Apparent increasing importance of Adriatic Sea as a developmental habitat for Mediterranean green sea turtles (Chelonia mydas)

Abstract

In the Mediterranean, the green sea turtle (Chelonia mydas) has exhibited increase in the number of nests over the past two decades. While the Eastern Mediterranean is recognized as a high use area, scarce observations of green turtles in Adriatic Sea suggested only low-level utilization of this area. This study presents new findings of green sea turtles in the Adriatic Sea and analyses the importance of the region for the species. In combination with published records, we present 75 findings of the species in the Adriatic including eight new records. The number of records is generally low but shows an intriguing ten-fold increase since 2000. This may be a result of three confounding factors: (i) positive population trend at main nesting sites in Mediterranean; (ii) increased institutional capacity for sea turtle research and conservation in the past two decades, and (iii) raising sea temperatures. Documented increases in the sea surface temperatures may have established suitable and recurring thermal corridors along Ionian-Adriatic developmental pathway and provided environmental cues for immigration of juvenile green turtles into the Adriatic. As the abundance of the species will likely increase in the future, research and conservation efforts will be needed to avoid the Adriatic Sea becoming a sink habitat for the Mediterranean green turtle population.