Morphological Variations in the Green Turtle (Chelonia mydas): A Field Study on an Eastern Mediterranean Nesting Population.

Abstract

Morphological studies in marine turtles might be used to obtain information about changes in developmental habitats. Information regarding mortality and growth rates can be obtained by collecting data on the size of nesting females on the nesting beach. Morphometric and meristic traits of female green turtles (Chelonia mydas) were recorded on Samandağ Beach, Turkey, during the 2006-2016 nesting seasons. The study aimed to determine the mean and minimum curved carapace length (CCL) of the nesting green turtle and the differences in body size and scute pattern over the years. The relationship between the body size of nesting green turtles and latitude was also analysed. CCL and curved carapace width (CCW) were recorded for 365 individuals and meristic measures were recorded for 292 individuals. The mean CCL and CCW were recorded as 86.9 (± 6.14) and 77.9 (± 5.95) cm, respectively. The minimum CCL of nesting green turtles was also recorded as 72 cm. The CCL and CCW showed differences over the years and they tended to become smaller from 2006 to 2016. However, this trend was not significant according to the Mann-Kendall trend test. The CCL value was negatively correlated with the latitude and rejected Bergmann's rule. There was no relationship between year and carapace scute deviation. The Samandağ green turtle population had the smallest nesting green turtle based on CCL. In addition to environmental factors, recruitment of females, and growth and mortality rates, and the nesting shift between nesting beaches may be some of the reasons behind a smaller value over the years.