Maternal transfer of trace elements in leatherback turtles (Dermochelys coriacea) of French Guiana

Abstract

a b s t r a c tIn sea turtles, parental investment is limited to the nutrients and energy invested in eggs that will support embryonic development. Leatherback females have the largest clutches with the biggest eggs of the sea turtles and the highest reproductive output in reptiles. The migration between foraging sites and nesting beaches also represents high energy expenditure. The toxicokinetic of pollutants in the tissues is thus expected to vary during those periods but there is a lack of information in reptiles. Concentrations of essential (Copper, Zinc, Selenium) and non-essentials elements (Cadmium, Lead, Mercury) were determined in blood (n = 78) and eggs (n = 76) of 46 free-ranging leatherback females collected in French Guiana. Maternal transfer to eggs and relationships between blood and eggs concentrations during the nesting season were investigated. All trace elements were detectable in both tissues. Levels of toxic metals were lower than essential elements likely due to the high pelagic nature of leatherbacks that seems to limit exposure to toxic elements. Significant relationships between blood and egg concentrations were observed for Se and Cd. Se could have an important role in embryonic development of leatherback turtles and Cd transfer could be linked to similar carrier proteins as Se. Finally, as multiple clutches were sampled from each female, trends in trace elements were investigated along the nesting season. No change was observed in eggs but changes were recorded in blood concentrations of Cu. Cu level decreased while blood Pb levels increased through the nesting season. The high demand on the body during the breeding season seems to affect blood Cu concentrations. Calcium requirement for egg production with concomitant Pb mobilization could explain the increase in blood Pb concentrations along the nesting season.

Post-mortem investigations on a leatherback turtle Dermochelys coriacea stranded along the Northern Adriatic coastline

“…Pb, Hg, Cd and As) but significantly lower hepatic Fe levels compared with those indicated by (albeit scarce) existing data on Dermochelys coriacea (Davenport & Wrench 1990, Caurant et al 1999, Godley et al 1999, Deem et al 2006, Guirlet et al 2008, Innis et al 2010, Harris et al 2011. The data obtained for Se, Zn, Hg, Cd and Pb concentrations were also higher than those reported for loggerhead and green sea turtles from the Mediterranean area (Andreani et al 2008).…”

Addressing current knowledge gaps on radionuclide transfer to reptiles

“…Positive correlations have been identified for particular blood, tissue and element combinations, such as mercury concentrations in blood and muscle of Nerodia sipedon (Northern water snakes) [18], and blood sampling may therefore provide an alternative route to investigating element concentrations in adult reptiles. Although blood has been used exclusively by some authors for evaluating contaminant uptake in reptiles [30], blood generally reflects recent contaminant exposure [18] and the complex kinetics of elements within blood [27] are likely to result in high uncertainties.…”

“…Therefore, some studies have considered the extent to which egg contaminant burdens may be used to predict tissue and whole-body contaminant burdens in the female which laid the egg (e.g. [26,27] and these have provided positive support for the use of this non-lethal sampling strategy. For example, analysis of stable element concentrations in the tissues and eggs of female sea turtles has demonstrated that concentrations in sea turtle eggs can be used to estimate concentrations in adult female turtles for elements such as Cd and Zn [28].…”

The comparative cytotoxicity and genotoxicity of hexavalent chromium in humans and sea turtles.

“…Several studies have investigated metal levels in leatherback sea turtles around the world and found their tissues can accumulate metals such as mercury, cadmium, lead, and arsenic [34][35][36][37][38][43][44][45][46][47]. To my knowledge only one study has investigated Cr levels in leatherback sea turtles, but did not measure Cr levels in lung tissue [47].…”

“…Leatherbacks are found throughout all of the world's oceans and commonly travel long distances during their lives. The extended amount of time leatherbacks spend in the ocean subjects them to exposure to pollutants and contaminants that may be present [32][33][34][35][36][37][38]. These pollutants have the potential to lead to detrimental health effects including reproductive issues [34,38,39].…”