Ecological classification of the freshwater Ostracoda (Crustacea) based on physicochemical properties of waters and habitat preferences

Abstract

The relationship between ecological characteristic of freshwater ostracods and their habitat preferences has been a critical issue for understanding of both current and past aquatic conditions. To evaluate this idea, 121 water bodies with 11 different habitat types were randomly sampled in the province of Kutahya. Water quality measurements indicated high to low (Ca2+ > Mg2+ > Na+) cations and relatively low (SO42- > Cl- > F-) anion concentrations with Ca2+ being the dominant ion. Sixteen of 23 species were new reports for the area. Alpha diversity (H' = 3.64) was found relatively high. Four most abundant species with ca. 93% of similarities contributed highest alpha values in warm to cooler (lower than 25 degrees C), alkaline (pH 8.22), and fresh to slightly brackish waters. Heterocypris sauna and Ilyocypris bradyi also revealed the highest tolerances for electrical conductivity. Based on habitat type, species were clustered into three main groups (I-III). Canonical Correspondence Analyses explained about 57.4% of correlation between species and environmental variables. Redox potential, pH, water temperature and electrical conductivity were found to be the most effective factors on species occurrences while habitat type and dissolved oxygen were not effective. Total number of species showed strong negative and positive relationships with water temperature and dissolved oxygen, respectively. Results clearly showed that cosmopolitan species exhibited relatively wide tolerance ranges to different environmental variables. Accordingly, having wide tolerance ranges seems to provide advantages to cosmopolitan species, increasing their survival chances in a variety of habitats.