Bioaccumulation of organochlorine compounds in large, threatened elasmobranchs off northern New South Wales, Australia

The effects of estuarine outflows on coastal marine ecosystems in New South Wales, Australia

In the state of New South Wales (NSW), Australia, recent legislative action has focused on identifying key threats to the marine estate. We used a systematic literature review to evaluate the knowledge status of the effects of estuarine outflows on coastal marine ecosystems, within the environmental, hydrological, and physicochemical context of NSW waters. Results focussed on studies that measured outcomes for marine biota (n = 56). Trace elements and organochlorines were the most frequently studied contaminant types, with reported biological concentrations often below guideline values but detected at the highest concentrations adjacent to urban sources. Few studies measured the impacts of legacy and emerging contaminants to animal health, or the flow on effects to marine ecosystems in NSW. Our review highlights key biological and geographical data gaps in estuarine outflow research in NSW, particularly of the impact on ecosystems of exported carbon and nutrients to the oligotrophic waters of NSW.

Per/Polyfluoroalkyl Substances (PFASs) in a Marine Apex Predator (White Shark, Carcharodon carcharias) in the Northwest Atlantic Ocean

Per/polyfluoroalkyl substances (PFASs) are ubiquitous, highly persistent anthropogenic chemicals that bioaccumulate and biomagnify in aquatic food webs and are associated with adverse health effects, including liver and kidney diseases, cancers, and immunosuppression. We investigated the accumulation of PFASs in a marine apex predator, the white shark (Carcharodon carcharias). Muscle (N = 12) and blood plasma (N = 27) samples were collected from 27 sharks during 2018-2021 OCEARCH expeditions along the eastern coast of North America from Nova Scotia to Florida. Samples were analyzed for 47 (plasma) and 43 (muscle) targeted PFASs and screened for >2600 known and novel PFASs using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS). Perfluoroalkyl carboxylates with carbon chain-length C11 to C14 were frequently detected above the method reporting limits in plasma samples, along with perfluorooctanesulfonate and perfluorodecanesulfonate. Perfluoropentadecanoate was also detected in 100% of plasma samples and concentrations were estimated semiquantitatively as no analytical standard was available. Total concentrations of frequently detected PFASs in plasma ranged from 0.56 to 2.9 ng mL-1 (median of 1.4 ng mL-1). In muscle tissue, nine targeted PFASs were frequently detected, with total concentration ranging from 0.20 to 0.84 ng g-1 ww. For all frequently detected PFASs, concentrations were greater in plasma than in muscle collected from the same organism. In both matrices, perfluorotridecanoic acid was the most abundant PFAS, consistent with several other studies. PFASs with similar chain-lengths correlated significantly among the plasma samples, suggesting similar sources. Total concentrations of PFASs in plasma were significantly greater in sharks sampled off of Nova Scotia than all sharks from other locations, potentially due to differences in diet. HRMS suspect screening tentatively identified 13 additional PFASs in plasma, though identification confidence was low, as no MS/MS fragmentation was collected due to low intensities. The widespread detection of long-chain PFASs in plasma and muscle of white sharks highlights the prevalence and potential biomagnification of these compounds in marine apex predators.

Persistent Organic Pollutants in Whale Shark (Rhincodon typus) Skin Biopsies from Bahía de Los Ángeles, Mexico

The whale shark (Rhincodon typus) is a filter-feeding organism that can be considered a sentinel species, and Bahía de los Ángeles (BLA) in the Gulf of California is an important sighting site for these elasmobranchs. This filter-feeding organism can be considered a pollutant sampler from the marine environment. Persistent organic pollutants are toxic compounds with high mobility and environmental persistence, bioaccumulation and trophic transfer. Among these are polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs). The present work aimed to determine concentrations of PAHs and OCPs in whale shark skin biopsies, collected in 2021 at BLA. Mean detected levels of PAHs and OCPs were 279.4 ng/g dw (dry weight) and 1478.1 ng/g dw, respectively. Analysis of similarities between the ordered sizes (4.2-7.6 m) and the concentrations of PAHs and OCPs indicated no significant differences. Individual PAHs detected indicate pyrogenic and petrogenic sources; the presence of pesticides at levels higher than those of hydrocarbons may be related to agricultural activity in the areas surrounding the Baja California peninsula. This study is the first report of PAH levels in R. typus for the Gulf of California and Mexico.

Bioaccumulation of trace elements and hydrocarbons in chondrichthyans of the western Arabian Gulf: Environmental and human health risk assessment and implications for conservation

This is a first attempt to assess the levels of trace elements, PAHs, and TPHs in six elasmobranch species (Carcharhinus dussumieri, C. sorrah, Chiloscyllium arabicum, Gymnura poecilura, Sphyrna lewini, S. mokarran) from the Arabian Gulf. The chemical analysis showed that the concentrations of contaminants differed significantly between liver and muscle samples with both pelagic and benthic species and all families. For all species, contaminant concentrations were significantly higher in the liver than in the muscle. While muscle contaminant concentrations differed significantly with respect to species' lifestyles and families, those of liver showed no significant differences between pelagic and benthic species, neither between the four families nor between the six species. None of the analysed contaminants exceeded the internationally recognized standards in all studied species. These results enrich the knowledge on the bioaccumulation of contaminants in elasmobranchs and allow to assess the environmental status of the Arabian Gulf.

Persistent Organic Pollutants (POPs) in three bathyal chondrichthyes from the North-Western Mediterranean Sea

The deep-sea can act as a sink for legacy contaminants such as organochlorines (OCs), causing damages in its inhabitants for their persistence and their prolonged effects in the organisms. HCB, DDT and its isomers, and 28 PCBs congeners were detected in muscle and embryonic tissues of three deep-sea chondrichthyes Chimaera monstrosa (n = 16), Dalatias licha (n = 12) and Etmopterus spinax (n = 51) sampled in Ligurian and Tyrrhenian Sea (Mediterranean Sea). Contaminant distribution in E. spinax and C. monstrosa was PCBs > DDTs ≫ HCB while in D. licha was DDTs > PCBs ≫ HCB. Statistically significant differences were highlighted in OC levels among the species, but no such differences were found among sexes. Ratios between DDT isomers highlighted an historical input of the pesticide in the environment. For the first time was also demonstrated maternal transfer in deep water chondrichthyes, specifically in E. spinax where was highlighted that transfer of contaminants increases with increasing compound's Log Kow.

Associations between total mercury, trace minerals, and blood health markers in Northwest Atlantic white sharks (Carcharodon carcharias)

The ecology and life-histories of white sharks make this species susceptible to mercury bioaccumulation; however, the health consequences of mercury exposure are understudied. We measured muscle and plasma total mercury (THg), health markers, and trace minerals in Northwest Atlantic white sharks. THg in muscle tissue averaged 10.0 mg/kg dry weight, while THg in blood plasma averaged 533 μg/L. THg levels in plasma and muscle were positively correlated with shark precaudal length (153-419 cm), and THg was bioaccumulated proportionally in muscle and plasma. Nine sharks had selenium:mercury molar ratios in blood plasma >1.0, indicating that for certain individuals the potential protective effects of the trace mineral were diminished, whereas excess selenium may have protected other individuals. No relationships between plasma THg and any trace minerals or health markers were identified. Thus, we found no evidence of negative effects of Hg bioaccumulation, even in sharks with very high THg.

To what extent are filter feeder elasmobranchs exposed to marine pollution? A systematic review

Filter feeding elasmobranchs may be considered as biological indicators of marine pollution, despite most of these species are under some degree of extinction risk. Among threats to this taxonomic group, marine pollution might represent an additional concern for their survival. In this review, a comprehensive systematic search of scientific literature on pollutants in filter feeding elasmobranchs was conducted to evaluate the bioaccumulation patterns, and risk for human consumers. We found that, despite an increasing trend in the number of published studies, the geographical coverage is still very limited and most of the studies focused solely on trace elements (70.8%). Among sharks, Rhincodon typus was the most represented species (66.7%), while Mobula mobular the most studied ray species (41.7%). Comparing the levels of pollutants in filter feeders between ocean basins, this review highlighted that Hg, As and Cd levels are mostly higher in those areas affected by both strong natural and anthropogenic source of emissions, such as the Indian Ocean. With regards to OCs, ΣPCB levels in muscle of C. maximus were between 4.3 and 50.5 μg kg^-1 ww, highlighting a persistent contamination of PCB in the Mediterranean Sea. Some species exceeded the maximum allowable limits for foodstuff consumption for As, Cd and Pb. A total of 77.8% of the analyzed species exceeded the Environmental Quality Standards for Hg, while they were always below the EQS_biota for HCB, PBDEs, PFOS and DDT. Given their feeding mechanism that continuously samples the marine environment, further investigations are urgently needed to determine not only the extent of contaminant exposure in different hotspot locations but also the risks posed to the elasmobranch health.

Organochlorine contaminants in Rio skate (Rioraja agassizii), an endangered batoid species, from southeastern coast of Brazil

A global movement towards decreases in elasmobranch overfishing has been noted in the last decades. However, discussion concerning the effects of POP contamination on the health and survival of these organisms is still recent. These compounds can affect the immune and endocrine systems of both sharks and batoids, impairing reproduction and impacting species recruitment, acting synergistically alongside overfishing effects. In this context, this study investigated the concentration of organochlorine compounds in liver of 29 individuals of Rioraja agassizii, a commercially exploited skate classified as Vulnerable by IUCN and as Endangered in Brazil. Contaminant concentrations were higher in adults compared to juveniles. Distinct contamination profiles were observed, suggesting different groups within the investigated population and revealing contaminants as a potential tool to assess population ecology. PCB levels were considered a concern as they resemble concentrations in ecosystems from the northern hemisphere, where deleterious effects on elasmobranchs have been observed.

Characterization of Halogenated Organic Compounds in Pelagic Sharks and Sea Turtles Using a Nontargeted Approach

Halogenated organic compounds (HOCs) in marine species collected from the Atlantic Ocean [3 shortfin mako (Isurus oxyrinchus) and 1 porbeagle (Lamna nasus)], and 12 sea turtles collected from the Pacific Ocean [3 loggerhead (Caretta caretta), 3 green (Chelonia mydas), 3 olive ridley (Lepidochelys olivacea), and 3 hawksbill (Eretmochelys imbricata)] were analyzed with a nontargeted analytical method using two-dimensional gas chromatography coupled to high-resolution time-of-flight mass spectrometry. Sharks and sea turtles had distinct HOC profiles. Halogenated methoxyphenols (halo-MeOPs) were the most abundant compound class identified in sea turtle livers, while polychlorinated biphenyls (PCBs) were the most abundant in shark livers. In addition to legacy contaminants and halo-MeOPs, a total of 110 nontargeted/novel HOCs (NHOCs) were observed in the shark livers. Shortfin mako collected from the northern Gulf of Mexico contained the largest number (89) and most diverse structural classes of NHOCs. Among all NHOCs, a group of compounds with the elemental composition C₁₄H_12-nCl_n (n = 5-8) exhibited the highest concentrations, followed by chlorocarbazoles and tris(chlorophenyl) methanes (TCPMs). Using nontargeted workflows, a variety of known and unknown HOCs were observed, which demonstrate the need to develop more complete chemical profiles in the marine environment.

Persistent organic pollutants and chlorpyrifos in the cockfish Callorhinchus callorynchus (Holocephali: Callorhynchidae) from Argentine coastal waters: Influence of sex and maturity

Organic contaminants are of great environmental concern due to their negative impacts on coastal ecosystems, especially on highly vulnerable species as chondrichthyans. Accumulation of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and chlorpyrifos was assessed in muscle, gonads, and liver of the cockfish Callorhinchus callorynchus for both sexes and maturity stages. This species has a wide distribution in South Atlantic Ocean and it is an important resource for coastal Argentine fisheries. Pollutants were quantified by gas chromatography with electron capture detector and the distribution pattern found in C. callorynchus was the following: (∑OCPs+chlorpyrifos) > ∑PCBs>∑PBDEs. Endosulfan was predominant among OCP groups, penta-CBs and hexaCBs among PCBs and BDE 47, 66, 99, and 100 in PBDE group. The highest levels were found in liver followed by muscle and gonads. The highest percentage of lipids was also observed in the liver. Moreover, the concentrations of ∑OCPs and ∑PCBs in C. callorynchus liver varied with maturity stage, and ∑OCPs also with sexes. Females presented higher values than males, and mature individuals showed higher concentrations than immature ones, according with biological parameters such as age, sex, maturity stage, metabolic and redistribution processes and habitat use influence. These results indicate that C. callorynchus reflects a historical and recent contamination in their tissues, and therefore, especially females, becomes as a good biomonitor of these pollutants in the marine environment. To our knowledge, this work represents one of the few investigations on the occurrence of POPs and chlorpyrifos in chondrichtyans from South Atlantic Ocean; therefore more research is mandatory for an adequate management and conservation of existing fisheries and aquatic resources.

Evaluation of muscle tissue as a non-lethal proxy for liver and brain organic contaminant loads in an elasmobranch, the Bonnethead Shark (Sphyrna tiburo)

Elasmobranch ecotoxicological investigations are complicated because accessing organs that accumulate organic contaminants is usually lethal. Several metrics among liver, muscle, and brain were evaluated to determine their relative organic contaminant loads and the efficacy of using muscle as a non-lethal proxy for liver. Liver contained the highest concentrations (368-4020 ng/g wet weigth [ww]) and greatest estimated total load of contaminants. Brain had higher toxin concentrations than muscle (4.18-84.2 ng/g ww versus 0.94-4.73 ng/g ww). Liver and brain were similar to each other in terms of contaminant detection occurrence and signature overlap, whereas muscle poorly reflected those of liver and brain. However, the identity of contaminants detected in muscle constituted those that substantially contributed to summed liver and brain concentrations. Thus, studies utilizing muscle as a non-lethal liver alternative to study organic contaminant exposure in elasmobranchs should craft questions with care, considering its limited ability to serve as an accurate proxy.

Legacy and emerging organic contaminants in two sympatric shark species from Reunion Island (Southwest Indian Ocean): Levels, profiles and maternal transfer

The contamination of tiger sharks (Galeocerdo cuvier) and bull sharks (Carcharhinus leucas) by legacy persistent organic pollutants (POPs) and emerging organic contaminants was investigated in specimens from Reunion Island (Southwest Indian Ocean) in 2018 and 2019. Contamination levels were determined in the muscle of adult individuals of both sexes in relation to biological and trophic parameters. Maternal transfer was additionally investigated in one set of embryos in each species. Polychlorinated biphenyl (PCB), organochlorinated pesticide (OCP) and perfluoroalkylated substance (PFAS) concentrations were 2597 ± 2969, 785 ± 966 and 267 ± 194 pg g-1 ww, respectively, in bull sharks, and 339 ± 270, 1025 ± 946 and 144 ± 53 pg g-1 ww in tiger sharks. The results highlighted higher PCB contamination, and by the heavier congeners, in adult bull sharks versus tiger sharks. The significant differences found in PCB profiles and concentrations suggest that the two species are exposed to different contamination sources. As bull sharks rely on a more coastal habitat for feeding, their higher contamination by PCBs suggests the occurrence of local PCB sources. DDT concentrations were similar in both species, suggesting a more homogeneous contamination on the scale of the Southwest Indian Ocean. Female bull sharks showed lower OCP and PCB concentrations than males, while this trend was not observed in tiger sharks. The ratio of chlorinated contaminants in muscle between the mother and her embryos was related to molecule hydrophobicity in bull shark but not in tiger shark, suggesting that shark mode of gestation, known to be different in the two species, is a key driver of organic contaminant maternal transfer. Finally, the results show that organic contaminant levels in the studied species were lower than those of other shark species in the Southern Hemisphere, related to the limited urbanization and industrialization of Reunion Island.

Are concentrations of pollutants in sharks, rays and skates (Elasmobranchii) a cause for concern? A systematic review

This review represents a comprehensive analysis on pollutants in elasmobranchs including meta-analysis on the most studied pollutants: mercury, cadmium, PCBs and DDTs, in muscle and liver tissue. Elasmobranchs are particularly vulnerable to pollutant exposure which may pose a risk to the organism as well as humans that consume elasmobranch products. The highest concentrations of pollutants were found in sharks occupying top trophic levels (Carcharhiniformes and Lamniformes). A human health risk assessment identified that children and adults consuming shark once a week are exposed to over three times more mercury than is recommended by the US EPA. This poses a risk to local fishing communities and international consumers of shark-based products, as well as those subject to the widespread mislabelling of elasmobranch products. Wider screening studies are recommended to determine the risk to elasmobranchs from emerging pollutants and more robust studies are recommended to assess the risks to human health.