Restoration of the eutrophic Lake Eymir, Turkey, by biomanipulation after a major external nutrient control I

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 recovery. Even though diversion also reduced the in-lake TP level by half, the poor water clarity and low submerged plant coverage (112 +/- 43 cm and 2.5% coverage of the lake total surface area, respectively) persisted. Domination of the fish stock by planktivorous tench (Tinca tinca L.) and the benthivorous common carp (Cyprinus carpio L.) (66 +/- 0.7 and 31 +/- 1 kg CPUE, respectively) appeared to perpetuate the poor water condition. A substantial fish removal effort over 1 year achieved a 57% reduction in the fish stock which led to a 2.5-fold increase in Secchi disk transparency. This increase occurred largely because of a 4.5-fold decrease in the inorganic suspended solid concentration, and to some extent, a decrease in chlorophyll-a concentration. A strong top-down effect of fish on the large-sized grazers was evident as density and the body size of Daphnia pulex de Geer increased significantly after the fish removal. Even though the spring and annual euphotic depths occurred well above the maximum and mean depths of the lake, respectively, re-development of submerged plants was poor (6.2% coverage). A weak re-establishment of submerged plants might be attributed to an insufficiently viable seed bank, inappropriate chemical conditions of the sediment (severe oxygen deficiency), or to the high coot (Fulica atra L.) density. However, the top-down effect of fish appeared to be of great importance in determining water clarity, and in turn, conditions for submerged plant development in a warm temperate lake as recorded in the north temperate lakes. Furthermore, this study provides evidence for the importance of top-down control of fish, which, in turn, can be effectively utilised as a restoration strategy in warm-temperate lakes as well. More applications, along with long monitoring programs, are needed to develop a better understanding about requirements for biomanipulation success in this climate.


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...
Toward predicting climate change effects on lakes: a comparison of 1656 shallow lakes from Florida and Denmark reveals substantial differences in nutrient dynamics, metabolism, trophic structure, and top-down control
Jeppesen, Erik; Canfield, Daniel E.; Bachmann, Roger W.; Sondergaard, Martin; Havens, Karl E.; Johansson, Liselotte S.; Lauridsen, Torben L.; Tserenpil, Sh; Rutter, Robert P.; Warren, Gary; Ji, Gaohua; Hoyer, Mark (Informa UK Limited, 2020-04-01)
Rapid climate changes may potentially have strong impacts on the ecosystem structure and nutrient dynamics of lakes as well as implications for water quality. We used a space-for-time approach to elucidate such possible effects by comparing data from 1656 shallow lakes (mean depth 100 mu g L-1) in the FL lakes, but coverage was higher in the DK lakes at low TP. We also found lower oxygen saturation in the nutrient-rich FL lakes than in the DK lakes, suggesting lower net ecosystem production in the FL lakes....
Long-term changes in littoral fish community structure and resilience of total catch to re-oligotrophication in a large, peri-alpine European lake
Sabel, Maike; Eckmann, Reiner; Jeppesen, Erik; Roesch, Roland; Straile, Dietmar (Wiley, 2020-08-01)
The littoral zone of lakes is used as spawning, shelter, or feeding habitat for many fish species and hence is of key importance for overall lake functioning. Despite this, hardly any studies exist examining the long-term dynamics and response of the littoral fish community, composed mostly of juvenile fish, to environmental change. Here, we study the response of total catch per unit effort (CPUE) and individual species CPUE of such a community to 17 years of oligotrophication and examine whether the specie...
Long-term effects of warming and nutrients on microbes and other plankton in mesocosms
ÖZEN, ARDA; Sorf, Michal; Trochine, Carolina; Liboriussen, Lone; Beklioğlu, Meryem; Sondergaard, Martin; Lauridsen, Torben L.; Johansson, Liselotte S.; Jeppesen, Erik (Wiley, 2013-03-01)
1.We followed microbial and other planktonic communities during a 4-month period (FebruaryMay) in 12 outdoor flow-through mesocosms designed to elucidate the effect of global warming and nutrient enrichment. The mesocosms were established in 2003. 2.Warming had a smaller effect than nutrients on the biomass of the microbial and planktonic communities, and warming and nutrients together exhibited complex interactions. 3.We did not find direct effects of warming on the biomass of bacterioplankton or ciliates;...
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 (Springer Science and Business Media LLC, 2010-06-01)
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 intercon...
Citation Formats
M. Beklioğlu and I. Tuzun, “Restoration of the eutrophic Lake Eymir, Turkey, by biomanipulation after a major external nutrient control I,” HYDROBIOLOGIA, pp. 93–105, 2003, Accessed: 00, 2020. [Online]. Available: