Elevational distribution and species diversity of freshwater Ostracoda (Crustacea) in Çankırı region (Turkey)

We investigated how the richness and ecological characteristics of non-marine ostracod species varied across nine 100-m elevation bands (from 549 to 1457 m) in the Çankırı region. We collected a total of 37 taxa (25 living and 12 sub-recent) from 114 of 130 aquatic sites sampled during September of 2011; 34 of the taxa were new records for the region. Eight widely distributed ‘cosmopolitan’ species (Candona neglecta, Cypridopsis vidua, Heterocypris incongruens, Ilyocypris bradyi, Limnocythere inopinata, Potamocypris villosa, Prionocypris zenkeri, and Psychrodromus olivaceus) were found more frequently than other species. The first two axes of canonical correspondence analyses (CCA) explained 73.2% of the correlation between 11 species and 5 environmental variables. Of which, electrical conductivity (F = 3.99, p = 0.028) and altitude (F = 2.69, p = 0.004) were the most explanatory (p < 0.05) variables for species. Optimum altitude and water temperature values of the cosmopolitan species were relatively higher than the other species. Significant regression models (p < 0.01, r² = 0.81) indicate that the frequency of occurrence was affected by changes in numbers of samplings sites from 549 to 1457 m. When highest numbers of species (15 spp.) were found at the range of 1231–1332 m, numbers of asexual species (10 spp.) were twice of the sexual species (5 spp.) with no statistical difference between numbers of swimming (7 spp.) and non-swimming (8 spp.) species. Results were discussed based on the ecological conditions that individual species prefer.