Acute exposure to perfluorooctane sulfonate exacerbates heat-induced oxidative stress in a tropical coral species

Anthropogenic stressors and the marine environment: From sources and impacts to solutions and mitigation

Human-released contaminants are often poorly understood wholistically in marine ecosystems. This review examines the sources, pathways, impacts on marine animals, and mitigation strategies of five pollutants (plastics, per- and polyfluoroalkyl substances, bisphenol compounds, ethynylestradiol, and petroleum hydrocarbons). Both abiotic and biotic mechanisms contribute to all five contaminants' movement. These pollutants cause short- and long-term effects on many biological processes genetically, molecularly, neurologically, physiologically, reproductively, and developmentally. We explore the extension of adverse outcome pathways to ecosystem effects by considering known inter-generational and trophic relations resulting in large-scale direct and indirect impacts. In doing so, we develop an understanding of their roles as environmental stressors in marine environments for targeted mitigation and future work. Ecosystems are interconnected and so international collaboration, standards, measures preceding mass production, and citizen involvement are required to protect and conserve marine life.

Co-exposure of environmental contaminants with unfavorable temperature or humidity/moisture: Joint hazards and underlying mechanisms

In the context of global climate change, organisms in their natural habitats usually suffer from unfavorable climatic conditions together with environmental pollution. Temperature and humidity (or moisture) are two central climatic factors, while their relationships with the toxicity of contaminants are not well understood. This review provides a synthesis of existing knowledge on important interactions between contaminant toxicity and climatic conditions of unfavorable temperature, soil moisture, and air humidity. Both high temperature and low moisture can extensively pose severe combined hazards with organic pollutants, heavy metal ions, nanoparticles, or microplastics. There is more information on the combined effects on animalia than on other kingdoms. Prevalent mechanisms underlying their joint effects include the increased bioavailability and bioaccumulation of contaminants, modified biotransformation of contaminants, enhanced induction of oxidative stress, accelerated energy consumption, interference with cell membranes, and depletion of bodily fluids. However, the interactions of contaminants with low temperature or high humidity/moisture, particularly on plants and microorganisms, are relatively vague and need to be further revealed. This work emphasizes that the co-exposure of chemical and physical stressors results in detrimental effects generally greater than those caused by either stressor. It is necessary to take this into consideration in the ecological risk assessment of both environmental contamination and climate change.

Individual and combined effects of herbicide prometryn and nitrate enrichment at environmentally relevant concentrations on photosynthesis, oxidative stress, and endosymbiont community diversity of coral Acropora hyacinthus

Nitrogen pollution and pesticides such as photosystem II (PSII) inhibitor herbicides have several detrimental impacts on coral reefs, including breakdown of the symbiosis between host corals and photosynthetic symbionts. Although nitrogen and PSII herbicide pollution separately cause coral bleaching, the combined effects of these stressors at environmentally relevant concentrations on corals have not been assessed. Here, we report the combined effects of nitrate enrichment and PSII herbicide (prometryn) exposure on photosynthesis, oxidative status and endosymbiont community diversity of the reef-building coral Acropora hyacinthus. Coral fragments were exposed in a mesocosm system to nitrate enrichment (9 μmol/L) and two prometryn concentrations (1 and 5 μg/L). The results showed that sustained prometryn exposure in combination with nitrate enrichment stress had significant detrimental impacts on photosynthetic apparatus [the maximum quantum efficiency of photosystem II (Fv/Fm), nonphotochemical quenching (NPQ) and oxidative status in the short term. Nevertheless, the adaptive mechanism of corals allowed the normal physiological state to be recovered following 1 μg/L prometryn and 9 μmol/L nitrate enrichment individual exposure. Moreover, exposure for 9 days was insufficient to trigger a shift in Symbiodiniaceae community. Most importantly, the negative impact of exposure to the combined environmental concentrations of 1 μg/L prometryn and 9 μmol/L nitrate enrichment was found to be significantly greater on the Fv/Fm, quantum yield of non-regulated energy dissipation [Y(NO)], NPQ, and oxidative status of corals compared to the impact of individual stressors. Our results show that interactions between prometryn stress and nitrate enrichment have a synergistic impact on the photosynthetic and oxidative stress responses of corals. This study provides valuable insights into combined effects of nitrate enrichment and PSII herbicides pollution for coral's physiology. Environmental concentrations of PSII herbicides may be more harmful to photosystems and antioxidant systems of corals under nitrate enrichment stress. Thus, future research and management of seawater quality stressors should consider combined impacts on corals rather than just the impacts of individual stressors alone.

Ecological characteristics impact PFAS concentrations in a U.S. North Atlantic food web

This is the first comprehensive study of per- and polyfluoroalkyl substances (PFAS) in a coastal food web of the U.S. North Atlantic, in which we characterize the presence and concentrations of 24 targeted PFAS across 18 marine species from Narragansett Bay, Rhode Island, and surrounding waters. These species reflect the diversity of a typical North Atlantic Ocean food web with organisms from a variety of taxa, habitat types, and feeding guilds. Many of these organisms have no previously reported information on PFAS tissue concentrations. We found significant relationships of PFAS concentrations with respect to various ecological characteristics including species, body size, habitat, feeding guild, and location of collection. Based upon the 19 PFAS detected in the study (5 were not detected in samples), benthic omnivores (American lobsters = 10.5 ng/g ww, winter skates = 5.77 ng/g ww, Cancer crabs = 4.59 ng/g ww) and pelagic piscivores (striped bass = 8.50 ng/g ww, bluefish = 4.30 ng/g ww) demonstrated the greatest average ∑PFAS concentrations across all species sampled. Further, American lobsters had the highest concentrations detected in individuals (∑PFAS up to 21.1 ng/g ww, which consisted primarily of long-chain PFCAs). The calculation of field-based trophic magnification factors (TMFs) for the top 8 detected PFAS determined that perfluorodecanoic acid (PFDA), perfluorooctane sulfonic acid (PFOS), and perfluorooctane sulfonamide (FOSA) associated with the pelagic habitat biomagnified, whereas perfluorotetradecanoic acid (PFTeDA) associated with the benthic habitat demonstrated trophic dilution in this food web (calculated trophic levels ranged from 1.65 to 4.97). While PFAS exposure to these organisms may have adverse implications for ecological impacts via toxicological effects, many of these species are also key recreational and commercial fisheries resulting in potential for human exposure via dietary consumption.

Biochemical, histopathological and untargeted metabolomic analyses reveal hepatotoxic mechanism of acetamiprid to Xenopus laevis

Acetamiprid, a commonly detected neonicotinoid in aquatic ecosystems, poses a threat to aquatic non-target organisms. However, limited information is available on the toxic effects of acetamiprid on nontarget aquatic organisms. This study assessed the toxic effects of acetamiprid on Xenopus laevis, a typical model organism. The acute toxicity for 96 h revealed that acetamiprid had detrimental effects with a median lethal concentration (LC₅₀) value of 64.48 mg/L. Toxicity assays, including oxidative stress, histopathology and untargeted metabolomics of acetamiprid to X. laevis, were performed for 28 d at 1/10 and 1/100 LC₅₀ by studying the liver, which is the most antioxidant and major metabolic organ. The results demonstrated that acetamiprid exposure significantly changed the oxidant status of and caused histological damage to the liver. Furthermore, the untargeted metabolomic analysis based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) identified the endogenous metabolites that were significantly altered. There were 89 differential metabolites compared to the controls: 64 in the 1/10 LC₅₀ group, 47 in the 1/100 LC₅₀ group, and 23 metabolites in the 1/10 LC₅₀ group were the same as those in the 1/100 LC₅₀ group. Sixteen pathways that were mainly associated with amino acid metabolism and lipid metabolism, such as sphingolipid metabolism, glycerophospholipid metabolism and histidine metabolism, were disrupted, revealing the hepatotoxic effects of acetamiprid on X. laevis at the molecular level. These findings provide crucial information for evaluating the aquatic risks of neonicotinoids.

Spatial distribution of per- and polyfluoroalkyl substances (PFAS) in waters from Central and South Florida

Per- and polyfluoroalkyl substances (PFAS) are notoriously persistent pollutants that are found ubiquitously present in aquatic environments. They pose a big threat to aquatic life and human health given the bioaccumulation feature and significant adverse health effects associated. In our previous study, PFAS were found in surface waters from Biscayne Bay and tap waters from the East coast of South Florida, at levels that arouse human health and ecological concerns. Considering that Florida supports millions population as well as treasured, sensitive coastal and wetland ecosystems, we have expanded the PFAS monitoring study on the occurrence, composition, spatial distribution, and potential sources encompassing tap waters from counties on the West coast of South Florida and Central Florida, and surface waters from Tampa Bay, Everglades National Park adjacent canals, Key West, including Biscayne Bay area. A total of 30 PFAS were analyzed based on solid-phase extraction (SPE) followed by liquid chromatography tandem mass spectrometry (LC-MS/MS). PFAS were detected in all tap water (N = 10) and surface water samples (N = 38) with total concentrations up to 169 ng L^-1. Higher PFAS concentrations (> 60 ng L^-1) are mostly observed from polluted rivers or coastal estuaries in Biscayne Bay, and sites nearby potential points sources (military airbases, wastewater facilities, airports, etc.). Our findings on current PFAS contamination levels from diverse aquatic environments provide additional information for the development of more stringent screening levels that are protective of human health and the environmental resources of Florida, which is ultimately anticipated as scientific understanding of PFAS is rapidly growing.

First report on per- and polyfluoroalkyl substances (PFASs) in coral communities from the Northern South China sea: Occurrence, seasonal variation, and interspecies differences

In this study, the contamination levels and seasonal variation of 22 PFASs were investigated in coastal reef-building corals (n = 68) from the northern South China Sea (SCS) during wet and dry seasons. Perfluorohexane sulfonate (PFHxS) was the predominant PFASs in all coral samples, representing 43% of the total PFAS. Long-chain PFASs, as well as PFAS alternatives, were frequently detected above the MQL (>88%) but showed relatively low concentrations compared to short-chain PFASs in most species and seasons. Seasonal variation of PFAS concentrations were observed in branching corals, indicating that the accumulation of PFASs may be associated with coral morphological structures. Interspecies differences in PFAS levels agree well with different bioaccumulation potentials among coral species. Redundancy analysis (RDA) showed that seasonal factor and coral genus could partly influence PFAS concentrations in coral tissues. In summary, our study firstly reported the occurrence of PFASs in coral communities from the SCS and highlights the necessity for future investigations on more toxicity data for coral communities.