Multiple distant origins for green sea turtles aggregating off Gorgona Island in the Colombian eastern Pacific.

Mitochondrial DNA analyses have been useful for resolving maternal lineages and migratory behavior to foraging grounds (FG) in sea turtles. However, little is known about source rookeries and haplotype composition of foraging green turtle aggregations in the southeastern Pacific. We used mitochondrial DNA control region sequences to identify the haplotype composition of 55 green turtles, Chelonia mydas, captured in foraging grounds of Gorgona National Park in the Colombian Pacific. Amplified fragments of the control region (457 bp) revealed the presence of seven haplotypes, with haplotype (h) and nucleotide (π) diversities of h = 0.300±0.080 and π = 0.009±0.005 respectively. The most common haplotype was CMP4 observed in 83% of individuals, followed by CMP22 (5%). The genetic composition of the Gorgona foraging population primarily comprised haplotypes that have been found at eastern Pacific rookeries including Mexico and the Galapagos, as well as haplotypes of unknown stock origin that likely originated from more distant western Pacific rookeries. Mixed stock analysis suggests that the Gorgona FG population is comprised mostly of animals from the Galapagos rookery (80%). Lagrangian drifter data showed that movement of turtles along the eastern Pacific coast and eastward from distant western and central Pacific sites was possible through passive drift. Our results highlight the importance of this protected area for conservation management of green turtles recruited from distant sites along the eastern Pacific Ocean.

Biotic and abiotic factors affect the nest environment of embryonic leatherback turtles, Dermochelys coriacea.

Clutches of leatherback turtles, Dermochelys coriacea, have lower hatching success than those of other sea turtles, but causes of high embryonic mortality are unknown. We measured characteristics of clutches along with spatial and temporal changes in PO(2) and temperature during incubation to determine the extent to which they affected the developmental environment of leatherback embryos. Minimum PO(2) in nests decreased as both the total number and mass of metabolizing embryos increased. Increases in both the number and mass of metabolizing embryos caused an increase in maximum nest temperature. However, neither PO(2) nor temperature was correlated with hatching success. Our measurements of relatively high nest PO(2) (lowest 17.1 kPa or 16.9% O(2)) indicate that hypoxia apparently does not cause the low hatching success of leatherback clutches. Oxygen partial pressure increased and temperature decreased from the center toward the periphery of leatherback nests. We inferred from these measurements that positions of eggs within nests vary in quality and potentially affect overall developmental success of entire clutches. The large metabolic mass of leatherback clutches and limits to gas flux imposed by the sand create a situation in which leatherback embryos collectively affect their own environment.