| Organochlorine (OC) contaminants, including polychlorinated biphenyls (PCBs) and pesticides, may have contributed to population declines by negatively affecting the immune and endocrine systems of many wildlife species. Little is known about the effects of contaminants on threatened or endangered sea turtles. This study investigated the effects of OC concentrations in tissues of juvenile loggerhead sea turtles (Caretta caretta) on their clinical health, immunity, and endocrine parameters. OC concentrations in blood, determined by gas chromatography with electron capture detection and mass spectrometry, significantly correlated with concentrations measured in adipose tissue. The correlations suggest that non-invasive blood sampling can be used to monitor accumulated concentrations of OCs in sea turtles. The OC concentrations significantly correlated to indicators of health, such as blood chemistries and hematology. Concentrations of some OC compounds correlated with an indicator of tissue damage (↑ aspartate aminotransferase), with alterations of protein, carbohydrate, and ion regulation (↑ blood urea nitrogen, ↑ total plasma protein, ↓ albumin:globulin ratio, ↓ glucose, ↑ osmolality, ↑ sodium, ↓ magnesium), with indicators of anemia and a modulated immune system (↓ red blood cells, ↓ hematocrit, ↓ hemoglobin, ↑ total white blood cells, ↑ heterophil:lymphocyte ratio). Moreover, turtles exhibiting signs of wasting (extremely emaciated and lethargic) had two orders of magnitude higher blood OC concentrations than apparently healthy turtles. OC concentrations also correlated positively with mitogen-induced lymphoproliferative responses, suggesting immunoenhancement. Vitellogenin (VTG), an egg yolk precursor protein, was detected in the plasma of most female loggerhead turtles with straight carapace lengths of 77 cm or longer. Two to three percent of the females smaller than 77 cm were precociously expressing VTG and had higher blood OC concentrations compared to normal females of this size class that were not expressing VTG. Since it is not feasible to experimentally expose endangered sea turtles to toxicants, this study characterized a green sea turtle testes cell line for the activity of cytochrome P450 aromatase, an enzyme responsible for converting testosterone to estradiol. Aromatase activity in this in vitro model was induced by atrazine and inhibited by 4,4′-DDE. These findings suggest that the current concentrations of OCs in loggerhead sea turtles may be affecting their immune and endocrine systems. |
