Emphasis has been placed on characterisation of endocrine hormones in reptiles and specifically on the profile of the major endogenous oestrogens in adult female marine turtles. Endogenous oestrogen profiles in marine turtles have not been conclusively profiled, leaving a gap in the basic endocrinology of female marine turtles. In order to identify the major endogenous oestrogens, high-pressure liquid chromatography (HPLC) was used. HPLC separation of oestrogens in marine turtle blood plasma revealed oestrone and oestradiol as the most prevalent oestrogens. Enzyme-linked immuno-sorbent assay (ELISA) techniques were applied to marine turtle blood plasma for the quantification of circulating oestrone. Vitellogenic female marine turtles were the primary focus of the analyses and revealed levels ranging from 150.0 pg/ml to 2000.0 pg/ml in 100µl of plasma; however, this was dependent on reproductive stage. These findings represent the first qualitative analysis of oestrogenic compounds in marine turtles and provide a basis from which further reproductive physiology can be further investigated.
Marine turtles, as long-lived species, are likely to accumulate endocrine disrupting compounds; carnivorous turtle species may also be at significant risk due to biomagnification of these compounds. To date no information is available about endocrine disrupting compounds in turtles Malaysian waters. A basic survey of marine turtles was done for endocrine disrupting toxins in eggs. Several substances classed as organochlorine pesticides (OCs) and poly chlorinated biphenyls (PCBs) were found to be endocrine disrupters in United States Environmental Protection Agency (EPA) studies and recently have been identified in Malaysian coastal waters and the South China Sea. According to the literature, oviparous species such as the marine turtle will concentrate lipophilic chemicals like OCs and PCBs in the yolk of the egg to be absorbed by the developing young. These chemicals may show effects ranging from morphometric abnormalities and decreased offspring health, to altered gonad development, sex reversal, or even an increased mortality rate in developing reptiles. Human consumption of eggs in countries such as Malaysia is an additional threat to future green turtle populations, as well as a potential health risk to egg consumers. Eggs of the Malaysian Green turtle (Chelonia mydas) were analysed for organochlorine pesticides and polychlorinated biphenyls. Gas chromatography with electrochemical detection (GC-ECD) resuhs showed 71.02% to 91.41% for PCB mix and 83.23% to 99.40% for OC mix recoveries in plasma. Analysis of 7 eggs (10-g, 2-g and 5-g aliquots) from 3 locations showed traces of OCs and PCBs in the 5-g aUquot samples. The 2-g aliquots were too small to measure any OCs and PCBs in marine turtle eggs. Tengram aliquots were too large for the apparatus available and some sample was lost during extraction. Five-gram aliquots of egg from Kuantan-Mersing and Sabah found Endosulfan Alpha to have a concentration of 4.91 x 10-8-mg/L and 2.18 x 10-8-mg/L, respectively. These levels are lower than the maximal residue limits set by the Australia and New Zealand Food Standards Code (ANZFA) (2001). Endosulfan is suspected to be oestrogenic in wildlife, however, oestrogenicity of endosulfan in reptiles has not been conclusively examined.