Drought-induced changes in nutrient concentrations and retention in two shallow Mediterranean lakes subjected to different degrees of management

Ozen, Arda
Karapinar, Burcu
Kucuk, Ismail
Jeppesen, Erik
Beklioğlu, Meryem
While extensive knowledge exists on the relationship between nutrient loading and nutrient concentrations in lakes in the cold temperate region, few studies have been conducted in warm lakes, not least in warm arid lakes. This is unfortunate as a larger proportion of the world's lakes will be situated in arid climates in the future due to climate change and a larger proportion will suffer from a higher frequency of intensive drought. We conducted a comprehensive 11-13 year mass balance study in two interconnected shallow Mediterranean lakes in Turkey, covering a period with substantial changes in climate conditions. The upstream lake was only affected by natural changes in nutrient loading, while the downstream lake was additionally influenced by sewage diversion and restoration by fish removal. Contrasting to experience from north temperate lakes we found an increase in in-lake concentrations of total phosphorus and inorganic nitrogen (ammonia as well as nitrate) in dry years despite lower external nutrient loading, and submerged macrophytes did not increase the nitrogen retention capacity of the lakes. In contrast, fish removal modulated the nitrogen concentration as in north temperate lakes, but the effect was not long-lasting. Our results suggest that climate warming reduces the nutrient retention capacity of shallow lakes in the Mediterranean and exacerbates eutrophication. Lower thresholds of nutrient loading for shifting turbid shallow lakes to a clear water state are therefore to be expected in arid zones in a future warmer climate, with important management implications.


Water level and fish-mediated cascading effects on the microbial community in eutrophic warm shallow lakes: a mesocosm experiment
ÖZEN, ARDA; Bucak, Tuba; Tavsanoglu, Ulku Nihan; Cakiroglu, Ayse Idil; Levi, Eti Ester; Coppens, Jan; Jeppesen, Erik; Beklioğlu, Meryem (Springer Science and Business Media LLC, 2014-11-01)
Information on the effects of water level changes on microbial planktonic communities in lakes is limited but vital for understanding ecosystem dynamics in Mediterranean lakes subjected to major intra- and inter-annual variations in water level. We performed an in situ mesocosm experiment in an eutrophic Turkish lake at two different depths crossed with presence/absence of fish in order to explore the effects of water level variations and the role of top-down regulation at contrasting depths. Strong effects...
Restoration of the eutrophic Lake Eymir, Turkey, by biomanipulation after a major external nutrient control I
Beklioğlu, Meryem; Tuzun, I (Springer Science and Business Media LLC, 2003-01-01)
Nutrient loading in lakes is recognized as a serious threat to water quality. Over 25 years of raw sewage effluent discharge shifted Lake Eymir from a state dominated by submerged plants to a turbid water state. Successful effluent diversion undertaken in 1995 achieved 88% and 95% reductions in the areal loading of total phosphorus (TP) and dissolved inorganic nitrogen (DIN), respectively. Furthermore, the reduced load of TP was very close to the suggested threshold areal load (0.6 g m(-2) yr(-1)) to attain...
Energy-based top-down and bottom-up relationships between fish community energy demand or production and phytoplankton across lakes at a continental scale
Bartrons, Mireia; Mehner, Thomas; Argillier, Christine; Beklioğlu, Meryem; Blabolil, Petr; Hesthagen, Trygve; Sweden, Kerstin Holmgren; Jeppesen, Erik; Krause, Teet; Podgornik, Samo; Volta, Pietro; Winfield, Ian J.; Brucet, Sandra (Wiley, 2020-04-01)
Fish community feeding and production rates may differ between lakes despite similar fish biomass levels because of differences in size structure and local temperature. Therefore, across-lake comparisons of the strength and direction of top-down and bottom-up fish-phytoplankton relationships should consider these factors. We used the metabolic theory of ecology to calculate size- and temperature-corrected community energy demand (CEDom) and community production (CP) of omnivorous fishes in 227 European lake...
Decadal changes in zooplankton biomass, composition, and body mass in four shallow brackish lakes in Denmark subjected to varying degrees of eutrophication
He, Hu; Jeppesen, Erik; Bruhn, Dan; Yde, Morten; Hansen, Jacob Kjerulf; Spanggaard, Lasse; Madsen, Niels; Liu, Wei; Sondergaard, Martin; Lauridsen, Torben L. (Informa UK Limited, 2020-04-01)
During the past century, many brackish shallow lakes worldwide have become eutrophic. How the zooplankton have responded to this development is not well elucidated. Here, we analysed the decadal changes (from 1999-2000 to 2017-2018) in zooplankton biomass, body mass, and potential top-down control on phytoplankton during summer in 4 Danish shallow brackish lakes (Lund Fjord, Han Vejle, Selbjerg, and Glombak) subjected to varying degrees of eutrophication. Significant reductions of zooplankton biomass, body ...
Climate change impacts on lakes: an integrated ecological perspective based on a multi-faceted approach, with special focus on shallow lakes
Jeppesen, Erik; Meerhoff, Mariana; Davidson, Thomas A.; Trolle, Dennis; Sondergaard, Martin; Lauridsen, Torben L.; Beklioğlu, Meryem; Brucet, Sandra; Volta, Pietro; Gonzalez-Bergonzoni, Ivan; Nielsen, Anders (PAGEPress Publications, 2014-01-01)
Freshwater ecosystems and their biodiversity are presently seriously threatened by global development and population growth, leading to increases in nutrient inputs and intensification of eutrophication-induced problems in receiving fresh waters, particularly in lakes. Climate change constitutes another threat exacerbating the symptoms of eutrophication and species migration and loss. Unequivocal evidence of climate change impacts is still highly fragmented despite the intensive research, in part due to the...
Citation Formats
A. Ozen, B. Karapinar, I. Kucuk, E. Jeppesen, and M. Beklioğlu, “Drought-induced changes in nutrient concentrations and retention in two shallow Mediterranean lakes subjected to different degrees of management,” HYDROBIOLOGIA, pp. 61–72, 2010, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/42143.