Evaluation of zooplankton composition and water quality in Karakaya dam lake

Karakaya Dam Lake, the third biggest dam lake after Atatürk and Keban Dam Lakes, was established in 1987 on River Euphrates, Turkey. The lake is mainly used for fishing, recreational activity and irrigation by the neighboring communities of the city of Malatya and Elazıg. Before the beginning of the treatment of Malatya city sewages in 2004, this lake was polluted directly for many years. Besides this, agricultural pollutants such as pesticides and other chemicals are the main contributing sources for the pollution of the lake. Six sampling points, representing the whole water body, were selected. Eleven water samples from the selected locations were collected monthly between October 2005 and November 2006, and the physico-chemical characteristics of water were determined. Zooplankton content of water from these points was also determined. The results showed that zooplankton were belong to 20 taxa from Rotifera, Cladocera and Copepoda. Rotifera group members were the most abundant in the lake. Keratella cochlearis, Polyarthra vulgaris and Asplanchna priodonta were the denser species. Distribution of the identified species among sampling locations were examined according to frequency, density, dominance, diversity and similarity. These results were tested by Unweighted Pair-Group Method Using Arithmetic Averages (UPGMA) and Canonical Correspondences Analysis (CCA). The CCA was performed on zooplankton and environmental factors that influence the distribution of zooplankton. UPGMA analysis was carried out to detect the relationship between zooplankton and environmental factors. Classification of similar sampling points was based on zooplankton species. According to water quality values, the trophic level of the Dam Lake was determined as ultra-oligotrophic and mesotrophic level, while zooplankton species were -mesosaprobic level. These results showed that the lake is found to be as mesotrophic. KEYWORDS: Limnology, water quality, zooplankton, Karakaya Dam Lake, biodiversity, biomonitoring, UPGMA, canonical correspondence analysis (CCA).