Current situation and environmental factors affecting the distribution of Emys orbicularis in Sèquia Major (NE Iberian Peninsula) in syntopy with Mauremys leprosa

Abstract

This study describes the situation and population distribution of the European pond turtle (Emys orbicularis) in the protected area of Sequia Major and adjacent area. Between 2013 and 2015, 77 E. orbicularis were captured, with a sex ratio close to 1:1. Regarding the population structure, biometric data showed that the population is aging, with 79.22% of the captured animals being adults with an average carapace length of 141 mm in females and 137 mm in males. Different trophic parameters, competition with other species, habitat use and physico‐chemical characteristics of the water were analysed. Results showed that the factors influencing the species distribution in the area were the vegetation coverage in ponds, the abundance of the aloctonous red swamp crayfish Procambarus clarkii, the presence of Mediterranean turtles (Mauremys leprosa), the trophic status of the water and the concentration of phosphates in the water. Very low recruitment was detected because of the temporary flooding of more than 80% of the nesting area, which potentially slows down the spreading of the population.