Exploring contaminants as a disruptor of temperature-dependent sex determination in sea turtle hatchlings

Sea turtle nesting beaches are experiencing increased sand temperatures as climate change progresses. In one major green turtle (Chelonia mydas) nesting beach in the northern Great Barrier Reef, over 99 percent of hatchlings are female. The effects of contaminants on sea turtle hatchling sex determination are not often explored. Liver samples were collected from green turtle hatchlings that were sacrificed for histological sex determination in a parallel study on the effects of sand cooling on sex ratios, and analysed for trace elements via acid digestion and organic contaminants via in vitro cytotoxicity bioassays. Chromium, antimony, barium, and cadmium have previously been demonstrated to be estrogenic, and concentrations of these elements were used to calculate three estrogenic indexes for each clutch: predicted relative estrogenic potency (PEEQA), the sum of percent trace elements above the median of all samples (TEOM), and the sum of percent estrogenic elements above the median of all samples (EstroEOM). Excluding an outlier clutch, cadmium, antimony, and EstroEOM had significant positive relationships with sex ratio deviation. Mean clutch cobalt, lead, antimony and barium, also had a significant positive relationship with clutch sex ratio. There was no relationship between in vitro cytotoxicity of liver extracts and sex ratio, however, 9% of hatchlings had organic contaminants high enough to suggest potential cellular damage. Contaminant effects on sex determination are likely to be caused by a mixture of contaminant interactions as well as temperature. Many trace elements detected in this study have also been linked to negative health effects on hatchlings in previous studies. Considering the risks of feminization due to climate change and potential contaminant effects on hatchling health and sex determination, future studies exploring contaminant effects on sea turtle hatchling sex determination are recommended

Effect-based approach for screening of chemical mixtures in whole blood of green turtles from the Great Barrier Reef

Organisms are exposed to mixtures of both known and unknown chemicals which are diverse and variable, and thus difficult and costly to characterise and monitor using traditional target analyses. The objective of this study was to validate and apply in vitro effect-based methods by which whole blood can be used to screen internal exposure to such complex chemical mixtures. For this study, we used whole blood of green sea turtles (Chelonia mydas). To ensure the chemical mixture in blood is transferred with minimal losses or bias, we tested a modified QuEChERS extraction method specifically developed for multi-and non-target instrument analysis. The extracts were dosed to a battery of in vitro bioassays (AhR-CAFLUX, AREc32, NF kappa B-bla, VM7Luc4E2, Microtox), each with a different mode of action (e.g., AhR receptor mediated xenobiotics, NrF2-mediated oxidative stress, NF kappa B-mediated response to inflammation, estrogen activity and baseline toxicity oxidative stress, respectively) in order to cover a wide spectrum of chemicals. Results confirmed the absence of interferences of the blood extract with the responses of the different assays, thus indicating the methods' compatibility with effect-based screening approaches. To apply this approach, whole blood samples were collected from green turtles foraging in agricultural, urban and remote areas of the Australian Great Barrier Reef. The effect-based screening revealed significant differences in exposure, with higher induction of AhR-CAFLUX, AREc32 and Microtox assays in turtles from the agricultural foraging ground. Overall, these results corroborated with concurrent health, target and non-target analyses in the same animals performed as part of a larger program. This study provides evidence that the proposed effect-based approach is suitable for screening and evaluating internal exposure of organisms to chemical mixtures. The approach could be valuable for advancing understanding on multiple levels ranging from identification of priority chemicals in effect-directed investigations to exploring relationships between exposure and disease, not only in sea turtles, but in any organism. (C) 2017 Elsevier B.V. All rights reserved

Coastal bays and coral cays: multi-element study of Chelonia mydas forage in the Great Barrier Reef (2015–2017)

There is increasing interest in understanding potential impacts of complex pollutant profiles to long-lived species such as the green sea turtle (Chelonia mydas), a threatened megaher bivore resident in north Australia. Dietary ingestion may be a key exposure route for metals in these animals and marine plants can accumulate metals at higher concentrations than the surrounding environment. We investigated concentrations of 19 metals and metalloids in C. mydas forage samples collected from a group of offshore coral cays and two coastal bays over a period of 2–3 years. Although no samples exceeded sediment quality guidelines, coastal forage Co, Fe, and V concentrations were up to 2-fold higher, and offshore forage Sr concentrations were ~3-fold higher, than global seagrass means. Principal Component Analysis differentiated coastal bay from coral cay forage according to patterns consistent with underlying terrigenous-type or marine carbonate-type sediment geochemistry, such that coastal bay forage was higher in Fe, Co,Mn, Cu, andMo (and others) but forage from coral cays was higher in Sr and U. Forage from the two coastal bay swas differentiated according to temporal variation in metal profiles,which may be associated with a more episodic sediment disturbance regime in one of the bays. For all study locations, some forage metal concentrations were higher than previously reported in the global literature. Our results suggest that forage metal profiles may be influenced by the presence of some metals in insoluble forms or bound to ultra-fine sediment particles adhered to forage surfaces. Metal concentrations in Great Barrier Reef forage may be present