Impact of abiotic factors and road networks on the freshwater turtle Emys orbicularis (Linnaeus, 1758) (Reptilia: Emydidae) in northern Iran.

Emys orbicularis is one of the freshwater turtles occurring in Europe, Middle East and Western Asia, but also occur in Caucasus region as Georgia, Armenia, Azerbaijan and Southern Caspian Sea region (northern Iran provinces as Guilan, Mazandaran, Golestan). In this study, seventeen localities in three Iranian provinces were investigated to study the response of this species to abiotic factors (water quality parameters) and road mortality. To test for differences in occurrence of E. orbicularis between sites that could be explained by variation in abiotic factors, one-way ANOVA test and Tukey's HSD post hoc tests were conducted. These showed significant differences in conductivity (CON) and Total Dissolved Solids (TDS) between locations in the three provinces of Golestan, Mazandaran and Gilan [CON: (F (2, 13) = 9.824, p = 0.003); TDS: (F (2, 13) = 13.957, p = 0.001)]. Differences in four other abiotic variables-water temperature, pH, salinity and dissolved oxygen (DO)-were not significant between provinces, although there were differences. These findings suggested that the species can occur in ponds with the following features: temperature 21-28 °C; pH 7-8; salinity > 750 mg/L; DO > 30%. Road mortality might be another factor that could contribute to the decline of this turtle's population in northern Iran, noting that the roads were created by human within the species' habitat and increased the mortality rate. Roads should be monitored in order to evaluate their effect on freshwater turtle mortality. Overall, our results demonstrated the advantage of using analysis of abiotic variables as a valid approach for defining species-responses to abiotic factors in E. orbicularis and recommended monitoring roads to find high-risk mortality of this species and create under road tunnels for moving turtles without any risk to reduce high rate of mortality.