Karen L. Eckert

Embryo mortality and hatch success in In situ and translocated leatherback sea turtle Dermochelys coriacea eggs

Abstract At Sandy Point National Wildlife Refuge, St Croix, US Virgin Islands, natural beach erosion results in the loss of 45–60% of the leatherback sea turtle Dermochelys coriacea eggs laid there per annum. In a 4-year study (1982–1985), 31·4–68·1% of the eggs laid annually (312 of 582 total clutches) were collected at oviposition and reburied in stable beach zones in an effort to mitigate losses to erosion. Reburial did not significantly increase the proportion of eggs per clutch that failed to develop, the proportion of eggs that contained pre-term dead embryos, the occurrence of embryonic deformity, or the risk of depredation for eggs or hatchlings. However, a consistently larger proportion of pipped, dead hatchlings in clutches that had been moved reduced overall hatch success in translocated as compared to in situ clutches (53·7% versus 64·1%, respectively). Collection and reburial of otherwise doomed eggs resulted in a net gain of c . 6650 hatchlings over 4 years.

Pre-reproductive Movements of Leatherback Sea Turtles (Dermochelys coriacea) Nesting in the Caribbean

The temporal pattern of colonization by epibionts on leatherback sea turtles (Dermochelys coriacea) nesting at Sandy Point, St. Croix, provides unique insight into the pre-reproductive movements of the turtles. Recruitment of the pantropical pelagic cirriped, Conchoderma virgatum, was rapid and continuous once the turtles arrived at the nesting grounds. The date at which individual turtles arrived at the nesting grounds was extrapolated from a von Bertalanffy growth model estimating the age of barnacles present during a turtles first nesting. The data suggest that gravid turtles do not arrive from temperate latitudes until just prior to nesting, and that they go directly to a preferred nesting beach rather than nesting opportunistically en route. The Sandy Point nesters apparently arrive at the nesting beach asynchronously over a period of 4 mo and, irrespective of date, individuals commence nesting within relatively few days of arrival. Mating presumably occurs prior to or during the migration and not in tropical waters. The occurrence of five additional species of epibiotic cirripeds and the presence of a parasitic isopod, Excorallana antillensis, are documented.