhopper penguins, largely because they are starting the breeding season with lower body weight and energy reserves than before.’ Gentoo penguins have decreased by 30% since the mid-1990s, also due to poor breeding success. There are currently only 900 breeding pairs of gentoo penguins on Marion Island. NMMU’s various research projects on the island fall within the South African National Antarctic Programme (SANAP) and are conducted in collaboration with researchers from the Department of Environmental Affairs (DEA) and the Percy FitzPatrick Institute for African Ornithology, University of Cape Town. ‘Each year, we weigh rockhopper and macaroni penguins when they arrive on the island,’ said Pistorius. ‘This gives us an indication of prey availability. They are now arriving in poorer body condition than they did 10 to 20 years ago. They are often not finding sufficient food and this leads to high chick mortality and poor subsequent recruitment into the adult population.’ There is not much fishing activity in this area, but Pistorius believes that warmer temperatures are influencing prey availability partly by forcing food sources to move further south. ‘These penguins will often swim hundreds of kilometers during a single foraging trip. They go where food is predictable, but the level of predictability has diminished and they are swimming further to find food and bringing less back for their offspring.’ King penguins swim even further – up to about 3 000 km on a single foraging trip. Among the penguin populations on Marion Island, their numbers are the most stable, but this could also be
Macaroni penguins walk over a data logger which picks up information stored in passive integrated transponders (microchips) implanted under their skin. This information is stored in transponder readers, powered by solar panels. Image: NMMU
Nelson Mandela Metropolitan University zoology senior lecturer Dr Pierre Pistorius and zoology honours student Makabongwe Sigqala implant special microchips called passive integrated transponders into macaroni penguins on Marion Island, to monitor survival rates and the time it takes them to forage for food. Sigqala spent the last year on the island, conducting research on burrowing seabirds. Image: NMMU
due to the fact that they dive to great depths to find their prey, where conditions are likely to be more stable. During the research trip, Pistorius continued an existing programme to fit GPSs to king penguins, to get a more accurate picture of their foraging distribution. ‘We know little about them, despite Marion Island having one of the largest populations of king penguins in the world.’ He also continued a project started last year to fit passive integrated transponders (microchips) to macaroni penguins.The data collected enables scientists to work out individual survival rates and the durations of their foraging trips. ‘A long time spent foraging is an indication of a shortage of food.’ ‘Seabirds as a group are among the most threatened of any group of animals … The sub-Antarctic regions have globally significant proportions of seabirds. We monitor numbers and breeding performance every year as part of a long-term monitoring programme. This gives us an indication of their conservation status as well as any changes in the subantarctic marine ecosystem.’ Pistorius said global change showed its most severe impacts at high latitudes (polar regions). ‘By studying top predators like seabirds, you get a window into changes in the ecology of these environments. If foraging or demographic parameters change, it reflects changes in the food chain.’
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Back page science
Breaking the rules may be ‘cool’ – or not Journal of Consumer Research and World Science staff
Research has found that people and brands become ‘cool’ by understanding what’s considered normal, obeying the rules considered necessary, then diverging from those considered not necessary. Coolness helps sell everything from fashion and music to electronics and cigarettes, note the authors of the work, published in the Journal of Consumer Research. ‘Our research explores how brands and people become cool in the eyes of consumers. We reasoned that brands could become cool by breaking rules that seemed unnecessary or unfair, but not by breaking legitimate rules,’ write authors Caleb Warren of Texas A&M University and Margaret C Campbell of the University of Colorado. In one study, participants were asked to assess an advertisement that advocated either breaking or following a dress code. Some participants read that the dress code existed for a legitimate reason (to honour war veterans), whereas others read that it existed for an illegitimate reason (to honour a corrupt dictator). Results indicated that breaking the dress code made the brand seem cooler in the second case than in the first. The problem is that it’s hard to be cool to everyone: what some see as cool, others will label deviant. ‘Collectively, our studies find that coolness is a subjective, positive trait perceived in people, brands, products, and trends that are autonomous in an appropriate way,’ the authors conclude. Source: World Science, http://www.world-science.net
Scientists take step toward usable fusion energy Special to World Science
Scientists have taken a key step toward using fusion, the process that powers the Sun, to produce energy, according to a report in the research journal Nature. Fusion energy is envisioned as a way to produce virtually unlimited power to supply the Earth’s needs, but no one has succeeded in devising a fusion process that gives out more energy than it takes in. Physicists at Lawrence Livermore National Laboratory in California said they succeeded in at least releasing more
energy through a fusion reaction than is absorbed by the fuel that triggers the reaction. But that energy is still only about a hundredth of the total energy needed to set up the process in the first place, they said, most of which goes into compressing a fuel pellet where fusion takes place. The whole process took place in a space less wide than a human hair and in only the tiniest fraction of a second – 150 picoseconds, to be exact. Their process used inertial confinement fusion, which initiates nuclear fusion reactions by heating fuel pellets until they implode, compressing the fuel. The fuel consists of deuterium and tritium – isotopes, or variant forms, of hydrogen. When squeezed together, they merge, creating a helium nucleus, and releasing energy along with a neutron or subatomic particle. The confinement squeezes the atoms of fuel to get them running toward each other at high velocity, which overcomes their mutual electrical repulsion. Source: World Science, http://www.world-science.net
Two atoms, deuterium and tritium, fuse together, forming a helium nucleus, a neutron and lots of energy. Image: F4E
Compact and extremely smallscale incubator microscope to examine cells in time lapse Biologists and doctors rely heavily on incubators and microscopes. Now the Fraunhofer Institute for Biomedical Engineering has come up with a novel solution that combines the functions of both these tools in a compact and extremely small-scale system. It is ideally suited for time-lapse examination over a number of weeks and for automatic observation of cell cultures. The incubator microscope is no bigger than a soda can and costs 30 times less than buying an incubator and a microscope separately. Source: Fraunhofer-Gesellschaft
No bigger than a soda can, the small-scale incubator microscope is a space-saving and cost-effective solution for time-lapse observation of cell cultures. Image: Fraunhofer IBMT
Hubble sees starbursts in the wake of a fleeting romance The image below from NASA/ESA’s Hubble Space Telescope shows galaxy NGC 4485 in the constellation of Canes Venatici (The Hunting Dogs). The galaxy is irregular in shape, but it hasn’t always been so. Part of NGC 4485 has been dragged towards a second galaxy, named NGC 4490 – which lies out of frame to the bottom right of the image. Between them, these two galaxies make up a galaxy pair called Arp 269. Their interactions have warped them both, turning them from spiral galaxies into irregular ones. NGC 4485 is the smaller galaxy in this pair, which provides a fantastic real-world example for astronomers to compare to their computer models of galactic collisions. Many of the stars in this connecting trail could never have existed without the galaxies’ fleeting romance. When galaxies interact hydrogen gas is shared between them, triggering intense bursts of star formation. The orange knots of light in this image are examples of such regions, clouded with gas and dust. Source: European Space Agency, via NASA
Galaxy NGC 4485. Image: ESA/Hubble & NASA, Acknowledgement: Kathy van Pelt
MIND-BOGGLING MATHS PUZZLE FOR Quest READERS Q uest Maths Puzzle no. 29
You are a prisoner sentenced to death. The emperor offers you a chance to live by playing a simple game. He gives you 50 black marbles, 50 white marbles and two empty bowls. He then says, ‘Divide these 100 marbles into these two bowls. You can divide them any way you like as long as you use all the marbles. Then I will blindfold you and mix the bowls around. You then can choose one bowl and remove ONE marble. If the marble is WHITE you will live, but if the marble is BLACK ... you will die.’ How do you divide the marbles up so that you have the greatest probability of choosing a WHITE marble?
Answer to Maths Puzzle no. 28:
Solution Ace of Diamonds, King of Hearts, Two of Spades. The winner of Maths Puzzle no: 28 was Akani Mathivha.Congratulations!
10| 2 2014
Win a prize! Send us your answer (fax, e-mail or snail-mail) together with your name and contact details by 15:00 on Friday, 11 July 2014. The first correct entry that we open will be the lucky winner. We’ll send you a cool Truly Scientific calculator! Mark your answer ‘Quest Maths Puzzle no. 29’ and send it to: Quest Maths Puzzle, Living Maths, P.O. Box 195, Bergvliet, 7864, Cape Town, South Africa. Fax: 0866 710 953. E-mail: email@example.com. For more on Living Maths, phone (083) 308 3883 and visit www.livingmaths.com.
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