Tolerance, optimum ranges, and ecological requirements of freshwater Ostracoda (Crustacea) in Lake Aladağ (Bolu, Turkey)

Abstract

AbstractDuring monthly sampling from Lake Aladağ (Bolu, Turkey) between April 2003 and June 2004, nine ostracod taxa (Candona candida, Cypridopsis vidua, Darwinula stevensoni, Eucypris virens, Eucypris sp., Heterocypris sp., Limnocythere inopinata, Physocypria kraepelini, and Tonnacypris lutaria) were recorded from seven stations. Physocypria kraepelini was commonly found in the lake while the others were recorded in particular months. UPGMA analyses clustered three groups based on their occurrence. Accordingly, the occurrence of species (C. candida, E. virens, and T. lutaria) was positive and significantly related to each other. Two species, P. kraepelini and D. stevensoni, showed a significant positive relationship with electrical conductivity. A significant negative correlation was found between the occurrence of P. kraepelini and dissolved oxygen, while there was a significant positive correlation between the occurrence of P. kraepelini and turbidity. About 76% of the relationship between species and environmental factors was explained by the first two axes of canonical correspondence analyses (CCA). Temperature and dissolved oxygen were the two most important influences on the species assemblages. All species showed different but high optima and tolerance ranges, corresponding with their cosmopolitan characteristics. These responses may be related to unstable ecological characteristics of Lake Aladağ, which is often subjected to human activity.