Ultramarine 2023 | Stories from the oceanic frontline

ICY POLE? News from the deep, deep south

FISHY BUSINESS How they tell fact from fear

WHALE TALES Southern rights, orcas and more

PLUS Climate, discovery, research and data

ULTRA MARINE 2023

STORIES FROM THE OCEANIC FRONTLINE

Contents

06

22

08 At a crossroad

24 SWOT team

12 Spotlight

28 Spotlight

14 Shorts

30 Shorts

05 Editor’s letter

A toe in the water

In Focus 20 Ocean tech 36 Great Barrier Reef 52 Citizen Science 68 Marine mammals 84 Back page

2 mindaroo.org minderoo.org

An exploration of the impact of ocean oxygen levels on the survival of yellowfin tuna.

Eukaryotic eureka

Seal slumbers Super-deep super star Depth division Orca culture

CLIMATE

At sea with researchers using SWOT satellite data to study ocean currents.

Weather or not

Southern reef Flood zones Coastal retreat Ocean heatwaves

FROM LEFT: BERNARD RADVANER, DKART / GETTY IMAGES.

DEEP DIVE

38

54

70

40 Back from the brink

56 Taking stock

72 Below the surface

44 Spotlight

60 Spotlight

76 Spotlight

46 Shorts

62 Shorts

78 Shorts

FROM LEFT: ANDREW PEACOCK, PAUL SOUDERS, HUDIEMM / GETTY IMAGES.

ANTARCTICA

The southern right whale’s road to recovery has been long and fraught with obstacles.

Imposing Emperor

Deep ocean currents Sea ice Pollution Southern Ocean

MARINE LIFE

The citizen science project at the heart of a recent grey nurse shark census.

Fur seal facts

Octopus dreams Ichthyosaur Baleen whales Fish misinformation

HUMANS AT SEA

The likely impact of deep-sea mining on the complex and understudied seabed.

Plastic (not so) fantastic

Fukushima Chemical extraction Wind farms Leafy sea dragon

cosmosmagazine.com

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Dive into the science beneath our oceans

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Supported by Minderoo Foundation 4 mindaroo.org

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JEFF ROTMAN / GETTY IMAGES

From the Editors As anyone who’s rolled out of a boat in diving or snorkelling gear into deep water knows, there’s nothing as thrilling as e ­ ntering the ocean and peering inside it. Whether in warm tropical waters or the shiverinducing briny of temperate and lower marine environments, Earth’s oceans and seas brim with life, wonder and mystery.

These vastly wide and deep aquatic spaces are not a place of home comfort for humans, but our lives depend on them in myriad different ways, from global climate to food to the many systems that rely on the ocean’s components for survival. And yet oceans are among the world’s habitats that have been most affected by human activity, and many of the problems afflicting them are now piling up. It’s going to take a lot of effort and scientific knowledge to set things right.

That’s the essential mission behind the Minderoo Foundation’s commitment to ocean science, and the reason Cosmos partnered with Minderoo to create the Ultramarine project. Minderoo Oceans Executive Director Dr Tony Worby has dedicated his career to ocean science, including long and important stints at the Australian ­A ntarctic Division and CSIRO. We’re delighted to be working with Tony and acknowledge his interest and support.

As 2023 ticks to a close, we wanted to showcase some of the stories that have appeared this year under the Ultramarine banner, and an e-yearbook seemed the perfect vehicle. We have p­ublished some 120 stories with a marine focus over the past 9 months; a small selection of those appears in this yearbook.

Ian Connellan Editor-in-Chief, Royal Institution of Australia cosmosmagazine.com

5

BART MAXBZW7MKS4 / UNSPLASH

DEEP

6 minderoo.org

How creatures lived and behaved below the ocean’s surface was long an unknown, but researchers are slowly revealing the deep’s mysteries.

DIVE cosmosmagazine.com

7

8 minderoo.org

DEEP WATER * FEATURE

GIORDANO CIPRIANO / GETTY IMAGES

Breathe deep: yellowfin tuna oxygen needs reveal marine problems In the vast expanse of our planet’s tropical and sub-tropical waters, the yellowfin tuna (Thunnus albacares) reigns supreme. Known for their speed and agility, these large fish have long been sought after by pelagic fisheries across their global range.

By Melissa Márquez

cosmosmagazine.com

9

DEEP WATER * FEATURE

A

study has tracked the habits of these tuna in the Galapagos region, and explains their reliance on oxygen for speed and agility. But what if oxygen levels are changing due to climate change?

Residing among the top ten species in terms of landing weight worldwide, these tunas are the darlings of the Eastern Pacific Ocean. In 2021 alone, approximately 260,000 tonnes were hauled in from this region.

The Eastern ­Pacific Ocean’s yellowfin tuna population isn’t currently overexploited, according to the study. At p ­ resent, the stocks seem to hover around the modelled maximum sustainable yield of 288,000 tonnes. However, the risk of ­surpassing this critical threshold looms large, potentially jeopardising the species’ equilibrium.

While the yellowfin ­t una’s prowess serves it well, in tropical zones the c­hanges in habitats are becoming evident. With their o ­xygen ­demands heightened by their vigorous gill-­ breathing lifestyle, yellowfin tuna are ­being impacted by expanding low-oxygen zones. A deeper understanding of the species’ ecological habits is crucial in gauging their vulnerability.

Previous tracking studies have revealed that yellowfin tuna often stick to their tagged areas without significant migrations. Their preferred ‘hangout’ is the mixed layer, an oceanic zone where surface temperatures remain stable, allowing them to maintain their active lifestyle. However, they do venture deeper, diving ­below the thermocline into colder waters to forage for prey.

Here they can maintain a higher muscle temperature than their surroundings, allowing them to ­navigate into colder waters for brief hunting ­expeditions. The availability of food dictates the extent of their dives, and there’s a delicate interplay between prey presence and temperature and oxygen constraints.

While they can acclimatise to lower oxygen ­levels through physiological adjustments, there’s

“

a breaking point. Oxygen concentrations below ­certain thresholds affect their blood oxygen reserves, ultimately curtailing their ability to meet metabolic demands.

Oxygen in our oceans plays a crucial role in various biological and chemical processes. It gets into the water through two primary mechanisms: physical exchange at the water’s surface (diffusion) and biological processes within the water (such as photosynthesis).

Climate change can impact oxygen levels in water through various mechanisms, including ­warming waters (which hold less dissolved ­oxygen), ­disrupting ocean circulation patterns (leading to changes in the distribution of oxygen-rich and oxygen-poor water masses), exacerbating conditions that favour harmful ­a lgal blooms (which consume large amounts of oxygen), and ocean acidification.

The Marine Reserve in the Galápagos has emerged as a pivotal location in the yellowfin ­t una’s life. Situated in the path of the South Equatorial Current, this reserve serves as a crossroads for warm and cool waters, creating a hotspot of productivity.

This part of the ocean – the Eastern Tropical Pacific – faces unique c­ hallenges due to its relative oxygen levels.

Dissolved oxygen levels at 100 metres dive below 2.4ml/l throughout the Galápagos Marine Reserve, painting a picture of limited oxygen availability.

This deficiency is ­attributed to high surface productivity, a strong pycno­cline (density boundary), and sluggish oceanic ventilation.

Yet the habitat used by tuna here remains ­largely unstudied, until now. New research from the Galapagos Science Center with the U ­ niversity of Southampton, Universidad San Francisco de Quito, and the Marine Megafauna Foundation (MMF) has sought to examine the vertical movements of ­yellowfin tuna.

Eight yellowfin tuna were equipped with ­satellite tags, allowing researchers to monitor their movements both vertically and horizontally for ­periods

The habitat used by tuna here remains largely unstudied, until now.

10 mindaroo.org

© OSCAR JOHNSON VIA INATURALIST (CC BY-NC ND 4.0)

Yellowfin tuna in the Gulf of Mexico.

ranging from four to 97 days. ­Surprisingly, these tuna, usually found near the surface at a ­median depth of 24.3 metres, occasionally ventured into colder, oxygen-deficient waters.

“These occasional deep-water dives, predominantly during the day, followed by recuperative ­periods near the surface, suggest the tuna’s need to re-oxygenate post venturing into oxygen-­deprived areas,” explained MMF’s Dr Chris Rohner, lead ­author of the movement study.

While short tag retention limited their tracking, the researchers believe it is evident that these tuna maintain their presence within the reserve’s boundaries.

Yet, the implications of climate change are ­undeniable. As oxygen levels drop and the extent of

suitable habitat shrinks, the yellowfin tuna might need to make compromises.

These fish may need to frequent shallower depths or adapt their diving behaviours to ­accommodate their oxygen needs. Such shifts have ramifications, influencing predation dynamics, prey choices, and, ultimately, their susceptibility to fishing gear. This change could possibly make them more susceptible to surface fishing methods.

Though the study orbits around the Galápagos, its revelations hold global significance.

“Our research on the yellowfin tuna in the Galápagos paints a cautionary tale of the future of global marine life in a changing climate. The ­urgency to fortify our marine conservation efforts has never been clearer,” says Rohner. cosmosmagazine.com

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DEEP WATER * SPOTLIGHT

Meet your oldest eukaryotic ancestor found in 1.6-billionyear-old rock A “lost world” of organisms that lived in Earth’s ancient waterways about 1.6 billion years ago has been found fossilised in rock from the ocean near Australia’s Northern Territory.

Name: Protosterol Biota – remnants of an era when more advanced organisms including algae and fungi started to flourish.

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Size: Likely larger and more complex than bacteria, with which they shared their environment.

Diet: May have been the world’s first predators, hunting and devouring bacteria.

NNEHRING / GETTY IMAGES



Habitat/range: In waterways worldwide from about 1.6 billion to 800 million years ago.

Conservation status: Abundant and widespread – but only as fossils.

Superpower: Oldest remnants and originators of all modern eukaryotic forms, including humans.

cosmosmagazine.com

13

DEEP WATER * SHORT

Elephant seals rest at sea in downward-diving “sleep spirals”

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SEALS

Scientists have scanned the brains of 13 elephant seals and discovered how they sleep when they’re foraging in the ocean.

VICKI JAURON, BABYLON AND BEYOND PHOTOGRAPHY / GETTY IMAGES

By Ellen Phiddian They’ve found that the seals function on two hours of sleep per day out at sea, which they grab in 10-minute bursts on deep dives, where they spiral gently towards the sea floor.

“For years, one of the central questions about elephant seals has been when do they sleep,” says Professor Daniel Costa, director of the Institute of Marine Sciences at the University of California – Santa Cruz (UCSC), US. On land in breeding season, elephant seals can sleep for more than 10 hours per day, but can spend as much as eight months at a time on foraging trips in the Pacific Ocean.

“The dive records show that they are constantly diving, so we thought they must be sleeping during what we call drift dives, when they stop swimming and slowly sink, but we really didn’t know,” says Costa.

The researchers developed an electroencephalograph (EEG) system that could track the seals’ brainwaves while they were at sea.

“We used the same sensors you’d use for a human sleep study and a removable, flexible adhesive to attach the headcap so that water couldn’t get in and disrupt the signals,” says lead author Dr Jessica Kendall-Bar.

Sleepy divers: elephant seals.

They tested the neoprene headcaps with five captive seals.

“I spent a lot of time watching sleeping seals,” says Kendall-Bar. “Our team monitored instrumented seals to make sure they were able to reintegrate with the colony and were behaving naturally.”

They caps were then fitted on eight wild seals, along with depth recorders and accelerometers to track the seals’ movements.

Researchers collected data from 104 sleep dives, which showed that the seals go into a deep sleep stage while gliding downward, then switched to rapid eye-movement (REM) sleep.

“They go into slow-wave sleep and maintain their body posture for several minutes before they transition into REM sleep, when they lose postural control and turn upside down,” says Kendall-Barr.

The seals are deep enough at this point that they tend to keep sinking, drifting downwards in a corkscrew “sleep spiral”, and occasionally ending up resting gently on the sea floor.

“It tells us something about the decision-making processes of these seals to see where in the water column they feel safe enough to go to sleep,” says Terrie Williams, director of the Comparative Neurophysiology Lab at UCSC. The EEG “sleepscape” might be useful for showing researchers where to direct conservation efforts.

“Normally, we’re concerned about protecting the areas where animals go to feed, but perhaps the places where they sleep are as important as any other critical habitat,” says Williams. cosmosmagazine.com

15

“Living asteroid” new, super-deep sea star A “living asteroid” – or sea star – is lurking off the coast of southern Australia, in waters 3,850 metres deep.

DISCOVERY

By Ellen Phiddian

What do deep sea creatures and batteries have in common?

Listen now: Poraniomorpha tartarus, a sea star discovered in deep waters off the coast of Gippsland.

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It’s the deepest known occurrence of a sea star in the continent’s waters, and also a brand-new species. Dubbed Poraniomorpha tartarus, the sea star was collected in a 2017 ocean expedition led by the Museums Victoria Research Institute.

Deep-sea expeditions such as this yield many more specimens than there are experts to identify them – there are an estimated 250,000 undiscovered species in deep Australian waters, which is why it’s taken six years for the new sea star to be described in Memoirs of Museum Victoria.

These sea-stars are sometimes referred to as asteroids, not because they are from out of this world, but because they are from the class Asteroidea.

“This is the first time this genus has been recorded from not just Australia, but also the Southern Hemisphere,” says Dr Christopher Mah, a researcher at the Smithsonian National Museum of Natural History, US, and selfdescribed “world’s expert on living asteroids” who was brought to Australia to help with taxonomy and description.

Mah says it was “pretty obvious” that the sea star was a new species once he’d seen it, “mainly because no members of this ... family, Poraniidae, were known from Australia”.

The cold water-loving family has been spotted elsewhere, particularly in the North Atlantic Ocean and while this is the deepest star formally reported in Australian waters, Mah knows they go deeper.

“Deep-sea expeditions around Australia have been very active in the last 5-10 years,” he says. These trips have yielded asteroids in deeper areas.

“Experts ... must secure relationships, time, and funds to work on these specimens,” says Mah. “One [aspect] of the ‘biodiversity crisis’ is that experts in taxonomy – the science of identification, naming, and recognising species – are increasingly fewer for certain groups.

“Sea stars might be familiar to the public, but there’s surprisingly few specialists who work on them.

In part, this is why they brought me down to Australia in the first place.”

MUSEUMS VICTORIA

DEEP WATER * SHORT

Chemical compounds help identify discrete ocean regions CHEMISTRY

Concentrations of chemical compounds in specific ocean layers may contribute to the biodiversity of species found in the darkest depths of the planet..

By Matthew Ward Agius

SMARTEX PROJECT / NERC

This abyssal brisingid is a close relative to sea stars, likely from the genus Freyastera.

A British National Oceanography Centre-led collaboration has found evidence for a biogeographic boundary that divides groups of organisms.

The Clarion-Clipperton Zone (CCZ) spans from about 3,500 metres below the water’s surface to the seafloor, around 6,000m deep.

Now, a study, published in Nature, has broken the region into shallow and deep abyssal areas thanks to a transitional boundary at depths of 4,300–4,800m.

Here, the chemical composition

of the water fluctuates, with concentrations of calcium carbonate higher in the shallow abyss. Saturation levels of calcium carbonate in this upper layer support molluscs, cnidarian and echinoderms with harder structures.

“We have known for some time that the abyssal plains are relatively high in biodiversity,” says study co­­ author Dr Adrian Glover, principal scientist at the Natural History Museum in London.

“What has been missing is knowledge of how that diversity is distributed and how it changes across broad spatial scales.

These new data revolutionise our understanding of abyssal Pacific biogeography.”

Glover says the research will be “inform urgent policy decisions on potential deep-sea mining”.

cosmosmagazine.com

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DEEP WATER * SHORT

North Pacific orca culture sheds light on killer whale colonies

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DOLPHINS

Genetic analyses and vocal interpretations have revealed more about killer whales that live in the North Pacific.

WILDESTANIMAL / GETTY IMAGES

By Ian Mannix A study published in Marine Mammal Science has explored the complex interaction between orca culture and the post-glacial history of their time living in the North Pacific.

Marine biologist Olga Filatova from the University of Southern Denmark and her colleagues have shown that orca pods living near Nemuro Strait in northern Japan descend from animals that settled there during the last glacial maximum (LGM), around 20,000 years ago, when heavy ice covered extensive areas of the western North Pacific.

The authors say revealing migration patterns of orcas since the LGM helps understand contemporary genetic diversity and population structure and could help future conservation initiatives.

“The southern resident killer whale community inhabiting the waters of southern British Columbia and Washington State is socially and genetically isolated from the northern resident community,” says the report.

“Southern residents are critically endangered, numbering only about 70 whales and declining, while northern residents comprise more than 300 individuals and their numbers are growing.

Historical isolation has created distinct genetic populations of orca.

“The lack of contact between these communities likely results from the historical geographical isolation due to range shifts during the LGM; after the retreat of the glaciers, their ranges expanded but social isolation persisted likely due to the differences in cultural traits [for example vocal dialects] accumulated over the period of geographical isolation.”

Filatova told Phys.org that orcas are conservative and traditionbound creatures “who do not move or change their traditions unless there is a very good reason for it”.

The research team collected data from free-ranging orcas in Nemuro Strait in May-June 2021 and 2022, using camera equipment to record their movements. They also performed remote biopsies of the animals using crossbows and floating arrows and identified individual whales by their unique markings.

By identifying individuals, the researchers were able to study the patterns of orca movement within the region.

“As top predators, killer whales are sensitive to the disturbances in their prey resources, which may be impacted by rapid climate change,” they write.

“When predators return to their former range they can cause knockon effects in an ecosystem if the predators are effective enough to reduce the abundance or alter the behaviour of their prey, changing the pressure on the next lower trophic level.”

Although orcas are commonly referred to as killer whales, they are actually the largest member of the dolphin family. cosmosmagazine.com

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AMAZING TECH * IN FOCUS

In focus: Amazing tech

Meet Hullbot: Underwater autonomous robots which clean boat hulls and improve ocean health



Seaweed-based edible electronics could outperform other health sensors

 



New buoys for coastal town beset by foreshore erosion

Great idea enables tradies to dispose of cement slurry to avoid damaging the environment



HULLBOT

3D sharks! New interactive online display brings oceans to life

cosmosmagazine.com

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CLI BRAD BOOTH / GETTY IMAGES

Climate change is altering oceans and those changes threaten both human and marine life. Science is learning more and more about what can – and can’t – be done.

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IMATE cosmosmagazine.com

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CLIMATE * FEATURE

Taking the ocean’s temperature “It’s a bit rough tod–”. Shane Keating suddenly turns around to look through the porthole behind him. “Woah! That was a big one!” An Associate Professor in Oceanography at the University of New South Wales, Keating is talking to me from the CSIRO research vessel RV Investigator as it sails through heavy seas, roughly 700 kilometres east of Sydney. He brings his camera closer to the porthole for me to see outside.

There’s a gloomy grey sky above large, white-crested peaks that are crashing against the 94-metre research vessel.

NASA

By Drew Rooke

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The SWOT s­ atellite altimeter operated by NASA and CNES is making the first global survey of Earth’s surface water.

cosmosmagazine.com

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CLIMATE * FEATURE

“

Staring at a screen isn’t ideal in conditions like this,” Keating says, laughing. “Yesterday was beautiful: glassy water, light breeze. But it’s really picked up overnight and we’ve actually got a front coming in tonight. So, it’s gonna get even bigger and more roll-y.”

The RV Investigator set sail from Sydney Harbour on October 9 on a 24-day voyage off Australia’s southeast coast, with more than 60 scientists, support staff and crew on board. And although they’ve had some moments to admire the pods of migrating humpback whales and flocks of short-tailed shearwaters, the majority of their time has been spent in a much less leisurely manner.

“Most of us are working flat out, twelve hours every day.” Keating – who is on the 2:00AM to ­ 2:00PM shift – explains.

“There’s always people up and doing science.”

Much of the science that is happening on board is connected to science that ­ is happening hundreds of ­k ilometres above the ship.

In December 2022, NASA and Centre National D’Etudes, the French space agency, launched a satellite as part of the Surface Water and Ocean Topography (SWOT) ­mission.

It is making the first global survey of Earth’s surface ­water and mapping, in unprecedented detail, the ocean’s topography, using an instrument called the Ka-band radar interferometer.

“The ocean is not flat,” Keating explains. “It actually changes height as you move across it. It can be a few metres higher in one location than another.

And the reason for that is low- and high-pressure systems, just like we have in the atmosphere.”

Oceanographers like Keating use the detailed topographical measurements gathered by the SWOT satellite to study the behaviour of ocean currents.

These vast rivers of seawater were once thought to exist in a state of relative permanence, but in recent times, scientists have detected ocean currents like the Gulf Stream and the East Australian Current becoming more energetic.

“

In pursuit of knowledge Keating says that improving our knowledge of how ocean currents are changing is important for a number of reasons, including developing a better understanding of how ecosystems that contain commercially-important fisheries are responding to climate change, and how to make better use of ocean environments.

“For example, if you’re driving a ship and want to save a bit of fuel, you can go with the flow if you know where the currents are,” Keating says.

He also points out that the ocean has a strong influence on the atmosphere. “We suspect that regions in the ocean where there are strong temperature differences are associated with the formation of large-scale weather systems. We need to understand that better.”

But in order to properly ­interpret the data collected b ­y the SWOT mission and understand what ocean currents are doing, comparative data must be simultaneously collected from the locations the satellite passes over.

This is the responsibility of a large consortium of international scientists and it is ­e xactly why Keating is out on the RV Investigator.

“This cruise is the first to make measurements in the blue ocean around Australia,” he says. But as he points out, rendezvousing with a satellite that is roughly 900 kilometres overhead and moving at very high speeds is “a tricky thing to get right.”

Yet, despite the logistical challenge, “we’ve managed to do it several times already on this cruise and have a few more opportunities before we sail back into Sydney.”

The last flyover occurred a few days earlier, above a large, biologically-rich cold eddy about 500km offshore of Eden, on the New South Wales south coast. With the ship in position, Keating and his colleagues scanned the sky (in vain) to spot the satellite. They then deployed a TRIAXUS, a microwave-shaped instrument which is towed through the water to measure variables such as ­temperature and salinity.

26 mindaroo.org

CSIRO

The ocean is not flat. It actually changes height as you move across it

CSIRO’s research vessel Investigator.

This voyage of the RV Investigator has other ­ bjectives aside from collecting data for the SWOT o mission. Keating’s colleagues have also been ­s urveying seabird populations; measuring biological activity throughout the water column using a laser ­optical plankton counter that is fixed to the TRIAXUS; and tracking a serious marine heatwave that has r­ ecently developed in the region.

“One of the eddies we have been studying this month at sea is enormous and hot, with anomalously hot temperatures extending hundreds of metres down through the water column – more than 3ºC above average,” RV Investigator voyage leader Professor Moninya Roughan says.

“The warm eddy is offshore, so not yet fully impacting coastal waters ... If it pushes down the

coast or onshore it will bring the warm water with it likely earlier than normal.”

The SWOT satellite will continue orbiting Earth and collecting data about its surface for three more years, before a controlled deorbit. Keating says that once the mission complete, it will “totally revolutionise our view of the ocean”.

“Just to put it in perspective, the spatial resolution that we’ll get from the satellite will be ten times what we’re able to see right now. I did a quick calculation, and that’s kind of like going from black and white television to high-definition television in one go,” Keating says.

“We currently view the ocean as a kind of slowly ... evolving thing. In fact, it’s incredibly complex, ­t urbulent and chaotic – and SWOT will reveal that.” cosmosmagazine.com

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CLIMATE * SPOTLIGHT

Explainer: ENSO, IOD, etc: what are the climate features that influence Australian weather?

We’ve all heard the names of Australia’s climate influences.

Where are they, what are they, and what do they do?

Influence: Indian Ocean Dipole.

IOD: The difference in ocean temperatures between west and east tropical Indian Ocean can shift moisture towards or away from Australia.

28 mindaroo.org minderoo.org

Influence: Australian monsoon.

The monsoon drives the tropical wet summer and dry winter. It has active (stormy and wet) and inactive (reduced rainfall (phases.

Influence: Madden-Julian oscillation. This large-scale band cloudiness moves eastwards in the tropics. Thought to affect active/ inactive monsoon.

GOOGLE EARTH



Influence: Southern Annular Mode. SAM is the north-south shift in prevailing westerlies.

It affects rainfall and temperature.

Influence: El Niño. Warmer tropical Pacific waters bring lower rainfall and higher temperatures to eastern Australia.

Influence: La Niña. Cooler tropical Pacific waters bring higher rainfall and lower temperatures to Australia.

cosmosmagazine.com

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CLIMATE * SHORT

PHILIP THURSTON / GETTY IMAGES

The 8,000km Great Southern Reef is in peril

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TEMPERATURE

Even though it fringes more than 8,000 kilometres of densely populated coastline and is a global biodiversity hotspot on par with the Great Barrier Reef, few people have heard of Australia’s other great reef.

By Drew Rooke Comprised of thousands of temperate rocky reefs that are interconnected through oceanographic, ecological and evolutionary processes, the Great Southern Reef stretches from northern New South Wales, down to Tasmania and around the rugged southern coast, and up to Kalbarri in Western Australia.

It is dominated by vast kelp forests which are home to hundreds of species of sponges, echinoderms, crustaceans, chordates, bryozoans, fish and molluscs – at least 70% of which are endemic to the region.

But a new study published in Nature and led by Professor Graham Edgar, Senior Research Fellow at the Institute for Marine and Antarctic Studies at the University of Tasmania, has shown that the reef’s unique biodiversity is in more peril than its famous tropical counterpart.

The study examined population trends of more than 1,000 marine species from 1,636 sites around Australia in the decade to 2021. To complete the “most comprehensive assessment of marine species

Forests of kelp and other seaweeds dominate the Great Southern Reef.

population trends to date”, the researchers relied on a network of volunteer divers trained in scientific data collection as part of the Reef Life Survey.

That data, together with data collected by the Australian Temperate Reef Collaboration and the Australian Institute of Marine Science in Queensland, showed that while a handful of species had increased slightly in number, the populations of more than half of all shallow-reef species around Australia had decreased – with as many as 138 decreasing so much that they are eligible for Endangered and Critically Endangered listing on the IUCN Red List.

While overfishing has contributed to the decline of shallow reef species, the primary driver is increasing ocean temperature associated with human-induced climate change. But the reason temperate-species are being disproportionately impacted by this is more nuanced.

Part of the problem is that the area of the ocean in which the reef is located is a climate change hotspot: in recent years, the rate of ocean warming there has been in the top 10% globally. This warming is particularly acute in the waters surrounding Tasmania, which have warmed by around 1.50C in the past century.

This means that the temperate species that inhabit these rapidly warming waters need to migrate poleward, where the water is cooler, in order to survive. But this isn’t possible, because there is no more suitable habitat to colonise; there is only, as Edgar says, “a cliff at the Southern Ocean barrier”. cosmosmagazine.com

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Despite warnings countries increasing exposure to highhazard flood zones

SNORKEL

A new report has revealed that between 1985 and 2015, urban development around the world has expanded “continuously and rapidly” into high-hazard flood zones like floodplains and riverbeds.

By Tyler Fisher

Riverland Highway turned river: Murray River flooding in South Australia.

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A report in Nature shows that growth in these areas has more than doubled (122%) in the period, compared to growth in less flood prone settlements (60%).

“In many regions, growth in the most hazardous flood zones is outpacing growth in non-exposed zones by a large margin,” says the paper.

“Year-on-year growth estimates confirm that … settlement growth in the highest-hazard flood category has increased by almost 3% a year.”

Urban development in the highest-hazard zones is most prevalent in the East Asia and the Pacific region. “‘No hazard’ settlements expanded by more ­than 100%, whereas ‘very high hazard’ settlements expanded by more ­­than 160%.”

There were some surprises.

South Australia — sometimes called “the driest state in the driest continent” — experienced greater than 50% growth in people living in flood prone areas, while Queensland, which was inundated in the 2010-2011 floods, and suffers cyclones every year, is experiencing a reduction in population in risky regions.

In analysing historical floods, the study noted that not all types of floods were recorded (fluvial, pluvial, and coastal flooding).

Fluvial floods are river floods; pluvial floods are flash floods and surface water; and coastal floods are storm surges on the sea shore.

The report also shows economic status influences an individuals’ risk to live on flood prone areas.

“Of the 36,500 square kilometres of settlements built in highesthazard zones since 1985, 1.1% are in low-income countries, 20.5% are in lower-middle-income countries, 60.8% are in upper-middle-income countries and 17.6% are in highincome countries.”

Why are we building on floodplains? The paper suggests “urbanization, land scarcity, socioeconomic trends and institutional and regulatory factors,” are responsible for the trends.

FROM LEFT: BEYONDIMAGES, CORAL_BRUNNER / GETTY IMAGES.

CLIMATE * SHORT

Coastal environment at risk with less than 10mm sea rise SEA LEVEL

A sea level rise of 5–7mm a year is enough to cause coastal landscapes like mangroves and wetlands to start to retreat, according to research published in Nature.

By Ian Mannix

Coastal wetlands east of Hinchinbrook Island, Queensland.

Coastal ecosystems have long been recognised as indispensable to the well-being and subsistence of millions of people by protecting shorelines, providing a breeding ground for sea life, and storing CO2.

The report warns, however, that “Widespread retreat of coastal habitat is likely at warming levels above 1.5°C.” Lead researcher Professor Neil Saintilan, a coastal wetlands specialist from Macquarie University, says there is a greater awareness of the rates of sea level rise which will affect coastal zones.

“Once you get above 5mm a year, or in places like the Indo-Pacific,

7mm a year, it’s highly unlikely that the mangroves will stay in place,” Saintilan told Science Detectives.

“By 8,000 years ago the rate of sea level rise was around 7mm a year and falling. The rate seemed to trigger the expansion of mangrove ecosystems ... as if that was the point at which they were finally able to actually hold their ground against sea level rise.”

Conversely, rising sea levels at the end of the last glacial period were correlated with very few mangroves surviving.

Mangroves provide a number of important ecosystem services.

As well as providing a habitat and nursery ground for fish, they also protect soft shorelines around the tropics from erosion. Mangroves are also significant carbon sinks.

“Mangroves take carbon dioxide out of the atmosphere which is locked away for thousands of years below ground. It’s what we call blue carbon.”

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CLIMATE * SHORT

Ocean heatwaves more frequent, intense

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DISCOVERY

While scientists have long warned of the negative effects marine heatwaves have at the ocean’s surface, new research suggests these temperature spikes are also having prolonged impacts deeper down.

By Matthew Ward Agius

Explainer: What is coral bleaching?

PHOTOGRAPHY BY MANGIWAU / GETTY IMAGES

PLAY VIDEO

The research, published in Nature Climate Change, found marine heatwaves were at their most intense in the “upper subsurface”, particularly in the equatorial Pacific and Indian Oceans, becoming more prolonged and frequent at lower levels of the water column closer to the poles.

More frequent subsurface marine heatwaves risks species living at around 250 metres beneath the ocean’s surface shifting their habitat and “consequent effects on ecological interactions and ecosystem processes”.

Marine heatwaves aren’t anything new. But the frequency of such events is on the rise, especially at depths below the water column’s ‘surface zone’, potentially extending hundreds of metres.

If ocean warming caused by anthropogenic climate change continues, the knock-on impact will be on ecosystems and marine organisms. That, says one of the study’s contributors Professor Thomas Wernberg, a marine botanist at the University of Western

Aerial view of coral bleaching near Cairns, Queensland, in 2017.

Australia’s Oceans Institute, could also wreak havoc with ocean food supplies.

“Various ecosystem services for people depend on the species at those depths … some fisheries that extend quite deep,” Wernberg says.

“It obviously has consequences whether or not those species persist, or whether they succumb to the heatwave in various ways, or they move.”

Species that exist in marine ecosystems in surface and subsurface water are quite mobile.

At greater depths, they might also be sensitive to small fluctuations i­ n temperature.

Just as land animals seek refuge from the heat, so too might those in the ocean. But when the temperature spikes in your marine neighbourhood, retreat means descending further. Should species resort to deep-diving to new, cooler habitats, the composition of fisheries and wider ecosystems could change.

“Many of these organisms are mobile, they can ... go deeper or they can move to another geographical location,” Wernberg says. “The extent to which they do that, and therefore, knowing where you can catch them ... becomes important.”

Shallow water heatwaves have been recorded for decades, but with improvements in research methods, scientists are expanding their knowledge to temperature spikes across greater ranges and depths.

Wernberg says, “The stuff at depth, there’s absolutely no reason to expect that you don’t have similar effects down there, but because [these regions are] out of sight, we won’t see the effect.” cosmosmagazine.com

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In focus Great Barrier Reef

Turtle nests are at risk from sea level rise

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Baby crown-of-thorns starfish can survive devastating heatwaves

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NAUTILUS CREATIVE / GETTY IMAGES

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GREAT BARRIER REEF * IN FOCUS

Cosmos Shorts: What’s in store for the Great Barrier Reef?

PLAY VIDEO

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Researchers call for reconsideration on indicators for reef health in Indian and Pacific oceans

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Suprising study finds coral bleaching reaches far below the ocean surface

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Great Barrier Reef hard coral recovery flatlines

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DYLAN SHAW / UNSPLASH

ANTAR

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RCTICA The deep south’s ice and ocean life are critical for our world’s natural systems. How will they fare through climate change? Are humans doing enough to help? cosmosmagazine.com

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ANTARCTICA * FEATURE

As the early morning sun cast a golden glow over the eastern coastline of Australia, a sense of anticipation filled the air. Excited onlookers gathered along the rugged shores, perched on cliffs, or nestled in the comfort of beachfront cafes. All shared one common purpose: to witness the awe-inspiring spectacle of southern right whales (Eubalaena australis) on their annual journey.

By Melissa Márquez

40 minderoo.org mindaroo.org

OVERSNAP / GETTY IMAGES

Bringing back southern right whales from the brink of extinction

(Dining) room with a view: a southern right whale feeding in Antarctic waters takes a dive.

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ANTARCTICA * FEATURE

S

uddenly, spectacular plumes of misty spray erupt from the surface. Each blow a signal that the giants of the sea are drawing near.

Excitement ripples through the gathering as the blows grow closer and more frequent.

The whales, moving in a slow and purposeful procession, seem to acknowledge their audience, offering glimpses of their mighty tails and elegant dorsal fins as they glide by. And as the last glimpse of a fluke disappears beneath the surface, the spectators remain, silently paying tribute to the enduring beauty of the natural world and wishing them good luck.

Primarily found in the southern hemisphere’s temperate waters, these whales are one of the largest whale species on the planet, often up to 15 meters long and weighing between 40 and 80 tonnes.

Their striking appearance features dark, nearly black skin adorned with patches of white callosities, which serve as unique identifiers for individual whales. They are filter feeders – baleen plates in their mouths strain planktonic organisms and small fish from the water.

Their feeding grounds are primarily in polar or subpolar regions, while they migrate to warmer coastal waters for breeding and calving.

Their cultural significance extends far beyond their ecological role and scientific interest. In many Indigenous cultures, southern right whales are revered, often regarded as spiritual symbols of wisdom, strength, and harmony with the natural world. Their enigmatic nature and awe-inspiring size have led to beliefs that they possess supernatural powers or embody the souls of ancestors.

Yet, the southern right whale bears witness to a tumultuous history that spans centuries. Targeted for commercial hunting from 1790 to 1980, they faced a perilous existence. The global death toll from this hunt exceeded 150,000 individuals, with the carnage being particularly severe in the

“

waters off New Zealand and southeastern Australia. More than 58,000 southern right whales died near New Zealand; 19,000 off Australia.

Coming back from the brink

The road to recovery for these giants has been slow and fraught with obstacles. Sadly, the eastern population is now estimated to comprise fewer than 300 individuals, including just 68 breeding females, while the western population boasts over 2,500 individuals.

“That’s not many when you consider there was probably at least 25,000 prior to whaling in the 1800s,” says Dr Stephen Burnell, Chief Investigator and pioneer of the long-term southern right whale research project at Head ­of Bight.

Cetaceans, often r­egarded as flagship species and ­ecological indicators, face mounting challenges in the form of consumption, climate change, pollution, industrial development, and fisheries, In particular, southern right whales in the eastern Australian population are exposed to anthropogenic threats, highlighting the urgent need for c­ onservation efforts throughout their range, including breeding and foraging areas.

Australia plays a vital role in these efforts, with two genetically distinct southern right whale populations: a Western Australian group that calve in South Australian and WA waters, and an ­eastern Australian population with breeding ranges ­extending from Victoria to southern Queensland.

The creatures possess a unique population structure driven by their distinct preferences for winter calving and summer foraging. Their choices are guided by a combination of strong site fidelity and ‘cultural memory,’ although they are capable of sudden location shifts, challenging our understanding of their behaviour.

The south-eastern coast of Australia remains crucial for the survival of the Eastern population,

For centuries, these marine mammals have woven themselves into the fabric of coastal communities in various parts of the world.

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ADAM CROPP / GETTY IMAGES

Like their southern right cousins, humpback whales migrate to Antarctica each southern summer to feed up.

with Logans Beach near Warrnambool in Victoria the sole established calving area in the region.

Remarkably, this site has retained its ‘cultural memory’ for southern right whales, likely due to the survival of females familiar with the location during the brutal whaling era.

Despite the dark chapters of their past, the story of southern right whales is one of resilience and hope. The Australian Southern Right Whale Study began surveying in 1991. In the years that have followed, scientists report a remarkable recovery from the brink of extinction: both populations are growing at a rate of approximately 5% per annum.

“They’re recovering well … they’re still nowhere near the numbers they were pre-whaling, but they’re recovering,” says Burnell. “It’s encouraging ... but it’s going to be some time before they’re fully back in their original habitats.”

Dr Claire Charlton from Curtin University, who has been collaborating on the study, revealed that primary calving sites are experiencing increased occupancy during years of heightened abundance.

“More and more whales [are] appearing in small and emerging calving grounds inside and outside of protected areas across the Australian marine park network,” says Charlton.

“The whales are actually choosing ... alternative calving habitat,” including locations like Fowlers Bay, Encounter Bay, Portland in Victoria, and Geographe Bay in Western Australia.

According to Burnell, years ago whales were calving approximately every three years. However, the average calving interval now falls between four and five years, signifying a discernible deceleration in population recovery. Charlton believes the abundance of these whales in Australia may provide insights into what’s transpiring in their foraging habitats.

The Southern Right Whale Conservation Ma nagement Plan, set out by the A ­ ustralian government, requires significant knowledge gaps in our understanding of the species’ needs, ­migratory patterns, and impacts of climate change to be addressed. cosmosmagazine.com

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ANTARCTICA * SPOTLIGHT

Regal bird – by name and by nature

Name: Emperor penguin, Aptenodytes forsteri.

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Size: Height: 1.1–1.3m (adult) Weight: from 45kg at start of breeding season to 23kg at end.

Diet: 2–3kg daily of Antarctic silverfish, krill and other fish species.

MARTIN RUEGNER / GETTY IMAGES

Antarctica’s largest penguin type is the only species that breeds during the bleak, dark southern winter.



What’s going on with the Adélie penguin populations in Antarctica?

PLAY VIDEO

Habitat/range: Endemic to Antarctica, primarily coastal sea ice.

Conservation status: Listed as near threatened by the IUCN Red List, which forecasts a loss of 80% of the species by the end of the century due to ice loss.

Superpower: The planet’s deepest diving bird, with one tagged animal recorded descending to 565m.

cosmosmagazine.com

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ANTARCTICA * SHORTS

HOLGER LEUE / THE IMAGE BANK / GETTY IMAGES

Scientists concerned Antarctic ice melt threatens to collapse the deep ocean currents that affect global temperature and marine habitats

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CLIMATE

Century-long impacts to marine ecosystems and global climate beckon if Antarctic deep ocean circulation collapses, say Australian scientists.

By Matthew Ward Agius The research, published in Nature, examines overturning circulation:a natural process by which deep-water ocean currents act like a conveyor belt, transporting nutrients, oxygen, carbon and heat from the depths of the sea around the globe, shaping climate systems and marine life.

The new modelling, led by Professor Matthew England from UNSW, says this process could slow by more than 40% and collapse by the midpoint of the century, assuming the current global rate of greenhouse gas emissions continues. This, more than other atmospheric influences, is pulling the handbrake on overturning circulation.

In Antarctica, hundreds of trillions of tonnes of dense salt water sinks to the bottom of the ocean every year. This water is rich in nutrients, thanks to the deterioration of dead animal matter sinking with it. Deep ocean currents convey this material northward to the Atlantic, Pacific and Indian oceans.

But the process is being altered by meltwater – the term given to

Overhead of glacier, Neko Harbor, Graham Land, Antarctic Peninsula, Antarctica.

freshwater released by thawing ice. The freshwater dilutes the density of deep ocean water. With less water sinking to the ocean’s depths, the overturning circulation process slows, in turn preventing the movement of nutrients, oxygen and heat to other regions.

England says this process has “knock on” effects that will see the ocean’s ability to absorb carbon reduced, and lead to changes in tropical rainfall bands and the health of marine ecosystem productivity.

These also affect North Atlantic overturning, which is already estimated by scientists to be at a thousand-year minimum. With the rate of ice melt driven by greenhouse gas rises, the research adds an important, antipodean perspective to add to existing research on North Atlantic overturning slowdown.

The modelling was performed under the ‘high’ IPCC climate change scenario, which puts the Earth on a three-degree warming pathway if there is little change to current global carbon emissions.

Aside from the impacts of slowed overturning processes on climate conditions, the consequences for marine productivity are also severe – directly impacting food chain foundations by diminishing phytoplankton availability and cutting feeding opportunities for larger fish and marine mammals.

Dr Steve Rintoul, who leads the CSIRO’s Southern Ocean research team says, “The choices we make today … commit us to a certain level of warming. That ... level of warming goes along with a certain amount of ice melt, so we commit ourselves now to this freshwater input.” cosmosmagazine.com

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“Couldn’t be more timely”: new data record shows marked decline in sea ice Global sea ice decline has been shown in unprecedented detail in a new data model released

by European researchers.

SEA ICE

By Matthew Ward Agius

An ultra-sharp image of the Petermann Glacier, in northwest Greenland, captured by the Copernicus Sentinel satellite system in 2022.

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Researchers from the European Space Agency Climate Change Initiative’s sea ice division have released a three-decade-long data record that shows a recession in sea ice coverage across the Arctic.

Ice melt in polar regions influences global weather and ocean currents, and local wildlife. In the Arctic, it can also impact quality-oflife among indigenous communities.

The ESA pushes high-quality imaging obtained by instruments mounted to orbiting US Defense Department’s meteorological

monitoring satellites through a specialised algorithm, which is then verified against data from ESA’s Copernicus Sentinel satellite system. The process results in highly detailed Arctic sea ice mapping, and is expected to be adopted by scientists seeking to understand the impact ice loss has on ocean and atmospheric systems.

Dr Dirk Notz, a climatologist from Hamburg University says “To evaluate these models, and to learn how well we understand the processes that drive the ongoing sea-ice loss on these scales, having access to satellite data with a similar spatial resolution is absolutely crucial, [it] couldn’t be more timely.”

A second dataset characterising late summer Arctic sea ice shows a reduction of more than three million square kilometres of coverage over the last four decades.

At the other end of the planet, scientists have confirmed earlier predictions of slowing deep-ocean currents in Antarctica.

Each year, 250 trillion tonnes of cold, oxygen-rich salt water descends to the Antarctic seafloor, bringing nutrients from dead animals with it. This water is then pumped around the planet, influencing ocean temperatures and rainfall patterns.

Melting freshwater ice dilutes and disrupts the process and deprives marine ecosystems of essential nutrition. Scientists have confirmed Antarctic overturning is now 30% slower than it was in the 1990s.

“The impacts of melting glaciers in Antarctica extend all the way to the deep sea,” says study co-author Dr Steve Rintoul. “It’s affecting climate and ocean chemistry, as well as sea level.”

LEFT: ESA. RIGHT: SHARON JONES / GETTY IMAGES.

ANTARCTICA * SHORTS

Antarctic pollution puts marine environment at risk POLLUTION

A new study investigating Antarctic pollution near Australia’s Casey Station has found that some sediment contaminant levels exceed international guidelines.

By Ian Mannix

A gentoo penguin (Pygoscelis papua) standing next to rusty old drums in Antarctica.

The survey, undertaken by the Australian Antarctic Division (AAD) monitoring team, identified how long pollutants contaminated the environment.

The findings, published in the journal PLOS ONE, indicate that “research stations such as Casey are likely to pose a moderate level of long-term ecological risk to local marine ecosystems through marine pollution.”

Located 3,880km due south of Perth, Australia, Casey Station is one of three permanent research outposts in East Antarctica. In the sediments surrounding the station, the researchers found consistently

higher concentrations of contaminants at locations disturbed by humans. Some contaminants exceeded international guidelines for sediment quality, including metals, hydrocarbons, and polychlorinated biphenyls.

The survey also revealed that despite improved environmental management practices over the past 20-30 years, contaminants in marine sediments in disturbed locations have remained at similar levels or are increasing.

Dr Jonny Stark, a marine ecologist with the AAD and lead author of the report says “Raising awareness of the contamination risks associated with Antarctic stations and implementing monitoring programs for marine environments adjacent to these stations can contribute to informed decision making and the improvement of environmental management practices in Antarctica.”

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ANTARCTICA * SHORTS

As the Southern Ocean starts feeling the heat scientists try to protect the region

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After five years scientists from across the globe have released a “mini-IPCC” for the Southern Ocean.

NATALIA TISHINA / GETTY IMAGES

DISCOVERY

By Imma Perfetto The Marine Ecosystem Assessment for the Southern Ocean (MEASO) is being described as “the first comprehensive assessment” of trends in the Southern Ocean.

The MEASO report is the result of collaboration between more than 200 scientists from 19 countries and is specifically designed for policy makers to inform decision-making about the Southern Ocean.

It stresses that climate change is the most significant driver of species and ecosystem change in the region, but also highlights the tools available and recommended research priorities for its conservation.

“Long-term maintenance of Southern Ocean ecosystems, particularly polar-adapted Antarctic species and coastal systems, can only be achieved by urgent global action to curb climate change and ocean acidification,” the report says. “[MEASO] has demonstrated the array of existing knowledge, data, tools and approaches available for informing decisions on conserving and sustaining the marine ecosystems in the region and the services they provide, and how implementation of those processes could be improved.”

The MEASO process was modelled on a working group of the

Antarctic pack ice.

Intergovernmental Panel on Climate Change (IPCC).

“MEASO is like an IPCC report for the Southern Ocean, and in a similar way we have distilled the science into an easy-to-read and concise summary to inform politicians and policy makers around the world,” says co-convenor Dr Andrew Constable of the University of Tasmania, Australia.

MEASO is designed to address two main questions: What is the state of the Southern Ocean system now? And what is its future?

“The unique wildlife of the Southern Ocean is feeling the heat and, together with additional pressures from fisheries, tourism, and pollution, faces an uncertain future,” says MEASO co-convenor Dr Jess Melbourne-Thomas from Australia’s national science agency CSIRO. “As well as its fundamental importance to biodiversity, the Southern Ocean is crucial to human welfare by providing us with food and helping to control our climate.”

Leader of the Australian Antarctic Program Partnership at the University of Tasmania, Professor Nathan Bindoff, says that the MEASO process should continue during this critical decade for action on climate.

“Currently assessments of change in habitats, species and food webs in the Southern Ocean are compiled separately for at least ten different international organisations or processes,” says Bindoff.

“Bringing the best-available science together in a timely fashion through the MEASO process is an excellent way to harmonise the information for policy makers.” cosmosmagazine.com

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CITIZEN SCIENCE * IN FOCUS

In focus: Citizen science Citizen science reveals the biodiversity floating alongside Great Pacific Garbage Patch

DENIS RIEK, THE GLOBAL OCEAN SURFACE ECOSYSTEM ALLIANCE (GO-SEA) FIELD GUIDE (CC-BY 4.0)

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Help conserve the Great Barrier Reef with this new citizen science platform

PLAY VIDEO

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Hunt for shark eggs this Easter with this citizen science project

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Australian scientists need public to help solve spider crab mystery

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Blue button jellyfish, Porpita porpita

Seagrass volunteers needed to help fish

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Citizen scientists on the Great Barrier Reef, get involved in Reef Blitz

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WILDEST ANIMAL / GETTY IMAGES

MARIN

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The life aquatic is fascinating and astonishingly varied – from the biggest creature that’s ever lived on Earth to microscopic marvels that underpin the oceans’ ecosystems.

NE LIFE cosmosmagazine.com

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MARINE LIFE WONDERS * FEATURE

Biannual surveys take stock of grey nurse shark numbers.

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WILDEST ANIMAL / GETTY IMAGES

Lifeline for the much maligned grey nurse shark A weekend citizen science census of grey nurse sharks has revealed “terrifyingly low” numbers of the iconic fish, the familiar silhouette of which has sparked 1000 scare campaigns of its own.

By Melissa Márquez

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MARINE LIFE WONDERS * FEATURE

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cientists are monitoring habitat to put in place conservation programs. But it’s not only scientists helping these sharks: citizen science projects and monitoring programs tracking the sharks’ movements are crucial to the shark’s survival, according to conservation bio­ logist Adam Stow who has studied the species for more than 20 years.

“It’s critically important, we need to know where they are [aggregation sites] and whether they’re changing,” he says. One of these citizen science projects employs photo identification (photo-ID) techniques to significantly increase the scope of research while reducing the cost of data collection, as well as supporting local tourism ventures and enhancing public education.

Besides unique spot markings on their flanking regions, grey nurse sharks can be identified by other important characteristics (e.g. jaw wounds, missing fin sections) in photographs.

There are biannual surveys of grey nurse sharks (­ January to February and July to A ­ ugust) that take into account seasonal variation in their distribution and movement patterns, as well as opportunistic photography taken by divers throughout the year at aggregation sites along the Australian east coast.

The “Ocean Lover’s Festival” Grey Nurse Shark Census, which was c­ onducted by multiple dive operators, led by shark conservationist Valerie Taylor, counted 249 individuals across 20 locations.

“That number is terrifyingly low,” says Captain Gordon Scott, who coordinates the census, and who believes this is an alarm to get more effective protections passed – “what we currently have is not enough.”

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fierce appearance, grey nurse sharks were killed at every possible opportunity, resulting in the drastic decline of their population.

The shark’s numbers further diminished in the late 1970s, but after realising that they were not “man-eaters”, lobbying for their protection began.

In 1984, the New South Wales (NSW) government declared them a protected species, making them the first protected shark in the world.

Today, they have “vulnerable” status globally and are “critically endangered” in Australia under the Environmental Protection and Biodiversity Conservation Act 1999 (EPBC Act). Both State and Commonwealth levels have taken steps to list and protect grey nurse shark populations in Australian waters.

In Australia, there are two separate recognised populations: one on the east coast ­between southern NSW and the Capricorn Coast Queensland, and the other along the coast of Western Australia. The east Australian population congregates at – and moves between – a few key sites along the coastline, from Montague Island, near Narooma, in the south to K’gari/Fraser Island, the world’s largest sand island, in southern Queensland.

Australia’s east coast has between 1,500 and 2,000 ­ grey nurse sharks, but the breeding population here is just roughly 400 sharks; this worrying lack of g ­ enetic diversity puts into question what the ­future holds for the predators.

In 1984, the New South Wales government declared them a protected species, making them the first protected shark in the world.

Deadly decline

Grey nurse sharks (Carcharias taurus) were falsely accused of being responsible for shark attacks off Sydney’s beaches in the 1950s and ’60s. Due to their 58 mindaroo.org

Tag teams

Scientists are following the national recovery plan in place for the species, obtaining population size and movement data from a tagging program conducted primarily by New South Wales Fisheries, with supporting research from Queensland Parks and Wildlife Service and CSIRO staff.

Marine biologist Dr Carley Kilpatrick, a senior conservation officer with the Queensland Department of Environment and Science (DES), is part

WILDEST ANIMAL / GETTY IMAGES

A school of grey nurse, or sand tiger, sharks near the entrance to Fish Rock Cave, near South West Rocks on the NSW north coast.

of a research team from DES and Sea World that uses tags to document important grey nurse shark ­habitats.

Researchers attach tracking tags to or near the dorsal fin and program them to pop off and float to the surface on a certain date, so they can transmit GPS signals and be retrieved. “We get a summary of data from a satellite transmission but if we get the tag back we get the full data set,” she said.

One of these tags has ­baffled ­researchers: it popped up prematurely about 600 kilometres off the NSW coast near Coffs Harbour and then pinged in Boambee Bay a few hours later.

“It could be in someone’s house, it could be buried in the sand, that one’s a real mystery but someone knows more about that tag,” Kilpatrick told ABC News. “Maybe someone’s been out there

on a charter fishing [trip], caught a flight back to Coffs [Harbour] and then not known what to do with the tag and thrown it overboard.”

The transmissions – which come from a tag that belonged to a male grey nurse shark – is one of two tags currently missing. The second belonged to a sexually mature female which measured 2.8 m long. This tag is particularly significant because the team hopes to gain a better understanding of the species to protect gestating females during ­migration.

Kilpatrick and her team say the public is crucial in helping them uncover this tag mystery and are urging those who live in the area to keep an eye out for the tags and to contact DES (phone number 07 3101 2085) if anyone has any information on ­either tag. cosmosmagazine.com

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MARINE LIFE WONDERS * SPOTLIGHT

Australian fur seal: cheeky, chunky, boof-head of the sea

Name: Australian fur seal (Arctocephalus pusillus doriferus), also known as Tasmanian fur seal 60 minderoo.org

Size: Length: 1.4m (females) 2.1m (males) Weight: 78kg (females) 220–360kg (males)

Diet: Carnivore (seafood, including fish and cephalopods like squid, octopus, and cuttlefish)

ALASTAIR POLLOCK PHOTOGRAPHY / GETTY IMAGES

With graceful moves and dives of distinction to as deep as 200m to catch prey, there’s much to admire about the world’s largest fur seal.

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about our marine mammal marvels on page 68

Habitat/range: South-eastern Australia, the Bass Strait, and waters surrounding lutruwita/ Tasmania

Conservation status: IUCN Least Concern.

Superpower: The Australian fur seal is the largest of all fur seals in the world: the big boofheads of the sea. cosmosmagazine.com

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MARINE LIFE WONDERS * SHORT

MAJD FORREST / GETTY IMAGES

Octopuses sleep like humans, but do they dream?

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RESEARCH

Just like humans, sleeping octopuses alternate between active and quiet sleep stages.

Quiet periods are interrupted by short bursts of frenzied activity where their arms and eyes twitch, their breathing rate quickens, and their skin flashes with vibrant colours..

By Petra Stock Researchers from the Okinawa Institute for Science and Technology (OIST) and the University of Washington (UW) investigated the brain activity of the octopus species Octopus laqueus while awake and asleep, publishing their findings in Nature.

For a long time, only vertebrates were known to cycle between two different sleep stages. This research reveals similar patterns in octopuses, which have complex cognition but completely different brain structures to mammals.

“The fact that two-stage sleep has independently evolved in distantly related creatures … suggests that possessing an active, wake-like stage may be a general feature of complex cognition,” says author Dr Leenoy Meshulam, from UW. The first step was to check whether the octopuses were truly asleep during this active period.

Researchers tested how the octopuses responded to a physical stimulus and found that when in both the quiet and active stage of

Do octopuses dream of electric fish?

sleep, the animal required stronger stimulation before reacting, compared to when they were awake.

The researchers then used probes to measure electro­physiological recordings, and found the brain activity of octopuses during the quiet sleep stage closely resembled brain wave patterns in mammal brains during non-REM sleep.

During octopus quiet sleep, the animals closed their eyes, adopted a flat resting posture and a uniformly white skin pattern.

Roughly once an hour, the octopuses entered an active sleep phase for around a minute. During this stage, the animal’s brain activity closely resembled their brain activity while awake, akin to REM sleep in humans. In this phase, octopuses also cycled through skin patterns used as camouflage when awake. This was accompanied by eye and body movements and increased breathing.

There are various possibilities for the similarities between the octopuses active sleep and awake states. One theory suggests the octopuses are practicing their skin patterns to improve their waking camouflage behaviour, or simply maintaining the pigment cells.

Another option is that the octopuses could be re-living and learning from their waking experiences, such as hunting or hiding from a predator, and reactivating the skin pattern associated with each experience.

“In this sense, while humans can verbally report what kind of dreams they had only once they wake, the octopuses’ skin pattern acts as a visual readout of their brain activity during sleep,” says Professor Sam Reiter, from OIST. cosmosmagazine.com

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Oldest ichthyosaur fossil suggests they evolved before the Age of Dinosaurs

DISCOVERY

Ichthyosaur fossils found in Norway suggest that the marine reptiles may have survived Earth’s greatest mass extinction event 252 million years ago.

By Evrim Yazgin

Illustration of a pod of shastasaurus [not the same species as the specimen found in Norway] swimming through Triassic seas.

Shastasaurus was a marine reptile belonging to the group known as ichthyosaurs.

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The Permian extinction event – also known as the “Great Dying” – saw an estimated 90% of life on Earth go extinct, and ushered in the Triassic period and the emergence of dinosaurs, which would dominate the globe until the next mass extinction event 66 million years ago.

Ichthyosaurs are marine reptiles, often mistakenly thought of as part of the dinosaur family because they lived at the same

time and shared the dinosaurs’ characteristic massive size. They resemble dolphins or sharks in body shape, and like dolphins and whales they were air-breathers, needing to surface to take in oxygen.

Both dinosaurs and the marine reptiles evolved sometime after the emergence of the first reptiles roughly 320 million years ago.

But exactly when reptiles re-invaded the water is not well understood. It was originally thought that ichthyosaurs evolved from landdwelling ancestors some time after the Permian-Triassic extinction, but new Norwegian fossils suggest that ichthyosaurs were around millions of years before the dinosaurs.

Research published in Current Biology examined 11 vertebrae and 15 bone fragments of an ancient marine reptile found on the Norwegian island of Spitsbergen, north of the Arctic circle. Analysis of rock chemistry and microscopic bone structure led palaeontologists to believe the fossils belong to the oldest ichthyopterygian.

This group of eel-like reptiles were water dwellers who evolved into the famous ichthyosaurs which ruled the seas during the Age of Dinosaurs. Comparing the vertebrae size to other known ichthyopterygians shows that the animal’s body was probably close to three metres in length.

“The vertebrae turned out to be from a highly advanced, fastgrowing, probably warm-blooded and fully oceanic ichthyosaur,” said Benjamin Kear from Sweden’s Uppsala University in New Scientist.

An earlier-than-expected evolution may help explain how ichthyosaurs got so big so quickly.

LEFT: MARK GARLICK / SCIENCE PHOTO LIBRARY / GETTY IMAGES. RIGHT: MARKO STEFFENSEN / ALAMY STOCK PHOTO

MARINE LIFE WONDERS * SHORT

Smallest baleen whales right at home in Australian waters WHALES

Pygmy right whales remain in Australian waters throughout the year, foregoing the longdistance migrations of larger whales, according to new research.

By Petra Stock

Migrate to Antarctica?

No thanks, say pygmy right whales.

Little is known about pygmy right whales (Caperea marginata), which grow to 6.5 metres long and weigh up to 3.5 tonnes, small for its species.

Researchers from the University of New South Wales revealed the new information about the animal’s diet and movements by analysing chemical clues in the animal’s baleen plates: the long bristles that hang from the whale’s upper jaw, allowing it to take in small food such as krill.

Publishing in Frontiers in Marine Science, researchers analysed chemical isotopes in the baleen plates of 14 pygmy right whales collected between 1980 and 2019.

In addition to taking in food, a pygmy right whale’s baleen plates are collecting chemical information about the whale’s movements in the form of isotopes of carbon and nitrogen. Each plate contains 3 to 4 years of data.

The data were gathered using an organic elemental analyser and isotope ratio mass spectrometer, then overlaid with data on the chemical isotopes and distribution of Australian and Antarctic krill species.

The analysis of these chemical clues revealing that unlike larger whale species, pygmy right whales tend to remain in Australian waters rather than migrating.

“Their isotopic record shows they remain in mid-latitude waters year-round off southern Australia, feeding on krill and copepods [small crustaceans],” lead author and marine ecologist Adelaide Dedden says. “There was no evidence of feeding in Antarctic waters at all, suggesting the waters off Southern Australia appear to be able to support their needs year-round.”

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MARINE LIFE WONDERS * SHORT

Fish know to stop the spread of misinformation

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BEHAVIOUR

Many social animals rely on each other for survival – for example, alerting one another when danger is present. But what happens when there is a false alarm?

GERARD SOURY / GETTY IMAGES

By Evrim Yazgin False alarms are the most common kind of misinformation among wild animals. An example of this is when an individual in a group produces an alarm signal when no real danger is present. Such actions in an individual can be perceived by others in the group as an indication of threat, which can result in a cascade of escape responses from animals.

Previous studies have shown how behavioural responses in an individual help control flawed decision making in such scenarios.

But it hasn’t been clear until now how groups of animals respond.

Now, a study of fish published in the Proceedings of the National Academy of Sciences journal shows that such misinformation is quickly stopped from spreading Researchers placed cameras on French Polynesian reefs to record the behaviour of wild foraging fish of different species. They compared the footage to reconstructions of the sensory information available to the fish before, during and after “escape events”, then modelled the fish’s decision-making process to assess whether the animal responded or not.

Fish in schools – such as these sardines – likely make decisions by taking cues from their neighbours.

According to the researchers, usually no more than a few individual foraging fish took the misinformation bait, despite escape events occurring frequently in the absence of predators. The researchers found that the animals form dynamic information networks of visual cues between each other.

“These networks are surprisingly robust to false alarms that occur when one individual flees in the absence of a true shared threat,” says Ashkaan Fahimipour, an assistant professor at Florida Atlantic University. “This robustness to misinformation about threats inherits from a specific property of their decision-making strategy: dynamic adjustments in sensitivity to socially acquired information. This property can be achieved through a simple and biologically widespread decision-making circuit.”

Escape responses in fish are controlled by specialised neural circuits that process sensory stimuli before passing the information on to premotor neurons, which are active when either the individual is performing an action, or observing another individual performing that same activity. It’s thought, then, that escape responses are triggered by visual cues produced when individuals in the group move.

The study’s results match up with previous thinking that animals pool the behavioural cues from neighbours to make decisions.

“It will be interesting to investigate whether the mechanisms revealed here also are important in driving individual decision-making and misinformation spread in other biological and social systems,” Fahimipour adds. cosmosmagazine.com

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MARINE MAMMALS * IN FOCUS

In focus: Marine mammals

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Blue whale: a talent beyond measure

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Australian snubfin dolphin: a dolphin that does yoga

MIKE KOROSTELEV / GETTY IMAGES

Humpback: Look out Eurovision – this Australian mammal can sing, jump and swim!

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Australian sea lion: much more than a weird wet dog

Dugong: realworld origin of mermaid mythology?

cosmosmagazine.com

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FELIX CESARE / GETTY IMAGES

HUMAN A

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NS AT SEA We have a complex relationship with the cradle of all Earth’s life. How we protect oceans will shape our future survival.

cosmosmagazine.com

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HUMANS AT SEA * FEATURE

The seabeds of Earth’s major oceans – the Pacific, Indian and Atlantic – are littered with rocks, but not the ‘ordinary’ undersea geology most of us associate with nearshore reefs. Melissa Márquez reports on an ocean conservation flashpoint.

By Melissa Márquez 72 minderoo.org mindaroo.org

LUDOVIC MARIN / GETTY IMAGES

Seabed mining might be the next big environmental campaign – what you need to know

French President Emmanuel Macron gestures while addressing delegates at the UN Ocean Conference in Portugal, in June 2022. The conference opened to a flurry of promises to protect oceans; it ended with more than 300 voluntary ocean protection commitments and about US$1 billion pledged for funding.

HUMANS AT SEA * FEATURE

T

hese rocks are polymetallic nodules — a potential mineral resource for copper, manganese, nickel, cobalt, iron, and rare earth elements. Their use in electronics have made them increasingly important in our lives. The purpose of deep-sea mining is to ­extract these minerals, but that’s likely to ­result in widespread damage to large sections of the deep-sea environment — one of the most complex and u ­ nderstudied habitats on our planet, While deep-sea mining seems like a recent advancement, in 1994 the United Nations established the International Seabed Authority (ISA) under the UN Convention on the Law of the Sea (Unclos) to manage, regulate and control mineral­related activities in international seabeds.

But an investigation of internal ISA ­documents by the New York Times found that a­ gency leadership downplayed environmental ­concerns and shared confidential information with companies involved in seabed mining.

Scientists, governments, NGOs and others are concerned that seabed mining will have a significant, irreparable environmental impact, given the limited knowledge we have on the biodiversity and ecology there.

While mining advocates say mining is needed for ­­renewable energy technologies, others say scientists may need decades to fully understand the seabed’s marine life and the ramifications from mining. In spite of these concerns, the ISA is writing a global mining code that could lead to the seabed being commercially exploited by 2024.

Many ISA Council member countries have called for an ocean floor mining pause. A legal adviser for the German mission to the UN, Michael Hasenau, stressed during the Convention meeting in 2022 that current knowledge and available science are insufficient to approve deep-seabed mining. To protect the marine environment, “a ­precautionary pause” is called for, he says.

Meanwhile, Brazil, the Netherlands, Portugal, Singapore, Ecuador, Italy and Switzerland have

“

i­ndicated that they will not approve mining contracts until adequate environmental protections are in place. A similar position was taken by the Group of Latin American and Caribbean Countries, and during the UN’s climate conference in ­ ­ November 2022, French President Emmanuel ­ Macron also asked for a complete ban on deep-sea mining.

What’s happening in Australia?

In Australia, seabed mining is still considered an emerging industry. In the first three nautical miles offshore, each state governs mineral exploration and recovery. Commonwealth law governs the area adjacent to the continental shelf beyond the first three nautical miles.

Currently, CSIRO is leading a consortium of organisations in creating “a blueprint for responsible, low-impact deep-sea mining,” which it says is: “to highlight any potential impacts of a deep-sea ­mining proposal from The Metals Company” (TMC — a North American mining company.)

“Initially, we will work with other experts to understand the entire ecosystem and how the different parts interact with each other,” says Dr Piers Dunstan, a r­esearcher with CSIRO’s Oceans and Atmosphere.

“That approach will allow us to begin identifying the parts of the ecosystem that are vulnerable to impacts from different activities – because clearly not every disturbance will have an impact on every part of the system,” Dunstan says.

They will then develop indicators they ­believe will be informative for monitoring and if the o ­ perations are permitted, they will set up a ­monitoring program that is a companion to them. The consortium will work on this analysis for the next two years, and TMC will submit to the ISA an Environmental Impact Statement based on the final report.

As of today, 30 exploration contracts have been approved by the ISA, involving 22 countries and covering more than 1.3 million square kilometres of ocean floor. These studies are aimed at ­gathering information on where and what ­ minerals are

Any proposal for deep-sea mining needs to be guided by strict environmental considerations.

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Specialist machinery designed to collect sea-floor metals is under development, but not yet commercially deployed.

­ resent on the seabed as well as collecting envip ronmental data; thus far, mining operations have not begun anywhere in the world.

THE METALS COMPANY

Where to from here?

Speaking at the annual Blue Solutions Summit in Sydney, UN scientist Dr Sandor Mulsow, a marine biogeochemist and expert in deep seabed mining, said: “…explore to protect first.”

Mulsow is raising awareness of the dire need to slow down, or better yet completely halt, the commencement of deep seabed mining.

“The model should be to explore to protect, not explore to exploit ... maybe in 100 years we might be able to intervene without destroying [the deep seabed environment].

Former CSIRO oceans expert Dr Tony Worby agrees. “There are more than enough minerals

available from land-based mining, if we extract them properly, recycle them properly.” “[The deep sea is] an integral part of the oceans.

And if, on a massive scale, we start to knock them over when they’ve taken thousands of years to establish, then we could be causing extinctions, we could be causing untold damage to fragile eco­ systems that we know precious little about. We’ve got an opportunity to stop ... before we start.”

Dunstan says the question isn’t for scientists.

“The question for all of us globally is are we ­w illing to accept some impact to extract m ­ inerals from the sea floor as a trade-off for decarbon­ isation and developing alternatives to fossil fuels?

“Whether we are willing to accept that ... is a question for society. What science can do is provide a robust evidence-based risk assessment to help with answering the question.” cosmosmagazine.com

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HUMANS AT SEA * SPOTLIGHT

(Un)fantastic plastic: an oceans pollution disaster

How much?

More than 11 million tonnes of plastic flows into the ocean each year; at current use, the number could almost double by 2040.

76 minderoo.org

How big is it?

Microplastic: <1mm Mesoplastic: 1–10mm Macroplastic:> 1cm

Where is it found?

Microplastics have been detected in marine organisms from plankton to whales, in commercial seafood, and even in drinking water.

MATTPAUL/ GETTY IMAGES

Plastic accounts for 85% of marine litter; the UN reports that a plastic grocery bag has been found in the Mariana Trench, the deepest point in Earth’s oceans. What to do?

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What is it?

Most plastic comes from hydrocarbons derived from crude oil, natural gas and coal – fossil fuels.

What’s the answer?

While research aims to turn plastic into soap; green steel and other materials, scientists warn that the only solution is to curb use.

What’s next?

175 member states of the United Nations have agreed to make a legally binding treaty on plastic pollution by the end of 2024.

cosmosmagazine.com

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HUMANS AT SEA * SHORT

TOKYO ELECTRIC POWER CO

Fukushima water release: experts say no danger but letting other countries verify methods will boost confidence

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POLLUTION

As Japan began releasing treated water from the Fukushima Daiichi nuclear power plant, scientists were encouraging international collaboration to improve trust in the process.

By Ellen Phiddian Following the nuclear disaster triggered by the 2011 earthquake and tsunami, Japanese authorities used 1.3 million tonnes of water to cool the plant’s damaged reactors.

The water is stored in tanks around the plant.

In 2021, with space running low, the Japanese government announced plans to release the water into the Pacific Ocean.

Prior to release, the water is treated with an Advanced Liquid Processing System to remove dangerous radioactive particles. This process has been double-checked by the International Atomic Energy Agency (IAEA).

Dr David Krofcheck, a physicist at the University of Auckland, New Zealand, says that he is “very comfortable” with the water being released, as long as scientists can guarantee that the radioactive particles have been released.

“It would be nice [to have] some kind of international collaboration, for people in the neighbourhood like Korea, Taiwan, China perhaps. We [could] get together and we [could]

Fukushima’s nuclear reactors were fatally damaged in the 2011 earthquake and tsunami.

1.3 million tonnes of water were used to cool them.

check and verify each other’s results,” says Krofcheck.

Associate Professor Tony Hooker, a physicist at the University of Adelaide, agrees that it’s important that scientists can ensure the water has been treated properly.

“The last report from the IAEA has done an inter laboratory comparison of testing that water. They concur with the Japanese in what levels are in that water,” says Hooker.

“I totally agree with David, we need to make sure that it’s only tritium and carbon-14 that’s released. And I think there’s some systems in place for that for that to happen.”

But Professor Bob Richmond, a marine biologist at the University of Hawai’i at Mānoa, US, says the releases are “premature, and presently, ill-advised”.

“The peoples of the Pacific did not contribute to the present problems, and have nothing to gain from Japan’s plan for the contaminated water release over the next 30+ years, but have much at risk for generations to come, in violation of the precautionary principle as well as transboundary safety considerations,” says Richmond.

Richmond says there are other places for the treated water to go, like concrete. Krofcheck believes that release into the ocean is the “least bad option”.

Hooker says his understanding is that “there is an independent third party laboratory within Japan already contracted to [under]take independent testing.”

“But I think being ... transparent, and opening up samples of water to as many laboratories as possible would just give the community much more confidence.” cosmosmagazine.com

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New material efficiently extracts uranium from seawater CHEMISTRY

The world’s largest reservoir of uranium is seawater: there’s about 4.5 billion tonnes dissolved in the oceans. But it’s in vanishingly low concentrations, and other more common things in seawater – like sodium, chloride and magnesium – make it very hard to extract.

By Ellen Phiddian

Oceans could be a sustainable source of chemical elements important to renewable energy.

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Hard, but not impossible, according to a study in Energy Advances that reports that researchers have made a powder that can efficiently extract uranium from seawater.

The material is a “layered double hydroxide,” explains senior author Dr Jessica Veliscek Carolan, a nuclear chemist at ANSTO. “[Ours has] magnesium hydroxide and

aluminium hydroxide in it.” In between the layers of the two hydroxide compounds are “anions”: negatively-charged molecules.

Once it’s in seawater, uranium – or more specifically, a compound that contains uranium called uranyl carbonate – displaces these anions and sits between the layers instead.

It also binds to the surfaces of the hydroxide layers. This means there are two different mechanisms by which the uranium is extracted.

The researchers tested the powder in “seawater-like” conditions.

The powder stuck only to uranium and not to other substances. “It showed some really nice selectivity, where it ... pulled out uranium and left all those other salts behind,” says Veliscek Carolan.

“Part of that selectivity is [because] the uranyl carbonate ... is anionic or negatively charged, whereas a lot of other metal species like sodium and calcium are cationic, or positively charged.”

The researchers also found that doping their substance with neodymium made it best at extracting uranium.

“It made that those metal hydroxide layers more ionic in character, which meant that it showed greater selectivity for the uranium,” says Veliscek Carolan.

When can we expect uranium extraction to start in the ocean? Not immediately.

“There are a couple of challenges that would still need to be overcome,” says Veliscek Carolan.

But given that most of the materials are low-cost, the researchers are optimistic that this substance, or one like it, could be used to extract uranium at scale.

LEFT: GLORIA PARKER / GETTY IMAGES. RIGHT: HOLGER LEUE / GETTY IMAGES.

HUMANS AT SEA * SHORT

Are offshore windfarms a problem for whales?

WHALES

Australia’s coasts could soon be home to a lot more offshore wind farms.

Currently, more than 50 are being proposed.

By Jacinta Bowler

The 175-turbine London Array, 20km off the Kent coast, UK, was the world’s largest offshore wind farm 2013–18. The array’s second phase was refused planning permission in 2014 owing to concerns about impacts on seabirds.

While this could be an important part of lowering our reliance on fossil fuels, there’s debate over whether marine mammals could be affected by the construction and the ongoing operation of the wind turbines.

Whales and many other marine mammals use sound. Some whales communicate with each other through song, while others use echolocation to guide themselves.

Having a relatively quiet ocean is vital, says Gabrielle Genty, an evolutionary biologist.

But wind turbines are not quiet.

Creating a fixed foundation for the wind turbine usually requires hydraulic hammers, which can be heard kilometres away. “Those construction noises are very loud and very low frequency, which tend

to affect baleen whales because they communicate through low frequencies,” says Genty.

There are ways of mitigating this.

A 2023 study found that acoustic deterrents used to protect marine mammals were working in Europe.

Researchers used a portable acoustic recorder and found that porpoises swam away from acoustic deterrents, while ‘bubble curtains’ can dampen the sound from the installation itself.

Once the turbines are in, there’s another (smaller) problem – the noise of the turbines themselves.

A recent paper suggests that for turbines under 20 MW there’s likely ‘negligible impact’ on the marine population. For bigger turbines, the sound can spread through the water up to 700 metres. If the turbines are less than 1400m apart, the whole windfarm might be an ‘impact area’.

Most scientists advocate for moving offshore wind farms away from areas important for marine mammals, instead of not doing it all together.

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HUMANS AT SEA * SHORT

ALASTAIR POLLOCK PHOTOGRAPHY / GETTY IMAGES

How citizen science unravelled the secrets of dragons

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CITIZEN SCIENCE

Mesmerising. That’s the only way to describe this dragon – a small, marine fish with elaborate leaf-like appendages.

By Melissa Márquez

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about citizen science projects on page 52

Meet the leafy seadragon (Phycodurus eques), a member of the Syngnathidae family, which also includes the more famous seahorses.

Leafy seadragons are found mainly in South Australia and Western Australia. They are relatively well-known now, even nicknamed “leafies”, but that wasn’t always the case.

In 1996, researchers and SA community organisations banded together to unravel the mysteries surrounding their beloved marine residents. Known as “Dragon Search SA”, the initiative encouraged anyone at the beach or swimming in the sea to contribute to scientific research by recording seadragon sightings through survey forms.

The data collected substantially expanded our knowledge regarding the behaviours, movements, and interactions of seadragons within their habitats. Simultaneously, targeted research was conducted

by Rod Connolly, who employed radio tracking to study individual seadragons.

The research confirmed what divers had long suspected – leafies tend to remain within a limited home

A leafy sea dragon under the jetty at Rapid Bay, about 100km south-west of Adelaide, SA.

range. Motivated by this knowledge and the need for more data to inform conservation planning, divers and dive tour operators embarked on individual projects to track seadragons, identifying each fish based on its unique markings.

Leafy seadragons are now well-known for their slender bodies sporting some remarkable camouflage that resembles drifting seaweed or kelp; they vary in colour and may include shades of brown, yellow and green, allowing them to blend seamlessly into seagrass beds and rocky reefs.

Although they lack teeth, their long, tubular snouts suck up a variety of prey such as small crustaceans, tiny fish, and other small invertebrates. Listed as Near Threatened on the International Union for Conservation of Nature (IUCN) Red List, they face various threats: habitat degradation, pollution, coastal development, incidental capture in fishing nets, and pressure from the illegal wildlife trade. As a result, conservation efforts, including research, monitoring, and habitat protection, are crucial for their long-term survival.

Their localised distribution, coupled with their unique appearance and vulnerability, makes them a species of great interest to researchers, divers, and nature enthusiasts.

Dragon Search SA has played a pivotal role in advancing current seadragon research initiatives and setting the stage for ongoing studies in the field. Data from contributors who have uploaded to the Dragon Search SA project is available on iNaturalist. cosmosmagazine.com

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About us

About the Royal Institution of Australia RiAus is an independent charity dedicated to connecting people with the practice and discoveries of science, which we believe is the key to a better future for our Earth.

Through Cosmos magazine, our free news site cosmosmagazine.com and free educational resources, we aim to be an inspirational resource centre for the wonders and achievements of Australian and the world’s scientific discoveries: we want to inspire the young, satisfy the curious, explain the baffling and ask the impossible.

We seek to spark in all people a desire to be science literate and to make informed decisions about their lives based on rigorously sought and tested evidence.

About the Minderoo Foundation Founded by Andrew and Nicola Forrest in 2001, the Minderoo Foundation takes on tough, persistent issues with the potential to drive massive change.

The Foundation incubates ideas, advocates for systems change and accelerates impact. Its vision is a society that values all people and natural ecosystems.

Its three main areas of focus are: Communities, which aims to raise child and community wellbeing through place-based approaches, arts and culture and early years solutions; Gender and Equality, which seeks to enhance humanity’s potential through equality for women and girls; and Oceans, which strives to return Earth’s oceans and seas to a healthy state, free from pollution and safeguarded for future generations.

THE ROYAL INSTITUTION OF AUSTRALIA ULTRAMARINE 2023

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SAMUEL J COE / GETTY IMAGES

A reef manta ray feeds over the Ningaloo Reef in Western Australia.