Climate change effects on shallow lakes: design and preliminary results of a cross-European climate gradient mesocosm experiment

• Published in: Estonian journal of ecology Vol. 63; no. 2; pp. 71 - 89
• Main Authors: Landkildehus, F, Søndergaard, M, Beklioglu, M, Adrian, R, Angeler, D G, Hejzlar, J, Papastergiadou, E, Zingel, P, Çakiroğlu, A I, Scharfenberger, U, Drakare, S, Nõges, T, Šorf, M, Stefanidis, K, Tavşanoğlu, N, Trigal, C, Mahdy, A, Papadaki, C, Tuvikene, L, Larsen, S E, Kernan, M, Jeppesen, E
• Format: Journal Article
• Language: English
• Published: Tallinn Estonian Academy Publishers 01.06.2014; Teaduste Akadeemia Kirjastus (Estonian Academy Publishers)
• Subjects: Climate change; Climatic changes; Environmental aspects; Environmental Sciences; Freshwater; Lakes; Miljövetenskap; Estonia; Greece; Turkey; Estonia, Vortsjarv L; Czech Rep., Bohemia; Germany, Berlin, Grosser Mueggelsee L; Sweden, Stockholm, Erken L
• ISSN: 1736-602X; 1736-7549
• DOI: 10.3176/eco.2014.2.02

Climate change is expected to profoundly affect both temperature and net precipitation, with implications for lake water level. We describe the design of a harmonized, simultaneous, cross-European mesocosm experiment to elucidate the effects of climate change on community structure, functioning, and metabolism in shallow lakes at low and high nutrient levels with contrasting depths (1 and 2 m). We used cylindrical (D = 1.2 m) tanks that were either 1.2 or 2.2 m high, each having a 10-cm sediment layer. We inoculated the mesocosms with a mixed sample of sediment and plankton from lakes with contrasting nutrient concentrations and added macrophytes and planktivorous fish. Sediment was pre-equilibrated to the required experimental nutrient concentration. During the experiment the water level decreased with increasing temperature (up to 90 cm in the Mediterranean mesocosms) while conductivity increased. The average chlorophyll a concentration increased with temperature in the deep mesocosms but was more variable in the shallow mesocosms. Macrophyte abundance increased with temperature, while the oxygen data suggest that net primary production peaked at intermediate temperatures. We conclude that our experimental design has the potential for tracking the interacting effects of global warming and eutrophication in shallow lakes. Key words: climate change, REFRESH project, macrophytes, nutrient enrichment, metabolism, water level effects, macroecology.