Jason P. van de Merwe

Using blood samples to estimate persistent organic pollutants and metals in green sea turtles (Chelonia mydas)

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.

Chemical Contamination of Green Turtle (Chelonia mydas) Eggs in Peninsular Malaysia: Implications for Conservation and Public Health

Background 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. Objective 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. Methods 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. Results 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. Conclusions 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.

Laccase–syringaldehyde-mediated degradation of trace organic contaminants in an enzymatic membrane reactor: Removal efficiency and effluent toxicity

Redox-mediators such as syringaldehyde (SA) can improve laccase-catalyzed degradation of trace organic contaminants (TrOCs) but may increase effluent toxicity. The degradation performance of 14 phenolic and 17 non-phenolic TrOCs by a continuous flow enzymatic membrane reactor (EMR) at different TrOC and SA loadings was assessed. A specific emphasis was placed on the investigation of the toxicity of the enzyme (laccase), SA, TrOCs and the treated effluent. Batch tests demonstrated significant individual and interactive toxicity of the laccase and SA preparations. Reduced removal of resistant TrOCs by the EMR was observed for dosages over 50μg/L. SA addition at a concentration of 10μM significantly improved TrOC removal, but no removal improvement was observed at the elevated SA concentrations of 50 and 100μM. The treated effluent showed significant toxicity at SA concentrations beyond 10μM, providing further evidence that higher dosage of SA must be avoided.

The current state and future directions of marine turtle toxicology research

Chemical contamination of marine turtles has been well documented in the literature, although information on the toxicological effects of these contaminants is poorly understood. This paper systematically and quantitatively presents the available marine turtle toxicological research (excluding oil chemicals and natural toxins) and the related fields of cell line establishment and biomarkers as indicators of exposure. Examination of the published literature identified a total of 49 papers on marine turtle toxicology, which were split into three categories: toxicity studies (n=33, 67%), cell line establishment (n=7, 14%), and publications using biomarkers (n=13, 27%). Toxicity studies were further broken down into four subcategories: those correlating contaminants with toxicological endpoints (n=16, 48%); in vitro exposure experiments (n=11, 33%); in vivo exposure experiments (n=5, 15%); and screening risk assessments using hazard quotients (n=3, 9%). In quantitatively assessing the literature, trends and gaps in this field of research were identified. This paper highlights the need for more marine turtle toxicology research on all species, particularly using high throughput and non-invasive in vitro assays developed for marine turtle cells, including investigations into further toxicological endpoints and mixture effects. This will provide more comprehensive species-specific assessment of the impacts of chemical contaminants on these threatened animals, and improve conservation and management strategies globally.

Impact of hazardous events on the removal of nutrients and trace organic contaminants by an anoxic-aerobic membrane bioreactor receiving real wastewater

The impacts of four simulated hazardous events, namely, aeration failure, power loss, and chemical shocks (ammonia or bleach) on the performance of an anoxic-aerobic membrane bioreactor (MBR) receiving real wastewater were investigated. Hazardous events could alter pH and/or oxidation reduction potential of the mixed liquor and inhibit biomass growth, thus affecting the removal of bulk organics, nutrients and trace organic contaminants (TrOC). Chemical shocks generally exerted greater impact on MBR performance than aeration/power failure events, with ammonia shock exerting the greatest impact. Compared to total organic carbon, nutrient removal was more severely affected. Removal of the hydrophilic TrOCs that are resistant and/or occur at high concentrations in wastewater was notably affected. The MBR effectively reduced estrogenicity and toxicity from wastewater, but chemical shocks could temporarily increase the endocrine activity of the effluent. Depending on the chemical shock-dose and the membrane flux, hazardous events can exacerbate membrane fouling.

Biocatalytic degradation of pharmaceuticals, personal care products, industrial chemicals, steroid hormones and pesticides in a membrane distillation-enzymatic bioreactor

Laccase-catalyzed degradation of a broad spectrum of trace organic contaminants (TrOCs) by a membrane distillation (MD)-enzymatic membrane bioreactor (EMBR) was investigated. The MD component effectively retained TrOCs (94-99%) in the EMBR, facilitating their continuous biocatalytic degradation. Notably, the extent of TrOC degradation was strongly influenced by their molecular properties. A significant degradation (above 90%) of TrOCs containing strong electron donating functional groups (e.g., hydroxyl and amine groups) was achieved, while a moderate removal was observed for TrOCs containing electron withdrawing functional groups (e.g., amide and halogen groups). Separate addition of two redox-mediators, namely syringaldehyde and violuric acid, further improved TrOC degradation by laccase. However, a mixture of both showed a reduced performance for a few pharmaceuticals such as primidone, carbamazepine and ibuprofen. Mediator addition increased the toxicity of the media in the enzymatic bioreactor, but the membrane permeate (i.e., final effluent) was non-toxic, suggesting an added advantage of coupling MD with EMBR.

Habitat use by green turtles (Chelonia mydas) nesting in Peninsular Malaysia: local and regional conservation implications

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.

Concentrations of levonorgestrel and ethinylestradiol in wastewater effluents: Is the progestin also cause for concern?

Synthetic hormones have been widely reported in treated sewage effluents, and consequently receiving aquatic environments. Ethinylestradiol (EE2) is a potent synthetic estrogen commonly used in conjunction with levonorgestrel in oral contraceptive pills. Both EE2 and levonorgestrel have been identified in the aquatic environment, but although there is a significant amount of literature on EE2, there is much less information on levonorgestrel. Using Australian prescription data as well as excretion and predicted wastewater removal rates, the concentrations of EE2 and levonorgestrel in Australian wastewater were calculated at 0.1 ng/L to 0.5 ng/L and 0.2 ng/L to 0.6 ng/L, respectively. Both compounds were analyzed in treated wastewater and surface water grab samples from 3 Southeast Queensland, Australia sites. The predicted no-effect concentration (PNEC) for EE2 of 0.1 ng/L was exceeded at most sites, with EE2 concentrations up to 2 ng/L in treated effluent, albeit quickly diluted to 0.1 ng/L to 0.2 ng/L in the receiving environment. A provisional PNEC for levonorgestrel of 0.1 ng/L derived in the present study was slightly lower than predicted effluent concentrations of 0.2 ng/L to 0.6 ng/L, indicating a potential risk of endocrine-related effects in exposed aquatic species. The detection limit for levonorgestrel in the present study was 2.5 ng/L, and all samples were below detection limit. The present studys results suggest that improvements in analytical capabilities for levonorgestrel are warranted to more accurately quantify the risk of this compound in the receiving environment. Environ Toxicol Chem 2016;35:1378-1385.

Altered bioenergetics and developmental effects in striped marsh frog (Limnodynastes peronii) tadpoles exposed to UV treated sewage.

Effectively treating domestic wastewater so that it can be safely discharged or reused is critical for maintaining the integrity of freshwater resources, and for protecting the health of animals that rely on these systems. Amphibians are currently facing widespread population declines, so there is a particularly urgent need to investigate exposure scenarios that might result in weakened amphibian populations. Domestic sewage has received little attention as a possible factor that could influence the survival, growth and development, or general health of amphibians. However, wastewater reuse for crop irrigation and other purposes is increasing and holding ponds and constructed wetlands exist at many wastewater treatment facilities, introducing conceivable pathways that could result in the exposure of amphibians to treated wastewater. We exposed developing striped marsh frog (Limnodynastes peronii) tadpoles, to control water and 12.5, 25, 50 and 100% UV treated domestic sewage, and quantified effects on growth and development, hepatic energy reserves, and enzymatic pathways associated with detoxification and oxidative stress. Growth and development were accelerated and relative liver size was increased in exposed animals. The exposure resulted in an apparently hormetic increase in hepatic triglycerides and dose-dependent reduction in glycogen stores, as well as increased lipase and NADPH activity, indicating a general disruption to energy metabolism and/or mobilization. Contrary to expectations based on published studies with fish, we found no evidence of lipid peroxidation or induction of the detoxification enzyme Superoxide Dismutase (SOD), however, this may reflect the use of UV treatment as opposed to chlorination for disinfection. Chemical analysis and risk-based prioritization consistently identified fluoxetine, triclosan and diazinon as high-risk contaminants in the wastewater, with nonylphenol and mestranol flagged as risks during one early collection. Research is needed to explore the potential for these specific contaminants to elicit the responses identified in the present study, and to perform similar assessments using wastewater from other locations with different treatment options.

Effects of 1,2-dichlorobenzene on the growth, bioenergetics and reproduction of the amphipod, Melita longidactyla

The amphipod Melita longidactyla occurs in great abundance and serves important roles in the trophic transfer and nutrient recycling in marine systems along the Chinese coast. This study investigated the lethal dose (48h LC(50)), as well as sub-lethal effects of a common xenobiotic, 1,2-dichlorobenzene (1,2-DCB), on the bioenergetics, growth and reproduction of this important species. The 48h LC(50) for M. longidactyla exposed to 1,2-DCB was 780 microgL(-1). Exposure to 20 microgL(-1) 1,2-DCB for 3 weeks resulted in 22% reduction in the growth (dry weight) and 57% reduction in the number of progeny, respectively. Furthermore, a significant reduction in RNA:DNA ratio was observed in amphipods exposed to 1,2-DCB at concentration as low as 5 microgL(-1), whereas significant reductions in scope for growth occurred upon exposure to higher concentrations of 1,2-DCB (10 and 20 microgL(-1)) for 3 and 5 weeks. Our results showed that environmentally relevant concentrations of 1,2-DCB can affect the bioenergetics and more importantly, growth and reproduction of M. longidactyla, implicating that 1,2-DCB may affect the recruitment and sustainability of natural populations of this ecologically important species.