Determination of environmental variables groups affecting the occurrence of non-marine ostracods (Crustacea) in the Eastern Mediterranean region of Turkey

Abiotic factors play important roles on the habitat preferences and dispersal decisions of species. The objective of this study was to estimate the groups of abiotic variables best explaining the variation of ostracods species taken from 31 water bodies (27 streams and 4 lakes) sampled twice (October 2020 and April 2021) in the Eastern Mediterranean region of Turkey. In this study, a total of 34 ostracod taxa (24 recent and 10 sub-fossil) were reported, and Ilyocypris bradyi and Prionocypris zenkeri were the most common species occurred more than 10 times. Based upon to the variation partitioning analysis, dissolved oxygen+elevation+magnesium (DO+Elev+Mg2+) was the best model with 12.66% explanation power in the variations of ostracod species in the present study. The distance-based redundancy analysis elucidated 14.1% of the total variation in the species distribution matrix that was significantly affected by Mg2+ and Elev. The effectiveness of variables on the occurrence of species was tested by Generalized Linear Models resulted in positive roles of Elev for Psychrodromus olivaceus, Neglecandona neglecta and Pseudocandona albicans, Ca2+ for Cyprideis torosa and P. albicans, and DO for P. olivaceus, but negative roles of Tw for N. neglecta and P. albicans, Ca2+ for Herpetocypris helenae, and DO for N. neglecta. A positively significant association was found between high Mg2+ values and the abundance of P. zenkeri. Results suggest that effectiveness rates of environmental factors on the occurrence of species can change according to ecoregional differences when the variables are evaluated in the analyses together. Therefore, especially ecoregion-based ecological information of species should be determined for better inferences about the ecological preferences of species.