Stratification strength and light climate explain variation in chlorophyll a at the continental scale in a European multilake survey in a heatwave summer

To determine the drivers of phytoplankton biomass, we collected standardized morphometric, physical, and biological data in 230 lakes across the Mediterranean, Continental, and Boreal climatic zones of the European continent. Multilinear regression models tested on this snapshot of mostly eutrophic lakes (median total phosphorus [TP] = 0.06 and total nitrogen [TN] = 0.7 mg L−1), and its subsets (2 depth types and 3 climatic zones), show that light climate and stratification strength were the most significant explanatory variables for chlorophyll a (Chl a) variance. TN was a significant predictor for phytoplankton biomass for shallow and continental lakes, while TP never appeared as an explanatory variable, suggesting that under high TP, light, which partially controls stratification strength, becomes limiting for phytoplankton development. Mediterranean lakes were the warmest yet most weakly stratified and had significantly less Chl a than Boreal lakes, where the temperature anomaly from the long-term average, during a summer heatwave was the highest (+4°C) and showed a significant, exponential relationship with stratification strength. This European survey represents a summer snapshot of phytoplankton biomass and its drivers, and lends support that light and stratification metrics, which are both affected by climate change, are better predictors for phytoplankton biomass in nutrient-rich lakes than nutrient concentrations and surface temperature.Additional co-authors: Jolanda Verspagen, Maria van Herk, Maria G. Antoniou, Nikoletta Tsiarta, Valerie McCarthy, Victor C. Perello, Danielle Machado-Vieira, Alinne Gurjao de Oliveira, Dubravka Špoljaric Maronic, Filip Stevic, Tanja Žuna Pfeiffer, Itana Bokan Vucelic, Petar Žutinic, Marija Gligora Udovic, Anđelka Plenkovic-Moraj, Ludek Blaha, Rodan Geriš, Markéta Frankova, Kirsten Seestern Christoffersen, Trine Perlt Warming, Tõnu Feldmann, Alo Laas, Kristel Panksep, Lea Tuvikene, Kersti Kangro, Judita Koreiviene, Jurate Karosiene, Jurate Kasperoviciene, Ksenija Savadova-Ratkus, Irma Vitonyte, Kerstin Häggqvist, Pauliina Salmi, Lauri Arvola, Karl Rothhaupt, Christos Avagianos, Triantafyllos Kaloudis, Spyros Gkelis, Manthos Panou, Theodoros Triantis, Sevasti-Kiriaki Zervou, Anastasia Hiskia, Ulrike Obertegger, Adriano Boscaini, Giovanna Flaim, Nico Salmaso, Leonardo Cerasino, Sigrid Haande, Birger Skjelbred, Magdalena Grabowska, Maciej Karpowicz, Damian Chmura, Lidia Nawrocka, Justyna Kobos, Hanna Mazur-Marzec, Pablo Alcaraz-Parraga, Elżbieta Wilk-Wozniak, Wojciech Krzton, Edward Walusiak, Ilona Gagala-Borowska, Joana Mankiewicz-Boczek, Magdalena Toporowska, Barbara Pawlik-Skowronska, Michał Niedzwiecki, Wojciech Pęczuła, Agnieszka Napiorkowska-Krzebietke, Julita Dunalska, Justyna Sienska, Daniel Szymanski, Marek Kruk, Agnieszka Budzynska, Ryszard Goldyn, Anna Kozak, Joanna Rosinska, Elżbieta Szeląg-Wasielewska, Piotr Domek, Natalia Jakubowska-Krepska, Kinga Kwasizur, Beata Messyasz, Aleksandra Pełechata, Mariusz Pełechaty, Mikolaj Kokocinski, Beata Madrecka-Witkowska, Iwona Kostrzewska-Szlakowska, Magdalena Frąk, Agnieszka Bankowska-Sobczak, Michał Wasilewicz, Agnieszka Ochocka, Agnieszka Pasztaleniec, Iwona Jasser, Ana M. Antao-Geraldes, Manel Leira, Vitor Vasconcelos, Joao Morais, Micaela Vale, Pedro M. Raposeiro, Vítor Gonçalves, Boris Aleksovski, Svetislav Krstic, Hana Nemova, Iveta Drastichova, Lucia Chomova, Spela Remec-Rekar, Tina Elersek, Lars-Anders Hansson, Pablo Urrutia-Cordero, Andrea G. Bravo, Moritz Buck, William Colom-Montero, Kristiina Mustonen, Don Pierson, Yang Yang, Christine Edwards, Hannah Cromie, Jordi Delgado-Martín, David García, Jose Luís Cereijo, Joan Gomà, Mari Carmen Trapote, Teresa Vegas-Vilarrúbia, Biel Obrador, Ana García-Murcia, Monserrat Real, Elvira Romans, Jordi Noguero-Ribes, David Parreño Duque, Elísabeth Fernandez-Moran, Barbara Úbeda, José Angel Galvez, Núria Catalan, Carmen Pérez-Martínez, Eloísa Ramos-Rodríguez, Carmen Cillero-Castro, Enrique Moreno-Ostos, José María Blanco, Valeriano Rodríguez, Jorge Juan Montes-Pérez, Roberto L. Palomino, Estela Rodríguez-Pérez, Armand Hernandez, Rafael Carballeira, Antonio Camacho, Antonio Picazo, Carlos Rochera, Anna C. Santamans, Carmen Ferriol, Susana Romo, Juan Miguel Soria, Arda Özen, Tünay Karan, Nilsun Demir, Meryem Beklioglu, Nur Filiz, Eti Levi, Ugur Iskin, Gizem Bezirci, Ülkü Nihan Tavsanoglu, Kemal Çelik, Koray Ozhan, Nusret Karakaya, Mehmet Ali Turan Koçer, Mete Yilmaz, Faruk Maras¸lıoglu, Özden Fakioglu, Elif Neyran Soylu, Meral Apaydın Yagcı, Sakir Çınar, Kadir Çapkın, Abdulkadir Yagcı, Mehmet Cesur, Fuat Bilgin, Cafer Bulut, Rahmi Uysal, Köker Latife, Reyhan Akçaalan, Meriç Albay, Mehmet Tahir Alp, Korhan Özkan, Tugba Ongun Sevindik, Hatice Tunca, Burçin Önem, Hans Paerl, Cayelan C. Carey, Bastiaan W. Ibeling

State of knowledge on UK agricultural peatlands for food production and the net zero transition

Agricultural peatlands are the most productive soils in the UK for the cultivation of many food crops. Historical drainage of peat for agriculture (i.e., cropland and managed grassland), without consideration of other associated environmental and climatic impacts, has resulted in a significant emission of greenhouse gases (GHGs). There is a need to reduce GHG emissions without compromising the rural economy and jeopardizing food security in the UK to a greater extent than is currently being experienced. In March 2023, in a bid to identify alternative land management systems for agricultural peatlands to support the UK’s commitment to achieving net zero GHG emissions by 2050, a group of forty investigators met at a workshop convened by the AgriFood4NetZero Network+. The workshop reviewed the state of knowledge surrounding the Fens of Eastern England and their importance for food provision, the economy, cultural identity, and climate change mitigation. A broad consensus emerged for research into how GHG emissions from agricultural peatlands could be reduced, whether alternative farming methods, such as seasonal farming or paludiculture, would offer a solution, and how a localized approach for the Fens could be defined. The development of a holistic, inclusive, and plausible land use scenario that considers all aspects of ecosystem services provided by the Fens is urgently needed

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.Peer reviewe

Assessment of sample freezing as a preservation technique for analysing the molecular composition of dissolved organic matter in aquatic systems

Dissolved organic matter (DOM) is widely studied in environmental and biogeochemical sciences, but is susceptible to chemical and biological degradation during sample transport and storage. Samples taken in remote regions, aboard ships, or in large numbers need to be preserved for later analysis without changing DOM composition. Here we compare high-resolution mass spectra of solid phase extractable DOM before and after freezing at -20 & DEG;C. We found that freezing increases compositional dissimilarity in DOM by between 0 to 18.2% (median = 2.7% across 7 sites) when comparing replicates that were frozen versus unfrozen, i.e., processed immediately after sampling, as compared with differences between unfrozen replicates. The effects of freezing primarily consisted of a poorer detection limit, but were smaller than other sample preparation and analysis steps, such as solid phase extraction and variable ionisation efficiency. Freezing samples for either 21 or 95 days led to similar and only slight changes in DOM composition, albeit with more variation for the latter. Therefore, we conclude that sample freezing on these time scales should not impede scientific study of aquatic DOM and can be used where it makes logistical sense, such as for large spatial surveys or study of archived samples

Assessment of sample freezing as a preservation technique for analysing the molecular composition of dissolved organic matter in aquatic systems.

Funder: Carl Tryggers Stiftelse för Vetenskaplig Forskning; doi: https://doi.org/10.13039/501100002805; Grant(s): CTS20:170Dissolved organic matter (DOM) is widely studied in environmental and biogeochemical sciences, but is susceptible to chemical and biological degradation during sample transport and storage. Samples taken in remote regions, aboard ships, or in large numbers need to be preserved for later analysis without changing DOM composition. Here we compare high-resolution mass spectra of solid phase extractable DOM before and after freezing at -20 °C. We found that freezing increases compositional dissimilarity in DOM by between 0 to 18.2% (median = 2.7% across 7 sites) when comparing replicates that were frozen versus unfrozen, i.e., processed immediately after sampling, as compared with differences between unfrozen replicates. The effects of freezing primarily consisted of a poorer detection limit, but were smaller than other sample preparation and analysis steps, such as solid phase extraction and variable ionisation efficiency. Freezing samples for either 21 or 95 days led to similar and only slight changes in DOM composition, albeit with more variation for the latter. Therefore, we conclude that sample freezing on these time scales should not impede scientific study of aquatic DOM and can be used where it makes logistical sense, such as for large spatial surveys or study of archived samples

Dissolved organic matter composition from a large scale enclosure experiment

During the summer of 2015, we reproduced three levels of browning and seven levels of nutrients using water from lake Stechlin (North-East Germany). We applied ultra-high-resolution mass-spectrometry and dissolved organic matter optical properties to retrieve the composition of the DOM at different levels of resolutions. Using a network analysis approach, we found that molecular formulas clustering together share a common origin

Interactive effects of multiple drivers on ecosystem metabolism in a large-scale lake enclosure experiment

International audienc

State of knowledge on UK agricultural peatlands for food production and the net zero transition

This is the author accepted manuscript.Data Availability Statement: No new data were created or analyzed in this study. Data sharing is not applicable to this article.Agriculturally-used lowland peatlands are the most productive soils in the UK for growing many food crops. This requires drainage of the peat, which subsequently leads to significant greenhouse gas (GHG) emissions. Historically, there has been a focus on using this land to increase food production, without considering the associated negative environmental and climate impacts. Focusing only on eliminating GHG emissions, would have economic consequences and jeopardise food security in the UK to a greater extent than is currently being experienced. This could result in food price inflation and trade barriers, and would risk transferring GHG emissions from food production to other countries. In March 2023, in a bid to identify alternative land management systems for peatlands to support the UK’s commitment to achieving net zero GHG emissions by 2050, a group of 40 investigators met at a workshop convened by the AgriFood4NetZero Network+. The expert workshop reviewed the state of knowledge surrounding the Fens of eastern England and their importance for food provision, economic value, cultural identity, and climate change mitigation. A broad consensus emerged that a holistic and plausible land use scenario that considers all aspects of ecosystem services provided by the Fens urgently needs to be defined.UKRI AgriFood4NetZero Network+Natural Environment Research Council (NERC

State of Knowledge on UK Agricultural Peatlands for Food Production and the Net Zero Transition

Peer reviewed: TrueAcknowledgements: The authors wish to thank the AgriFood4NetZero Network+ for providing funds for the organization of the workshop. Further thanks to R.M.F. and H.D. for organizing in-person hubs at Newcastle University and the University of Cambridge, respectively, and to C.D.E., L.E.F., J.K., P.N. and S.E.P. for giving plenary lectures at the workshop.Publication status: PublishedFunder: Centre for Landscape RegenerationAgricultural peatlands are the most productive soils in the UK for the cultivation of many food crops. Historical drainage of peat for agriculture (i.e., cropland and managed grassland), without consideration of other associated environmental and climatic impacts, has resulted in a significant emission of greenhouse gases (GHGs). There is a need to reduce GHG emissions without compromising the rural economy and jeopardizing food security in the UK to a greater extent than is currently being experienced. In March 2023, in a bid to identify alternative land management systems for agricultural peatlands to support the UK’s commitment to achieving net zero GHG emissions by 2050, a group of forty investigators met at a workshop convened by the AgriFood4NetZero Network+. The workshop reviewed the state of knowledge surrounding the Fens of Eastern England and their importance for food provision, the economy, cultural identity, and climate change mitigation. A broad consensus emerged for research into how GHG emissions from agricultural peatlands could be reduced, whether alternative farming methods, such as seasonal farming or paludiculture, would offer a solution, and how a localized approach for the Fens could be defined. The development of a holistic, inclusive, and plausible land use scenario that considers all aspects of ecosystem services provided by the Fens is urgently needed