Benthi-planktivorous Fish-Induced Low Water Quality of Lake Eymir Before Biomanipulation

Authors : Meryem BEKLİOĞLU, S Levent BURNAK, Özlem İNCE

Pages : 315-326

View : 19 | Download : 5

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :In this study, Lake Eymir, Eymir inflow 1, Kışlakçı brook and Eymir outflow were sampled monthly betwen March 1997and April 1998 for physico-chemical and biological parameters. Within the catchment of the lake, there are small-scale industries, sewage effluent of TEK residence and recreational activities causing high concentrations of dissolved inorganic nitrogen insert ignore into journalissuearticles values(DIN); and total phosphorus insert ignore into journalissuearticles values(TP); in the eymir inflow 1 and in Kışlakçı brook. In Lake Eymir although diversion of sewage effluent of the Mogan municipality to İmrahor valley appeared to have led to a decrease in TP and DIN concentrations compared with those found in 1994, especially the lake TP concentration was still found to be very high insert ignore into journalissuearticles values(annual mean: 305 µg l -1 ); this may be due to the high inflows concentrations. The lake had a high spring increase in chlorophyll-a concentration which remained relatively low throughout the summer insert ignore into journalissuearticles values(annual mean: 19 mg -1 );, perhaps due to very low DIN/TP ratios implying possible N-limitation at the very high TP concentration. Moreover, the Secchi depth was also relatively low throughout summer at the low chlorophyll-a concentration possibly due to feeding of the dominant fish tench insert ignore into journalissuearticles values( Tinca tinca); and carp insert ignore into journalissuearticles values( Cyprinus carpio); of the lake by stirring up the sediment. The densities of large-bodied zooplankters, Daphnia and Arctodiaptomus remained low in summer following the high spring densities probably due to fish prediation exerted on them by tench and carp. In Lake Eymir, top-down or fish-induced control of the water quality appeared to be the predominant factor,following the reduction of 30% of the tench and carp insert ignore into journalissuearticles values(biomanipulation);, has led to very high Secchi depth and densities of the large grazes.
Keywords : Benthivorus fish, biomanipulation, eutrophication, chlorophyll a planktivorous fish, Secchi depth, total phosphorus