[Show abstract][Hide abstract] ABSTRACT: Herbivorous turtle, Chelonia mydas, inhabiting the south China Sea and breeding in Peninsular Malaysia, and Natator depressus, a carnivorous turtle inhabiting the Great Barrier Reef and breeding at Curtis Island in Queensland, Australia, differ both in diet and life history. Analysis of plasma metabolites levels and six sex steroid hormones during the peak of their nesting season in both species showed hormonal and metabolite variations. When compared with results from other studies progesterone levels were the highest whereas dihydrotestosterone was the plasma steroid hormone present at the lowest concentration in both C. mydas and N. depressus plasma. Interestingly, oestrone was observed at relatively high concentrations in comparison to oestradiol levels recorded in previous studies suggesting that it plays a significant role in nesting turtles. Also, hormonal correlations between the studied species indicate unique physiological interactions during nesting. Pearson correlation analysis showed that in N. depressus the time of oviposition was associated with elevations in both plasma corticosterone and oestrone levels. Therefore, we conclude that corticosterone and oestrone may influence nesting behaviour and physiology in N. depressus. To summarise, these two nesting turtle species can be distinguished based on the hormonal profile of oestrone, progesterone, and testosterone using discriminant analysis.
[Show abstract][Hide abstract] ABSTRACT: Hatcheries are commonly used to protect sea turtle eggs from poaching and predation; however, there is currently limited scientific evidence to support good hatchery management practices, particularly post-hatching. This study investigated the effects of retaining hatchlings in hatcheries after emergence and delaying nest excavations on the quality of green turtle Chelonia mydas hatchlings. In addition, the effect of artificial lighting on the sea-finding ability of green turtles was investigated to highlight the importance of hatchling release locations on hatchery beaches. Hatchling running speed, an indicator of vigour and predation exposure, progressively decreased when hatchlings were retained in the hatchery for 1, 3 and 6 hours following emergence. Similarly, body condition (mass : straight carapace length), an indicator of dehydration and/or energy consumption, decreased after being retained for 3 and 6 hours. It was estimated that hatchlings retained for 6 hours after emergence would become significantly dehydrated and double their exposure to beach slope predation. Residual hatchlings that were immediately excavated from emerged nests had similar running speed and body condition to naturally emerged siblings. However, residual hatchlings removed from nests 5 days later had significantly reduced running speed and body condition, resulting in estimates of double the exposure to predation in near-shore areas. The mean angle of hatchling dispersal varied at different sites along the Ma’Daerah beach in relation to proximity to artificial lighting. Important recommendations for post-hatching management of sea turtle hatcheries worldwide can be made from the results of this study. To maximize release of hatchlings in the best condition as is possible, hatchlings should be released immediately after emergence, including excavation of any residual hatchlings. In addition, the dispersal angles of hatchlings should be tested at each hatchery beach to determine suitable release sites for efficient dispersal.
No preview · Article · Jun 2013 · Animal Conservation
[Show abstract][Hide abstract] ABSTRACT: A variety of trace metals were measured in the egg contents of three clutches of Chelonia mydas collected from Kuala Terengganu state in Peninsular Malaysia. We quantified Mn, Cu, Zn, Se (essential trace metals) and As (anthropogenic pollutant) at several developmental stages obtained by incubating eggs at two different temperatures (27°C and 31°C). The incubation temperatures were chosen because they produce predominantly male or predominantly female hatchlings, respectively. The eggs were removed from the sand and washed before being placed in incubators, to ensure that the only possible source of the detected metals was maternal transfer. Other metals: Mo, Co, Ni, Cd, Sn, Sb, Hg, Tl and Pb (all non-essential metals) were detected at concentrations below the lower limit of quantitation (LLOQ). Trace metal concentrations, particularly [Zn], increased during development, other metals (Cu, As, Se and Cr) accumulated to a lesser degree than zinc but no significant differences were observed between the incubation temperatures at any stage of incubation. To date, only a few studies on trace metals in turtle embryos and hatchlings have been reported; this study will provide basic knowledge on the accumulation of trace metals during development at two different incubation temperatures.
Full-text · Article · Mar 2013 · Science of The Total Environment
[Show abstract][Hide abstract] ABSTRACT: Low concentrations of several pesticides including organochlorines and polychlorinated biphenyls were found in the blood and eggs of nesting female flatback turtles, Natator depressus, collected from Curtis Island in Queensland, Australia.
No preview · Article · Dec 2012 · Chelonian Conservation and Biology
[Show abstract][Hide abstract] ABSTRACT: The histological characteristics of the gonads and paramesonephric ducts were investigated to allow a quantitative distinction among male, female, and intersex hatchling Green Sea Turtles (Chelonia mydas) from peninsular Malaysia. Hatchling sexes were identified initially as either males or females based on the incubation temperatures, and intersex hatchlings were collected from in situ nests. Traditionally, this assignment is confirmed by qualitative visual assessment of histological sections of the gonads and paramesonephric ducts. We describe a quantitative method for measuring these parameters to distinguish hatchling sex. The thickness of the paramesonephric duct epithelium area, the height of the nucleus in cells within the gonadal cortical epithelium, and the width of the gonadal ridge were measured in sections from 116 hatchlings. Upon examination of the histological material, hatchlings identified initially by incubation temperature as females were found to have significantly thicker paramesonephric duct epithelium and greater gonadal ridge width and cortical epithelium nuclear height compared with hatchlings identified as males. In addition, some hatchlings demonstrated histological characteristics of both sexes (designated here as intersex hatchlings) in some or all of the traditional histological sexing criteria. The "intersex" group could be divided into two subgroups by the quantitative measurements described here. Using this method, hatchlings could be classified as either males, females, or intersexes with a male-appearing gonad and female-appearing duct or a female-appearing gonad and male-appearing duct. The method outlined here provides a quantitative way to distinguish sex and provides insight in intersex grouping in hatchling C. mydas.
No preview · Article · Sep 2012 · Journal of Herpetology
[Show abstract][Hide abstract] ABSTRACT: The use of off-road vehicles (ORVs) on sandy beaches creates ruts in the sand that may interfere with the beach dispersal of sea turtle hatchlings. The present study investigated the influence of simulated ORV ruts of 3 depths (5, 10 and 15 cm) on the success and speed of green sea turtle Chelonia mydas hatchling dispersal. Almost all hatchlings (91%) were unable to traverse a single 15 cm rut, indicating that ruts of this depth are particularly detrimental to hatchling dispersal. Hatchlings had greater success traversing the 5 and 10 cm ruts, although they spent 2.6 and 18.6 times longer to get through a single rut, respectively (compared to the flat sand control path). It took progressively longer to get through subsequent ruts, and 99 and 53% of the hatchlings crawled along the 10 and 5 cm ruts, respectively, instead of attempting to crawl out of them. It was estimated that if hatchlings had to traverse 100 ORV ruts during dispersal, it would take 1.9 and 25.1 h for 5 and 10 cm deep ruts, respectively. The results from the present study indicate that green sea turtle hatchlings would spend considerable time navigating through ORV ruts, even as shallow as 5 cm, resulting in increased exposure to predation, dehydration and energy expenditure during this initial stage of dispersal.
Preview · Article · Jul 2012 · Endangered Species Research
[Show abstract][Hide abstract] ABSTRACT: Long prehibernation photoperiod did not significantly influence female receptive behavior on emergence, indicating that neuroendocrine control of ovarian activation and sexual behavior may be separate in this species. Ovarian development was clearly tied to duration of cold temperature dormancy. Females receiving 7 or 17 weeks of exposure to cold (4oC) underwent vitellogenesis at similar frequencies. Most females receiving 0 or only 4 weeks of exposure to cold (4oC) did not become vitellogenic. Mating on emergence was not a requirement for initiation of vitellogenesis.-from Authors
Full-text · Article · Feb 2011 · Canadian Journal of Zoology
[Show abstract][Hide abstract] ABSTRACT: The blood and eggs of the flatback turtle (Natator depressus) sampled when nesting at Curtis Island, Queensland, Australia. In the blood, zinc was present at the highest concentration of 151.15 ± 1.45 μg/L followed by copper (7.74 ± 0.09 μg/L). Lead was found only in some individuals. The measured trace elements in the blood were maternally transferred into the eggs. Other metals and metalloids detected in eggs were chromium, manganese, arsenic and selenium. Eggs showed a more complex trace element profile than blood, suggesting that they provided more representative tissues for determining maternal levels of trace element accumulation in N. depressus. Intra-clutch variation was over 15% for most of the studied trace elements suggesting one egg is not in sufficient to determine trace element accumulation within a clutch. Copper was the only element which was positively correlated with breeding age. Furthermore, no detectable levels of tin compound derivates were measured in N. depressus.
Full-text · Article · Sep 2010 · Marine environmental research
[Show abstract][Hide abstract] ABSTRACT: Persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominatecl diphenyl ethers (PBDEs), have a wide range of toxic effects on humans and wildlife, and have been reported in a number of endangered sea turtle populations. The present study screened for POPs in a green sea turtle Chelonia mydas population in Peninsular Malaysia and investigated the maternal transfer and effects of POPs on embryonic development. At the Ma'Daerah Turtle Sanctuary, blood, eggs and hatchling blood were collected from 11 nesting female C. mydas. Samples were analysed for 83 PCBs, 23 OCPs and 19 PBDEs using gas chromatography with tandem mass spectrometry. The chemical profiles of eggs from individual turtles were significantly different, indicating variable contaminant uptake during foraging. There was evidence of maternal transfer of POPs to eggs and hatchlings, with significant correlations in sum of PCBs (Sigma PCB), sum of PBDEs (Sigma PBDE), gamma-hexachlorocyclohexane (gamma-HCH), trans-chlordane and mirex concentrations between maternal blood and eggs (p < 0.05, R-2 < 0.71), between eggs and hatchling blood (p < 0.05, R-2 < 0.83), and between maternal and hatchling blood (p < 0.05, R-2 < 0.61). In addition, there was congener-specific transfer of PCBs with less lipophilic congeners (e.g. PCB 99) more readily transferred to hatchlings than the more lipophilic congeners (e.g. PCBs 180 + 193). There was also a significant correlation between increasing egg POP concentration and decreasing hatchling mass:length ratio. POPs may therefore have subtle effects on the development of C. mydas eggs, which may compromise offshore dispersal and predator avoidance.
Full-text · Article · Mar 2010 · Marine Ecology Progress Series
[Show abstract][Hide abstract] ABSTRACT: Persistent organic pollutants (POPs) and heavy metals have been reported in a number of green turtle (Chelonia mydas) populations worldwide. However, due to ethical considerations, these studies have generally been on tissues from deceased and stranded animals. The purpose of this study was to investigate the use of blood samples to estimate the tissue contamination of live C. mydas populations. This study analysed 125 POP compounds and eight heavy metals in the blood, liver, kidney and muscle of 16 C. mydas from the Sea World Sea Turtle Rehabilitation Program, Gold Coast, Australia. Strong correlations were observed between blood and tissue concentrations for a number of POPs and metals. Furthermore, these correlations were observed over large ranges of turtle size, sex and condition. These results indicate that blood samples are a reliable non-lethal method for predicting chemical contamination in C. mydas.
Full-text · Article · Dec 2009 · Marine Pollution Bulletin
[Show abstract][Hide abstract] ABSTRACT: Context. Many green sea turtle (Chelonia mydas) populations are declining worldwide owing to their susceptibility to human impacts in the marine environment. Identifying the habitats used throughout different lifecycle stages is therefore important for managing the interactions between turtles and humans. Aims. To identify the habitat utilisation of a C. mydas nesting population in Peninsular Malaysia during breeding, inter-nesting, migration and foraging lifecycle stages. Methods. Satellite telemetry was used to track the movement of three C. mydas nesting females and one adult male from the Ma'Daerah rookery (Peninsular Malaysia). Key results. The male and female turtles remained within 30 km of the nesting beach during the breeding and inter-nesting periods, which includes habitat beyond the 'no trawl zone' designed to protect turtles in this area. Following the breeding season, the tracked turtles migrated up to 1955 km to four different foraging grounds in Vietnam, Indonesia, Peninsular Malaysia and Borneo Malaysia. During foraging, turtles occupied areas threatened by human activities such as fishing and pollution. Conclusions. The habitats used by the Ma'Daerah C. mydas population during breeding are outside current local protection zones and extend into unprotected international waters during migration and foraging. Implications. Identification of habitats used by C. mydas populations is a critical element of management and conservation of this endangered, migratory species. Our study highlights the need to increase offshore protection around Ma'Daerah during the nesting season. Furthermore, this study has identified the countries within South-east Asia that Malaysia must cooperate with to ensure effective management of this C. mydas population. This information is particularly relevant to sea turtle conservation and management in regions like South-east Asia, where many coastal countries occupy a small geographical area.
Full-text · Article · Nov 2009 · Wildlife Research
[Show abstract][Hide abstract] ABSTRACT: Persistent organic pollutants (POPs)-such as organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs)-and heavy metals have been reported in sea turtles at various stages of their life cycle. These chemicals can disrupt development and function of wildlife. Furthermore, in areas such as Peninsular Malaysia, where the human consumption of sea turtle eggs is prevalent, egg contamination may also have public health implications.
In the present study we investigated conservation and human health risks associated with the chemical contamination of green turtle (Chelonia mydas) eggs in Peninsular Malaysia.
Fifty-five C. mydas eggs were collected from markets in Peninsular Malaysia and analyzed for POPs and heavy metals. We conducted screening risk assessments (SRAs) and calculated the percent of acceptable daily intake (ADI) for POPs and metals to assess conservation and human health risks associated with egg contamination.
C. mydas eggs were available in 9 of the 33 markets visited. These eggs came from seven nesting areas from as far away as Borneo Malaysia. SRAs indicated a significant risk to embryonic development associated with the observed arsenic concentrations. Furthermore, the concentrations of coplanar PCBs represented 3 300 times the ADI values set by the World Health Organization.
The concentrations of POPs and heavy metals reported in C. mydas eggs from markets in Peninsular Malaysia pose considerable risks to sea turtle conservation and human health.
Full-text · Article · Sep 2009 · Environmental Health Perspectives
[Show abstract][Hide abstract] ABSTRACT: Investigation into persistent organic pollutants (POPs) in sea turtles is an important area of conservation research due to the harmful effects of these chemicals. However, the analysis of POPs in the green sea turtle (Chelonia mydas) has been limited by methods with relatively high limits of detection and high costs associated with multiple sample injections into complex arrangements of analytical equipment. The present study aimed to develop a method that could detect a large number of POPs in the blood, eggs and tissue of C. mydas at trace concentrations. A gas chromatography with tandem mass spectrometry (GC-MS/MS) method was developed that could report 125 POP compounds to a limit of detection of <35 pg g(-1) using a single sample injection. The recoveries of internal standards ranged from 30% to 96%, and the standard reference materials were reported to within 70% of the certified values. The coefficient of variation of ten replicates of pooled egg sample was <20% for all compounds, indicating low within-run variation. This GC-MS/MS method is an improvement of previous methods for analysing POPs in C. mydas in that more compounds can be reported at lower concentrations and the accuracy and precision of the method are sound. This is particularly important for C. mydas as they occupy a low trophic level and have lower concentrations of POPs. This method is also simple to set up, and there are minimal differences in sample preparation for the different tissue types.
Full-text · Article · Mar 2009 · Analytical and Bioanalytical Chemistry
[Show abstract][Hide abstract] ABSTRACT: Quantifying health in wild marine turtles is challenging because reptiles have characteristically wide-ranging normal reference values for many indicators of health and because of the shortage of population-specific baseline data for wild animals. We measured blood biochemistry profiles (calcium, magnesium, sodium, lactate dehydrogenase (LDH), urea, cholesterol, triglycerides, and glucose) of green turtles (Chelonia mydas) in Moreton and Shoalwater Bays, Australia, and compared them in relation to capture site, age, sex and exposure to harmful algal blooms of the toxic cyanobacteria Lyngbya majuscula. Turtles were considered to be clinically healthy when no external injuries or lesions were observed and there was no evidence of disease or emaciation. Differences in blood profiles were detected between sites, but not between age groups or sexes. Turtles that were exposed to L. majuscula generally had lower plasma glucose concentrations and decreased LDH activity, which may represent a metabolic downregulation resulting from food limitation. This study provides the first blood biochemistry reference values for green turtles in Queensland, Australia, that can be used in future assessments of green turtles in these foraging habitats.
Full-text · Article · Jan 2008 · Australian Journal of Zoology