Species diversity and distribution of Ostracoda (Crustacea) in mesosaline Lake Bafa (Aegean Region, Turkey)

Abstract

This study was carried out in order to determine Ostracoda fauna of Lake Bafa (Aydin-Mugla, Turkey) and investigate their distribution from 20 sites in February, May, July and September of 1997. The ostracods assemblages comprised a mixture of 14 freshwater and brackish-marine origin species. The most common and abundant species were the brackish-water ostracods Cyprideis torosa and Loxoconcha elliptica. According to Shannon-Weiner diversity index, it was found that Lake Bafa had a mean diversity value of H’= 0.85. The ostracod abundance showed an increase in the warmer period starting from late spring and reached maximum values in May. We analysed the dominance and distribution of ostracod assemblages and their relation to environmental factors (temperature, dissolved oxygen, pH, and salinity) by using classification and ordination techniques. Canonical correspondence analysis (CCA) was used to characterize the relationship between ostracods and the environmental variables. According to the first axis of CCA, we determined salinity to be the most important environmental variable affecting ostracod species distribution. According to Jaccard similarity coefficient (Jaccard Index) analysis results, sampling stations and ostracod species assemblage were clustered into two groups with the non-weighted pair-group method with arithmetic mean based on presence/absence of species. Besides multivariate analysis, Spearman correlation analysis indicated that some species (Cyprideis torosa. torosa, Loxoconcha elliptica, Cytheroisrnfischeri, and Leptocythere lacertosa) had a positive correlation with salinity, whereas there are strong negative correlations between salinity and other nine species, which are, more related to freshwater environments