Determining effective environmental factors and ecology of non-marine Ostracoda (Crustacea) in Giresun, Turkey

To determine influential environmental factors on ostracod species, 105 aquatic sampling sites were sampled from the Giresun province. Sixteen species collected from 69 sites are new records for the study area. Seven of 16 species were found in their expected geographical distribution while two species (Ilyocypris bradyi, Psychrodromus olivaceus) showed different distribution (P < 0.05). Of which, P. olivaceus displayed a limited distribution in the northern region of the study area. Geographical distribution of some species and their co-occurrences varied among habitats. The mean values of three variables (water temperature, electrical conductivity, and elevation) were significantly different in northern region than the values of the sampling sites in the southern region (P < 0.01). Canonical Correspondence Analysis explained 72.5% of the significant relationship (P < 0.05) between species and four most effective environmental variables (water temperature, electrical conductivity, elevation, and magnesium). Heterocypris salina and Potamocypris fallax exhibited maximum and minimum tolerance (and optimum) values for electrical conductivity, respectively. Heavy metal presence on the carapace surfaces was investigated using Energy Dispersive X-ray Analysis (EDX) along with SEM photographing. The observation of metals such as copper, aluminum, silver and even radioactive element such as technetium on the carapace surfaces suggests that the organisms studied actually carry much more information about their aquatic environment than it was thought. Overall, our results support the findings of previous studies that water temperature and electrical conductivity were the two most effective factors on ostracod species and can be responsible for their distribution and occurrences in sampling area. 16 ostracods are new records for Giresun. Distribution and co-occurrences of some species varied among habitats. The means of water temperature, electrical conductivity, and elevation were different in the northern region than the south. CCA explained 72.5% of the relationship between species and four variables. Copper, aluminum, silver and technetium were found on the carapace