Maternal transfer of chlorinated contaminants in the leatherback turtles, Dermochelys coriacea, nesting in French Guiana

Abstract

a b s t r a c tWe examined the maternal transfer of organochlorine contaminants (OCs), pesticides (DDTS and HCHs) and polychlorinated biphenyls (PCBs), and the temporal variation of blood and eggs concentrations from 38 leatherback turtles (Dermochelys coriacea) nesting in French Guiana. PCBs were found to be the dominant OCs with respective mean concentrations of 55.14 ng g À1 lipid-mass for egg and 1.26 ng mL À1 wetmass for blood. OC concentrations were lower than concentrations measured in other marine turtles which might be due to the lower trophic position (diet based on gelatinous zooplankton) and to the location of their foraging and nesting grounds. All OCs detected in leatherback blood were detected in eggs, suggesting a maternal transfer of OCs. This transfer was shown to depend on female blood concentration for RDDTs and for the most prevalent PCB congeners, since significant relationships were found between paired blood-egg concentrations. During the nesting season, OC concentrations in eggs and the percentage of lipid in eggs were found to decline in successive clutches, highlighting a process of offloading from females to their eggs and a decreasing investment of lipid from females into their clutches. OCs in eggs tended to be higher in females spending 3 years in the foraging grounds between two nesting seasons than in those spending 2 years, suggesting an impact of time spacing two breeding seasons, called remigration interval, and of location of the foraging grounds.

Comparative Health Assessment of Western Pacific Leatherback Turtles (Dermochelys Coriacea) Foraging Off the Coast of California, 2005–2007

“…Values for curved carapace length and width in foraging leatherbacks in this study were similar to those reported for nesting female leatherbacks in Costa Rica (Southwood et al, 1999(Southwood et al, , 2005, Gabon (Deem et al, 2006), Papua New Guinea (Benson et al, 2007c), Trinidad (Harms et al, 2007), and French Guiana (Guirlet et al, 2008). However, mean body weights of foraging female leatherbacks in California (512.466.82 kg; 380-607 kg; n513) were significantly higher than those previously reported in nesting adult female leatherbacks in Trinidad (287626 kg; 242-324 kg; n510) and Costa Rica (268644 kg; 196-308 kg; n56), where there was no overlap of ranges (Wallace et al, 2005;Harms et al, 2007).…”

“…Unfortunately, comparisons were not possible between foraging and nesting females from the same metapopulation or within the same ocean basin. Lead levels were not different between foraging (0.2060.08 ppm) and nesting female leatherbacks (0.1560.03 ppm) in this study, and they appear similar to nesting leatherbacks from French Guiana (0.1860.05 ppm; Guirlet et al, 2008) and slightly higher than levels measured in nesting leatherbacks in Gabon (0.08760.031 ppm; Deem et al 2006). Cadmium and lead might compete with essential metals for binding sites on metalloenzymes and both are carcinogenic and teratogenic; however, the toxicokinetics and threshold for toxic effects of metals in reptiles have not been determined (Linder and Grillitsch, 2000).…”

“…Although the sample size for males was too small for statistical comparison, a subjective assessment of the data indicates that the metal concentrations are similar for both sexes, with overlap of the ranges for all metals. Blood cadmium levels were highest in foraging Pacific female leatherback turtles (0.106 0.05 ppm), as compared to Atlantic nesting turtles from St. Croix (0.0460.02 ppm) and French Guiana (0.0860.03 ppm; Guirlet et al, 2008). Unfortunately, comparisons were not possible between foraging and nesting females from the same metapopulation or within the same ocean basin.…”

“…Female leatherback turtles can reduce contaminant burdens in blood through maternal transfer to eggs, whereas males lack a comparable physiologic mechanism for excretion of toxicants (Guirlet et al, 2008). Although the sample size for males was too small for statistical comparison, a subjective assessment of the data indicates that the metal concentrations are similar for both sexes, with overlap of the ranges for all metals.…”

“…Compared to other species of sea turtles, few reports document disease in leatherback turtles, including bacterial infections (Ogden et al, 1981;Obendorf et al, 1987;Miller et al, 2009), metabolic disease (Davenport et al, 1993), and parasitic infestations (Threlfall, 1979). Heavy metals and persistent organic pollutants have been detected in low concentrations in the blood of Atlantic nesting female leatherbacks (Deem et al, 2006;Guirlet et al, 2008Guirlet et al, , 2010, but no comparative studies have been performed in the Pacific population or in foraging leatherbacks.…”