Effects of Petroleum on the Development and Survival of Marine Turtle Embryos

Fritts, Thomas; McGehee, M. Angela

An investigation of the effects of petroleum on the development and survival of marine turtle embryos was conducted to determine the vulnerability of marine turtle progeny to petroleum spills in adjacent and distant waters. Field studies of Lepidochelys kempi (Kemp's ridley turtle) involved the analysis of the concentration and distribution of hydrocarbons on the nesting beach in Tamaulipas, Mexico and the effects of petroleum on the development of embryos. Analysis of sands from the nesting beach indicated that the on spilled in marine waters was deposited within the nesting zone by wave action. Field experiments in which paired samples of turtle eggs were incubated in clean and contaminated sands from the beach did not result in significant effects related to oil contamination. In laboratory experiments, eggs of Caretta caretta (the loggerhead turtle) were incubated in sands treated with varying amounts of crude on at different times during incubation. Experiments using varying quantities of on mixed with the sand at the initiation of incubation resulted in differences in hatchling morphology but not in survival. Experiments in which oil was added on top of the sand containing the eggs after incubation was partially complete resulted in significant embryonic mortality and differences in hatchling morphology. The results suggested that aged petroleum is less toxic to turtle embryos than is fresh petroleum. The aged oil found on the beach studied in field experiments produced no detectable effects on turtle embryos, whereas fresh oil in the laboratory produced a variety of effects. Our results suggest that a marine on spill resulting in contamination of turtle nesting beaches before the nesting season may affect nesting success for only a short period, if at all. However, a spill resulting in the deposition of oil on eggs or on top of a nest already constructed is likely to increase mortality and affect hatchling morphology. The timing of the spill and age of oil may be critical in determining the overall effect on turtles. The effects of on contamination on marine turtles in ocean waters remain unknown. However, the present study provides a basis for evaluating potential effects of on contamination and for developing on spill contingency plans for turtle nesting beaches.