Ecological requirements of freshwater Ostracoda (Crustacea) intwo limnocrene springs (Bolu, Turkey)

Abstract

Ecological requirements of ostracods in two limnocrene springs (Usta and Çetin Bey) were investigated between January 2000and July 2002 in Bolu, Turkey. Ten taxa (Candona neglecta, Darwinula stevensoni, Eucypris virens, Eucypris sp., Heterocyprisincongruens, Herpetocypris sp., Ilyocypris bradyi, Potamocypris sp., Scottia pseudobrowniana, Tonnacypris lutaria) werefound. Canonical correspondence analysis (CCA) showed that species with wide cosmopolitan distribution could tolerate highlevels of changes in environmental variables. CCA explained about 80 % and 77 % of the relationships between species andenvironmental variables in Usta and Çetin Bey springs, respectively. Electrical conductivity and dissolved oxygen were the twomost influential factors on species occurrence in each spring. According to Spearman correlation analysis, there were no significantrelationships between the numbers of species and environmental variables in both springs. When dissolved oxygen showedsignificant negative correlations to electrical conductivity, water and air temperature in Usta spring, such correlation wasonly negatively significant (P <0.05, r = -0.46) between electrical conductivity and dissolved oxygen in Çetin Bey spring.Clustering analysis (UPGMA) of presence/absence data divided species into four main groups. Results may suggest that anthropogenicactivities were responsible for decreasing water quality of these springs and reducing species richness. Although increasingincentives for conservation of natural springs were proposed, Çetin Bey spring and especially Usta spring are now highlydegraded.