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

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

The impact of warming and nutrients on algae production and microcystins in seston from the iconic lake lesser Prespa, Greece

Lake Lesser Prespa and its adjacent pond, Vromolimni in Greece, is a shallow freshwater system and a highly protected area hosting an exceptional biodiversity. The occurrence of microcystins (MCs) producing cyanobacterial blooms in these waters during recent years can be harmful to the wildlife. We tested the hypothesis that both cyanobacterial biomass and MCs are strongly influenced by nutrients (eutrophication) and warming (climate change). Lake and pond water was collected from two sites in each water body in 2013 and incubated at three temperatures (20°C, 25°C, 30°C) with or without additional nutrients (nitrogen +N, phosphorus +P and both +N and +P). Based on both biovolume and chlorophyll-a concentrations, cyanobacteria in water from Lesser Prespa were promoted primarily by combined N and P additions and to a lesser extent by N alone. Warming seemed to yield more cyanobacteria biomass in these treatments. In water from Vromolimni, both N alone and N+P additions increased cyanobacteria and a warming effect was hardly discernible. MC concentrations were strongly increased by N and N+P additions in water from all four sites, which also promoted the more toxic variant MC-LR. Hence, both water bodies seem particularly vulnerable to further N-loading enhancing MC related risks

First report of Economidichthys pygmaeus (Holly, 1929) (Gobiidae) in Lake Lesser Prespa, Greece

Lake Lesser Prespa in Greece is part of the Prespa Lakes area which is a Ramsar site and a Special Protection Area due to its international importance for endemic biodiversity and migratory birds. Twenty fish taxa have been reported in that lake. From a field survey in July 2016, the species Economidichthys pygmaeus (Holly, 1929) (Gobiidae) was identified based on a molecular analysis and can be added to the list of fish species inhabiting Lake Lesser Prespa, which is the most northern location where this species has been found in Greece

Assessment of possible solid-phase phosphate sorbents to mitigate eutrophication : Influence of pH and anoxia

Managing eutrophication remains a challenge to water managers. Currently, the manipulation of biogeochemical processes (i.e., geo-engineering) by using phosphorus-adsorptive techniques has been recognized as an appropriate tool to manage the problem. The first step in finding potential mitigating materials is conducting a sequence of upscaling studies that commence with controlled laboratory experiments. Here, the abilities of 10 possible solid–phase-sorbents (SPS) to adsorb P were examined. Four materials adsorbed P, and two of these materials were modified, i.e., a lanthanum-modified-bentonite (LMB) and an aluminum-modified-zeolite (AMZ), and had the highest adsorption capacities of 11.4 and 8.9 mg P g− 1, respectively. Two natural materials, a red soil (RS) and a bauxite (BAU), were less efficient with adsorption capacities of 2.9 and 3.4 mg P g− 1, respectively. Elemental composition was not related to P adsorption. Since SPS might be affected by pH and redox status, we also tested these materials at pH values of 6, 7, 8 and 9 and under anoxic condition. All tested materials experienced decreased adsorption capacities under anoxic condition, with maximum adsorptions of 5.3 mg P g− 1 for LMB, 5.9 mg P g− 1 for AMZ, 0.2 mg P g− 1 for RS and 0.2 mg P g− 1 for BAU. All materials were able to adsorb P across the range of pH values that were tested. The maximum adsorption capacities of LMB and RS were highest at pH 6, AMZ was higher at a pH of 9 and BAU at a pH of 8. Thus, pH influenced P adsorption differently. Given the effects of pH and anoxia, other abiotic variables should also be considered. Considering the criteria that classify a useful SPS (i.e., effective, easy to produce, cheap and safe), only the two modified materials that were tested seem to be suitable for upscaling to enclosure studies with anoxic sediments.</p

Colonial nesting waterbirds as vectors of nutrients to Lake Lesser Prespa (Greece)

The nutrients imported by breeding waterbirds should be considered when identifying the main sources of nutrient input to lakes. Lake Lesser Prespa (Greece), including the adjacent Vromolimni pond, hosts numerous protected waterbirds that nest in densely populated colonies across the reedbeds. The accelerated eutrophication of the lake in recent years has been of increasing concern. In addition to likely large sources of nutrients (i.e., anthropogenic activities, especially agriculture), nutrient input via waterbird excrement may further trigger eutrophication. We estimated the annual phosphorus (P) and nitrogen (N) input by the most abundant colonial-nesting waterbirds (great white pelican, Dalmatian pelican, great cormorant, and pygmy cormorant) into the lake and investigated their influence on water and sediment quality. Near the waterbird colonies, soluble nutrient concentrations in the lake sediments were higher, and chlorophyll measurements indicated higher algal growth near these sites in summer. Stable isotope analysis suggests that near the colonies, waterbirds are responsible for nutrient loadings that affect the lake sediment. The estimated N and P nutrient input into the lake by both pelican and cormorant species is at least 1243 and 1649 kg/yr, respectively. On a landscape scale, this level of loading could be of minor importance for the lake because N and P can reach 32.8 (SD 9.3) and 38.9 (5.8) mg/m2 per year, respectively. Locally, however, this level of loading might induce cyanobacterial blooms, illustrated by the analysis of isolated Vromolimni pond near the lake. Our findings emphasize the likely importance of nutrient loading by waterbirds for the lake system.</p

Effects of guanotrophication and warming on the abundance of green algae, cyanobacteria and microcystins in Lake Lesser Prespa, Greece

Lake Lesser Prespa in Greece is a vital breeding habitat for the Dalmatian and Great White Pelican and a shelter for numerous rare and endemic species. However, eutrophication processes are distressing the lake system and the outbreaks of cyanobacterial blooms during the warm months may pose a threat to aquatic organisms due to the presence of microcystins (MCs). In this study we hypothesize that nutrients (eutrophication), nutrient-rich pelican droppings (guanotrophication) and warming (climate change) can affect the algal growth and MCs production in the water layer of Lake Lesser Prespa. Seston collected from three lake sites was incubated at ambient (20°C) and high (30°C) temperature with or without the addition of nutrients (nitrogen (N), phosphorus (P)), or pelican droppings. Results showed increased chlorophyll-a at higher temperature (30°C). N addition yielded higher chlorophyll-a levels than the non-treated water or when only P was added. The addition of both N and P as well as the addition of pelican dropping resulted in the highest chlorophyll-a at both temperatures. Notably, in the dropping-treatments, cyanobacteria and MCs were promoted while changes were evoked in the relative contribution of toxic MC-variants. Guanotrophication may thus influence the cyanobacterial dynamics and most likely their toxicity profile at Lesser Prespa

Interannual and Spatial Variability of Cyanotoxins in the Prespa Lake Area, Greece

Contains fulltext : 230810.pdf (publisher's version ) (Open Access

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 degrees 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.Peer reviewe