Using different indices to estimate trophic state of a shallow freshwater lake
Abstract
The lakes are world’s important aquatic ecosystems and freshwater resources for human, wildlife, irrigation, fisheries, tourism, drinking water, recreation and national park. The over use, increasing anthropogenic pressures and climate change make lakes subject to growing negative impacts. Lakes are experiencing water loss, drying out, degradation and pollution, causing rapid trophic state (TS) rise and eutrophication. The structure, pollution, degradation, usability, and sustainability of lakes are closely linked to their TS. For lake management and conservation; to determine and interpret of TS are need objective, realistic, easily applicable methods. Various TS or level indices have been developed and being applied globally. Kovada is a shallow freshwater lake (Isparta, Turkiye), lake and surroundings were designated as national park. In this study, Kovada Lake and its inlet's TS were assessed and interpreted on monthly samplings and standard chemical analyses conducted between May and October 2024. Carlson Trophic State Index, New Zealand Trophic Level Index, Türkiye Surface Water Quality Regulation Index and OECD TS criteria were employed. The high TP, TN levels, moderate Chl-a, and low SD were characteristic. According to applied TS indices and criteria lake's TS is classified as hypertrophic, besides SD measurement difficulties, used indices were appropriate and effective. The canal influences lake's hydrology, nutrients and TS. Agricultural, domestic and industrial pollutants transported via canal, along with drought-induced water level declines and progressive shallowing, are exacerbating eutrophication.
Keywords
Hypertrophic, Kovada, shallow lake, trophic level, trophic state indices
Supporting Institution
Eğirdir Fisheries Research Institute
Ethical Statement
No specific ethical approval was necessary for this study.
Thanks
The field-laboratory facilities were supported by the Eğirdir Fisheries Research Institute (SAREM) affiliated with a ongoing lakes monitoring Project that funded by Turkish MoAF, Agricultural Research and Policy General directorate. The authors thank a lot the SAREM administration.
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