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LAHTI LAKES 2018

Restoration of Eutrophic Lakes: Current Practices and Future Challenges

ABSTRACTS AND SCHEDULE June 4.–6. 2018, Lahti, Finland


Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Table of Contents Organizing committee.................................................. 2 Locations in Lahti ......................................................... 4 Essential information ................................................... 6 Welcome letter ............................................................ 7 Quick timetable ............................................................ 8 Full program ............................................................... 10 Plenary speakers ........................................................ 17 Fieldtrip on Lake Vesijärvi .......................................... 18 Abstracts .................................................................... 20 Full list of participants ................................................ 75

*Abstracts in this volume have been edited by the organizing committee 1


Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Organizing committee

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Tom Jilbert Assistant Professor in Aquatic Biogeochemistry University of Helsinki

Heikki Mäkinen Program Director Lake Vesijärvi Foundation Lahti, Finland

Jukka Horppila Professor in Limnology University of Helsinki

Irma Peltola Communications Specialist Lake Vesijärvi Foundation Lahti, Finland

Kalevi Salonen Emeritus Professor in Limnology University of Helsinki

Kaisa Vuorivirta Operations Manager University of Helsinki Lahti Science Campus


Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Mirva Ketola Lake Ecologist Lake Vesijärvi Foundation Lahti, Finland

Liisa Hämäläinen Lahti Lakes 2018 Senior Assistant Finnish Environment Institute (SYKE)

Anna Kangas Lahti Lakes 2018 Student Assistant University of Helsinki

Aino Syrjänen Lahti Lakes 2018 Student Assistant University of Helsinki

Anne-Mari Räihä Lahti Lakes 2018 Assistant Lake Vesijärvi Foundation Lahti, Finland

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Locations in Lahti

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

1 2 3 4 5 6 7 8 9 10 11 12

Lake Vesijärvi Sibelius Hall Lahti City Hall M/S Vellamo (fieldtrip vessel, tuesday) Restaurant Voitto (symposium dinner, tuesday) Lahti Travel Center, railway station Sokos Hotel Lahden Seurahuone (reception location, monday) Hotel Cumulus City Lahti Hotel Grand Lahti Hotel Scandic Lahti Hotel Forenom Lahti Santa Fe bar and restaurant (ice breaker location, sunday)

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Essential information Time zone of Finland: UTC +2 (winter), UTC +3 (summer) Currency: Euro (€) Emergency services contact number Finland: 112 Drinking water: Tap water is OK! WiFi code of Sibelius Hall: [Network] Sibeliusnet [Password] kullervo Street address of Sibelius Hall: Ankkurikatu 7 15140 Lahti Street address of Restaurant Voitto: Salpausselänkatu 8, 15110 Lahti Telephone number of Tom Jilbert (organizing committee): +358 44 974 6564 Taxis in Lahti: +358 (0)601 100 01 (reservation fee 1.24 €/call + 48 cent/min) Some basic phrases in Finnish: hello good morning! goodbye I would like… two beers please a glass of red wine where is the….? Sibelius Hall hotel restaurant I am originally from… Canada USA Germany Denmark Britain Sweden Estonia Argentina Russia The Netherlands Switzerland New Zealand Serbia welcome to Finland!

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moi huomenta! moi moi haluaisin… kaksi olutta kiitos lasin punaviiniä missä on…? Sibeliustalo hotelli ravintola olen kotoisin… Kanadasta Amerikasta Saksasta Tanskasta Britanniasta Ruotsista Virosta Argentiinasta Venäjältä Hollannista Sveitsistä Uudesta-Seelannista Serbiasta tervetuloa Suomeen!


Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Welcome letter Dear friends and colleagues, Welcome to Lahti! We are delighted that so many of you have chosen to join us for what we hope will be an inspiring few days discussing the latest developments in lake restoration science. At the time of writing, we are expecting approximately 80 participants from 15 different countries to attend Lahti Lakes 2018. This alone will provide plenty of opportunities to compare and critically examine the different approaches to lake restoration available in the world today. Furthermore the presentations cover a wide range of lake systems from regions of contrasting climate, lake characteristics and anthropogenic pressures. We are especially pleased to welcome our plenary speakers, Martin Søndergaard, Gertrud Nurnberg and Jouko Sarvala. All three have carried out significant work in different areas of lake restoration science during their distinguished careers. Martin, Gertrud and Jouko will give extended talks at the start of the Monday, Tuesday and Wednesday programs, respectively. We also extend a special thank you to Juha Keto, who has being a driving force behind research into the restoration of Lake Vesijärvi for several decades. Juha will give a keynote presentation during the fieldtrip onboard M/S Vellamo on Tuesday afternoon. Looking forward to meeting you all, and enjoy your stay in Lahti!

Tom Jilbert, Chair of the organizing committee

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Quick timetable Monday 4th June (a.m.) 08.00

08.30

09.00

Arrival and coffee

09.30

10.00

10.30

Søndergaard Welcome

11.00

Lürling Coffee

11.30 Vuorio

12.00

12.30

Lunch

Gustafsson Cooper

THE BIG PICTURE OF LAKE RESTORATION

Tuesday 5th June (a.m.) 08.00

08.30

09.00

09.30

Nürnberg

10.00

10.30

Woodward Coffee Huser

Mucci

11.00

11.30

Aurola

Västilä

12.00

12.30

Beutel

Niemistö

Lunch

11.30

12.00

PHYSICAL AND CHEMICAL APPROACHES

Wednesday 6th June (a.m.) 08.00

08.30 Sarvala

09.00

09.30

10.00

Saar Koljonen

10.30 Coffee

Paerl

Tuvikene

Sammalkorpi Kraft

CASE STUDIES OF LAKE RESTORATION

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11.00

Važić Lunch

12.30


Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Monday 4th June (p.m.) 13.00

13.30 14.00 14.30

Taipale

Vuori

15.00

Coffee

Rusanov Zingel

15.30

16.00 16.30 17.00 17.30 18.00

Ruuhijärvi Posters Ventelä

FOODWEBS AND BIOMANIPULATION

Rask

End POSTER SESSION

Monday 19.00 Reception at Sokos Hotel Lahden Seurahuone (map location 7).

Tuesday 5th June (p.m.) 13.00

13.30

Molot

14.00

14.30 15.00 15.30 16.00 16.30 17.00 17.30

Hellweger Pflug.-L.

Fieldtrip (featuring keynote: Keto)

Transfer

CYANOBACTERIA

End FIELDTRIP

Tuesday 19.30 Symposium dinner at Restaurant Voitto (map location 5). Bus transport included. Tuesday 21.30 Visit to Salpausselkä skijumping tower. Bus transport included.

Wednesday 6th June (p.m.) 13.00

13.30

14.00

McCarthy Couture Jilbert

14.30

15.00

Tammeorg End

Steins.

Closing

SEDIMENTS/BIOGEOCHEM.

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Full program MONDAY 4th JUNE 08.00 Arrival and registration 09.10 Opening of the symposium, Saara Bäck, Environment Counsellor, Ministry of Environment 09.30 SESSION 1: THE “BIG PICTURE” OF LAKE RESTORATION 09.30 PLENARY Søndergaard “Restoration of eutrophic lakes: What have we learned and where should we go from here?” 10.20 Coffee 10.40 SESSION 1 (continued) 10.40 ORAL Lürling “In-lake measures remain crucial in mitigating eutrophication nuisance in the upcoming decades” 11.00 ORAL Gustafsson “Eutrophication of the Baltic Sea: Nutrient cycling and management” 11.20 ORAL Vuorio “Phosphorus thresholds for cyanobacteria in northern European lakes: a means for setting reduction targets” 11.40 ORAL Cooper “Using systems modelling to design safe operating spaces for shallow lakes” 12.00 Lunch 13.00 SESSION 2: FOODWEBS AND BIOMANIPULATION 13.00 ORAL Taipale “Eutrophication and lake restoration influence nutritional quality of food webs”

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

13.20 ORAL Rusanov, Trifonova “Long-term changes of plant community structure in a eutrophic shallow reservoir and perspectives of its restoration” 13.40 ORAL Vuori “Large Woody Debris (LWD) stimulates biodiversity and population densities of littoral zoobenthos communities in forest lakes” 14.00 ORAL Zingel “Having an old friend for dinner - why the little things matter?” 14.20 Coffee 14.50 SESSION 2 (continued) 14.50 ORAL Ventelä “Is this the largest biomanipulation project in the world? - New biomanipulation concept of Lake Säkylän Pyhäjärvi is closely linked to commercial fishery” 15.10 ORAL Ruuhijärvi “Responses of food web to hypolimnetic aeration in Lake Vesijärvi” 15.30 ORAL Rask “Zooplankton and fish community responses to food web manipulation in eutrophicated Lake Tuusulanjärvi, southern Finland” 15:50 SESSION 3: POSTER SESSION POSTER Einola, Mäkelä “Observed changes in macrophytes over several decades in two boreal lakes” POSTER Fernandez “Modelling artificial aeration based on reservoir bathymetry and the effects of a curtain on algal blooming in a eutrophic reservoir” POSTER Filatov “Experiences of restoration of the ecosystems of lakes in Russian Karelia” POSTER Hietala “Lake Tuusulanjärvi, southern Finland: 20 years of restoration”

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

POSTER Huotari “Nutrient recovery from waste waters by using microalgae" POSTER Kangro “Lake restoration: a view from space to the changes in L. Ülemiste during and after biomanipulation” POSTER Kiani “Sediment internal phosphorus loading before and after excavation of a shallow lake” POSTER Kisand “From lake sediment to the soil: phosphorus mobility” POSTER Niemistö “Restoration of a eutrophied lake by withdrawal of hypolimnetic water - sedimentary phosphorus recovered as a circular economical resource” POSTER Ott “Limnological investigations prior to restoration of a shallow macrophyte covered lake (Lake Lahepera)” POSTER Salmi “Practical calibration of single-wavelength fluorometer data for in situ chlorophyll monitoring of humic lakes” POSTER Salonen “Succession of phytoplankton in a eutrophic lake during restoration by food web manipulation and deep-water oxygenation” POSTER Shirokova “Restoration of small boreal lake ecosystems subjected to natural and anthropogenic factors: case study of NW Russia” POSTER Vicente “Eutrophication in El Val reservoir (Aragón, Spain): a case study” 18.00 End of poster session 19.00 Reception at Sokos Hotel Lahden Seurahuone

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

TUESDAY 5th JUNE 08.30 SESSION 4: PHYSICAL AND CHEMICAL APPROACHES IN LAKE RESTORATION 08.30 PLENARY Nürnberg “Benefits and optimization of hypolimnetic withdrawal as a lake restoration technique” 09.20 SESSION 4 (continued) 09.20 ORAL Huser “Effectiveness and longevity of Al treatment for lake restoration” 09.40 ORAL Woodward “The effectiveness of alum and allophane as geoengineering tools across a gradient of lakes with increasing peat influence” 10.00 ORAL Mucci “Whole lake combined PAC-Phoslock® treatment to manage eutrophication and cyanobacteria” 10.20 Coffee 10.40 SESSION 4 (continued) 10.40 ORAL Västilä “Environmental two-stage channels: potential for catchment-scale reductions in nutrient transport?” 11.00 ORAL Aurola “Lime treatment options to inhibit eutrophication in lakes” 11.20 ORAL Niemistö “Effects of hypolimnetic aeration on the quantity and quality of settling material in a eutrophied dimictic lake” 11.40 ORAL Beutel “Experimental assessment of oxygenation to repress methylmercury release at the profundal sediment-water interface in Hodges Reservoir, California, USA” 12.00 Lunch

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

13.00 SESSION 5: FOCUS ON CYANOBACTERIA 13.00 ORAL Molot “Hierarchy of approaches to cyanobacteria management: integrating knowledge of dissolved oxygen and trace metals with point source phosphorus and nitrogen controls” 13.20 ORAL Pflugmacher-Lima “Can aquatic macrophytes help us to reduce cyanobacterial blooms? - the Green Liver Concept” 13.40 ORAL Hellweger “Predicting the effect of nutrient load reduction using dynamic, mechanistic, molecular-level modeling of cyanobacteria” 14.00 Transfer to boat 14.30 Fieldtrip on Lake Vesijärvi (M/S Vellamo), featuring: KEYNOTE Keto “The management and operation of Lake Vesijärvi restoration; top-down and bottom up?” 17.30 End of fieldtrip 19.30 Symposium dinner at Restaurant Voitto, Lahti (bus transport included) 21.30 Visit to Salpausselkä skijump tower (bus transport included)

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

WEDNESDAY 6th JUNE 08.30 SESSION 6: CASE STUDIES OF LAKE RESTORATION 08.30 PLENARY Sarvala “Adaptive management of a shallow lake based on intensive ecological monitoring: from aeration, submerged plant removal and biomanipulation to chemical treatment” 09.20 SESSION 6 (continued) 09.20 ORAL Koljonen “Monitoring restoration impacts; from a draft to action” 09.40 ORAL Saar “Restoration problems in coastal lagoon lakes” 10.00 ORAL Paerl “Mitigating eutrophication and toxic cyanobacterial blooms in Lake Taihu, China: Dual nutrient (N and P) input reductions are a bottom line necessity” 10.20 Coffee 10.40 SESSION 6 (continued) 10.40 ORAL Sammalkorpi “Long term biomanipulation at high external phosphorus load - does it work?” 11.00 ORAL Tuvikene “Dreams, needs and possibilities in lake restoration” 11.20 ORAL Kraft “Development of Lake Vesijärvi through four decades of restoration attempts” 11.40 ORAL Važić “Two case studies of cyanobacteria-related water quality problems and solutions in Serbia” 12.00 Lunch

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

13.00 SESSION 7: FOCUS ON SEDIMENTS AND BIOGEOCHEMISTRY 13.00 ORAL McCarthy “Measuring nitrogen transformation rates in large, eutrophic lakes: challenges, solutions, and future needs” 13.20 ORAL Jilbert “Long term recovery from eutrophication in Lake Vesijärvi: the role of sedimentary phosphorus feedbacks” 13.40 ORAL Couture “Modeling the response of lake sediments to catchment-scale changes in biogeochemical dynamics” 14.00 ORAL Steinsberger “Quo vadis oxygen? The sinks of hypolimnetic oxygen in deep Swiss lakes” 14.20 ORAL Tammeorg “Factors behind sedimentary P release in lakes: potential linkage to lake water quality management” 14.40 Closing comments and information about Special Issue in Hydrobiologia 15.00 End of symposium

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Plenary speakers Martin Søndergaard Bioscience, Aarhus University, Denmark. MONDAY 09.30 Martin is specialized in freshwater ecology and applied research and has been active in these fields since 1985. His key areas of research have included nutrient dynamics in shallow lakes and the interactions between nutrient cycling and biological structure, trophic structure and dynamics in lakes and the impact from nutrients, as well as recovery after nutrient loading reduction and methods for lake restoration. Martin’s specific research interests include: phosphorus exchange between sediment and water, internal phosphorus loading, and how to implement the European Water Framework for lakes in Denmark. Martin has been involved in multiple international research projects (EU: FP5-FP7) and national projects in Denmark (funded by regional authorities (counties, municipalities), national authorities (Forest and Nature Agency, Danish Agency for Science, Technology and Innovation), and private foundations (Aage V. Jensen’s Foundations, the Carlsberg Foundation, Strategic research programmes, Villum Kann Rasmussen’s Foundation). He has published extensively in English, with >150 papers in Web of Science and ISI h-index of 50.

Gertrud Nürnberg Freshwater Research, Baysville, ON, Canada TUESDAY 08.30 Gertrud is head of Freshwater Research, a limnological company focusing on the restoration and modeling of eutrophic lakes and reservoirs. She founded the company in 1984, after completing her Ph.D. in biology/limnology at McGill University in Montreal, Canada. Gertrud has worked with lake associations, governmental agencies, NGOs, engineering companies and the private sector in the US, Canada, and Europe. She has published 60 peer-reviewed papers on comparative research, empirical lake models on phosphorus, iron and anoxia, and on lake management techniques in numerous scientific journals. She has been involved with the North American Lake Management Society (NALMS.org) in various positions and has won several awards in recognition of outstanding research and publications in lake restoration. More information about Gertrud’s work can be found via the website http://www.fwr.ca.

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges Jouko Sarvala University of Turku, Finland WEDNESDAY 08.30 Jouko is an expert in aquatic ecosystem ecology with special expertise on fish, zooplankton and zoobenthos in the northern temperate and subarctic as well as tropical lakes. His recent studies have concentrated on the lakes Säkylän Pyhäjärvi, Littoistenjärvi and several other lakes in Finland (1982-2017; ecosystem studies, management), Tanganyika (East Africa; ecosystem and fisheries studies 1992-2017), and Taihu (China, 2011-2014). In most cases, these projects were initiated to fill knowledge gaps related to practical problems, but maintaining strong links to ecological theory. Jouko has collaborated extensively within Finland and internationally, publishing > 250 English- and Finnish- language papers since 1971.

Fieldtrip on Lake Vesijärvi TUESDAY 14.30‒17.30 Everyone is welcome onboard M/S Vellamo for the fieldtrip on Lake Vesijärvi. The boat will depart from Lahti harbor, just outside the Sibelius Hall. We will sail through the various basins of Vesijärvi, indluding Enonselkä, Komonselkä and Kajaanselkä before returning to Lahti. As well as plentiful refreshments and a great view, we will hear about research and management activities in Vesijärvi from symposium participants including Juha Keto, Ismo Malin, Jukka Ruuhijärvi and Pauliina Salmi.

The keynote presentation of the fieldtrip will be given by Juha Keto. Juha has worked in various roles connected to the restoration of Vesijärvi since 1975. He has published numerous English- and Finnish-language papers on diverse topics including phosphorus cycle feedbacks, foodweb interactions and catchment measures to reduce nutrient loading. Juha will talk about the history of restoration work in Vesijärvi and the key role of local people in lake management.

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Lake Vesijärvi Drainage area Surface area Maximum depth Mean depth Retention time

515 km2 109 km2 42 m 6.8 m 5.4 yr

Source: Keto J. et al., Vesijärvi: Daughter of the Salpausselkä Ridges (Lahti Region Environment Services, 2012).

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Abstracts Restoration of eutrophic lakes: What have we learned and where should we go from here? Martin Søndergaard (1, 2), Erik Jeppesen (1, 2, 3), Torben Lauridsen (1, 2, 3), Liselotte S. Johansson (1) (1) Department of Bioscience, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark (2) Sino-Danish Centre for Education and Research, Beijing, China (3) Arctic Research Centre, Aarhus University, Silkeborg, Denmark Reduction of the external loading of nutrients to sufficiently low levels is the only way to ensure a permanently good ecological quality of eutrophic lakes. However, external nutrient reduction is not always enough to create immediate effects and, in addition, a number of internal measures or lake restoration methods can be used to speed up the process towards improved water quality. We will give an overview of different restoration techniques and the results obtained combined with our experience gained from specific case studies in Denmark and abroad. The techniques include physico-chemical methods like alum treatment and hypolimnetic oxygenation and biological methods such as removal of zooplanktivorous and benthivorous fish. Generally, the outcome of lake restoration projects varies greatly from no effects to very marked effects that fundamentally change the whole ecosystem functioning. Future perspectives for the use of lake restoration in eutrophic lakes will be presented. These include the use of combined treatments, more lake-specific restoration techniques, improved use of results and experience from ‘failed restorations’ and the need to address further challenges and perspectives arising from climate changes, increased populations and intensified agricultural activities. PLENARY MONDAY 09.30 ms@bios.au.dk

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

In-lake measures remain crucial in mitigating eutrophication nuisance in the upcoming decades Miquel Lürling (1,2) Maíra Mucci (1) Frank van Oosterhout (1) (1) Aquatic Ecology & Water Quality Management Group, Wageningen University, P.O. Box 47, 6700 AA, Wageningen, The Netherlands (2) Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOOKNAW), P.O. Box 50, 6700 AB, Wageningen, The Netherlands Eutrophication due to high nutrient loading is the prime water quality issue in inland waters world-wide. Nuisance symptoms of eutrophication, such as massive cyanobacterial blooms, are expected to further increase in the future due to urbanization and predicted climate change. In many waters, ongoing point and nonpoint source nutrient pollution will prohibit any improvement in water quality in the upcoming decades. Mitigating nuisance and minimizing impairment of important ecosystems services requires proper diagnosis. We will point out that inlake measures are particularly important for speeding-up recovery and in bringing real-time relief. In lakes where internal load is fueling cyanobacterial blooms management of internal load is straightforward, which can only be achieved by inlake intervention. In oligotrophic lakes, where problems are caused by cyanobacterial biomass accumulation rather than external and/or internal nutrient load, in-lake measures are the single logical interventions. Even in lakes where external nutrient load is driving cyanobacterial nuisance, catchment measures simply may take too long to become effective, or they may turn not effective enough, pressing the need for repeated in-lake actions. In all of these, geoengineering techniques that can rapidly remove cyanobacteria out of the water column and/or permanently immobilize phosphate may be powerful tools to be included in the lake managers’ toolbox. We will provide a few examples of whole lake diagnoses and subsequent whole lake experiments in areas with continuing diffuse loading. ORAL MONDAY 10.40 miquel.lurling@wur.nl

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Eutrophication of the Baltic Sea: Nutrient cycling and management Bo G. Gustafsson (1,2) (1) Baltic Nest Institute, Baltic Sea Centre, Stockholm University, Svante Arrhenius väg 20F, SE-106 91, Stockholm, Sweden (2) Tvärminne Zoological Station, University of Helsinki, J.A. Palmenin tie 260, FI-10900, Hanko, Finland The Baltic Sea shares many characteristics with eutrophic lakes. It has long suffered from widespread hypoxia and frequent extensive cyanobacteria blooms caused by anthropogenic nutrient inputs. Nutrient inputs to the Baltic have been strongly declining for decades due primarily due to extensive development of modern sewage treatment. However, despite the long-lasting reduction of nutrient inputs, the extension of hypoxia and anoxia and the phosphorus content in the water column have reached unprecedented levels during the past decade. Models suggest that the Baltic Sea will react to the nutrient input reduction, but it will take a long time. This has in the scientific community led to intensified discussions on legacy phosphorus and internal load, and has created frustration in the management and political community. In this context, suggestions of sea-based measures such as oxygenation and phosphorus precipitation have gained attention as they are promising a fast track towards improvement. In this presentation, the general nutrient dynamics and history that led to the current environmental situation will be presented as well as model scenarios of the future development. The experiences from advising management on necessary further input reductions for a recovery, as well as recent discussions on phosphorus cycling and possibilities for sea-based engineering solutions, will be presented. ORAL MONDAY 11.00 bo.gustafsson@su.se

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Phosphorus thresholds for cyanobacteria in northern European lakes: a means for setting reduction targets Kristiina Vuorio (1), Marko Järvinen (1), Niina Kotamäki (2) (1) Finnish Environment Institute SYKE, Mechelininkatu 34a, 00260 Helsinki, Finland (2) Finnish Environment Institute SYKE, Jyvaskyla office, Survontie 9A, 40500 Jyvaskyla, Finland One major target for lake restoration is reduction of cyanobacterial blooms that limit the use of lakes and reservoirs for recreation and have negative impacts on ecosystem services. Phosphorus (P) is usually the nutrient best explaining cyanobacterial biomass in lakes. Determination of P threshold values of different cyanobacteria can help to set robust targets for management/restoration of lakes. We used long-term (>40 years) harmonised phytoplankton and environmental data from >600 Finnish lakes to evaluate the P threshold values for cyanobacterial total biomass and different cyanobacterial genera. Correlation analysis and multiple regressions confirmed the importance of P in regulation of cyanobacterial biomass. Regression trees were performed between cyanobacteria (July-August) and total P (TP) to determine the threshold values. The analyses were carried out for all lakes, but also separately for clear-water (water colour <50 mg L-1 Pt) and humic lakes (brown-water lakes, water colour >50 mg L-1 Pt). For the whole lake data, the TP threshold value was 40 mg m-3 for the total biomass of cyanobacteria. Then harmful bloom forming taxa formed most cyanobacteria biomass. For clear-water and humic brown-water lakes the respective values were 33 and 49 mg m-3 TP. For individual cyanobacterial genera the TP threshold was highest (65 mg m -3) for Microcystis, and lowest for Aphanizomenon and Woronichinia (20 mg m -3). Our results suggest that the P threshold values can be used to set P reduction targets in different restoration projects, to validate, check and set criteria for the demonstration and forecasting tools to describe and disseminate the occurrence probabilities of algal blooms and bloom taxa in lakes. ORAL MONDAY 11.20 kristiina.vuorio@ymparisto.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Using systems modelling to design safe operating spaces for shallow lakes Gregory S. Cooper (1), John A. Dearing (1), Peter G. Langdon (1) (1) Geography and Environment, University of Southampton, Southampton, SO17 1BJ, United Kingdom The planetary boundaries framework provides a novel way to conceptualise the environmental limits of human actions at the global scale. Present efforts to downscale the concept are helping to raise awareness of regional biophysical thresholds, highlight the importance of local ecological stewardship and match the scales of national and regional governance. Palaeoenvironmental and/or contemporary records can track the proximity of ecological conditions to known system thresholds. In turn, projections exploring the future sustainability of socialecological systems are further enhanced by understanding the driver interactions and feedbacks underpinning system dynamics. To this end, simulation modelling provides decision-making tools by synthesising complex social-ecological interactions to generate plausible future pathways of conditions relative to ecologically safe outcomes. Through the Phosphorous Loops in Soil Sediment (PLUM) system dynamics model of lake water phosphorus accumulation, we present a novel framework that designs safe operating spaces to guide governors of social-ecological systems along permissible driver trajectories, interactions and feedbacks. To assess system resilience, Monte Carlo techniques generate a spectrum of future scenarios for two external drivers (agricultural and nonagricultural phosphorus inputs) and one internal driver (phosphorus load regulation), with resulting lake phosphorus dynamics characterised by a priori definitions of safe (persistent clear water), cautionary (recovery from eutrophication) and dangerous (persistent eutrophication) spaces. This framework uncovers important insights for decision-makers of shallow lake systems vulnerable to eutrophication and/or requiring restoration, including the sensitivity of shallow lakes to external-internal driver combinations (e.g. synergistic or antagonistic relationships), trajectories and challenges, thus advising which plausible futures and governance interventions to follow. ORAL MONDAY 11.40 gsc1g11@soton.ac.uk

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Eutrophication and lake restoration influence nutritional quality of food webs Sami J. Taipale (1), Sanni L. Aalto (1), Aaron W. E. Galloway (2), K. Kuoppam채ki (3), and E. Peltomaa (3,4) (1) Department of Biological and Environmental Science, University of Jyv채skyl채, Finland (2) Oregon Institute of Marine Biology, University of Oregon, Charleston, OR, U.S.A. (3) Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland (4) Lammi Biological Station, University of Helsinki, Lammi, Finland. Food quality, defined as ingestibility and availability of essential biomolecules (amino acids, polyunsaturated fatty acids [PUFA], sterols and phosphorus), is one of the key factors influencing population dynamics of zooplankton. In freshwater systems, zooplankton diet includes phytoplankton, bacteria and terrestrial detritus, which vary substantially in their nutritional quality and suitability for zooplankton. Eutrophication influences phytoplankton composition by decreasing the availability of algae with high nutritional quality, and in general, drives phytoplankton communities from the predominance of diatoms towards that of cyanobacteria and green algae. Lake restoration practices rarely takes into account the dietary requirements of zooplankton in terms of nutritional quality. We analyzed the nutritional quality of phytoplankton in Lake Vesij채rvi in 1979-2016, taking into account the impacts of lake restoration on the abundance of high quality phytoplankton (diatoms, cryptophytes, synyrophytes). Our analysis showed dominance of poor nutritional quality phytoplankton throughout the years. We also analyzed the diet of Daphnia in 2016, when hypolimnetic aeration was used as a measure to reduce internal phosphorus load. In 2016, hypolimnetic aeration did not prevent cyanobacteria from blooming and poor quality phytoplankton consisted 70-95% of all phytoplankton biomass in June and July. Nevertheless, Daphnia preferred consuming mainly phytoplankton of high nutritional quality, which was seen as Daphnia biomass increasing in August, when phytoplankton of high nutritional quality increased in biomass. Both juvenile and adult Daphnia are able locate regions with high quality food, which can support rapid population growth due to the parthenogenetic reproduction strategy of Daphnia. Since hypolimnetic aeration homogenizes phytoplankton distribution on the water 25


Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

column, such patches with high food availability do not exist in the pelagial and, thus, Daphnia needs to filter more water to obtain high nutritional quality. This may slow down the reproduction cycle of Daphnia. Our results suggest that lake restoration should look for measures that promote high nutritional quality phytoplankton. ORAL MONDAY 13.00 sami.taipale@jyu.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Long-term changes of plant community structure in eutrophic shallow reservoir and perspectives of its restoration Alexander G. Rusanov (1), Irina S. Trifonova (1), Natalya V. Ignatieva (1), Oksana A. Pavlova (1) (1) Institute of Limnology RAS, Sevastyanova 9, 196105, St. Petersburg, Russia Results of an ecological survey of shallow reservoir Sestroretskiy Razliv (northwestern Russia) in 2015‒2016 were compared with those of previous observations carried out in the 1980s and the 2000s. Changes in hydrochemical characteristics, as well as phytoplankton and macrophyte community structure have been recorded. Average year concentration of total phosphorus increased from 73 µg L-1 in the 1980s to 142 µg L-1 in the 2000s and 103 µg L-1 in 2015‒ 2016. There was a marked increase in average spring-summer concentration of chlorophyll a from 14 µg Chl a L-1 in the 1980s to 84 µg Chl a L-1 in the 2000s. In the 1980s, phytoplankton was dominated by diatoms (Aulacoseira ambigua, A. islandica, A. subarctica). In the 2000s, the cyanobacteria Planktothrix agardhii was dominant in phytoplankton all year round. A significant increase in concentration of chlorophyll a and shift in phytoplankton composition from diatoms to cyanobacteria indicated a change in the trophic status of the reservoir from mesotrophic into eutrophic in the 2000s. In 2015‒2016, high concentrations of chlorophyll a (average 52 µg Chl a L-1) were observed constantly during spring and summer, indicating persistent eutrophic conditions. Diatoms (mainly Aulacoseira muzzanensis) were dominant presumably due to unfavourable weather conditions (low summer temperatures, high turbidity). Total area of aquatic vegetation declined from 157 ha in the 1980s to 76 ha in 2015‒2016. Submerged macrophytes showed the highest decrease in vegetation cover (by a factor of four). The decline of vegetation cover of the macrophyte community was possibly a result of increase in phytoplankton biomass and water turbidity. Based on the results of our observations, besides the decrease of nutrient loading, such restoration measures as macrophyte planting and biomanipulation treatment (introduction of piscivorous fishes) were proposed. ORAL MONDAY 13.20 a_rusanov@yahoo.com 27


Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Large Woody Debris (LWD) stimulates biodiversity and population densities of littoral zoobenthos communities in forest lakes Kari-Matti Vuori (1) (1) Finnish Environment Institute SYKE, Survontie 9a, Fi-40500, Jyväskylä, Finland Positive impacts of large woody debris (LWD) on sediment and nutrient retention, secondary production, biodiversity and other ecosystem services in rivers has been extensively studied. While the role of LWD in lakes is less studied, it is known that LWD may supply littoral ecosystems with a large amount of allochtonous organic matter and stimulate abundance, diversity and productivity of littoral biota. I studied the amount of LWD and its potential role in structuring the littoral macroinvertebrate communities in five pristine lakes (reference) and five lakes affected by forest harvesting (forestry lakes). The study was conducted in the headwater lakes of the Hiitolanjoki river basin in South-Eastern Finland. Reference lakes sustained significantly higher amount (average 192 m3 ha-1) of LWD as compared to Forestry lakes (81 m3 ha-1). Riparian sites with a history of extensive clear cuttings yielded the lowest LWD stocks (20 m3 ha-1), whereas the most pristine sites with dense old growth forests had very high LWD stocks (maximum 395 m3 ha1). The highest numbers were related to the presence of several whole trunks of old dead trees with a diameter over 30 cm. Macroinvertebrate species richness and abundance was significantly higher in the reference lakes than in forestry lakes. Species number and population density of several taxons correlated positively with the amount of LWD and the average values of reference lakes exceeded those of forestry lakes with one or more orders of magnitude. The results demonstrate the significant role of LWD for the structure and function of littoral zoobenthos communities. Supplementing LWD habitats in littoral areas should be considered as a fundamental element in future lake restorations. ORAL MONDAY 13.40 kari-matti.vuori@ymparisto.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Having an old friend for dinner - why the little things matter? Priit Zingel (1) (1) Centre for Limnology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences; Kreutzwaldi 1; 51014; Tartu; Estonia Eutrophication is still a nuisance for many lakes. Despite numerous measures the state of water quality is not improving as fast as we would like. Elimination of redundant algae that result from eutrophication is a topic of continuing and increasing interest. Biomanipulation has been used in many lakes throughout the world to reduce phytoplankton biomass and enhance lake conditions. This method is built on a series of approaches aimed at benefiting lakes by manipulation of their trophic structure. However, quite often the results of biomanipulation are not satisfactory. There can be numerous reasons for failure that are quite obvious, e.g. insufficient loading reduction, insufficient number of fish removed, high resuspension of loose sediment, high internal phosphorus loading from a sediment pool, etc. One simple reason for failure can also be that we simply do not understand the particular lake trophic structure and food web functioning well enough. In many cases it is possible that we have not noticed or recognised the key species that are driving the changes in the particular food web dynamics. In our presentation we shall show some simple examples of how outwardly similar lake ecosystems can actually behave very differently. We shall point out that in many cases the reason for this is the presence or absence of some seemingly unimportant and inconspicuous species. The role of these invisible key figures is discussed in more detail. ORAL MONDAY 14.00 priit.zingel@emu.ee

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Is this the largest biomanipulation project in the world? New biomanipulation concept of Lake Säkylän Pyhäjärvi is closely linked to commercial fishery Anne-Mari Ventelä (1,2), Tero Forsman (1), Henri Vaarala (1), Teija Kirkkala (1), Jouko Sarvala (2) (1) Pyhäjärvi Institute, Sepäntie 7, 27500 Kauttua, Finland (2) University of Turku, 20014 Turun yliopisto, Finland Säkylän Pyhäjärvi (SW Finland, North Europe) is a large (155 km2) and shallow lake (5.5 m), which has vital commercial fishery with 22 fulltime and 60 halftime fishermen. Water quality of Pyhäjärvi is closely linked to both commercial fishery and the quality and quantity of fish stocks. The most important mechanism is via the planktivorous fish ‒ zooplankton ‒ phytoplankton food chain. Secondly, in 1995‒2016 more than 9 million kilos of planktivores and cyprinids have been removed (total catch 15 million kg) and with this, about 100 000 kg of total phosphorus has been removed from the system. Based on the annual P-budget, annually 25‒30% of the incoming phosphorus is removed from the system in the fish catch. Thirdly, the internal nutrient load is maintained by benthic fish and fishery on these species is beneficial for the water quality. Traditionally, the most important commercial fish catch species was vendace (introduced to the lake in 1950s), caught with winter seine from above the ice. The annual harvest rate approached the total production of vendace, implying that the commercial fishery for decades (1960s‒1990s) acted as intensive biomanipulation. In the 1980s the first symptoms of eutrophication became visible and since 1995 the Pyhäjärvi restoration project has subsidized the harvest of commercially unwanted fish species. Fishing was especially intensive in 2002‒2006, when EU funded projects were implemented and the economic support for fishermen was high. This cut off the rapid eutrophication process of the lake and reduced the phytoplankton biomasses. Since 2008, both the fishery and fish stocks have dramatically been affected by climate change (loss of ice, collapse of cold water species), and fishery has been forced to adapt to the new situation. This has also changed the concept of biomanipulation and an increasing share of the catch has become commercially viable, as the value of clean local food is increasing in Europe. ORAL MONDAY 14.50 anne-mari.ventela@pji.fi 30


Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Responses of food web to hypolimnetic aeration in Lake Vesijärvi Jukka Ruuhijärvi (1), Tommi Malinen (2), Kirsi Kuoppamäki (3), Pasi Ala-Opas (1), Mika Vinni (2) (1) Natural Resources Institute Finland, Latokartanonkaari 9, FI-00790, Helsinki, Finland (2) University of Helsinki,PL 65 Viikinkaari 1, FI-00014, Helsinki, Finland (3) University of Helsinki, Niemenkatu 73, FI-15140, Lahti, Finland Hypolimnetic aeration has been used as a measure to reduce internal phosphorus loading induced by anoxia in Enonselkä Basin of Lake Vesijärvi. As a consequence, deep water temperature has risen in summer and declined in winter. Such changes together with the constantly turbulent environment may have detrimental impacts on fish and zooplankton species dependent on seasonally optimal temperature, especially cool hypolimnion during summertime. As the lake has been successfully restored by management fishing (biomanipulation) for 30 years, the possible consequences of aeration on the food web are of major interest and, thus, we studied fish stocks, zooplankton community and algal biomasses before aeration and during 8 years of aeration in 2010‒2017. The population of smelt, the dominant pelagial planktivorous fish, collapsed in the first year of aeration resulting in very low fish densities during the following summer. Smelt was partly replaced by young perch, while no evidence on the increase of cyprinids was seen in the pelagial. Smelt stock gradually recovered and in 2015‒2017 reached extremely high abundance with almost exclusively only 0+ individuals. The share of percids in the fish community of the entire basin, both pelagial and littoral, was high in 2010-2013 and declined thereafter. The share of cyprinids has been fairly constant during the aeration period. Following the collapse of smelt, the body size of cladoceran grazers increased but their biomass decreased, while the recovery of smelt populations resulted in declining size of cladocerans and no major changes in biomasses, accompanied with higher algal biomasses. Thus, the top-down control of smelt is high and probably enhanced by aeration, as large-bodied cladocerans cannot escape to their dark, hypoxic hypolimnetic refuge. ORAL MONDAY 15.10 jukka.ruuhijarvi@luke.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Zooplankton and fish community responses to food web manipulation in eutrophicated Lake Tuusulanjärvi, southern Finland Martti Rask (1), Tommi Malinen (2), Jukka Ruuhijärvi (3), Mikko Olin (2) (1) University of Helsinki, Lammi Biological Station, Pääjärventie 320, FI-16900 Finland (2) Institute of Environmental Sciences, Aquatic Sciences, Viikinkaari 1, FI00014 University of Helsinki, Finland (3) Natural Resources Institute Finland, Latokartanonkaari 9, FI-00790 Helsinki, Finland Mass removal of planktivorous fish in eutrophic Lake Tuusulanjärvi was started in 1997. In the first years of this food web manipulation, an increase in cladoceran biomasses was recorded after high annual fish catches (> 100 kg ha -1 a-1), mainly from autumnal seining. Another important factor was the almost total collapse of the smelt population during the very warm summer of 1999, when artificial mixing raised the temperature in the whole water column. As a result, the highest zooplankton biomasses were observed in summer 2000. Later in 2000s, the fish removal catches remained at lower levels, as did the biomasses of crustacean zooplankton. This was reflected in the fish monitoring as the biomass catches in Nordic gill nets increased during 1996‒2003. The fish removal probably promoted the reproduction of roach and white bream. Bream and bleak catches in gill nets decreased first but recovered in early years of 2000s. Among percids, perch increased, ruffe decreased and pikeperch fluctuated with no trend. According to echo soundings and experimental trawling, the fish biomass in pelagial water deeper than 5 m varied between 60‒150 kg ha-1 during 2004‒2013 with bream and white bream dominating in most years. Smelt and 0+ pikeperch contributed in some years with a significant proportion, up to 20‒30 kg ha-1. Virtual population analyses (VPA) calculations suggested that during 2005‒2011 the removal fishing was effective enough to prevent further increase in the biomass of roach. Instead, the biomass of white bream and, especially, bream increased. The latter was probably connected to the sharp increase in growth of bream in the years of removal fishing. ORAL MONDAY 15.30 martti.rask@helsinki.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Observed changes in macrophytes over several decades in two boreal lakes Eeva Einola (1), Suvi Mäkelä (1), Heini-Marja Hulkko (2) (1) Vanajavesi Centre, Perttulantie 84, 13430 Hämeenlinna, Finland (2) Häme Centre for Economic Development, Transport and the Environment, P.O.Box 29, 15141 Lahti, Finland Inland waters are subject to various pressures originating from human activities and natural processes. Pressures include nutrient and solid matter loading, water level regulation and introduction of invasive species. In boreal lakes, such pressures are known to alter the lake ecosystems and to impact the status of lakes and rivers. Aquatic vegetation and especially macrophytes have been recognised as a useful indicator when assessing the both the status of the watershed and the prevailing trend in the changes of lake status. Macrophyte vegetation of two lakes in Southern Finland were studied in this study in order to find out about the long term changes in boreal lakes. Both lakes are classified Natura2000 sites. The macrophytes in Lake Ansionjärvi were first studied in 1977, and again in 2017. The macrophytes of Lake Ormajärvi were studied by in 1990, and again in 2017. All the studies were carried out in situ. The macrophyte oservations were marked on maps, species were identified, and areas covered by each vegetation type were determined. Both qualitative and quantitative analyses were carried out. The results of these studies will be discussed in the presentation. The main findings will include long term changes in macrophyte vegetation and its areal coverage, species variety, and the role of invasive species. POSTER MONDAY 15.50 ‒ 18.00 eeva.einola@vanajavesi.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Modelling artificial aeration based on reservoir bathymetry and the effects of a curtain on algal blooming in a eutrophic reservoir Rocio Luz Fernandez (1), Matias Bonansea (1) (1) National Scientific and Technical Research Council (CONICET), Bruselas 14, 5152, Carlos Paz, Argentina Vertical mixing of water is suppressed by thermal stratification during summer in most temperate reservoirs. Air injection diffuser systems are then a common technique for enhancing water column circulation and mixing to improve dissolved oxygen (DO) by eliminating the vertical density gradients that lead to low DO concentrations in the bottom waters. The influence of morphometric parameters on the air distribution efficiency is analysed here by means of numerical modelling in the oldest, medium-sized reservoir of Argentina (San Roque Reservoir). Results allow to identify a series of related aspects that can be helpful during the design of these aeration systems. For instance, the localization of diffusers should be based on the goal to reach: thermal destratification or evaporation reduction. Moreover, air diffusers evenly distributed within the reservoir may be more effective in avoiding diurnal stratification, as well as the destratification of the water column may be reached quickly with this configuration. Regarding other different alternatives for water quality amelioration, a vertical curtain is also modelled to reduce the input of nutrients and sediment into the deepest part of the reservoir. This pre-dam acted by modifying the flow pattern and dilution capacity of the river inflow with the standing water. POSTER MONDAY 15.50 â&#x20AC;&#x2019; 18.00 rocioluz@yahoo.com

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

An experience of restoration of the ecosytems of lakes in Russian Karelia Nikolai Filatov (1), Tatjana Regerand (1) (1) Northern Water Problems Institute, Petrozavodsk, Karelia, Russia This presentation examines the problems of restoration of the ecosystems of lakes in Russian Karelia undergoing eutrophication. There are two types of lakes exposed to eutrophication in this region. These are (1) the largest lakes of Europe: Ladoga and Onego, which experienced intensive eutrophication during the 1970s, and (2) relatively small lakes such as Lake Pryazhskoye, whose ecosystem restoration was carried out within the framework of the European Interregproject "LakePromo". The challenges for their rational use and conservation include pollutions and eutrophication from industries and domestic wastewater discharges, as well as impacts of alien species (invasive species) and global warming. Minimising these anthropogenic impacts, which jeopardize the quality of the already limited freshwater resources, is essential to sustain the well-being of the riparian population, as well as the downstream city of Saint-Petersburg. This necessity has triggered various scientific studies, in order to conserve, restore, and efficiently use the resources of these large lakes. The sustainable use of water and biodiversity resources in Lakes Ladoga and Onego was declared a high priority in 2013 by the Russian Security Council. Since 1970, Lake Ladoga has changed from oligotrophic to mesotrophic conditions, and is slowly returning to a more oligotrophic state. It reached its maximum eutrophication in 1980s with phosphorus concentrations of up to 26 µgP/L due to industrial wastes and increasing population. The economic collapse in Russia in the 1990s led to a certain decrease of the phosphorus load on Lake Ladoga (from 6100 t P/yr in 1984‒1995 to 4000 t P/yr in 1996‒2003). The anthropogenic load on Lake Onego in 1970‒1986 resulted in the evolution of the lake trophic status from oligotrophic to mesotrophic only in semi-enclosed bays. In the last 15 years, the lake as a whole has retained its oligotrophic status. Currently, Ptot in the lake is 8 µg P/L. Lake Onego is now at the stage of ecosystem destabilization and in the initial phase of eutrophication. The phosphorus load on Lake Onego changed from 1003 t P/yr in 1992‒1997 to 786 t P/yr in 2001‒2002. Mathematical modeling with the phosphorus load determined that Lake Ladoga would preserve its weakly mesotrophic status. In a case where the initial higher load would be decreased to 4000 t P/yr, the lake returns to a weakly mesotrophic status in 5 years. For Lake Onego, simulations of the lake ecosystem functioning 35


Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

under different type of phosphorus load showed that the load of 800 t P/yr and 15000 t N/yr is the most desirable for the lake ecosystem stability. The water quality was further improved by an enforcement of the regulations to treat wastewater. However, even if the phosphorus inputs returned to acceptable levels, primary production in the lake remained mesotrophic. POSTER MONDAY 15.50 â&#x20AC;&#x2019; 18.00 nfilatov@rambler.ru

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Lake Tuusulanjärvi, southern Finland: 20 years of restoration Jaana Hietala (1) (1) Mid-Uusimaa Board for Water Protection, Finland The heart of the Mid-Uusimaa region is Lake Tuusulanjärvi, one of the most extensively studied lakes in Finland. It is known for the Tuusulanjärvi artists’ community of the early 1900s. It is also known by the huge cyanobacterial blooms that have dominated the lake since the 1960s. Intensive restoration measures were started in 1997 and have continued thereafter. Restoration measures of the lake aim to decrease the levels of diffuse nutrient loading, correct the disturbances in the food-chain structure, aerate the hypolimnion and provide better access to the lake for recreation. The external loading from diffuse sources is still twice the critical load and has remained high despite of the measures taken in the catchment area. The internal nutrient loading has decreased by biomanipulation and cyanobacterial blooms do not occur yearly. The lake is today in a better state than it was 20 years ago when the restoration was started. However, the ecological status of the lake is still only ‘tolerable’ and the goal of ‘good’ status should be reached by the year 2021. Therefore, restoration of the lake needs to be continued for several years. POSTER MONDAY 15.50 ‒ 18.00 jaana.hietala@kuves.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Nutrient recovery from wastewaters by using microalgae Jussi Huotari (1), Marika Kokko (2), Maritta Kymäläinen (3), Sanni Manninen Johansen (4), Jarkko Nummela (2), Jonna Piiparinen (5), Jukka Rintala (2), Kristian Spilling (5), Tiina Tulonen (1), Lauri Arvola (1) (1) Faculty of Biological and Environmental Sciences, Ecosystems and Environment Research Programme, Lammi Biological Station, University of Helsinki, Finland (2) Tampere University of Technology, Finland (3) Häme University of Applied Sciences, Finland (4) Vanajavesi Centre, Finland (5) Finnish Environment Institute SYKE, Finland Present wastewater treatment wastes nutrients by binding phosphorus in chemical compounds recalcitrantly available for plant production, whereas most of nitrogen is degassed into the atmosphere. A remarkable portion of the nutrients entering the wastewater treatment plants (WWTP) could be captured at the source by harvesting with microalgae within the solutions of higher concentrations of nutrients than after dilution in the sewer system with less concentrated household waters. In the algal biomass nutrients would be packed in the organic form with optimal proportions readily to be used as fertilizer and in soil amelioration. Additionally, algal harvesting can be applied as tertiary treatment at WWTP, reducing nutrient load to recipient water courses. In this project funded by the Finnish Ministry of the Environment (2018‒2019) we have chosen to demonstrate algal harvesting in various waste-waters, such as the reject water of a biogas production plant, landfill leachate, separately drained human urine from a residential area equipped with composting toilets as well as treated municipal wastewater. We study the optimization of the harvesting conditions, test the suitability of the algal biomass as fertilizer for plant production and estimate the potential of nutrient harvesting and recycling with microalgae from waste-waters in Finland. POSTER MONDAY 15.50 ‒ 18.00 lauri.arvola@helsinki.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Lake restoration: a view from space to the changes in L. Ülemiste during and after biomanipulation Kersti Kangro (1,2), Krista Alikas (1), Kristel Panksep (2), Evelin Kangro (1) (1) Tartu observatory of Tartu University, Tõravere, Nõo county, 61602, Estonia (2) Estonian University of Life Sciences, Centre for Limnology, Elva county, 61117, Estonia Lake Ülemiste is the main source of drinking water of Estonian capital city Tallinn. Eutrophication processes resulting high cyanobacterial biomass have been an issue from 19th century, complicating the purification process for drinking water. From 2002 until 2009 biomanipulation activities took place on the lake, including fish selective removal (mainly bream) during winter time together with introduction of predatory fish larvae. The focus of this study is to combine in situ and Earth Observation data to detect spatial and temporal changes of phytoplankon (Chl a concentration) and transparency during and after the biomanipulation. From in situ measurements an increase in transparency and reduction in Chl a was evident during 2007‒2009. Phytoplankton community shifted from filamentous cyanobacteria (Limnothrix redekei-dominated) to dominance of colonial cyanobacteria including various Microcystis species, which may lead to potential problems with algal toxins. In situ data will be combined with EnviSat/MERIS (period 2002‒2011) and Sentinel-3/OLCI (from 2016 onwards) to analyse the changes in the phytoplankton and transparency. MERIS and OLCI data allwos to derive information about phytoplankton on 300 m resolution via two spectral indices (Maximal Chlorophyll Index and Fluorescence Line Height) and transparency estimated as Secchi depth.

POSTER MONDAY 15.50 ‒ 18.00 kiti@ut.ee

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Sediment internal phosphorus loading before and after excavation of a shallow lake Mina Kiani (1), Priit Tammeorg (1), Juha NiemistĂś (2), Asko Simojoki (1), Jukka Horppila (2), Olga Tammeorg (2) (1) Department of Agricultural Sciences, University of Helsinki, P.O. Box 27, 00014, Helsinki, Finland (2) Department of Environmental Sciences, University of Helsinki, P.O. Box 65, 00014, Helsinki, Finland Mankind is taking advantage of numerous services by small shallow lakes such as drinking water supply, irrigation, transportation, recreational function and aesthetic values; however, eutrophication drives many of them to a deteriorated state. Internal loading of phosphorus (P) may often be the main reason why shallow lakes are unresponsive to watershed nutrient management programs. In this case, removal of sediments enriched in P is a possible method to reduce the internal P loading. In our study, we examined the changes in sediment P mobility and internal phosphorus loading after excavation of a 1-ha highly eutrophicated lake in Viljandi, Estonia. For that, we measured redox potential of the surficial sediments, sediment pore water P concentrations and calculated diffusive fluxes in the deepest location before excavation in 2015 and in three locations (close to the inflow, close the outflow, and in the center of the lake) after excavation in 2017. Additionally, total phosphorus (TP), iron (Fe), and fractions of P were determined from the sediments before and after excavation. The P fractionation analyses revealed an increase in P retention capacity after lake excavation, indicated by an increase in Fe/P ratio of the sediments. Moreover, we observed a decrease in the concentrations of potentially mobile forms of P, as labile-P and Fe-bound P at all sampling sites. However, we observed notable spatial differences. At the station that displayed the highest Fe/P ratio, the redox potential of the surficial sediments was highest and the pore water SRP concentrations had lowest value. The diffusive fluxes were found to be highest at a sampling site that displayed anoxia in the near-bottom water layer. The lake will be monitored also in 2018 for the changes in P mobility and water quality.

POSTER MONDAY 15.50 â&#x20AC;&#x2019; 18.00 mina.kiani@helsinki.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

From lake sediment to the soil: phosphorus mobility Anu Kisand (1), Merrit Shanskiy (1) (1) Estonian University of Life Sciences, F.R. Kreutzwaldi Street 5, EE51014, Tartu, Estonia Phosphorus is an essential nutrient for all living organisms, and agricultural systems demand continuous input of phosphorus. For European countries, phosphorus supply mainly originates from outside of EU and thus the recycling of that phosphorus along with efficient exploitation of the local resources is especially important from the viewpoint of food security. Lake sediments can contain considerable amounts of phosphorus, often supporting eutrophication of the water body by internal P load. While lakes can benefit from removal of the bottom sediments, the latter can be considered as valuable phosphorus source. However, often the sediment removal during lake restoration is not coupled by processing these sediments as fertilizers in agriculture. The potential of lake sediments as soil fertilizer may depend both on sediment properties and soil properties. In this presentation, we will discuss the composition of sediment phosphorus forms, sediment iron/phosphorus ratio as well as soil properties - how the change of sediment physicochemical conditions at transfer from lake bottom to the soil can influence phosphorus mobility.

POSTER MONDAY 15.50 â&#x20AC;&#x2019; 18.00 anu.kisand@emu.ee

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Restoration of eutrophied lake by withdrawal of hypolimnetic water - sedimentary phosphorus recovered as a circular economical resource Juha Niemistö (1), Soila Silvonen (1), Tom Jilbert (1), Leena Nurminen (1), Anne-Mari Aurola (2), Ismo Malin (3), Matti Kotakorpi (3) Jukka Horppila (1) (1) University of Helsinki, Viikinkaari 1, P.O. Box 65, 00014, Univ. of Helsinki, Finland (2) Nordkalk Oy Ab, Skräbbölentie 18, 21600 Parainen, Finland (3) City of Lahti, Askonkatu 2 FI-15100 Lahti, Finland Restoration of eutrophied lakes has often led only to temporary improvements in water quality. A major problem is that the largest internal storage of nutrients such as phosphorus (P) is in the bottom sediment, which cannot easily be removed. Therefore many restoration methods aim to retain P in the sediment. This restoration strategy includes two main problems. By retaining P in the sediment, the long-term recovery of the lake may be delayed. Moreover, P in the sediments cannot be recovered for potential use as a circular economical resource. In Lake Kymijärvi (southern Finland), we are currently testing a restoration method that can overcome these problems. Nutrient-rich hypolimnetic water will be pumped through a calcium filter to trap P, and returned to the lake through a wetland. The pilot restoration project funded by the Finnish Ministry of Environment will start in summer 2018. Here we present the method and the results from a study of the reference conditions in 2017. The lake was strongly stratified in June‒August, with the thermocline depth varying from 4 to 5 m. The hypolimnion became anoxic rapidly after the onset of stratification and dissolved P accumulated in the near-bottom water. The concentration of total P rose to 140 µg L-1 and the concentration of dissolved P to 80 µg L1 . In the sediment pore water concentration of dissolved P increased during the summer. In August at 9.5 m water depth, the concentration reached 5000 µg L-1 at 10 cm sediment depth. The diffusion rate of P from the sediment to the water was highest at 7-9 m depth and reached 8 mg P m-2 d-1. The results show that the hypolimnetic pumping strategy should be strongly focused in the late-summer period, when the P efflux from sediments is at a maximum.

POSTER MONDAY 15.50 ‒ 18.00 juha.niemisto@helsinki.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Limnological investigations prior to restoration of a shallow macrophyte covered lake (Lake Lahepera) Ingmar Ott (1), Katrin Saar (1), Ronald Laarmaa (1), Margot Sepp (1), Kairi Maileht (1), Maili Lehtpuu (1), Katrin Ott (1) (1) Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences, Chair of Hydrobiology and Fishery; Kreutzwaldi 1, 51014, Tartu, Estonia Eutrophication is a widespread problem in all waterbodies, including lakes. Estonian lakes have suffered from an excessive nutrient loading for decades. Many hypertrophic lakes are overgrown with macrophytes, opulent filamentous algae and are filling up with (organic) nutrient-rich sediments. These lakes in some cases are important as spawning areas and habitats for waterfowl. Lake Lahepera (surface area 100.4 ha) is a shallow (average depth 2 m) hypertrophic lake in East-Estonia connected via a small river to Lake Peipsi, the largest lake in Estonia. In summertime, the lake is overgrown with macrophytes and has been resulting in high rate of decomposition and deposition in autumn and winter. Extensive oxygen fluctuations are not suitable for hydrobionts and finally the outcome of moderate or poor ecological quality is obvious. The hypothesis of this project was that heavily eutrophic Lake Lahepera has unstable aquatic communities and there is a high potential of phosphorus release from the sediments to the water column. External loading into the lake was calculated by nutrient mass balances. It was complicated since sometimes outflow turns into inflow - water from Lake Peipsi flows into Lake Lahepera. Analysis of catchment area pointed out that essential decreasing of the nutrient loading is not possible. For the estimation of phosphorus internal loading, phosphorus fractions, dry weight and loss of ignition were analyzed from the sediments collected from 4 stations in the lake. Furthermore, an incubation experiment was conducted to estimate phosphorus, iron, nitrate and ammonium release from the sediment under anoxic conditions. Lake Lahepera, a very important lake for fish spawning and waterfowl nesting, is suffering from high internal phosphorus loading. The high amount of phosphorus has accumulated in the sediment of Lake Lahepera and approximately half of it is in the mobile pool. Actions for restoring the lake must be undertaken.

POSTER MONDAY 15.50 â&#x20AC;&#x2019; 18.00 ingmar.ott@emu.ee

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Practical calibration of single-wavelength fluorometer data for in situ chlorophyll monitoring of humic lakes Jonna Kuha (1), Marko Järvinen (2), Pauliina Salmi (1) and Juha Karjalainen (1) (1) Department of Biological and Environmental Science, University of Jyväskylä, PO Box 35, FI-40014 University of Jyväskylä, Finland (2) Freshwater Centre/Monitoring and Assessment Unit, Finnish Environment Institute (SYKE), P.O.Box 140, FI-00260 Helsinki, Finland Organic Matter (OM) is known to affect fluorometric in situ assessments of chlorophyll concentration in lake waters. For this reason, calibrating fluorometric measurements according to ambient conditions is important. In this study, chlorophyll (Chl) fluorescence was measured in situ with a sonde (YSI 6600) equipped with Chl fluorometer (ex.470/em.650700 nm). Fluorometric measurements from 14 Finnish lakes were compared against traditional spectrophotometric laboratory assessments of Chl-a and water colour. On six of the study lakes, the YSI 6600 water quality sonde was also equipped with fluorometric sensor for organic matter (ex.350/em.430nm) to determine its applicability in calibration of the fluorometric Chl results. A good correlation was found between in situ Chl fluorescence and laboratory Chl-a concentration. However, inclusion of water colour into a multiple linear regression model improved the correlation between the Chl assessments markedly. When in situ OM fluorescence was used as a substitute for water colour in the multiple linear regression model, correlation was also enhanced but slightly less than with laboratory water colour. Based on the results, when in situ Chl fluorometers are used on multiple lakes, correction with laboratory water colour measurements or in situ measurements of organic matter fluorescence offers practical means to control the variation in OM background.

POSTER MONDAY 15.50 ‒ 18.00 pauliina.u.m.salmi@jyu.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Succession of phytoplankton in a eutrophic lake during restoration by food web manipulation and deep-water oxygenation Mikael Kraft (1), Pauliina Salmi (2), Juha Keto (3), Kalevi Salonen (1) (1) University of Helsinki, Lammi Biological Station, FI-16900 Lammi, Finland (2) University of Jyväskylä, Department of Biological and Environmental Science, PL 35, FI-40014 Jyväskylä, Finland (3) City of Lahti, Technical and Environmental Services, Askonkatu 2, FI-15100 Lahti, Finland Untreated waste waters of the city of Lahti discharged to the Enonselkä basin of Lake Vesijärvi led to severe eutrophication. In the middle of 1970s waste waters were diverted, but it took about seven years before phytoplankton fresh biomass in summer decreased to about 3 g m-3. Thereafter the decrease was much slower so that 30 years later biomass had further reduced by ca. 50%. In the middle of 1980s cyanobacteria were still abundant and hence a mass removal of fish was organized in 1989‒1994, later in smaller scale. Its aim was to control phytoplankton biomass, by increasing large zooplankton and reducing benthivorous fish which might release nutrients from the sediment. After the beginning of the mass removal of fish, both phytoplankton biomass and cyanobacteria of the Enonselkä basin decreased, but in the 2000s those, together with deep-water nutrient concentrations, returned to the earlier levels. Occasionally, however, equally low values as in the middle of 1990s were observed. Although changes in phytoplankton, chlorophyll a and deep-water nutrients were favorable, another basin of Lake Vesijärvi without mass removal of fish had similar temporal trends without the same lake restoration measurements. Therefore, it cannot be confirmed that mass removal of fish led to the observed favorable changes in phytoplankton in the Enonselkä basin. In 2010 an extensive effort of pumping epilimnetic water with high concentration of oxygen into the deeps of the basin was introduced to improve the status of the Enonselkä basin. During the pumping years phytoplankton biomasses were the significantly lower than before. However, these results were in line with decreased total phosphorus and particularly nitrogen concentrations in deep water since the beginning of pumping. The results show that long time series and supportive other determinations are needed to interpret the development of phytoplankton in the Enonselkä basin.

POSTER MONDAY 15.50 ‒ 18.00 kalevi.salonen@helsinki.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Restoration of small boreal lake ecosystems subjected to natural and anthropogenic factors: case study of NW Russia L.S. Shirokova (1,2), N.M. Kokryatskaya (1), K.V. Titova (1), T.Ya. Vorobieva (1), S.A. Zabelina (1), S.I. Klimov (1), O.Yu. Moreva (1), A.V. Chupakov (1), N.M. Makhnovich (3), E.I. Sobko (1), N.V. Shorina (1,4), O.S. Pokrovsky (1,2,5) (1) Institute of Environmental Problems of the North, N Laverov Federal Center for Integrated Arctic Research, Russian Academy of Sciences, Severnoy Dviny Embankment, 23, 163000, Arkhangelsk, Russia (2) Georesources and Environnement Toulouse GET UMR 5563 CNRS, UniversitĂŠ Paul Sabatier, 14 Avenue Edouard Belin 31400 Toulouse, France (3) The North-Western Branch of the P.P. Shirshov Institute of Oceanology of the Russian Academy of Sciences, 112/3, Northern Dvina Embankment, 163061 Arkhangelsk, Russia (4) Lomonosov Northern (Arctic) Federal University, 17, Northern Dvina Embankment, 163002 Arkhangelsk, Russia (5) BIO-GEO-CLIM Laboratory, Tomsk State University, pl.Lenina, 36, 634050, Tomsk, Russia Small aquatic ecosystems of the boreal zone are known to be most sensitive indicators of on-going environmental change as well as local anthropogenic pressure while being highly vulnerable to external impacts. Compared to rather detailed knowledge of the evolution of large and small lakes in Scandinavia and Canada and large lakes in Eurasia, highly abundant small boreal lakes of NW Russia have received very little attention, although they may become important centers of attraction of growing rural population in the near future. This work presents an overview of results of multidisciplinary study of the Lake Svyatoe, conducted since 2001 to the present time. This lake was subjected to sizeable pressure of human activity since the beginning of the 20th century, but both the population and anthropogenic pressure have strongly decreased since the 1990s. To monitor the recovery of the lake, one shallow (3 m) and one deep (16 m) site were regularly sampled for a range of chemical and biological parameters. Average multi-daily, summer-time values of the epilimnion (upper oxygenated) layer of the lake provided indications of possible trends in temperature, nutrients, and bacterio-plankton concentration that revealed the local pollution impact in the shallow zone and overall environmental trend in the deep sampling point of the lake. The capacity of lake self-purification depended on the ratio of primary productivity to mineralization of organic matter. This ratio remained > 1 both during winter and summer periods which suggests high potential of lake recovery from the input of allochthonous dissolved organic matter and local anthropogenic pollution. Over more than a decade of monitoring of the lake ecosystem in the summer period, we demonstrate that 46


Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges the trophic status of the water body, the gas exchange with the atmosphere and the exchange of dissolved components with the sediments are largely determined by the concentration of autochthonous and allochthonous DOC. Overall, we demonstrate the synchronous behavior of macro- and micronutrients in the deep and shallow zones of the lake and we assess the degree of local anthropogenic pollution versus global climate trends, as well as catastrophic weather events. We conclude on the necessity of complex, multidisciplinary studies of small humic lakes in the boreal zone, because these ‘model’ lakes can serve as important proxies of on-going environmental changes in highly abundant aquatic ecosystems of poorly accessible regions of NW Russia. We acknowledge support from FASO Russia (theme no. 0409-2015-0140) and program of the RAS (no. 18-9-5-29). POSTER MONDAY 15.50 ‒ 18.00 LShirocova@yandex.ru

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Eutrophication in El Val reservoir (Aragón, Spain): a case study Eduardo Vicente (1, 2), Xavier Soria (2), Juan M. Soria (2), María D. Sendra (1) (1) Instituto Cavanilles de Biodiversidad y Biología Evolutiva, University of Valencia, 46920, Paterna, Spain (2) Department of Micribiology and Ecology University of Valencia, 46100, Burjassot, Spain Eutrophication in lakes and reservoirs is one of the most serious problems affecting the world, given that they are the reserve of water for irrigation and supply in regions where water is a scarce resource. One of the concerns of the EU Water Framework Directive is precisely to ensure that the water bodies are in good condition by the year 2022. However, in some ecosystems this will be difficult to achieve, as it is the case of the reservoir of El Val. Built in 1996, it is amongst the northern foothills of the Iberian mountain range, on the hillside of Moncayo, 620 meters above sea level. Its drainage basin has an area of 179 km2, its depth is 66 m and its capacity is 24 hm3. It is a monomictic, calcareous humid zone reservoir, at river headwaters, where average annual temperature is less than 15°C, with an average replacement time of 7 months. The samples evaluated show that temporal evolution of the trophic state stays always at the mesotrophic and eutrophic levels and in some cases chlorophyll-a concentration becomes hypereutrophic. No trend in improvement of the trophic state is noticed for these years, oscillating up and down about the mean, since the value of chlorophyll-a is maintained at an average value of 21 µg/L, remaining always at the level of eutrophy. The total phosphorus value estimated in the same samples also has an average of 38 µg/L, also at the eutrophic level, except in year 2013. The river that feeds the reservoir has a total P concentration of 458 µg/L. These P values are diluted in the reservoir and transformed into algal biomass, consequently in the reservoir tail area the total P value is 48 µg/L, in the central zone is 45 µg/L and in the dam area is 40 µg/L. Nitrogen values follow a similar pattern, presenting a value of 7 mg/L in the river and over 2 mg/L in the reservoir. It is therefore necessary to reduce the loads of nutrients going to the reservoir to improve its trophic state. Remote sensing will help us to improve the reservoir management along the time. POSTER MONDAY 15.50 ‒ 18.00 eduardo.vicente@uv.es

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Benefits and optimization of hypolimnetic withdrawal as a lake restoration technique Gertrud K. Nürnberg (1) (1) Freshwater Research, Baysville, ON, Canada Hypolimnetic withdrawal is an established lake restoration technique that slowly decreases eutrophication in lakes and reservoirs. Its operating and maintenance efforts are low, because it is based on the damming of surface outflow and the discharge of bottom water, thus removing unwanted substances from the hypolimnion. Since the first application in 1954 in a Polish lake, hypolimnetic withdrawal has been studied in more than 50 lakes, and has been applied many times elsewhere, including the deep water withdrawal in large reservoirs, in small man-made ponds, and in remote lakes. Current and new applications include Swedish Bornsjön, the back-up drinking water system for Stockholm Vatten, an urban impoundment in Michigan to treat cyanobacteria blooms, a Californian canyon reservoir, a Canadian agricultural lake, and a pilot project for Finnish Kymijärvi that investigates a novel treatment of the withdrawal water. The comparison of water quality variables before and during treatment indicates decreasing eutrophication in many treated lakes. The current study investigates the working principle of hypolimnetic withdrawal and strives to separate treatment effect from concomitant influences, including external load reduction and climate effects. Potential negative effects of hypolimnetic withdrawal due to influences on the thermal structure of a lake are explored. Models based on case studies and from the literature are consulted to determine a lake’s suitability with respect to a successful hypolimnetic withdrawal treatment. Further, the importance of considering the downstream receiving waters and ways of treating the withdrawal water are presented.

PLENARY TUESDAY 08.30 gkn@fwr.ca

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Effectiveness and longevity of Al treatment for lake restoration Brian J. Huser (1) (1) Sveriges lantbruksuniversitet Box 7050 75007 Uppsala Sweden Aluminum (Al) addition has been used for over 50 years to reduce the release of legacy phosphorus (P) in sediments and improve water quality in lakes. Results have varied in the past, however, leading to contention and uncertainty as to the usefulness of this restoration method. In a recent study, we analyzed data for over 100 Al treated lakes from around the world to identify factors related to longevity of water quality improvements. Based on declines in epilimnetic TP, longevity averaged 15 years for all lakes (months to 45 years). Al dose, watershed to lake area ratio, and lake morphometry were the most important factors related to success, explaining 82% of the variation in treatment longevity. The reasons underlying these general factors, such as binding efficiency of the added Al and benthic fish effects will be discussed. Newly developed models for improving treatment efficiency and effectiveness will be presented as well. Although the success of Al treatments has improved greatly in recent years due to improved dosing methodology, there remain a number of final hurdles to overcome to further improve treatment effectiveness. Current work we are doing to address these issues, which will also benefit other methods to inactivate excess sediment P, will be presented as well. ORAL TUESDAY 09.20 brian.huser@slu.se

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

The effectiveness of alum and allophane as geo-engineering tools across a gradient of lakes with increasing peat influence Kenneth B Woodward (1), Deborah Hofstra (1) (1) National Institute of Water and Atmosphere, Gate 10 Silverdale Rd Hillcrest, 3251, Hamilton, New Zealand Many shallow lakes in New Zealand have become eutrophic and have switched ("flipped") from a clear water state with submerged rooted plants to a turbid/phytoplankton dominated state. Such a ‘flip’ in ecological state can be caused by a single or multiple factors including; the presence of pest fish and invasive plants and high rates of internal and external nutrient loading. To reduce the internal loading of phosphorus, lakes have been ‘geo-engineered’ to lock phosphorus (P) into the sediments. This process is referred to as sediment capping. Alum and allophane, sediment capping agents, have been shown to be effective at reducing sediment P flux in multiple New Zealand lakes. However, their performance was greatly reduced in a peat lake. It was suggested that high concentrations of humic materials, found in peat lakes, compete with phosphorus for binding sites on alum and allophane, reducing their effectiveness as sediment capping agents. This project aims to identify the effectiveness of alum and allophane, as sediment capping agents, across a gradient of lakes with increasing peat influence. Lake water humic content will be estimated using its absorbance at 254 nm and DOC concentration. Lake sediments will be characterised by their total nitrogen, phosphorus and organic carbon content. The ability of alum and allophane to block sediment P release will be measured in two ways. Firstly, using continuous flow incubations, completed with two cycles of aerobic and anaerobic conditions in the overlying water. The difference in P concentration before and after incubation will be compared between sediment cores with and without alum or allophane dosing. Secondly, after the completion the incubations sequential extractions will be performed on the upper sediment layers to investigate how the application of the products has altered sediment P storage. We expect to identify where, across this gradient of lakes, will alum and allophane be effective geo-engineering tools.

ORAL TUESDAY 09.40 ben.woodward@niwa.co.nz

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Whole lake combined PAC-Phoslock® treatment to manage eutrophication and cyanobacteria Maíra Mucci (1), Guido Waajen (2), Elisabeth J. Faassen (1,3), Miquel Lürling (1,4) (1) Aquatic Ecology & Water Quality Management Group, Department of Environmental Sciences, Wageningen iversity, P.O. Box 47, 6700 AA Wageningen, The Netherlands (2) Water Authority Brabantse Delta, P.O. Box 5520, 4801 DZ Breda, The Netherlands (3) RIKILT, BU Contaminants & Toxins, Wageningen University, 6708WB, Wageningen, The Netherlands (4) Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), P.O. Box 50, 6700 AB Wageningen, The Netherlands Lake de Kuil (The Netherlands, 6.7 ha, maximum depth 9 m) suffered from cyanobacterial blooms since the early 1990s as a consequence of eutrophication. Point source reduction did not yield improved water quality due to high internal loading. To control internal loading and cyanobacteria the lake was treated with a low dose of flocculent (4 tons of iron chloride) and a solid phase phosphate sorbent (42 tons of Phoslock®) in May 2009. The treatment aimed to target both dissolved and particulate phosphate, and to block P-release from the sediment. The treatment was successful in reducing total phosphate, chlorophylla and increasing water quality. Ongoing diffuse P-inputs, however, have gradually moved the lake back towards a eutrophic state. Thus, a re-application of flocculent and Phoslock® was done in May 2017. We have been monitoring the lake before, during, and after the application. Water samples from different depths were taken to analyse nutrients, chlorophyll-a, turbidity, cyanotoxins and pH. In situ Secchi depth, oxygen and light profiles were made. On May 8th, 8 tons of Phoslock® were applied to the lake (30 mg L-1) as ballast to sink the algae. The day after six tons of Polyaluminium chloride was applied (2.1 mg Al L-1) to flocculate the cells, while on May 10th 23 tons of Phoslock® was injected in the hypolimnion layer (4-5 meters) only in the deeper part of the lake to target the internal loading. The results of the monitoring will be presented shedding light on the efficacy of the treatment.

ORAL TUESDAY 10.00 maira.mucci@wur.nl

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Environmental two-stage channels: potential for catchmentscale reductions in nutrient transport? Kaisa Västilä (1), Jochen Aberle (2,3), Juha Järvelä (1), Monika Kalinowska (4), Thomas Meyn (3), Øyvind Mikkelsen (5), Paweł M. Rowiński (4) (1) Department of Built Environment, Aalto University School of Engineering, P.O.Box 15200, FI-00076 Aalto, Finland (2) Faculty of Architecture, Civil Engineering, and Environmental Sciences, Technische Universität Braunschweig, Katharinenstraße 3, 38106 Braunschweig, Germany (3) Department of Civil and Environmental Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway (4) Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland (5) Department of Chemistry, Norwegian University of Science and Technology, NO7491 Trondheim, Norway Environmental two-stage channels consisting of a main channel and a vegetated floodplain are an alternative for conventional agricultural drainage channels. Two-stage channels retain fine suspended sediment, but their potential to control the transport of nutrients remains unresolved. The goal of this presentation is to review the performance of twostage channels for reducing phosphorus (P) and nitrogen (N) transport, and identify further research needs. We conducted a literature survey synthesizing findings from mainly US, Finnish and Polish field sites. The reviewed two-stage channels showed on average slightly lower concentrations for reactive soluble and particulate P, and slightly higher concentrations for ammonium compared to conventional reference reaches. The effect on nitrate was on average negligible although constructed floodplains appeared to enhance the denitrification potential. A key factor influencing the retention is the frequency of floodplain inundation. Critical gaps in knowledge include the retention at overbank flow events and the relative importance of the different retention and release processes. For instance, information on the P binding to the transported and deposited cohesive sediment fractions is very limited although two-stage channels exhibit large geochemically active surface areas. Rough preliminary estimates on deposition and plant uptake were derived for an 850 m long Finnish floodplain. The estimated uptake of P and N into floodplain vegetation biomass accounted for around 2-3% of the annually transported total loads. We will continue research at two-stage sites by combining the understanding on flow hydrodynamics and biogeochemical processes. As a conclusion, two-stage channels appear to offer unused potential for controlling the loads of nutrients into downstream water bodies. Their performance is expected to improve through developing the guidance on channel design and maintenance, including the optimal level of the floodplain.

ORAL TUESDAY 10.40 kaisa.vastila@aalto.fi 53


Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Lime treatment options to inhibit eutrophication in lakes Anne-Mari Aurola (1), Kjell Weppling (1) (1) Nordkalk Corporation Skräbbölevägen 18 FI-21600 Pargas, Finland During the last decades municipalities have made great efforts to control aquatic eutrophication caused by phosphorus and nitrogen through enhanced wastewater treatment. The focus has gradually turned from point source nutrient reduction towards challenges related to diffuse nutrient sources. Significant nutrient loads are caused by runoff from cultivated areas and by lake bottom sediments. Different lime based options can provide cost effective tools to control eutrophication and simultaneously improve nutrient recycling. Traditional soil improvement by agricultural liming provides a cost efficient and secure way to protect lakes from eutrophication: lime secures an optimal soil pH and improves nutrient availability and a good soil structure, thus enhancing root growth as well as nutrient and water uptake. The structure of clay soils can be further improved by more efficient structure lime followed by immediate cultivation. A soil with good structure and pH demands less fertilizers as the water balance and nutrient uptake is optimal under such conditions. This reduces the risk of nutrient-rich surface runoff. Lime filters for agricultural runoff waters are most useful to reduce soluble phosphate when constructed as a part of wetlands. Reactive calcium hydroxide granules as a filter material will bind phosphate to particulate form and limestone post filters improve removal of suspended solids. Even hygienic quality of runoff waters can be improved by introducing lime in a filter material. Lime based filter products are also useful for farmers: used filter material is recycled to arable land and farmers will benefit both lime and the phosphorus content. During the 1970’s and 1980’s watercourses in Fennoscandia were severely impacted by acid rain caused by combustion of fossil fuels. Due to a successful reduction of sulphur emissions in Europe, many acidified lakes have recently more or less recovered. In areas dominated by sulphate soils aquatic ecosystems may, however, lose their neutralizing or buffering capacity completely. In such cases liming of watercourses can be the only way to save the ecosystem.

ORAL TUESDAY 11.00 anne-mari.aurola@nordkalk.com

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Effects of hypolimnetic aeration on the quantity and quality of settling material in a eutrophied dimictic lake Juha NiemistÜ (1), Soila Silvonen (1), Jukka Horppila (1) (1) University of Helsinki, Viikinkaari 1, P.O. Box 65, 00014, Univ. of Helsinki, Finland Effects of hypolimnetic aeration (here pumping of epilimnetic water to hypolimnion) on the quantity of settling material in a eutrophied Lake Vesijärvi, Finland, was studied by comparing the gross sedimentation rates as dry and organic matter measured prior to aeration activity (2009) and during two aerated years (2011 and 2016). The rate estimates were gained by spatially comprehensive sediment trap assemblage. The possible changes in the quality of the settling material were quantified by determining the organic content (as loss on ignition, LOI) as well as the carbon (C) and nitrogen (N) content and the ratio of these elements from the trap and surface sediment samples. During the aerated years, thermal stratification broke up earlier than prior to the initiation of the aeration, and the sedimentation rates peaked at that time. The absolute amount of material as dry and organic matter, and thus also the amount of C and N settling onto the lake bottom was significantly higher in aerated years. The organic content of the trap samples was lowest and the C to N ratio highest in 2011. In 2016, the organic content of the surface sediment in the lake deeps showed significantly lower values compared to the other years. However, the decrease was only 0.5%. The increased sedimentation rates were especially pronounced in the lake deeps indicating enhanced sediment focusing due to aeration. The increased sedimentation of organic material, C and N, reflected higher primary production during the aerated years, which most likely was associated with increased temperature and turbulence and the subsequent regeneration and recycling of nutrients in the water body. Although the increased C to N ratio of the settling material in the aerated years indicated enhanced degradation, the increased amount of the organic material reaching the lake bottom contradicted the ultimate aim of the restoration measure.

ORAL TUESDAY 11.20 juha.niemisto@helsinki.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Experimental assessment of oxygenation to repress methylmercury release at the profundal sediment-water interface in Hodges Reservoir, California, USA Marc Beutel (1), Byran Furhmann (1), Sarah Brower (2), Jeffery Pasek (2) (1) University of California, 5200 N. Lake Road, 95343, Merced, USA (2) City of San Diego Public Utilities Department, 92112, San Diego, USA The City of San Diego Public Utilities Department evaluated the feasibility of installing a 6 metric ton per day hypolimnetic pure oxygenation system to enhance bottom water dissolved oxygen and water quality in Hodges Reservoir (typical maximum depth ~ 25 m), a hypereutrophic water supply reservoir in northern San Diego, USA. As part of this assessment, we implemented a laboratory effort to assess metal and nutrient flux dynamics from reservoir sediments under oxic versus anoxic conditions. We monitored replicate experimental sediment-water interface chambers containing profundal sediment from two deep-water stations for a range of redox-sensitive water quality parameters including methylmercury. While the main target of lake oxygenation in Hodges Reservoir is to lower internal nutrient loading, in California there is growing interest in in situ management approaches to repress methylmercury release associated with hypolimnetic anoxia, and subsequent bioaccumulation into the aquatic food web. Sediment had an extremely high sediment oxygen demand, and as a result the sediment-water interface remained anoxic in some â&#x20AC;&#x2DC;oxicâ&#x20AC;&#x2122; chambers bubbled with air, even though chamber water contained dissolved oxygen. In general, maintenance of a well-oxygenated sediment-water interface repressed sediment release of methylmercury, phosphate, ammonia, manganese, dissolved organic carbon and sulfide. Results highlight the fact that maintaining elevated DO in water above the sediment does not guarantee a welloxygenated sediment-water interface, or the biogeochemical benefits of oxygenated surficial sediment. In addition, experimental results suggested that shifting from highly reduced to mildly reduced conditions at the sediment-water interface could actually enhance methylmercury release form sediment. Ensuring the transferring of oxygen to the sediment-water interface in Hodges Reservoir is critical to repressing internal loading of mercury and other pollutants of concern from profundal sediment.

ORAL TUESDAY 11.40 mbeutel@ucmerced.edu

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Hierarchy of approaches to cyanobacteria management: integrating knowledge of dissolved oxygen and trace metals with point source phosphorus and nitrogen controls Lewis A. Molot (1), Sherry L. Schiff (2), Jason J. Venkiteswaran (3), Mark J. Verschoor (4), Helen Baulch (5), Scott Higgins (6) (1) Faculty of Environmental Studies, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada (2) Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, N2L 3G1, Canada (3) Department of Geography and Environmental Studies, Wilfred Laurier University, Waterloo, ON, N2L 3C5, Canada (4) Department of Biology, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada (5) School of Environment and Sustainability, University of Saskatchewan, Saskatoon, SK, S7N 3H5, Canada (6) International Institute for Sustainable Development-ELA, 111 Lombard Avenue, Suite 325, Winnipeg, MB, R3B 0T4, Canada Watershed-scale approaches to cyanobacteria bloom management have empirically relied on total phosphorus (TP) removal to lower productivity. Recent work suggests that this is most effective at preventing blooms when external TP load results in redox at the sediment/water boundary high enough to prevent internal ferrous iron loading, a trigger for cyanobacteria dominance of phytoplankton in warm waters (Verschoor et al. 2017, CJFAS). We suggest a hierarchy of approaches to point source nutrient management based on maintaining a preventative sediment redox: TP removal followed by nitrification, and then denitrification. If TP loads can be lowered enough to protect sediment redox, supplemental nitrogen (N) management is not necessary. If target TP loads cannot be reached, then nitrification technology may offer some additional redox protection in N and P-limited waters with high inputs of reduced forms of N by lowering in situ oxygen demand by nitrifying microbes and generating nitrate, the consumption of which increases redox. N removal (nitrification + denitrification prior to effluent discharge) can lower in situ oxygen consumption but it will not starve N2-fixing blooms of N unless they become limited by trace metals essential to N2 fixation very early in the bloom, especially molybdenum (Mo is critical to the N2-fixing enzyme, nitrogenase) because N2 fixation is an efficient process when metals are replete (Molot 2017, Environ. Reviews). A Canadian trace metal sampling program revealed a wide range of dissolved Mo levels varying with geology and land use: low levels near or below uptake thresholds (< 2 nM) in some regions and higher levels (20200 nM) in urbanized, industrialized catchments as well some with Mo-rich geology. Hence, 57


Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges establishing a case for N management in a given system will depend on whether a TP target to maintain high redox can be practically achieved, the extent and type of N loading, and the availability of trace metals, especially Mo.

ORAL TUESDAY 13.00 lmolot@yorku.ca

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Can aquatic macrophytes help us to reduce cyanobacterial blooms? - the Green Liver Concept Stephan Pflugmacher-Lima (1,2), Maranda Esterhuizen-Londt (1) (1) University of Helsinki, Faculty Biological & Environmental Sciences, Niemenkatu 73, 15140 Lahti, Finland (2) Korean Institute of Science & Technology Europe, Campus E7 1, 66123 SaarbrĂźcken, Germany The protection and reasonable use of freshwater is one of the main goals for our future, as water is most important for all organisms on earth including humans. Due to pollution, not only with xenobiotics, but also with nutrients, the status of our water bodies has changed drastically. Excess nutrient load induces eutrophication processes and, as a result, massive cyanobacterial blooms during the summer time. As cyanobacteria are known to produce several toxic secondary metabolites, the so-called cyanotoxins, exhibiting hepato-, neuroand cell-toxicity, a potential risk is associated with using this water. Using aquatic macrophytes as a Green Liver might help to combat these problems. Examples will be given from different countries (PR China, Brazil, South Korea) showing the efficiency and potential the use of different aquatic macrophytes might have also in relation to lake restoration.

ORAL TUESDAY 13.20 stephan.pflugmacher@helsinki.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Predicting the effect of nutrient load reduction using dynamic, mechanistic, molecular-level modeling of cyanobacteria Ferdi L. Hellweger (1,2), Neil D. Fredrick (1), Mark J. McCarthy (3,4), Wayne S. Gardner (3), Steven W. Wilhelm (5), Hans W. Paerl (6) (1) Department of Civil and Environmental Engineering, Northeastern University, Boston, Massachusetts, USA (2) TU Berlin, Water Quality Engineering, Strasse des 17. Juni 135, Berlin, Germany (3) Marine Science Institute, The University of Texas at Austin, Port Aransas, Texas, USA (4) Department of Earth and Environmental Sciences, Wright State University, Dayton, Ohio, USA (5) Department of Microbiology, University of Tennessee, Knoxville, Tennessee, USA (6) Institute of Marine Sciences, The University of North Carolina at Chapel Hill, Morehead City, North Carolina, USA Phytoplankton (eutrophication, biogeochemical) models are important tools for ecosystem research and management, but they generally have not been updated to include modern biology. Here, we present a dynamic, mechanistic, molecular-level (i.e., gene, transcript, protein, metabolite) model of Anabaena- nitrogen interaction. The model was developed using the pattern-oriented approach to model definition and parameterization of complex agent-based models. It simulates individual filaments, each with individual cells, each with genes that are expressed to yield transcripts and proteins. Cells metabolize various forms of N, grow and divide, and differentiate heterocysts when fixed N is depleted. The model is informed by observations from 269 laboratory experiments from 55 papers published from 1942â&#x20AC;&#x2019;2014. Within this database, we identified 331 emerging patterns, and, excluding inconsistencies in observations, the model reproduces 94% of them. To explore a practical application, we used the model to simulate nutrient reduction scenarios for a hypothetical lake. For a 50% N only loading reduction, the model predicts that N fixation increases, but this fixed N does not compensate for the loading reduction, and the chlorophyll a concentration decreases substantially (by 33%). When N is reduced along with P, the model predicts an additional 8% reduction (compared to P only).

ORAL TUESDAY 13.40 fhellweger@gmail.com

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

The management and operation of Lake Vesijärvi restoration; ‘top-down’ and ‘bottom up’? Juha Keto (1), Ilkka Sammalkorpi (2) (1) Lake Vesijärvi Project, Lahti, Finland (2) Finnish Environment Institute, P.O. Box 140, Mechelininkatu 34, FIN-00251 Helsinki, Finland Successful restoration of polluted Lake Vesijärvi was carried out by biomanipulation following a reduction of external nutrient loading as a joint effort of authorities, scientists and local stakeholders. Biomanipulation was introduced to the management arsenal when due to the internal loading no improvement of the water quality had taken place in 10 years after the diversion of sewage loading. An active flux of opinions and information between authorities and local stakeholders was characteristic of the implementation. The stakeholder participation contributed a ‘bottom-up’ flux from the grass root level to authorities and organized project management. It emphasised a joint volunteer work of shoreline management for recreational use, fishing and habitat improvement of pike (Esox Lucius). The ‘top-down’ flux from authorities and academia emphasized reduction of both external and internal loading, monitoring and biomanipulation. Stakeholders introduced the mowing of reed stands and joined the biomanipulation by constructing and using fishing gear. They also contributed to a decrease in the external loading. Rural point sources were put right. Planned protection zones in the agricultural catchments were rapidly established. Biomanipulation changed the previous principles in the local fisheries management by adding management fishing and emphasizing of predatory fish stocking and mowing of the overgrown breeding areas of pike. Maintenance of the achieved good condition also resulted in vacancies of lake managers and increased part time work in the tertiary sector. Satellite projects with the same strategy were initiated nationwide. We attributed the environmental sensitivity and awareness of stakeholders to the fact that rural settlement with traditions of joint work, direct contact with the lake and social capital still existed in the region. The ‘bottom-up’ approach guaranteed public and private acceptance and funding for the sustainable long term management of Lake Vesijärvi.

KEYNOTE TUESDAY P.M. (DURING FIELDTRIP) keto.juha@gmail.com

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Adaptive management of a shallow lake based on intensive ecological monitoring: from aeration, submerged plant removal and biomanipulation to chemical treatment Jouko Sarvala (1) (1) Department of Biology, University of Turku, FI-20014 Turku, Finland The shallow lake Littoistenjärvi in SW Finland, a drinking water source in 1970‒1998, is increasingly important for recreation. Occasional cyanobacterial blooms and fish kills were reported since the early 1900s. Mass occurrences of the invasive submerged plant Elodea canadensis developed at 5‒6 year intervals in the 1980s and 1990s. Collapses of Elodea resulted in turbid water for one summer, with clear water in other years. Winter anoxia was prevented by aeration, but this favoured Elodea. Mechanical removal accelerated plant growth, and had to be abandoned. In winter 1998‒1999, aeration failed, leading to anoxia. Submerged plants declined, but fish reproduction improved, and the abundance of small fish exploded. Intense cyanobacterial blooms appeared in the hot summers 20012002. From 2003 to 2006 the summer phosphorus and chlorophyll levels unexpectedly jumped to a new high level because of greatly increased internal loading. External nutrient loading was reduced by diverting runoff from a previous arable field. Removal fishery was inefficient. More efficient winter aeration reduced phosphorus and chlorophyll by 20%, but the lake remained hypertrophic. As the last option, precipitation of phosphorus with AlCl3 was successfully performed in spring 2017. Multiple management approaches were necessary to face the changing problems. Collaboration between researchers, administrators and local citizens facilitated rational management based on long-term ecological monitoring. PLENARY WEDNESDAY 08.30 jouko.sarvala@utu.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Monitoring restoration impacts; from a draft to action Saija Koljonen (1), Ilkka Sammalkorpi (2), Markus Huttunen (2), Seppo Hellsten (3) (1) Finnish Environment Institute (SYKE), Survontie 9 A, Jyväskylä, Finland (2) Finnish Environment Institute (SYKE), P.O. Box 140, Mechelininkatu 34, FIN-00251 Helsinki, Finland (3) Finnish Environment Institute (SYKE), Paavo Havaksen tie 3, University of Oulu, FInland Restoring lakes and rivers has been a common practice for decades. Despite this, there is still a shortage of aggregated, comparable and research-based monitoring data to aid restoration projects. Restoration management needs monitoring and evaluation of the projects in order to determine whether these actions are implemented appropriately and the results indicate desired outcomes. We drafted a framework for monitoring lake and stream restorations to be practicable also with limited resources (money or expertise) and to be in two levels for technical (implementation) and biological (impact) monitoring. Project types are also separated between large and smaller (typically performed by NGO’s) scale measures in order to facilitate different possibilities. The basic idea of restoration being not just a single action, but a cycle of measures, needs to be highlighted. After monitoring and evaluation of the projects it may be evident that either the action was not directed to the bottleneck or after the action the bottleneck may be shifted to other factors in the ecosystem. The Finnish nationwide watershed model (VEMALA) which includes a database of water quality data, catchment properties, external loading and Vollenweider estimates of TP for all Finnish lakes acts as a cornerstone for planning of restoration measures. The model comprises spatially detailed information of hydrological conditions together with variety of parameters affecting the state of the ecosystem. VEMALA can also be applied for forecasting the effect of single or multiple actions in the drainage basin or water bodies. In practice this monitoring scheme has been now implemented in the Freshabit Life IP project (project time 2016-2021) in which restoration efforts are implemented in several pilot areas and monitored nationally with the uniform monitoring plan. ORAL WEDNESDAY 09.20 saija.koljonen@ymparisto.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Restoration problems in coastal lagoon lakes Katrin Saar (1), Ronald Laarmaa (1), Kairi Maileht (1), Margot Sepp (1), Katrin Ott (1), Ingmar Ott (1) (1) Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences, Chair of Hydrobiology and Fishery; Kreutzwaldi 1, 51014, Tartu, Estonia Coastal lagoon lakes are highly influenced by external factors due to their position between freshwater and sea. Therefore they are highly heterogeneous and dynamic systems. Estonian lagoon lakes have emerged recently in the geological time scale and are rapidly changing from marine communities to brackish, then to freshwater systems and eventually to meadows. The ecological status of these lakes largely depends on the influx of seawater. Shallow water level makes these ecosystems weak and sensitive to influences of climate change, eutrophication and other pressures. The sediment is often easily resuspendable and a considerable amount of nutrients is accumulated there. Therefore, these lakes may end up in crisis when the high amount of nutrients, high productivity and accumulation of organic matter will lead to oxygen depletion. This causes degradation of water quality and impoverishment of ecosystem. The ecological status can furthermore exacerbate when weather conditions are changing due to climate change and storms become more frequent. Due to higher wind speed and waves, even more phosphorus (P) can be mixed up from the deeper sediment layers and will contribute to the internal loading. In order to decide on proper restoration methods, a sediment P fractionation and incubation experiments were conducted with sediment cores collected from a lagoon lake, VÜÜla meri (NW Estonia). The analysis showed that a large amount of P has been accumulated in mobile forms and P is leaking from the sediment to water column. Thus, consequently due to the climate change these lakes could be considered as one of the most endangered water habitats of the world. Natural conservation and environmental management will inevitably have to address issues arisen with these water bodies, to maintain them as aquatic ecosystems or to allow these lakes to naturally overgrow and become swamps. ORAL WEDNESDAY 09.40 katrin.saar@emu.ee

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Mitigating eutrophication and toxic cyanobacterial blooms in Lake Taihu, China: Dual nutrient (N and P) input reductions are a ‘bottom line’ necessity Hans W. Paerl (1), Hai Xu (2), Guangwei Zhu (2), Mark J. McCarthy (3), Silvia E. Newell (3), Nathan S. Hall (1), Boqiang Qin (2) (1) University of North Carolina at Chapel Hill, Institute of Marine Sciences, 3431 Arendell Street, Morhead City, NC 28557, USA (2) Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing 210008, Jiangsu Province, China (3) Department of Earth and Environmental Sciences, Wright State University, Dayton, OH 45435 USA Lake Taihu, China’s 3rd largest freshwater lake, is located in the heavily urbanized, intensely farmed Yangtze River Delta region. Since the 1990s, this shallow (< 3 m) nutrient-impacted lake has experienced accelerated eutrophication and toxic cyanobacterial blooms (Microcystis spp.). In 2007, a massive bloom overwhelmed the lake’s drinking water plants, leaving ~4 million local residents without potable water for a week. The Taihu ecological catastrophe has become a rallying cry for establishing an intensive lake restoration program, including more fully treating and diverting wastewater effluent, closing ~4000 enterprises identified as significant wastewater sources, constructing wetland buffer zones around the lake, removing fish pens, dredging 37 million m3 of polluted sediment, and retrieval of >10 million tons of cyanobacterial scum at a cost of US$ 14billion. To reduce the lake’s water residence time and ‘flush’ the blooms out of the lake, a canal was constructed connecting the nearby Yangtze River to the lake. Despite these efforts, there has been no noticeable improvement in water quality. Stricter nutrient input reductions are needed. Traditionally, P reductions have been prescribed for combating eutrophication, but only reducing P inputs will not yield a ’quick fix’; Taihu suffers from a >30 year legacy of excessive P loading. Reducing N inputs in addition to P will speed up the recovery period, because the lake has relatively high rates of denitrification, to purge itself of N. Experimental evidence indicates that reducing N will significantly reduce cyanobacterial biomass without replacing non-N2 fixing Microcystis with N2 fixing species. Over time, a more P-exclusive reduction strategy may be feasible, but in the meantime, strict point source reductions of both N and P should be practiced along with enhancement of vegetative buffers, fertilizer management, minimizing urban wastewater and stormwater runoff to reduce non-point nutrient sources. ORAL WEDNESDAY 10.00 hpaerl@email.unc.edu

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Long term biomanipulation at high external phosphorus load - does it work? Ilkka Sammalkorpi (1), Arto Hautala (2) (1) Finnish Environment Institute, PB 140, 00251 Helsinki, Finland (2) Fisheries and Environment Services, Rantalantie 28, 69440 Lestijärvi, Finland Biomanipulation by mass removal of cyprinids was carried out in the eutrophic Lake Tuusulanjärvi to reduce the blooms of cyanobacteria. Pelagic seining in autumn was the main tool of biomanipulation. The effort and catches were highest from autumn 1997 to autumn 1999 when the total catch was 415 kg ha-1 and 101 000 fish ha-1 and, mainly roach (Rutilus rutilus) and bleak (Alburnus alburnus). These figures suggested that cyprinids had had an impact on the nutrient cycling and predation on herbivorous Cladocera. The removal resulted in a lower summer biomass of cyanobacteria in the 2000s and a decline in TP concentration. The fishing had to be continued annually due to very high external phosphorus loading. In the 2000s, the mean annual catch was 65 kg ha-1, the numbers removed varied from 1600 to 20000 fish ha-1 and the percentage of bream (Abramis brama) and white bream (Blicca bjoerkna) increased. The mean TP content of cyprinids was 0.7 % (f.w.). A TP pool equal to the content in water column was removed in the fish biomass in 1997‒99. The TP pool of cyprinid catch was up to 20 % of the mean annual external TP load and, respectively, 11 % in the 2000s. Fish removal by pelagic seining was based on pelagic shoaling and a habitat shift of cyprinids from littoral to deeper pelagic areas in autumn. Shoaling facilitated cost effective fish and nutrient removal. Up to 48 t ha-1a-1 could be removed from the main shoaling area covering < 5 % of the surface area of the lake. Bycatch of the piscivorous zander (Sander lucioperca) was low in the seine hauls with highest cyprinid biomass. This indicated that pelagic shoaling was primarily seeking for dark refuge from predation. Even though seining was on average a cost effective and reliable method it was also weather sensitive. Shoals broke up and catches collapsed if heavy autumn rains increased clay turbidity and transparency fell below 0.5 m and strong winds decreased shoaling intensity. ORAL WEDNESDAY 10.40 ilkka.sammalkorpi@env.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Dreams, needs and possibilities in lake restoration Lea Tuvikene (1), Arvo Tuvikene (1) (1) Institute of Agricultural and Environmental Sciences, Kreutzwaldi 5, Tartu 51014, Estonia In the 1950‒60s, ecological status of most Estonian lakes could be estimated as natural while by now, approximately 10‒12% of lakes should be restored. Requested by the Estonian Ministry of the Environment, Plans of Measures for improving the ecological status of four Estonian lakes were compiled in the frames of the EU INTERREG IVC project LakeAdmin by the end of 2015. The plans were approved by the Ministry of the Environment and the Environmental Board, and attached to the programmes of measures of the corresponding River Basin Management Plans (RBMP). For Lake Harku, located on the western border of the Estonian capital city Tallinn, the main negative factors are excessive external loading and phosphorus release from the sediments. The first attempt to improve the lake’s condition by means of biomanipulation was done in 1993‒1994, but due to short duration of the measures, the effect was also short-term. In Lake Veisjärv, lowering of the water level in 1924‒1925 by up to two meters and modification of discharge has fundamentally altered the ecosystem. In addition to remarkably higher internal nutrient loading from sediments since the water lowering, diffuse pollution from the fields in the mainly agricultural catchment area gives a remarkable contribution to the poor status of Lake Veisjärv. Also for partly meromictic Lake Verevi, the most profound problem is excessive internal load. Due to specific features of the lake (relatively deep, anaerobic hypolimnion, presence of H2S in bottom water layer) and chemical processes, phosphorus release from the sediments exceed its sedimentation. In the case of possible but fortunately not frequent full turnover, massive algal blooms may occur in Lake Verevi. We will give an overview of the planned measures to improve the status of these three lakes, and analyse the emerged problems in implementation of the measures. ORAL WEDNESDAY 11.00 lea.tuvikene@emu.ee

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Development of Lake Vesijärvi through four decades of restoration attempts Mikael Kraft (1,3), Jukka Horppila (1,3), Jouko Sarvala (2), Juha Keto (3), Ismo Malin (3), Kalevi Salonen (1,3) (1) University of helsinki, PL 3 (Fabianinkatu 33), 00014, Helsinki, Finland (2) University of Turku, 20014 Turun yliopisto, Turku, Finland (3) Päijät-Hämeen Vesijärvisäätiö, Askonkatu 9 C, 15100, Lahti, Finland The Enonselkä basin (area 26 km2) of Lake Vesijärvi in southern Finland was originally a clear-water lake, but due to waste waters of the nearby city of Lahti, it was heavily eutrophied. In the middle of the 1970s sewage waters were diverted and the lake started to recover. Since the end of the 1980s its recovery has been supported by mass removal of plankti- and benthivorous fish to reduce the development of phytoplankton. To limit the development of deep water anoxia and nutrient release from the sediment large scale pumping of surface water to the deepest parts of the lake was started in 2010. We report the development of nutrient concentrations in the Enonselkä basin in 1979‒2016 compared to a larger reference basin of the same lake (Kajaanselkä), which has been only indirectly affected by waste waters. The results show continuous slow improvement of the status of the Enonselkä basin, but in the reference basin, little, if any changes were observed. In some years before the oxygenation of the hypolimnion, deep water nutrient concentrations were higher than in some other years. Due to such stochasticity and parallel, albeit less extensive, changes in the Kajaanselkä basin, the effect of the mass removal of fish on lake status remains difficult to interpret. Pumping of epilimnetic water into the hypolimnion negligibly affected epilimnetic nutrient concentrations. However, in the deepest water layers the concentrations decreased. The change was most dramatic in total nitrogen concentration which was more than halved by denitrification, favored by the introduction of oxygen into deep water. ORAL WEDNESDAY 11.20 mikael.kraft@helsinki.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Two case studies of cyanobacteria-related water quality problems and solutions in Serbia Tamara Važić (1), Jussi Meriluoto (2), Tamara Palanački-Maleašević (1), Snežana Simić (3), Nevena Đorđević (3), Zorica Svirčev (1) (1) Department of Biology and Ecology, Faculty of Science, University of Novi Sad, Serbia (2) Biochemistry, Faculty of Science and Engineering, Åbo Akademi University, Tykistökatu 6 A, 20520 Turku, Finland (3) Institute of Biology and Ecology, Faculty of Science, University of Kragujevac, Serbia Many lakes in Serbia suffer from recurrent/continuous cyanobacterial blooms, which have negative impacts on the water ecosystem and surrounding communities. Two recent dramatic events involving toxigenic cyanobacteria were studied. In Aleksandrovac lake the proliferation of Cylindrospermopsis raciborskii killed almost all fish in 2012. Previously applied sanitation measures (drying, dredging, macrophyte removal), carried out after two massive fish kills in 2008, proved to be unsuccessful. A serious water crisis in the city of Uzice (pop. 70.000) was caused in 2013‒2014 by a massive bloom of Planktothrix rubescens in Vrutci reservoir, the source of the drinking water. Chlorine dioxide was applied in the water factory to eliminate cyanobacteria and cyanotoxins but the deep lake (mean depth 21 m) is still pending appropriate restoration. Generally speaking, prevention is preferred to cure: the causes of accelerated eutrophication (nutrients, distorted food webs etc.) should be treated in addition to the consequences (hypoxia, cyanobacterial blooms, cyanotoxins). The long-term solution for cyanobacterial problems is the restriction of excess nutrients. Coordinated use of specific environmentally friendly methods, collectively known as ecomanipulation, is proposed in order to provide a suitable treatment for each eutrophic ecosystem. The methods include dredging, mechanical removal of microalgal/cyanobacterial biomass and macrophytes, floating islands and extensive fishing. The use of the collected biomass as material and energy will be discussed. In addition to the long-term and gradual process of remediation by ecomanipulation, it is proposed to periodically apply hydrogen peroxide (H2O2) into the water. This allows for a selective removal of cyanobacteria with minimal impact on other water organisms. H2O2 should be used as an interventional method in order to eliminate a developing cyanobacterial bloom. ORAL WEDNESDAY 11.40 tamaravazic@gmail.com

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Measuring nitrogen transformation rates in large, eutrophic lakes: challenges, solutions, and future needs Mark J. McCarthy (1,2), Silvia E. Newell (1), Wayne S. Gardner (2) (1) Wright State University, 3640 Colonel Glenn Highway, Dayton, OH 45435 USA (2) The University of Texas at Austin, Marine Science Institute, 750 Channelview Drive, Port Aransas, TX 78373 USA Population growth and climate change are increasing anthropogenic pressure on aquatic systems, while our dependence on the health of these systems also increases. Impacted systems are often monitored intensively for evidence and mitigation of anthropogenic, nutrient-related impacts, such as hypoxia and harmful algal blooms. â&#x20AC;&#x2DC;Snapshotâ&#x20AC;&#x2122; nutrient concentration monitoring is common, but the most bioavailable nutrient forms (e.g., ammonium and reactive phosphorus) cycle rapidly within systems, which limits the usefulness of concentration measurements. For ammonium, and nitrogen (N) in general, the result is an underappreciation of its importance due to generally low concentrations measured in situ. Fully understanding N dynamics and its importance to contributing to eutrophication requires quantification of the rates at which various N forms are assimilated, recycled (e.g., remineralization), and ultimately removed (e.g., via denitrification). These measurements require labor and analytically intensive incubations necessitating the use of stable isotopes, expensive analyses, and multidisciplinary collaborations (e.g., genetic studies to confirm pathways). Once quantified, the challenge shifts toward interpretation and scaling of results for use in data-based regulatory and mitigation actions. Here, experiences from 20 years of conducting these measurements in large, eutrophic lakes around the world will be presented in the context of resolving these challenges and meeting future research needs to effectively manage the vital resources and ecosystem services provided by large lakes. ORAL WEDNESDAY 13.00 mark.mccarthy@wright.edu

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Long term recovery from eutrophication in Lake Vesijärvi: the role of sedimentary phosphorus feedbacks Tom Jilbert (1), Sami Jokinen (2), Timo Saarinen (2), Ulpu Mattus-Kumpunen (2), Asko Simojoki (3), Raoul-Marie Couture (4), Matthias Egger (5), Juha Niemistö (1), Jukka Horppila (1) (1) Ecosystems and Environment Research Program, Faculty of Biological and Environmental Sciences, PO Box 65, 00014 University of Helsinki, Finland (2) Department of Geography and Geology, 20014 University of Turku, Finland (3) Faculty of Agriculture and Forestry, PO Box 56, 00014 University of Helsinki, Finland (4) Laval University, 1045, av. de la Médecine, G1V0A6, Quebec, Canada (5) Department of Bioscience - Microbiology, Ny Munkegade 116, 8000 Aarhus C, Denmark Lake Vesijärvi has suffered from persistent eutrophication due to anthropogenic nutrient loading and the ongoing cycling of ‘legacy’ phosphorus (P) between its sediments and shallow water column. Multiple restoration approaches aimed at reducing the pool of bioavailable P in the water column have been employed in recent decades, including biomanipulation, hypolimnetic aeration and the construction of wetlands in the riparian zone. However, to date no systematic estimate has been made of the timescale of future recovery from eutrophication due to natural P removal processes, principally burial in sediments. Here we make the case that this is an essential step in the refinement of existing management strategies, whether in Vesijärvi or any other eutrophied lake. Using detailed biogeochemical profiling of sediments and pore waters, we first demonstrate the mechanisms of phosphorus burial and regeneration in Lake Vesijärvi today. Our long (2.5 m) sediment cores span the entire recent history of anthropogenic phosphorus accumulation, allowing all relevant post-depositional biogeochemical processes to be investigated. We show that in deeper areas of the lake, P-rich sediments deposited as long ago as 1970 are still diagenetically active today, and continue to fuel an upwards flux of soluble P to the surface sediments and the overlying water column. However, rapid accumulation is simultaneously burying these active sediment layers, decreasing the pore water concentration gradient and hence also the upwards P flux. Ongoing work will employ a diagenetic model to determine rates of change in both P burial and regeneration in the coming decades, providing a basis for improving the P budget and refining future management strategies. ORAL WEDNESDAY 13.20 tom.jilbert@helsinki.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Modeling the response of lake sediments to catchmentscale changes in biogeochemical dynamics Raoul-Marie Couture (1), Igor Markelov (2), Yan Lin (3), Ă&#x2DC;yvind Kaste (3) (1) Laval University, Department of Chemistry, 1045, av. de la MĂŠdecine, G1V 0A6, Quebec, Canada (2) University of Waterloo, Ecohydrology Group, 200 University Avenue, N2L 3G1, Waterloo, Canada (3) Norwegian Institute for Water Research, Gaustadalleen 21, 0655 Oslo, Norway Lakes and reservoirs are hot spots of biogeochemical activity in the landscape and as such are important regulators of environmental quality. Within the lake system, intense biogeochemical cycling occurs at the sediment-water interface (SWI), where the mineralization of organic carbon from catchment inputs and primary production stimulates oxygen consumption as well as the regeneration, or the sequestration, of nutrients and contaminants. To quantify the impact of the SWI on water-quality at the catchment scale, we updated the 1-D lake system model MyLake with a detailed biogeochemical reaction network relevant for both the water column and sediment diagenesis. The updated model represents hydrodynamics, ice formation, primary production, sediment processes and metabolic activities involving the oxidation of organic matter coupled to the reduction of O2 and to a sequence of terminal electron acceptors. We demonstrate the use of the lake model through its application to lakes in catchments from southern Norway, Canada and the Czech Republic where historical phosphorus (P), dissolved organic carbon (C), and sulfur (S) loadings have been previously modeled. Boundary conditions of the lake model setup were provided by a chain of models including a climate model (HadRM3) and catchment-scale hydrological (PERSiST) and biogeochemical models (the model INCA for P and the model MAGIC for S). We quantify the extent to which, given equal historical P loading in the catchment, changing climate, water residence time and geochemical fluxes affect eutrophication and bottom water anoxia. ORAL WEDNESDAY 13.40 raoul.couture@gmail.com

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Quo vadis oxygen? The sinks of hypolimnetic oxygen in deep Swiss lakes Thomas Steinsberger (1), Robert Schwefel (2), Martin Schmid (1), Alfred Wüest (1,2), Bernhard Wehrli (1,3), Beat Müller (1) (1) Eawag - Swiss Federal Institute of Aquatic Science and Technology, 6047, Kastanienbaum, Switzerland (2) Physics of Aquatic Systems Laboratory, Margaretha Kamprad Chair, École Polytechnique Fédérale de Lausanne, Institute of Environmental Engineering, 1015, Lausanne, Switzerland (3) Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, 8092, Zurich, Switzerland The hypolimnetic oxygen depletion in lakes can be divided into three main sinks: the water column mineralization rate (WCM), the sediment oxygen demand (SOU) and the flux of reduced substances diffusing out of anoxic sediments (Fred). Based on several dozens of sediment porewater measurements in different lakes and at various lake depths, we calculated Fred and its impact on the total hypolimnetic O2 depletion. A direct link between Fred and the total organic carbon mass accumulation rate (TOC-MAR) in lake sediments and a relationship between Fred and the mean hypolimentic depth (zH) is presented as a possible shortcut to estimate Fred and thereby circumventing elaborate porewater measurements. We further present SOU data and the resulting WCM values from two case studies: Lake Geneva and Lake Constance. In these very deep lakes, WCM contributes a large portion to the total hypolimnetic O2 depletion, in contrast to very low contributions of Fred. However, in shallow and medium deep lakes, the contribution of Fred can increase up to 80%. The contributions of SOU and Fred are further evaluated by calculating oxygen depletion rates derived from organic carbon budgets. These results have important implications for lake oxygen management as Fred can now be estimated from TOC-MAR and zH, and therefore more readily available data sets. The results further suggest that lakes dominated by Fred are more resilient to reoligotrophication trends than lakes dominated by WCM. ORAL WEDNESDAY 14.00 Thomas.Chwalek@gmail.com

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Factors behind sedimentary P release in lakes: potential linkage to lake water quality management Olga Tammeorg (1,2), Juha Niemistรถ (2), Jukka Horppila (2) (1) Centre for Limnology, Estonian University of Life Sciences, 61117 Rannu, Tartumaa, Estonia (2) Ecosystems and Environment Research Programme, University of Helsinki, P.O. Box 65, FI-00014, Helsinki, Finland We aimed at elucidating the factors that play important role in the linkage of lake water quality and benthic phosphorus flux (IPtot). IPtot was quantified for a broad set of lakes by combining sediment core measurements and mass balance calculations. The comparison of the regressions of the key water quality variables (concentrations of TP, SRP, Chl a) with the IPtot and sedimentary P release due to anoxia revealed a minor importance of anoxia in water quality control via benthic P release in stratifying lakes of the north temperate and boreal zone. Closer analysis of the temporal changes in the IPtot in one of the studied lakes supported the major contribution of the shallow areas associated with aerobic P release. In this lake, we observed an increase in IPtot over the decades despite numerous withinlake management efforts, including aeration. Destratification has increased the concentration of oxygen and decreased the concentration of soluble P in the near-bottom water but at the same time it has accelerated P release from aerobic bottoms. These findings suggest limitations for the use of aeration in lake water quality restoration. In a polymictic lake, we observed an increase in IPtot during the period of lower external P loading and worsened water quality (i.e, higher concentrations of SRP, TP and biomass of cyanobacteria). This was due to an increase in wave action that resulted in more frequent sediment resuspension. Finally, we introduced a model that takes account of lake specifics better than previously in the lake water quality control via benthic P release. ORAL WEDNESDAY 14.20 olga.tammeorg@emu.ee

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Full list of participants Lauri Arvola Lammi Biological Station, University of Helsinki, Finland lauri.arvola@helsinki.fi Raija Aura City of Lappeenranta, Finland raija.aura@lappeenranta.fi Anne-Mari Aurola Nordkalk Oy, Lohja, Finland anne-mari.aurola@nordkalk.com Marc Beutel University of California Merced, USA mbeutel@ucmerced.edu Gregory Cooper University of Southampton, UK gsc1g11@soton.ac.uk Raoul-Marie Couture Laval University, Quebec, Canada raoul.couture@gmail.com Eeva Einola Vanajavesi Centre, Hämeenlinna, Finland eeva.einola@vanajavesi.fi Rocio Fernandez Conicet, Argentina rocioluz@yahoo.com Bo Gustafsson Baltic Nest Institute, Stockholm University, Sweden bo.gustafsson@su.se Björn Gustbee Rädda Lumparn, Gottby, Finland bee@aland.net Ferdi Hellweger TU Berlin, Berlin, Germany fhellweger@gmail.com Jaana Hietala Mid-Uusimaa Board for Water Protection, Finland jaana.hietala@kuves.fi Märt Holtsmann Tallinn Environmental Department, Estonia Mart.Holtsmann@tallinnlv.ee Jukka Horppila University of Helsinki, Finland jukka.horppila@helsinki.fi Heini-Marja Hulkko Hämeen ELY-keskus, Lahti, Finland heini-marja.hulkko@ely-keskus.fi Brian Huser Sveriges lantbruksuniversitet, Uppsala, Sweden brian.huser@slu.se Tom Jilbert University of Helsinki, Finland tom.jilbert@helsinki.fi Joni Jurvanen University of Jyväskylä, Finland (student) joni.t.jurvanen@student.jyu.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges Paula Jäntti Eurofins, Lahti, Finland paula.jantti@dnainternet.net Juhani Järveläinen City of Lahti Environmental Services, Finland juhani.jarvelainen@lahti.fi Marko Järvinen SYKE – Finnish Environment Institute, Helsinki, Finland marko.jarvinen@ymparisto.fi Jenni Jäänheimo Ministry of the Environment, Finland jenni.jaanheimo@ym.fi Kersti Kangro Tartu University, Tartumaa, Estonia kiti@ut.ee Antton Keto Ministry of the Environment, Finland antton.keto@ym.fi Juha Keto Lake Vesijärvi Project, Lahti, Finland keto.juha@gmail.com Mirva Ketola Lake Vesijärvi Foundation, Lahti, Finland mirva.ketola@vesijarvi.fi Mina Kiani University of Helsinki, Finland mina.kiani@helsinki.fi Jorma Kirjavainen ELY-Centre for North Savo, Hämeenlinna, Finland jorma.kirjavainen@ely-keskus.fi Teija Kirkkala Vahanen Environment Oy, Tampere, Finland teija.kirkkala@vahanen.com Anu Kisand Estonian University of Life Sciences, Tartu, Estonia anu.kisand@emu.ee Saija Koljonen Finnish Environment Institute, Jyväskylä, Finland saija.koljonen@ymparisto.fi Mikael Kraft University of Helsinki, Finland mikael.kraft@helsinki.fi Ronald Laarmaa Estonian University of Life Sciences, Tartu, Estonia ronald.laarmaa@emu.ee Miquel Lürling Wageningen University, The Netherlands miquel.lurling@wur.nl Kairi Maileht Estonian University of Life Sciences, Tartu, Estonia kairi.maileht@emu.ee Ismo Malin City of Lahti Environmental Services, Lahti, Finland ismo.malin@lahti.fi Mark McCarthy Wright State University, Dayton, Ohio, USA mark.mccarthy@wright.edu Lewis Molot York University, Toronto, Ontario, Canada lmolot@yorku.ca 76


Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges Maíra Mucci Wageningen University, Netherlands maira.mucci@wur.nl Suvi Mäkelä Vanajavesi Centre, Hämeenlinna, Finland suvi.makela@vanajavesi.fi Heikki Mäkinen Lake Vesijärvi Foundation, Lahti, Finland heikki.makinen@vesijarvi.fi Anne Mäkynen Pirkanmaan ELY-keskus, Finland anne.makynen@ely-keskus.fi Juha Niemistö University of Helsinki, Finland juha.niemisto@helsinki.fi Gertrud Nürnberg Freshwater Research, Baysville, Canada gkn@fwr.ca Mikko Ortamala University of Helsinki, Finland (student) mikko.ortamala@proagria.fi Ingmar Ott Estonian University of Life Sciences, Tartu, Estonia ingmar.ott@emu.ee Hans Paerl University of North Carolina at Chapel Hill, USA hpaerl@email.unc.edu Elina Peltomaa University of Helsinki, Lahti, Finland elina.peltomaa@helsinki.fi Stephan Pflugmacher Lima University of Helsinki, Finland stephan.pflugmacher@helsinki.fi Pete Pihko PoTeHu Water Protection Society, Finland petepihko@hotmail.com Mikko Rahtola Natural Resources Institute (LUKE), Finland mikko.rahtola@luke.fi Martti Rask University of Helsinki, Lammi Biological Station, Finland martti.rask@helsinki.fi Tatjana Regerand Northern Institute of Water Problems, Russia regerand@nwpi.krc.karelia.ru Alexander Rusanov Inst. of Limnology, RAS, St. Petersburg, Russia a_rusanov@yahoo.com Jukka Ruuhijärvi Natural Resources Institute Finland, Helsinki, Finland jukka.ruuhijarvi@luke.fi Katrin Saar Estonian University of Life Sciences, Tartu, Estonia katrin.saar@emu.ee Erkki Saarijärvi Vesi-Eko oy, Finland erkki.saarijarvi@vesieko.fi Pauliina Salmi University of Jyväskylä, Finland pauliina.u.m.salmi@jyu.fi 77


Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Kalevi Salonen University of Helsinki, Lammi, Finland kalevi.salonen@helsinki.fi Ilkka Sammalkorpi Finnish Environment Institute, Helsinki, Finland ilkka.sammalkorpi@env.fi Jouko Sarvala University of Turku, Finland jouko.sarvala@utu.fi Margot Sepp Estonian University of Life Sciences, Tartu, Estonia margot.sepp@emu.ee Liudmila Shirokova Institute of Env. Problems of the North, Russia LShirocova@yandex.ru Soila Silvonen University of Helsinki, Finland (student) soila.silvonen@helsinki.fi Mika Sivil Varsiais-Suomen ELY-keskus, Finland mika.sivil@ely-keskus.fi Thomas Steinsberger Eawag, Kastanienbaum, Switzerland Thomas.Chwalek@gmail.com Martin Søndergaard Aarhus University, Silkeborg, Denmark ms@bios.au.dk Sami Taipale University of Jyväskylä, Finland sami.taipale@jyu.fi Olga Tammeorg Estonian University of Life Sciences, Tartu, Estonia olga.tammeorg@emu.ee Perttu Tamminen Varsinais-Suomen Ely-keskus, Helsinki, Finland perttu.tamminen@ely-keskus.fi Irina Trifonova Institute of Limnology RAS, St.Petersburg, Russia itrifonova@mail.ru Lea Tuvikene Estonian University of Life Sciences, Tartu, Estonia lea.tuvikene@emu.ee Tamara Važić University of Novi Sad, Serbia tamaravazic@gmail.com Anne-Mari Ventelä Pyhäjärvi Institute, Kauttua, Finland anne-mari.ventela@pji.fi Eduardo Vicente University of Valencia Paterna, Spain eduardo.vicente@uv.es Kari-Matti Vuori Finnish Environment Institute, Jyväskylä, Finland kari-matti.vuori@ymparisto.fi Kristiina Vuorio Finnish Environment Institute SYKE, Helsinki, Finland kristiina.vuorio@ymparisto.fi

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Lahti Lakes 2018 Restoration of eutrophic lakes: Current practices and future challenges

Jukka-Pekka Vähä Länsi-uudenmaan vesi ja ympäristö ry, Finland juha-pekka.vaha@luvy.fi Kaisa Västilä Aalto University School of Engineering, Aalto, Finland kaisa.vastila@aalto.fi Ben Woodward Nat. Inst. of Water and Atmosphere, New Zealand ben.woodward@niwa.co.nz Priit Zingel Estonian University of Life Sciences, Tartu, Estonia priit.zingel@emu.ee Satu Zwerver Company Zwerver, Kemiö, Finland info@zwerver.fi

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LAHTI LAKES 2018 is supported by:

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Lahtilakes2018  

Lahti Lakes 2018. Abstracts and Schedule. June 4.–6. 2018, Lahti, Finland

Lahtilakes2018  

Lahti Lakes 2018. Abstracts and Schedule. June 4.–6. 2018, Lahti, Finland

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