Acute ecotoxicology of natural oil and gas condensate to coral reef larvae

Bioconcentration and lethal effects of gas-condensate and crude oil on nearshore copepod assemblages

The progressive establishment of gas platforms and increasing petroleum accidents pose a threat to zooplankton communities and thus to pelagic ecosystems. This study is the first to compare the impacts of gas-condensate and crude oil on copepod assemblages. We conducted microcosm experiments simulating slick scenarios at five different concentrations of gas-condensate and crude oil to determine and compare their lethal effects and the bioconcentration of low molecular weight polycyclic aromatic hydrocarbons (LMW-PAHs) in eastern Mediterranean coastal copepod assemblages. We found that gas-condensate had a two-times higher toxic effect than crude oil, significantly reducing copepod survival with increased exposure levels. The LMW-PAHs bioconcentration factor was 1-2 orders of magnitude higher in copepods exposed to gas-condensate than in those exposed to crude oil. The median lethal concentration (LC50) was significantly lower in calanoids vs. cyclopoid copepods, suggesting that calanoids are more susceptible to gas-condensate and crude oil pollution, with potential trophic implications.

Molecular responses of sponge larvae exposed to partially weathered condensate oil

Anthropogenic inputs of petroleum hydrocarbons into the marine environment can have long lasting impacts on benthic communities. Sponges form an abundant and diverse component of benthic habitats, contributing a variety of important functional roles; however, their responses to petroleum hydrocarbons are largely unknown. This study combined a traditional ecotoxicological experimental design and endpoint with global gene expression profiling and microbial indicator species analysis to examine the effects of a water accommodated fraction (WAF) of condensate oil on a common Indo-Pacific sponge, Phyllospongia foliascens. A no significant effect concentration (N(S)EC) of 2.1 % WAF was obtained for larval settlement, while gene-specific (N(S)EC) thresholds ranged from 3.4 % to 8.8 % WAF. Significant shifts in global gene expression were identified at WAF treatments ≥20 %, with larvae exposed to 100 % WAF most responsive. Results from this study provide an example on the incorporation of non-conventional molecular and microbiological responses into ecotoxicological studies on petroleum hydrocarbons.

Tar patties are hotspots of hydrocarbon turnover and nitrogen fixation during a nearshore pollution event in the oligotrophic southeastern Mediterranean Sea

Weathered oil, that is, tar, forms hotspots of hydrocarbon degradation by complex biota in marine environment. Here, we used marker gene sequencing and metagenomics to characterize the communities of bacteria, archaea and eukaryotes that colonized tar patties and control samples (wood, plastic), collected in the littoral following an offshore spill in the warm, oligotrophic southeastern Mediterranean Sea (SEMS). We show potential aerobic and anaerobic hydrocarbon catabolism niches on tar interior and exterior, linking carbon, sulfur and nitrogen cycles. Alongside aromatics and larger alkanes, short-chain alkanes appear to fuel dominant populations, both the aerobic clade UBA5335 (Macondimonas), anaerobic Syntropharchaeales, and facultative Mycobacteriales. Most key organisms, including the hydrocarbon degraders and cyanobacteria, have the potential to fix dinitrogen, potentially alleviating the nitrogen limitation of hydrocarbon degradation in the SEMS. We highlight the complexity of these tar-associated communities, where bacteria, archaea and eukaryotes co-exist, likely exchanging metabolites and competing for resources and space.

Study on the hematological toxicity of Cyprinus carpio exposed to water-soluble fraction of crude oil and TiO2 nanoparticles in the dark and ultraviolet

This study is addressing the potential toxicity concerns of crude oil in common carp (Cyprinus carpio) with the novel use of TiO2-NP for enhancing photocatalytic degradation of WSF of crude oil prepared under UV light or darkness. Blood samples were taken, and the biochemical parameters were analyzed. The levels of ALT, AST and ALP were significantly higher in fish exposed to UV-treated WSF. However, they were significantly lower in the groups exposed to UV-treated TiO2-NPs and the combination of WSF and TiO2-NPs. The levels of total protein, triglycerides, albumin and cholesterol were significantly lower in treatments exposed to UV-treated and dark-conditioned WSF compared to the control group, but they were significantly higher in fish exposed to UV-treated TiO2-NPs and the combination of WSF and TiO2-NPs compared to fish exposed under dark conditions and were not significantly different from the control group. The toxicity of UV-treated WSF was significantly higher than that of dark-conditioned WSF. The toxicity of TiO2-NPs was lower in the presence of UV and was similar to the control treatment. The results of the study suggests that photocatalytic TiO2-NPs and UV radiation reduce toxicity of the water-soluble fraction of crude oil on common carp.

Effects of aromatic hydrocarbons and evaluation of oil toxicity modelling for larvae of a tropical coral

Application of oil toxicity modelling for assessing the risk of spills to coral reefs remains uncertain due to a lack of data for key tropical species and environmental conditions. In this study, larvae of the coral Acropora millepora were exposed to six aromatic hydrocarbons individually to generate critical target lipid body burdens (CTLBBs). Larval metamorphosis was inhibited by all six aromatic hydrocarbons, while larval survival was only affected at concentrations >2000 μg L-1. The derived metamorphosis CTLBB of 9.7 μmol g-1 octanol indicates larvae are more sensitive than adult corals, and places A. millepora larvae among the most sensitive organisms in the target lipid model (TLM) databases. Larvae were also more sensitive to anthracene and pyrene when co-exposed to ecologically relevant levels of ultraviolet radiation. The results suggest that the application of the phototoxic TLM would be protective of A. millepora larvae, provided adequate chemical and light data are available.

Polycyclic aromatic hydrocarbons in coral reefs with a focus on Scleractinian corals: A systematic overview

The impact of petroleum exploitation and oil spills in marine ecosystems has increased over time. Among the concerns regarding these events, the impact on coral reefs stand out because this ecosystem has ecological and economic importance and is globally threatened. We performed a systematic review and bibliometric analysis of studies that determine polycyclic aromatic hydrocarbons (PAHs) in coral reefs, attempting to answer how the studies were distributed around the globe, the main environmental matrices and species of coral studied, the main PAHs found and their mean concentrations, and the methodology used. A bibliographic search resulted in 42 studies with worldwide distribution. The bibliometric results presented more explored terms, such as sediments and toxicology, and newly investigated terms, which should encourage a new area of study, such as those related to zooxanthellae and mucus. The main matrices studied in coral reefs are sediments, corals, and water, whereas air and other invertebrates have rarely been studied. Approximately 45 species of corals with several morphotypes have been reported. PAHs recommended by the United States Environmental Protection Agency (US EPA) were analyzed in all studies, while additional compounds were analyzed in only five. The methods used to determine hydrocarbons are predominantly the most traditional; however, for corals, studies have tended to separate tissue, zooxanthellae, skeleton, and mucus. In the future, we recommend investment in improving the capacity to detect non-conventional PAHs, more studies in regions that are rarely explored in developing countries, and the creation of databases to facilitate management planning on marine coasts.

Sensitivity of the Indo-Pacific coral Acropora millepora to aromatic hydrocarbons

The risks posed by petroleum spills to coral reefs are poorly understood and quantifying acute toxicity thresholds for aromatic hydrocarbons to reef-building corals is required to assess their sensitivity relative to other taxa. In this study, we exposed Acropora millepora to toluene, naphthalene and 1-methylnaphthalene (1-MN) in a flow-through system and assessed survivorship and sublethal responses including growth, colour and the photosynthetic performance of symbionts. Median 50% lethal concentrations (LC50s) decreased over the 7-d exposure period, reaching asymptotic values of 22,921, 5,268, 1167 μg L^-1 for toluene, naphthalene and 1-MN, respectively. Corresponding toxicokinetic parameters (ε_LC50) defining the time progression of toxicity were 0.830, 0.692, and 0.256 d^-1, respectively. Latent effects after an additional 7-d recovery in uncontaminated seawater were not observed. Effect concentrations (EC50s) for 50% growth inhibition were 1.9- to 3.6-fold lower than the LC50s for each aromatic hydrocarbon. There were no observed effects of aromatic hydrocarbon exposure on colour score (a proxy for bleaching) or photosynthetic efficiency. Acute and chronic critical target lipid body burdens (CTLBBs) of 70.3 ± 16.3 and 13.6 ± 18.4 μmol g^-1 octanol (± standard error) were calculated for survival and growth inhibition based on 7-d LC50 and EC10 values, respectively. These species-specific constants indicate adult A. millepora is more sensitive than other corals reported so far but is of average sensitivity in comparison with other aquatic taxa in the target lipid model database. These results advance our understanding of acute hazards of petroleum contaminants to key habitat-building tropical coral reef species.

Recommendations for advancing media preparation methods used to assess aquatic hazards of oils and spill response agents

Laboratory preparation of aqueous test media is a critical step in developing toxicity information needed for oil spill response decision-making. Multiple methods have been used to prepare physically and chemically dispersed oils which influence test outcome, interpretation, and utility for hazard assessment and modeling. This paper aims to review media preparation strategies, highlight advantages and limitations, provide recommendations for improvement, and promote the standardization of methods to better inform assessment and modeling. A benefit of media preparation methods for oil that rely on low to moderate mixing energy coupled with a variable dilution design is that the dissolved oil composition of the water accommodation fraction (WAF) stock is consistent across diluted treatments.  Further, analyses that support exposure confirmation maybe reduced and reflect dissolved oil exposures that are bioavailable and amenable to toxicity modeling.  Variable loading tests provide a range of dissolved oil compositions that require analytical verification at each oil loading. Regardless of test design, a preliminary study is recommended to optimize WAF mixing and settling times to achieve equilibrium between oil and test media. Variable dilution tests involving chemical dispersants (CEWAF) or high energy mixing (HEWAF) can increase dissolved oil exposures in treatment dilutions due to droplet dissolution when compared to WAFs. In contrast, HEWAF/CEWAFs generated using variable oil loadings are expected to provide dissolved oil exposures more comparable to WAFs. Preparation methods that provide droplet oil exposures should be environmentally relevant and informed by oil droplet concentrations, compositions, sizes, and exposure durations characteristic of field spill scenarios. Oil droplet generators and passive dosing techniques offer advantages for delivering controlled constant or dynamic dissolved exposures and larger volumes of test media for toxicity testing. Adoption of proposed guidance for improving media preparation methods will provide greater comparability and utility of toxicity testing in oil spill response and assessment.

What are the toxicity thresholds of chemical pollutants for tropical reef-building corals? A systematic review

BACKGROUND

Tropical coral reefs cover only ca. 0.1% of the Earth's surface but harbour exceptional marine biodiversity and provide vital ecosystem services to millions of people living nearby. They are currently threatened by global (e.g. climate change) and local (e.g. chemical pollution) stressors that interact in multiple ways. While global stressors cannot be mitigated by local actions alone, local stressors can be reduced through ecosystem management. Here, we aimed to systematically review experimental studies assessing the toxicity of chemical pollutants to tropical reef-building corals to generate accessible and usable knowledge and data that can be used to calculate measurement endpoints in ecological risk assessment. From the quantitative estimates of effects, we determined toxicity thresholds as the highest exposures tested at which no statistically significant adverse effects were observed, and we compared them to regulatory predicted no effect concentrations for the protection of marine organisms, to assess whether these reference values are indeed protective of corals.

METHODS

The evidence was taken from a systematic map of the impacts of chemicals arising from human activity on tropical reef-building corals published in 2021. All studies in the map database corresponding to the knowledge cluster "Evidence on the ecotoxicological effects of chemicals on corals" were selected. To identify subsequently published literature, the search was updated using a subset of the search string used for the systematic map. Titles, abstracts and full-texts were screened according to the criteria defining the selected cluster of the map. Because the eligibility criteria for the systematic review are narrower than the criteria used to define the cluster in the systematic map, additional screening was performed. Studies included were critically appraised and each study was rated as low, unclear, medium, or high risk of bias. Data were extracted from the studies and synthesised according to a strategy dependent on the type of exposure and outcome.

REVIEW FINDINGS

The systematic review reports the known effects of chemical exposures on corals from 847 studies corresponding to 181 articles. A total of 697 studies (161 articles) were included in the quantitative synthesis and 150 studies (50 articles) in the narrative synthesis of the findings. The quantitative synthesis records the effects of 2706 exposure concentrations-durations of 164 chemicals or mixtures of chemicals, and identifies 105 toxicity thresholds corresponding to 56 chemicals or mixtures of chemicals. When toxicity thresholds were compared to reference values set for the protection of marine organisms by environmental agencies, the reference values appear to be protective of corals for all but three chemicals assessed: the metal copper and the pesticides diuron and irgarol 1051.

CONCLUSIONS

This open-access database of known ecotoxicological effects of chemical exposures on corals can assist managers in the ecological risk assessment of chemicals, by allowing easy determination of various ecotoxicological thresholds. Several limitations of the toxicity tests synthesised here were noted (in particular the lack of measurement of effective concentrations for more than half of the studies). Overall, most of the currently available data on coral toxicity should be replicated independently and extended to corals from less studied geographical regions and functional groups.

Aromatic hydrocarbons extracted by headspace and microextraction methods in water-soluble fractions from crude oil, fuels and lubricants

Two extraction protocols were developed for the determination of mono- and poly-aromatic hydrocarbons in water-soluble fractions from gasoline, diesel, crude, mineral insulating, and lubricant oils. Development of the procedures was based on clean miniaturized strategies, such as headspace extraction and vortex-assisted dispersive liquid micro-extraction, together with quantification by gas chromatography-mass spectrometry. The mono-aromatic hydrocarbons were extracted using the headspace extraction method. The linear range obtained was 10-500 µg L^-1, with r² > 0.99. Based on the parameters of the analytical curves, detection and quantification limits of 2.56-3.20 and 7.76-9.71 µg L^-1 were estimated. In addition, the method showed adequate recoveries of 69.4-83.5%, with a satisfactory precision of 4.7-17.1% (n = 5). Micro-extraction was applied for the poly-aromatics and the most favorable variables were sample volume (5.00 mL) in sodium chloride medium (1%, w/v), trichloromethane as extractor solvent (75 µL), acetone as disperser (925 µL) and vortexing for 1 min. Under these conditions, analytical curves of 0.15-4.00 µg L^-1 were obtained and limits of determination and quantification were 0.03-0.15 and 0.09-0.46 µg L^-1, respectively. Recovery values of 87.6-124.5% and a maximum relative standard deviation of 18.9% (n = 5) verify satisfactory accuracy and precision. This led to the achievement of enrichment factors for poly-aromatic hydrocarbons of 41-89 times. Finally, the methods were employed in samples of water-soluble fractions for the determination of analytes. The values followed the order: gasoline > diesel > crude > lubricant > mineral insulating oil. These results indicate an increase in lighter fractions, followed by poly-aromatics in more refined products.

The scleractinian coral Pocillopora damicornis relies on neuroendocrine regulation to cope with polycyclic aromatic hydrocarbons under heat stress

Polycyclic aromatic hydrocarbons (PAHs) are highly toxic environmental pollutants and are threatening scleractinian corals. In this study, PAHs treatment did not induce significant physiological responses of the coral Pocillopora damicornis and its algal symbionts, but biological processes including response to toxin, drug metabolic, and oxidation reduction were triggered at the mRNA level. These results implied that PAHs could be a group of slow-acting environmental toxicants, whose effects were moderate but persistent. Besides, it was interesting to find that PAHs activated the neuroendocrine system in the coral by triggering the expression of monoaminergic and acetylcholinergic system related genes, indicating that PAHs might function as environmental hormones. Moreover, the combined treatments of PAHs and heat caused a much obvious effect on the coral and its algal symbionts by elevating antioxidant activity and suppressing photosynthesis in the symbionts. Results from the transcriptome data further indicated that corals might perform stress responses upon PAHs and heat challenges through the TNF and apoptosis pathways, which perhaps was modulated by the neuroendocrine system of corals. Collectively, our survey demonstrates that the PAHs can function as environmental hormones and activate the neuroendocrine regulation in scleractinian corals, which may contribute to the stress responses of symbiotic association by modulating photosynthesis, antioxidation, and apoptosis.

Environmental DNA-based profiling of benthic bacterial and eukaryote communities along a crude oil spill gradient in a coral reef in the Persian Gulf

Coral reef ecosystems in the Persian Gulf are frequently exposed to crude oil spills. We investigated benthic bacterial and eukaryote community structures at such coral reef sites subjected to different degrees of polycyclic aromatic hydrocarbon (PAH) pollution using environmental DNA (eDNA) metabarcoding. Both bacterial and eukaryote communities responded with pronounced shifts to crude oil pollution and distinguished control sites, moderately and heavily impacted sites with significant confidentiality. The observed community patterns were predominantly driven by Alphaproteobacteria and metazoans. Among these, we identified individual genera that were previously linked to oil spill stress, but also taxa, for which a link to hydrocarbon still remains to be established. Considering the lack of an early-warning system for the environmental status of coral reef ecosystems exposed to frequent crude-oil spills, our results encourage further research towards the development of an eDNA-based biomonitoring tool that exploits benthic bacterial and eukaryote communities as bioindicators.

Coral recruits are highly sensitive to heavy fuel oil exposure both in the presence and absence of UV light

Oil pollution remains a prominent local hazard to coral reefs, but the sensitivity of some coral life stages to oil exposure remains unstudied. Exposure to ultraviolet radiation (UVR), ubiquitous on coral reefs, may significantly increase oil toxicity towards these critical habitat-forming taxa. Here we present the first data on the sensitivity of two distinct post-settlement life stages of the model coral species Acropora millepora to a heavy fuel oil (HFO) water accommodated fraction (WAF) in the absence and presence of UVR. Assessment of lethal and sublethal endpoints indicates that both 1-week-old and 2-month-old recruits (1-wo and 2-mo) were negatively affected by chronic exposures to HFO (7 and 14 days, respectively). Relative growth (1-wo and 2-mo recruits) and survival (1-wo recruits) at end of exposure were the most sensitive endpoints in the absence of UVR, with no effect concentrations (NEC) of 34.3, 5.7 and 29.3 μg L^-1 total aromatic hydrocarbons (TAH; ∑39 monocyclic- and polycyclic aromatic hydrocarbons), respectively. On average, UVR increased the negative effects by 10% for affected endpoints, and latent effects of exposure were evident for relative growth and symbiont uptake of recruits. Other sublethal endpoints, including maximum quantum yield and tissue colour score, were unaffected by chronic HFO exposure. A comparison of putative species-specific sensitivity constants for these ecologically relevant endpoints, indicates A. millepora recruits may be as sensitive as the most sensitive species currently included in oil toxicity databases. While the low intensity UVR only significantly increased the negative effects of the oil for one endpoint, the majority of endpoints showed trends towards increased toxicity in the presence of UVR. Therefore, the data presented here further support the standard incorporation of UVR in oil toxicity testing for tropical corals.

Global qualitative and quantitative distribution of micropollutants in the deep sea

Micropollutants (MPs) include a wide range of biological disruptors that can be toxic to wildlife and humans at very low concentrations (<1 μg/L). These mainly anthropogenic pollutants have been widely detected in different areas of the planet, including the deep sea, and have impacts on marine life. Because of this potential toxicity, the global distribution, quantity, incidence, and potential impacts of deep-sea MPs were investigated in a systematic review of the literature. The results showed that MPs have reached different zones of the ocean and are more frequently reported in the Northern Hemisphere, where higher concentrations are found. MPs are also concentrated in depths up to 3000 m, where they are also more frequently studied, but also extend deeper than 10,000 m. Potentially toxic metals (PTMs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDTs), organotins, and polycyclic aromatic hydrocarbons (PAHs) were identified as the most prevalent and widely distributed MPs at ≥200 m depth. PTMs are widely distributed in the deep sea in high concentrations; aluminum is the most prevalent up to 3000 m depth, followed by zinc and copper. PCBs, organotins, hexachlorocyclohexanes (HCHs), PAHs, and phenols were detected accumulated in both organisms and environmental samples above legislated thresholds or known toxicity levels. Our assessment indicated that the deep sea can be considered a sink for MPs.

Towards the Development of Standardized Bioassays for Corals: Acute Toxicity of the UV Filter Benzophenone-3 to Scleractinian Coral Larvae

Coral reefs have been declining globally at a historically unprecedented rate. Ultraviolet (UV) filters used in sunscreens may contribute to this decline at local scales, which has already led to bans on various organic UV filters in some regions. However, the underlying studies for these bans demonstrated significant flaws in the experimental design due to a lack of validated and standardized testing methods for corals. This study aimed to investigate options for the development of a standard acute toxicity test for the larval stage of scleractinian corals. Planula larvae of two brooding (Leptastrea purpurea and Tubastraea faulkneri) and two spawning (Acropora digitifera and A. millepora) species were exposed to the organic UV filter benzophenone-3 (BP3) for 48 h under static conditions. We observed interspecific variations in toxicity, with A. digitifera being the most sensitive (LC₅₀ = 0.75 µg L⁻¹) and T. faulkneri the least sensitive (LC₅₀ = 2951.24 µg L⁻¹) species. Inhibition of settlement was found to be a useful endpoint leading to an EC₅₀ of 1.84 µg L⁻¹ in L. purpurea larvae. Although the analytical challenges of measuring lipophilic substances in small volume test setups remain, the here applied test design and selected endpoints are suitable for further validation and subsequent standardization.

Coral Ecotoxicological Data Evaluation for the Environmental Safety Assessment of Ultraviolet Filters

There is growing interest in the environmental safety of ultraviolet (UV) filters found in cosmetic and personal care products (CPCPs). The CPCP industry is assessing appropriate environmental risk assessment (ERA) methods to conduct robust environmental safety assessments for these ingredients. Relevant and reliable data are needed for ERA, particularly when the assessment is supporting regulatory decision-making. In the present study, we apply a data evaluation approach to incorporate nonstandard toxicity data into the ERA process through an expanded range of reliability scores over commonly used approaches (e.g., Klimisch scores). The method employs an upfront screening followed by a data quality assessment based largely on the Criteria for Reporting and Evaluating Ecotoxicity Data (CRED) approach. The method was applied in a coral case study in which UV filter toxicity data was evaluated to identify data points potentially suitable for higher tier and/or regulatory ERA. This is an optimal case study because there are no standard coral toxicity test methods, and UV filter bans are being enacted based on findings reported in the current peer-reviewed data set. Eight studies comprising nine assays were identified; four of the assays did not pass the initial screening assessment. None of the remaining five assays received a high enough reliability score (R_n ) to be considered of decision-making quality (i.e., R1 or R2). Four assays were suitable for a preliminary ERA (i.e., R3 or R4), and one assay was not reliable (i.e., R6). These results highlight a need for higher quality coral toxicity studies, potentially through the development of standard test protocols, to generate reliable toxicity endpoints. These data can then be used for ERA to inform environmental protection and sustainability decision-making. Environ Toxicol Chem 2021;40:3441-3464. © 2021 Personal Care Products Council. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Derivation of toxicity thresholds for gas condensate oils protective of tropical species using experimental and modelling approaches

Toxicity thresholds for dissolved oil applied in tropical ocean risk assessments are largely based on the sensitivities of temperate and/or freshwater species. To explore the suitability of these thresholds for tropical habitats we experimentally determined toxicity thresholds for eight tropical species for a partially weathered gas condensate, applied the target lipid model (TLM) to predict toxicity of fresh and weathered condensates and compared sensitivities of the tropical species with model predictions. The experimental condensate-specific hazard concentration (HC5) was 167 μg L^-1 total aromatic hydrocarbons (TAH), with the TLM-modelled HC5 (78 μg L^-1 TAH) being more conservative, supporting TLM-modelled thresholds for tropical application. Putative species-specific critical target lipid body burdens (CTLBBs) indicated that several of the species tested were among the more sensitive species in the TLM database ranging from 5.1 (coral larvae) to 97 (sponge larvae) μmol g^-1 octanol and can be applied in modelling risk for tropical marine ecosystems.

A Comparison of Short-Term and Continuous Exposures in Toxicity Tests of Produced Waters, Condensate, and Crude Oil to Marine Invertebrates and Fish

Petroleum hydrocarbons can be discharged into the marine environment during offshore oil and gas production or as a result of oil spills, with potential impacts on marine organisms. Ecotoxicological assay durations (typically 24-96 h) used to characterize risks to exposed organisms may not always reflect realistic environmental exposure durations in a high-energy offshore environment where hydrocarbons are mixed and diluted rapidly in the water column. To investigate this, we adapted 3 sensitive toxicity tests to incorporate a short-term pulse exposure to 3 petroleum-based products: a produced water, the water-accommodated fraction (WAF) of a condensate, and a crude oil WAF. We measured 48-h mobility of the copepod Acartia sinjiensis, 72-h larval development of the sea urchin Heliocidaris tuberculata, and 48-h embryo survival and deformities of yellowtail kingfish Seriola lalandi, after exposure to a dilution series of each of the 3 products for 2, 4 to 12, and 24 h and for the standard duration of each toxicity test (continuous exposure). Effects on copepod survival and sea urchin larval development were significantly reduced in short-term exposures to produced water and WAFs compared to continuous exposures. Fish embryos, however, showed an increased frequency of deformities at elevated concentrations regardless of exposure duration, although there was a trend toward increased severity of deformities with continuous exposure. The results demonstrate how exposure duration alters toxic response and how incorporating relevant exposure duration to contaminants into toxicity testing may aid interpretation of more realistic effects (and hence an additional line of evidence in risk assessment) in the receiving environment. Environ Toxicol Chem 2021;40:2587-2600. © 2021 CSIRO. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Multiple benthic indicators are efficient for health assessment of coral reefs subjected to petroleum hydrocarbons contamination: A case study in the Persian Gulf

The ever-increasing anthropogenic activities have adversely impacted coral reef ecosystems and their ecological functions. This calls for an urgent assessment of the health state of these valuable ecosystems to justify the need for mitigation and proper management efforts. In this contribution, we used multiple indicators to assess the impact of intense oil-related activities on coral reefs in two near-by impacted and non-impacted islands in the northwestern Persian Gulf. The efficacy of indices was assessed using estimations of the effect size (omega-squared), precision, and decision trees (Classification and Regression Tree (CART)). The results demonstrated that the combination of bioaccumulation of ƩPAH in coral tissues, the percent of live coral cover, and the Sediment Constituent (SEDCON) Index were the most robust proxies reflecting the influence of human activities on reef's health. Based on sedimentary PAH concentration, the CART classified most of the indicators into two classes consisting of those in impacted and those in non-impacted locations, further supporting the feasibility of the employed indices. The findings of this study provided a warning of degradation in coral reefs of the island subjected to PAH pollution. This encourages decision-makers to execute routine monitoring and mitigation practices to maintain healthy reefs in the study areas.

Species sensitivity assessment of five Atlantic scleractinian coral species to 1-methylnaphthalene

Coral reefs are keystone coastal ecosystems that are at risk of exposure to petroleum from a range of sources, and are one of the highest valued natural resources for protection in Net Environmental Benefit Analysis (NEBA) in oil spill response. Previous research evaluating dissolved hydrocarbon impacts to corals reflected no clear characterization of sensitivity, representing an important knowledge gap in oil spill preparedness related to the potential impact of oil spills to the coral animal and its photosymbiont zooxanthellae. This research addresses this gap, using a standardized toxicity protocol to evaluate effects of a dissolved reference hydrocarbon on scleractinian corals. The relative sensitivity of five Atlantic scleractinian coral species to hydrocarbon exposure was assessed with 48-h assays using the reference polycyclic aromatic hydrocarbon 1-methylnaphthalene, based on physical coral condition, mortality, and photosynthetic efficiency. The threatened staghorn coral Acropora cervicornis was found to be the most sensitive to 1-methylnaphthalene exposure. Overall, the acute and subacute endpoints indicated that the tested coral species were comparatively more resilient to hydrocarbon exposure than other marine species. These results provide a framework for the prediction of oil spill impacts and impact thresholds on the coral animal and related habitats, essential for informing oil spill response in coastal tropical environments.

Comparative study of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) in corals, sediments and seawater from coral reefs of Hainan, China

This work investigated levels of PAHs and HMs in fourteen species from seven genera of scleractinian corals, adjacent sediments, and surface seawater in Hainan, China. The sources of contaminations were analyzed as well. The results showed that scleractinian corals had a relatively higher bioaccumulation capacity for PAHs from sediments than for HMs. There were inter-species differences for these contaminants enriched in corals. Pavona varians and Porites lutea could accumulate PAHs more readily. While higher concentrations of Cr, Mn and Pb occurred in Favites flexuosa, other metal levels, such as for Ni, Cu, Zn and As, were found to be elevated in Pocillopora damicornis, as well as for Cd in Acropora echinata. It was found that PAHs originated from petrogenic and pyrolytic sources, and were mainly linked to onshore and on-sea activities, such as motorboats. Mn, Ni, As and Cd were from crustal materials or natural weathering, while Cr, Cu, Zn and Pb were non-crustal origin connecting with the use of anti-fouling boat paint and agricultural and/or aquacultural chemicals. This study suggested that corals could serve as good bioindicators for two types of chemical pollution in the reef system, especially for the two species P. varians and P. lutea for PAHs contaminants.

Toxicity thresholds of three insecticides and two fungicides to larvae of the coral Acropora tenuis

Tropical marine ecosystems, such as coral reefs, face several threats to their health and resilience, including poor water quality. Previous studies on the risks posed by pesticides have focused on five priority herbicides; however, as the number of pesticides applied in coastal agriculture increases, a suite of 'alternative' pesticides is being detected in tropical nearshore waters. To improve our understanding of the risks posed by alternative pesticides to tropical marine organisms, the effects of three insecticides (diazinon, fipronil, imidacloprid) and two fungicides (chlorothalonil, propiconazole) were tested on larval metamorphosis of the coral Acropora tenuis. A. tenuis larvae were affected by all five pesticides and the reference toxicant copper. The no effect concentration (NEC) and the 10% and 50% effect concentrations (EC10 and EC50, respectively) for larval metamorphosis were estimated from concentration-response curves after 48 h exposure. The NEC, EC10 and EC50 (in µg L-1), respectively, of each pesticide were as follows: chlorothalonil (2.4, 2.8, 6.0); fipronil (12.3, 13.9, 29.1); diazinon (38.0, 40.8, 54.7); imidacloprid (263, 273, 347); and propiconazole (269, 330, 1008). These toxicity thresholds are higher than reported concentrations in monitoring programs; however, these data will contribute to improving water quality guideline values, which inform the total risk assessments posed by complex contaminant mixtures to which these pesticides contribute.

Toxicity of a mixture of monoaromatic hydrocarbons (BTX) to a tropical marine microcrustacean

This study evaluated the toxicity of benzene, toluene, and xylenes (BTX), isolated and in binary mixtures to Mysidopsis juniae. The organisms were exposed to BTX, and combined effect patterns were predicted by applying the theoretical models of Concentration Addition and Independent Action. According to the LC50 of the isolated compounds, xylene (16.1 ± 2.4 mg L^-1) was considered the most toxic, followed by toluene (38.0 ± 5.3 mg L^-1) and, lastly, benzene (78.0 ± 2.9 mg L^-1). The binary combinations showed deviations from additivity, with exposure to the xylene-benzene mixture presenting as antagonistic, while the xylene-toluene and toluene-benzene mixtures were better explained by a dose ratio deviation, with toluene being responsible for the antagonistic pattern. This study provides new insights into toxicity prediction of a BTX mixture, which adds value to the risk assessment procedure over evaluation of chemical hazards on a case-by-case basis.

Accumulation of 13C-labelled phenanthrene in phytoplankton and transfer to corals resolved using cavity ring-down spectroscopy

Polycyclic aromatic hydrocarbons (PAHs) are widespread pollutants in marine ecosystems including threatened and potentially sensitive coral reefs. Lower organisms such as phytoplankton, known to bioconcentrate PAHs, could serve as potential entry points for these chemicals into higher trophic levels. Here, we present a novel method using a ¹³C-labelled PAH and cavity ring-down spectroscopy (CRDS) to investigate accumulation, uptake rates and trophic transfer of PAHs in corals, which are key organisms to sustain biodiversity in tropical seas. We quantified the accumulation of ¹³C-phenanthrene in the marine microalga Dunaliella salina, and in the coral Acropora millepora after diffusive uptake from seawater or dietary uptake via labelled D. salina. Additionally, we monitored the photophysiological health of D. salina and A. millepora during phenanthrene exposure by pulse-amplitude modulation (PAM) fluorometry. Dose-dependent accumulation of ¹³C-phenanthrene in the microalga showed a mean bioconcentration factor (BCF) of 2590 ± 787 L kg^-1 dry weight. Corals accumulated phenanthrene from both exposure routes. While uptake of ¹³C-phenanthrene in corals was faster through aqueous exposure than dietary exposure, passive diffusion showed larger variability between individuals and both routes resulted in accumulation of similar concentrations of phenanthrene. The ¹³C-PAH labelling and analysis by CRDS proved to be a highly sensitive method. The use of stable isotopic label eliminated additional toxicity and risks by radioactive isotopic-labelling, and CRDS reduced the analytical complexity of PAH (less biomass, no extraction, fast analysis). The simultaneous, precise quantification of both carbon content and ¹³C/¹²C ratio (δ¹³C) enabled accurate determination of ¹³C-phenanthrene accumulation and uptake rate. This is the first study to provide empirical evidence for accumulation of phenanthrene in a phytoplankton-coral food chain.

The effects of ultraviolet radiation and climate on oil toxicity to coral reef organisms - A review

Oil pollution remains a significant local threat to shallow tropical coral reef environments, but the environmental conditions typical of coral reefs are rarely considered in oil toxicity testing and risk assessments. Here we review the effects of three environmental co-factors on petroleum oil toxicity towards coral reef organisms, and show that the impacts of oil pollution on coral reef taxa can be exacerbated by environmental conditions commonly encountered in tropical reef environments. Shallow reefs are routinely exposed to high levels of ultraviolet radiation (UVR), which can substantially increase the toxicity of some oil components through phototoxicity. Exposure to UVR represents the most likely and harmful environmental co-factor reviewed here, leading to an average toxicity increase of 7.2-fold across all tests reviewed. The clear relevance of UVR co-exposure and its strong influence on tropical reef oil toxicity highlights the need to account for UVR as a standard practice in future oil toxicity studies. Indeed, quantifying the influence of UVR on toxic thresholds of oil to coral reef species is essential to develop credible oil spill risk models required for oil extraction developments, shipping management and spill responses in the tropics. The few studies available indicate that co-exposure to elevated temperature and low pH, both within the range of current daily and seasonal fluctuations and/or projected under continued climate change, can increase oil toxicity on average by 3.0- and 1.3-fold, respectively. While all three of the reviewed environmental co-factors have the potential to substantially increase the impacts of oil pollution in shallow reef environments, their simultaneous effects have not been investigated. Assessments of the combined effects of oil pollution, UVR, temperature and low pH will become increasingly important to identify realistic hazard thresholds suitable for future risk assessments over the coming century.

Sources, presence and potential effects of contaminants of emerging concern in the marine environments of the Great Barrier Reef and Torres Strait, Australia

Current policy and management for marine water quality in the Great Barrier Reef (GBR) in north-eastern Australia primarily focusses on sediment, nutrients and pesticides derived from diffuse source pollution related to agricultural land uses. In addition, contaminants of emerging concern (CECs) are known to be present in the marine environments of the GBR and the adjacent Torres Strait (TS). Current and projected agricultural, urban and industrial developments are likely to increase the sources and diversity of CECs being released into these marine ecosystems. In this review, we evaluate the sources, presence and potential effects of six different categories of CECs known to be present, or likely to be present, in the GBR and TS marine ecosystems. Specifically, we summarize available monitoring, source and effect information for antifouling paints; coal dust and particles; heavy/trace metals and metalloids; marine debris and microplastics; pharmaceuticals and personal care products (PPCPs); and petroleum hydrocarbons. Our study highlights the lack of (available) monitoring data for most of these CECs, and recommends: (i) the inclusion of all relevant environmental data into integrated databases for building marine baselines for the GBR and TS regions, and (ii) the implementation of local, targeted monitoring programs informed by predictive methods for risk prioritization. Further, our spatial representation of the known and likely sources of these CECs will contribute to future ecological risk assessments of CECs to the GBR and TS marine environments, including risks relative to those identified for sediment, nutrients and pesticides.

Effect of Louisiana sweet crude oil on a Pacific coral, Pocillopora damicornis

Recent oil spill responses such as the Deepwater Horizon event have underscored the need for crude oil ecotoxicological threshold data for shallow water corals to assist in natural resource damage assessments. We determined the toxicity of a mechanically agitated oil-seawater mixture (high-energy water-accommodated fraction, HEWAF) of a sweet crude oil on a branched stony coral, Pocillopora damicornis. We report the results of two experiments: a 96 h static renewal exposure experiment and a "pulse-chase" experiment of three short-term exposure durations followed by a recovery period in artificial seawater. Five endpoints were used to determine ecotoxicological values: 1) algal symbiont chlorophyll fluorescence, 2) a tissue regeneration assay and a visual health metric with three endpoints: 3) tissue integrity, 4) tissue color, and 5) polyp behavior. The sum of 50 entrained polycyclic aromatic hydrocarbons (tPAH50) was used as a proxy for oil exposure. For the 96 h exposure dose response experiment, dark-adapted maximum quantum yield (Fv/Fm) of the dinoflagellate symbionts was least affected by crude oil (EC₅₀ = 913 μg/L tPAH50); light-adapted effective quantum yield (EQY) was more sensitive (EC₅₀ =  428 μg/L tPAH50). In the health assessment, polyp behavior (EC₅₀ = 27 μg/L tPAH50) was more sensitive than tissue integrity (EC₅₀ = 806 μg/L tPAH50) or tissue color (EC₅₀ = 926 μg/L tPAH50). Tissue regeneration proved to be a particularly sensitive measurement for toxicity effects (EC₅₀ = 10 μg/L tPAH50). Short duration (6-24 h) exposures using 503 μg/L tPAH50 (average concentration) resulted in negative impacts to P. damicornis and its symbionts. Recovery of chlorophyll a fluorescence levels for 6-24 h oil exposures was observed in a few hours (Fv/Fm) to several days (EQY) following recovery in fresh seawater. The coral health assessments for tissue integrity and tissue color were not affected following short-term oil exposure durations, but the 96 h treatment duration resulted in significant decreases for both. A reduction in polyp behavior (extension) was observed for all treatment durations, with recovery observed for the short-term (6-24 h) exposures within 1-2 days following placement in fresh seawater. Wounded and intact fragments exposed to oil treatments were particularly sensitive, with significant delays observed in tissue regeneration. Estimating ecotoxicological values for P. damicornis exposed to crude oil HEWAFs provides a basis for natural resource damage assessments for oil spills in reef ecosystems. These data, when combined with ecotoxicological values for other coral reef species, will contribute to the development of species sensitivity models.

Anthropogenic pollution of aquatic ecosystems: Emerging problems with global implications

Aquatic ecosystems cover over two thirds of our planet and play a pivotal role in stabilizing the global climate as well as providing a large array of services for a fast-growing human population. However, anthropogenic activities increasingly provoke deleterious impacts in aquatic ecosystems. In this paper we discuss five sources of anthropogenic pollution that affect marine and freshwater ecosystems: sewage, nutrients and terrigenous materials, crude oil, heavy metals and plastics. Using specific locations as examples, we show that land-based anthropogenic activities have repercussions in freshwater and marine environments, and we detail the direct and indirect effects that these pollutants have on a range of aquatic organisms, even when the pollutant source is distant from the sink. While the issues covered here do focus on specific locations, they exemplify emerging problems that are increasingly common around the world. All these issues are in dire need of stricter environmental policies and legislations particularly for pollution at industrial levels, as well as solutions to mitigate the effects of anthropogenic pollutants and restore the important services provided by aquatic ecosystems for future generations.

Current issues confounding the rapid toxicological assessment of oil spills

Oil spills of varying magnitude occur every year, each presenting a unique challenge to the local ecosystem. The complex, changeable nature of oil makes standardised risk assessment difficult. Our review of the state of science regarding oil's unique complexity; biological impact of oil spills and use of rapid assessment tools, including commercial toxicity kits and bioassays, allows us to explore the current issues preventing effective, rapid risk assessment of oils. We found that despite the advantages to monitoring programmes of using well validated standardised tests, which investigate impacts across trophic levels at environmentally relevant concentrations, only a small percentage of the available tests are specialised for use within the marine environment, or validated for the assessment of crude oil toxicity. We discuss the use of rapid tests at low trophic levels in addition to relevant sublethal toxicity assays to allow the characterisation of oil, dispersant and oil and dispersant mixture toxicity. We identify novel, passive dosing techniques as a practical and reproducible means of improving the accuracy and maintenance of nominal concentrations. Future work should explore the possibility of linking this tiered testing system with ecosystem models to allow the prediction and risk assessment of the entire ecosystem.

The Effects of Crude Oil and Dispersant on the Larval Sponge Holobiont

Larvae of the sponge R. odorabile survived exposure to high concentrations of petroleum hydrocarbons; however, their ability to settle and metamorphose was adversely affected at environmentally relevant concentrations, and these effects were paralleled by marked changes in sponge gene expression and preceded by disruption of the symbiotic microbiome. Given the ecological importance of sponges, uncontrolled hydrocarbon releases from shipping accidents or production could affect sponge recruitment, which would have concomitant consequences for reef ecosystem function.

Accidental oil spills from shipping and during extraction can threaten marine biota, particularly coral reef species which are already under pressure from anthropogenic disturbances. Marine sponges are an important structural and functional component of coral reef ecosystems; however, despite their ecological importance, little is known about how sponges and their microbial symbionts respond to petroleum products. Here, we use a systems biology-based approach to assess the effects of water-accommodated fractions (WAF) of crude oil, chemically enhanced water-accommodated fractions of crude oil (CWAF), and dispersant (Corexit EC9500A) on the survival, metamorphosis, gene expression, and microbial symbiosis of the abundant reef sponge Rhopaloeides odorabile in larval laboratory-based assays. Larval survival was unaffected by the 100% WAF treatment (107 μg liter⁻¹ polycyclic aromatic hydrocarbon [PAH]), whereas significant decreases in metamorphosis were observed at 13% WAF (13.9 μg liter⁻¹ PAH). The CWAF and dispersant treatments were more toxic, with decreases in metamorphosis identified at 0.8% (0.58 μg liter⁻¹ PAH) and 1.6% (38 mg liter⁻¹ Corexit EC9500A), respectively. In addition to the negative impact on larval settlement, significant changes in host gene expression and disruptions to the microbiome were evident, with microbial shifts detected at the lowest treatment level (1.6% WAF; 1.7 μg liter⁻¹ PAH), including a significant reduction in the relative abundance of a previously described thaumarchaeal symbiont. The responsiveness of the R. odorabile microbial community to the lowest level of hydrocarbon treatment highlights the utility of the sponge microbiome as a sensitive marker for exposure to crude oils and dispersants.

IMPORTANCE Larvae of the sponge R. odorabile survived exposure to high concentrations of petroleum hydrocarbons; however, their ability to settle and metamorphose was adversely affected at environmentally relevant concentrations, and these effects were paralleled by marked changes in sponge gene expression and preceded by disruption of the symbiotic microbiome. Given the ecological importance of sponges, uncontrolled hydrocarbon releases from shipping accidents or production could affect sponge recruitment, which would have concomitant consequences for reef ecosystem function.

Evaluation of Gene Bioindicators in the Liver and Caudal Fin of Juvenile Pacific Coho Salmon in Response to Low Sulfur Marine Diesel Seawater-Accommodated Fraction Exposure

Low sulfur marine diesel (LSMD) is frequently involved in coastal spills and monitoring ecosystem damage, and the effectiveness of cleanup methods remains a challenge. The present study investigates the concentration and composition of polycyclic aromatic hydrocarbons (PAHs) dispersed in LSMD seawater accommodated fractions (WAFs) and assesses the effects of exposure on juvenile coho salmon ( Onchorhynchus kisutch). Three WAFs were prepared with 333, 1067, and 3333 mg/L LSMD. The sum of 50 common PAHs and alkylated PAHs (tPAH50) measured by gas chromatography/triple quadrupole mass spectrometry showed saturation at ∼90 mg/L for all WAFs. These WAFs were diluted 30% for 96 h fish exposures. qPCR was performed on liver and caudal fin from the same genotypically sexed individuals to evaluate PAH exposure, general and oxidative stress, estrogenic activity, and defense against metals. Excluding metal response, our analyses reveal significant changes in gene expression following WAF exposure on juvenile salmon with differential sensitivity between males and females. The 3-methylcholanthrene responsive cytochrome P450-1a ( cyp1a) transcript exhibited the greatest increase in transcript abundance in the caudal fin (10-18-fold) and liver (6-10-fold). This demonstrates that cyp1a is a robust, sex-independent bioindicator of oil exposure in caudal fin, a tissue that is amenable to nonlethal sampling.

Urinary concentrations of monohydroxylated polycyclic aromatic hydrocarbons in adults from the U.S. Population Assessment of Tobacco and Health (PATH) Study Wave 1 (2013-2014)

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants formed from incomplete combustion of organic matter; some PAHs are carcinogens. Smoking, diet, and other activities contribute to exposure to PAHs. Exposure data to PAHs among combustible tobacco product users (e.g. cigarette smokers) exist; however, among non-combustible tobacco products users (e.g., e-cigarette users), such data are rather limited.

OBJECTIVES

We sought to evaluate exposure to PAHs among participants in Wave 1 (2013-2014) of the Population Assessment of Tobacco and Health (PATH) Study based on the type of tobacco product (combustible vs non-combustible), and frequency and intensity of product use.

METHODS

We quantified seven PAH urinary biomarkers in 11,519 PATH Study participants. From self-reported information, we categorized 8327 participants based on their use of tobacco products as never-tobacco user (never user, n = 1700), exclusive current established combustible products user (combustible products user, n = 5767), and exclusive current established non-combustible products user (non-combustible products user, n = 860). We further classified tobacco users as exclusive cigarette user (cigarette user, n = 3964), exclusive smokeless product user (SLT user, n = 509), and exclusive e-cigarette user (e-cigarette user, n = 280). Last, we categorized frequency of product use (everyday vs some days) and time since use (last hour, within 3 days, over 3 days). We calculated geometric mean (GM) concentrations, and evaluated associations between tobacco product user categories and PAH biomarkers concentrations.

RESULTS

Combustible products users had significantly higher GMs of all biomarkers than non-combustible products users and never users; non-combustible products users had significantly higher GMs than never users for four of seven biomarkers. For all biomarkers examined, cigarette users had the highest GMs compared to other tobacco-product users. Interestingly, GMs of 2-hydroxyfluorene, 3-hydroxyfluorene and ∑2,3-hydroxyphenanthrene were significantly higher in SLT users than in e-cigarette users; 3-hydroxyfluorene and 1-hydroxypyrene were also significantly higher in e-cigarette and SLT users than in never users. Everyday cigarette and SLT users had significantly higher GMs for most biomarkers than some days' users; cigarette and SLT users who used the product in the last hour had significantly higher GMs of most biomarkers than other occasional cigarette or SLT users respectively. By contrast, everyday e-cigarette users' GMs of most biomarkers did not differ significantly from those in some days' e-cigarette users; we did not observe clear trends by time of last use among e-cigarette users.

CONCLUSIONS

Users of tobacco products had higher PAH urinary biomarker concentrations compared to never users, and concentrations differed by type and frequency of tobacco product use.

Assessing chronic toxicity of aluminium, gallium and molybdenum in tropical marine waters using a novel bioassay for larvae of the hermit crab Coenobita variabilis

A novel bioassay is presented that allows for the estimation of the chronic toxicity of contaminants in receiving tropical marine environments. Relevant procedures to identify contaminants of concern and evaluate hazards associated with contamination in these environments have long remained inadequate. The 6-day bioassay is conducted using freshly hatched planktonic larvae of the hermit crab Coenobita variabilis and is targeted at generating environmentally relevant, chronic toxicity data. The developmental endpoint demonstrated consistently high control performance and was validated through the use of copper as a reference toxicant. In addition, the biological effects of aluminium, gallium and molybdenum were assessed. The endpoint expressed high sensitivity to copper (EC₁₀ = 24 µg L^-1) and moderate sensitivity to aluminium (EC₁₀ = 312 µg L^-1), whereas gallium and molybdenum elicited no obvious effects, even at high concentrations (EC₁₀ > 6000 µg L^-1), providing valuable information on the toxicity of these elements in tropical marine waters for derivation of water quality guidelines or testing of compliance limits.

Managers, modelers, and measuring the impact of species distribution model uncertainty on marine zoning decisions

Marine managers routinely use spatial data to make decisions about their marine environment. Uncertainty associated with this spatial data can have profound impacts on these management decisions and their projected outcomes. Recent advances in modeling techniques, including species distribution models (SDMs), make it easier to generate continuous maps showing the uncertainty associated with spatial predictions and maps. However, SDM predictions and maps can be complex and nuanced. This complexity makes their use challenging for non-technical managers, preventing them from having the best available information to make decisions. To help bridge these communication and information gaps, we developed maps to illustrate how SDMs and associated uncertainty can be translated into readily usable products for managers. We also explicitly described the potential impacts of uncertainty on marine zoning decisions. This approach was applied to a case study in Saipan Lagoon, Commonwealth of the Northern Mariana Islands (CNMI). Managers in Saipan are interested in minimizing the potential impacts of personal watercraft (e.g., jet skis) on staghorn Acropora (i.e., Acropora aspera, A. formosa, and A. pulchra), which is an important coral assemblage in the lagoon. We used a recently completed SDM for staghorn Acropora to develop maps showing the sensitivity of zoning options to three different prediction and three different uncertainty thresholds (nine combinations total). Our analysis showed that the amount of area and geographic location of predicted staghorn Acropora presence changed based on these nine combinations. These dramatically different spatial patterns would have significant zoning implications when considering where to exclude and/or allow jet skis operations inside the lagoon. They also show that different uncertainty thresholds may lead managers to markedly different conclusions and courses of action. Defining acceptable levels of uncertainty upfront is critical for ensuring that managers can make more informed decisions, meet their marine resource goals and generate favorable outcomes for their stakeholders.

Phototoxic effects of two common marine fuels on the settlement success of the coral Acropora tenuis

Coral reefs are at risk of exposure to petroleum hydrocarbons from shipping spills and uncontrolled discharges during extraction. The toxicity of petroleum hydrocarbons can substantially increase in the presence of ultraviolet radiation (UVR), therefore spills in shallow coral reef environments may be particularly hazardous to reef species. Here we investigated the sensitivity of coral larvae (Acropora tenuis) to dissolved hydrocarbons from heavy fuel oil (HFO) and diesel in the absence and presence of UVR. Larval settlement success decreased with increasing concentrations of dissolved HFO, and co-exposure to UVR doubled the toxicity: 50% effect concentrations (EC₅₀) decreased from 96 (−UVR) to 51 (+UVR) total petroleum aromatic hydrocarbons (TPAH). Toxic thresholds for HFO were similar to concentrations reported during marine spills: EC₁₀s of 24 (−UVR) and 15 (+UVR) µg l⁻¹. While less toxic, diesel also reduced settlement and exhibited phototoxicity: EC₁₀s of 122 (+UVR) and 302 (−UVR) µg l⁻¹. This study demonstrates that the presence of UVR increases the hazard posed by oil pollution to tropical, shallow-water coral reefs. Further research on the effects of oils in the presence of UVR is needed to improve the environmental relevance of risk assessments and ensure appropriate protection for shallow reef environments against oil pollution.

Population collapse dynamics in Acropora downingi, an Arabian/Persian Gulf ecosystem-engineering coral, linked to rising temperature

As in the tropical Atlantic, Acropora populations in the southern Persian/Arabian Gulf plummeted within two decades after having been ecosystem engineers on most wave-exposed reefs since the Pleistocene. Since 1996/1998 live coral cover in the Gulf declined by over 90% in many areas, primarily due to bleaching and diseases caused by rising temperatures. In the formerly dominant table-coral species A. downingi, population dynamics corresponding to disturbance regimes was quantified in three transition matrices (lower disturbance pre-1996; moderate disturbance from 1998 to 2010 and 2013 to 2017, disturbed in 1996/1998, 2010/11/12, 2017). Increased disturbance frequency and severity caused progressive reduction in coral size, cover, and population fecundity. Small size-classes were bolstered more by partial colony mortality than sexual recruitment. Some large corals had a size refuge and resisted die-back but were also lost with increasing disturbance. Matrix and biophysical larval flow models suggested one metapopulation. Southern, Arabian, populations could be connected to northern, Iranian, populations but this connectivity was lost under assumptions of pelagic larval duration at rising temperatures shortened to a third. Then, the metapopulation disintegrated into isolated populations. Connectivity required to avoid extinctions increased exponentially with disturbance frequency and correlation of disturbances across the metapopulation. Populations became unsustainable at eight disturbances in 15 years, when even highest theoretical recruitment no longer compensated mortality. This lethal disturbance frequency was 3-fold that of the moderately disturbed monitoring period and 4-fold of the preceding low-disturbance period-suggesting ongoing shortening of the disturbance-free period. Observed population collapse and environmental changes in the Gulf suggest that A. downingi is heading toward at least functional extinction mainly due to increasingly frequent temperature-induced mortality events, clearly linked to climate change.

Photo-induced toxicity following exposure to crude oil and ultraviolet radiation in 2 Australian fishes

Some polycyclic aromatic hydrocarbons (PAHs), components of crude oil, are known to cause increased toxicity when organisms are co-exposed with ultraviolet radiation, resulting in photo-induced toxicity. The photodynamic characteristics of some PAHs are of particular concern to places like Australia with high ultraviolet radiation levels. The objective of the present study was to characterize the photo-induced toxicity of an Australian North West Shelf oil to early life stage yellowtail kingfish (Seriola lalandi) and black bream (Acanthopagrus butcheri). The fish were exposed to high-energy water accommodated fractions for 24 to 36 h. During the exposure, the fish were either co-exposed to full-intensity or filtered natural sunlight and then transferred to clean water. At 48 h, survival, cardiac effects, and spinal deformities were assessed. Yellowtail kingfish embryos co-exposed to oil and full-spectrum sunlight exhibited decreased hatching success and a higher incidence of cardiac arrhythmias, compared with filtered sunlight. A significant increase in the incidence of pericardial edema occurred in black bream embryos co-exposed to full-spectrum sunlight. These results highlight the need for more studies investigating the effects of PAHs and photo-induced toxicity under environmental conditions relevant to Australia. Environ Toxicol Chem 2018;37:1359-1366. © 2018 SETAC.

Phototoxic effects of PAH and UVA exposure on molecular responses and developmental success in coral larvae

Exposure to polycyclic aromatic carbons (PAHs) poses a growing risk to coral reefs due to increasing shipping and petroleum extraction in tropical waters. Damaging effects of specific PAHs can be further enhanced by the presence of ultraviolet radiation, known as phototoxicity. We tested phototoxic effects of the PAHs anthracene and phenanthrene on larvae of the scleractinian coral Acropora tenuis in the presence and absence of UVA (320-400 nm). Activity of superoxide dismutase (SOD) enzyme was reduced by anthracene while phenanthrene and UVA exposure did not have any effect. Gene expression of MnSod remained constant across all treatments. The genes Catalase, Hsp70 and Hsp90 showed increased expression levels in larvae exposed to anthracene, but not phenanthrene. Gene expression of p53 was upregulated in the presence of UVA, but downregulated when exposed to PAHs. The influence on stress-related biochemical pathways and gene expresson in A. tenuis larvae was considerably greater for anthracene than phenanthrene, and UVA-induced phototoxicity was only evident for anthracene. The combined effects of UVA and PAH exposure on larval survival and metamorphosis paralleled the sub-lethal stress responses, clearly highlighting the interaction of UVA on anthracene toxicity and ultimately the coral's development.

Potential Impacts of Offshore Oil and Gas Activities on Deep-Sea Sponges and the Habitats They Form

Sponges form an important component of benthic ecosystems from shallow littoral to hadal depths. In the deep ocean, beyond the continental shelf, sponges can form high-density fields, constituting important habitats supporting rich benthic communities. Yet these habitats remain relatively unexplored. The oil and gas industry has played an important role in advancing our knowledge of deep-sea environments. Since its inception in the 1960s, offshore oil and gas industry has moved into deeper waters. However, the impacts of these activities on deep-sea sponges and other ecosystems are only starting to become the subject of active research. Throughout the development, operation and closure of an oil or gas field many activities take place, ranging from the seismic exploration of subseafloor geological features to the installation of infrastructure at the seabed to the drilling process itself. These routine activities and accidental releases of hydrocarbons during spills can significantly impact the local marine environment. Each phase of a field development or an accidental oil spill will therefore have different impacts on sponges at community, individual and cellular levels. Legacy issues regarding the future decommissioning of infrastructure and the abandonment of wells are also important environmental management considerations. This chapter reviews our understanding of impacts from hydrocarbon exploration and exploitation activities on deep-sea sponges and the habitats they form. These impacts include those (1) at community level, decreasing the diversity and density of benthic communities associated with deep-sea sponges owing to physical disturbance of the seabed; (2) at individual level, interrupting filtration owing to exposure to increased sedimentation; and (3) at cellular level, decreasing cellular membrane stability owing to exposure to drill muds. However, many potential effects not yet tested in deep-sea sponges but observed in shallow-water sponges or other model organisms should also be taken into account. Furthermore, to the best of our knowledge, no studies have shown impact of oil or dispersed oil on deep-sea sponges. To highlight these significant knowledge gaps, a summary table of potential and known impacts of hydrocarbon extraction and production activities combined with a simple "traffic light" scheme is also provided.

Comparative toxicity of five dispersants to coral larvae

Oil spill responders require information on the absolute and relative toxicities of chemical dispersants to relevant receptor species to assess their use in spill response. However, little toxicity data are available for tropical marine species including reef-building corals. In this study, we experimentally assessed the sub-lethal toxicity of five dispersants to larvae of the coral Acropora millepora over three short exposure periods (2, 6 and 24 h) reflecting real-world spill response scenario durations. Inhibition of larval settlement increased rapidly between 2 and 6 h, and was highest at 24 h: EC₅₀ Corexit EC9500A = 4.0 mg l⁻¹; Ardrox 6120 = 4.0 mg l⁻¹; Slickgone LTSW = 2.6 mg L⁻¹; Slickgone NS = 11.1 mg L⁻¹ and Finasol OSR52 = 3.4 mg L⁻¹. Coral larvae were more sensitive to dispersants than most other coral life stages and marine taxa, but the toxic thresholds (EC₁₀s) exceeded most realistic environmental dispersant concentrations. Estimating toxic threshold values for effects of dispersants on coral should benefit the decision-making of oil spill responders by contributing to the development of species sensitivity distributions (SSDs) for dispersant toxicity, and by informing net environmental benefit assessment (NEBA) for dispersant use.

Short-term toxicity of 1-methylnaphthalene to Americamysis bahia and 5 deep-sea crustaceans

There are few studies that have evaluated hydrocarbon toxicity to vertically migrating deep-sea micronekton. Crustaceans were collected alive using a 9-m² Tucker trawl with a thermally insulated cod end and returned to the laboratory in 10 °C seawater. Toxicity of the polycyclic aromatic hydrocarbon 1-methylnaphthalene to Americamysis bahia, Janicella spinacauda, Systellaspis debilis, Sergestes sp., Sergia sp., and a euphausiid species was assessed in a constant exposure toxicity test utilizing a novel passive dosing toxicity testing protocol. The endpoint of the median lethal concentration tests was mortality, and the results revealed high sensitivity of the deep-sea micronekton compared with other species for which these data are available. Threshold concentrations were also used to calculate critical target lipid body burdens using the target lipid model. Environ Toxicol Chem 2017;36:3415-3423. © 2017 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Petroleum hydrocarbon toxicity to corals: A review

The proximity of coral reefs to coastal urban areas and shipping lanes predisposes corals to petroleum pollution from multiple sources. Previous research has evaluated petroleum toxicity to coral using a variety of methodology, including monitoring effects of acute and chronic spills, in situ exposures, and ex situ exposures with both adult and larval stage corals. Variability in toxicant, bioassay conditions, species and other methodological disparities between studies prevents comprehensive conclusions regarding the toxicity of hydrocarbons to corals. Following standardized protocols and quantifying the concentration and composition of toxicant will aid in comparison of results between studies and extrapolation to actual spills.

Interactive effects of temperature and pCO2 on sponges: from the cradle to the grave

As atmospheric CO₂ concentrations rise, associated ocean warming (OW) and ocean acidification (OA) are predicted to cause declines in reef-building corals globally, shifting reefs from coral-dominated systems to those dominated by less sensitive species. Sponges are important structural and functional components of coral reef ecosystems, but despite increasing field-based evidence that sponges may be 'winners' in response to environmental degradation, our understanding of how they respond to the combined effects of OW and OA is limited. To determine the tolerance of adult sponges to climate change, four abundant Great Barrier Reef species were experimentally exposed to OW and OA levels predicted for 2100, under two CO₂ Representative Concentration Pathways (RCPs). The impact of OW and OA on early life-history stages was also assessed for one of these species to provide a more holistic view of species impacts. All species were generally unaffected by conditions predicted under RCP6.0, although environmental conditions projected under RCP8.5 caused significant adverse effects: with elevated temperature decreasing the survival of all species, increasing levels of tissue necrosis and bleaching, elevating respiration rates and decreasing photosynthetic rates. OA alone had little adverse effect, even under RCP8.5 concentrations. Importantly, the interactive effect of OW and OA varied between species with different nutritional modes, with elevated pCO₂ exacerbating temperature stress in heterotrophic species but mitigating temperature stress in phototrophic species. This antagonistic interaction was reflected by reduced mortality, necrosis and bleaching of phototrophic species in the highest OW/OA treatment. Survival and settlement success of Carteriospongia foliascens larvae were unaffected by experimental treatments, and juvenile sponges exhibited greater tolerance to OW than their adult counterparts. With elevated pCO₂ providing phototrophic species with protection from elevated temperature, across different life stages, climate change may ultimately drive a shift in the composition of sponge assemblages towards a dominance of phototrophic species.

Identification of genotoxic compounds in crude oil using fractionation according to distillation, polarity and Kow

We examined the degree of DNA damage caused by fractions of crude oil in accordance with the boiling points, polarity and log K_ow. Relatively high DNA damage was observed in the aromatic fraction (290-330°C) and resin and polar fraction (350-400°C). The resin and polar fraction showed relatively high genotoxicity compared with the aliphatic and aromatic fraction at the 1-4 log K_ow range. At the 6-7 log K_ow range, the aromatic fraction showed relatively high DNA damage compared with the aliphatic and resin and polar fraction. In particular, every detailed fraction in accordance with the log K_ow values (aliphatic and aromatic (310-320°C) and resins and polar fractions (370-380°C)) showed one or less than one DNA damage. However, the fractions before separation in accordance with log K_ow values (aliphatic and aromatic (310-320°C) and resin and polar (370-380°C) fractions) showed high DNA damage. Thus, we confirm the synergistic action between the detailed compounds.

Effects of coal contamination on early life history processes of a reef-building coral, Acropora tenuis

Successful reproduction and larval dispersal are important for the persistence of marine invertebrate populations, and these early life history processes can be sensitive to marine pollution. Coal is emerging as a contaminant of interest due to the proximity of ports and shipping lanes to coral reefs. To assess the potential hazard of this contaminant, gametes, newly developed embryos, larvae and juveniles of the coral Acropora tenuis were exposed to a range of coal leachate, suspended coal, and coal smothering treatments. Fertilisation was the most sensitive reproductive process tested. Embryo survivorship decreased with increasing suspended coal concentrations and exposure duration, effects on larval settlement varied between treatments, while effects on juvenile survivorship were minimal. Leachate exposures had negligible effects on fertilisation and larval settlement. These results indicate that coral recruitment could be affected by spills that produce plumes of suspended coal particles which interact with gametes and embryos soon after spawning.

Acute and subacute toxicity of the polycyclic aromatic hydrocarbon 1-methylnaphthalene to the shallow-water coral Porites divaricata: Application of a novel exposure protocol

Previous research evaluating hydrocarbon toxicity to corals and coral reefs has generally focused on community-level effects, and results often are not comparable between studies because of variability in hydrocarbon exposure characterization and evaluation of coral health and mortality during exposure. Toxicity of the polycyclic aromatic hydrocarbon 1-methylnaphthalene to the coral Porites divaricata was assessed in a constant exposure toxicity test utilizing a novel toxicity testing protocol uniquely applicable to shallow-water corals, which considered multiple assessment metrics and evaluated the potential for post-exposure mortality and/or recovery. Acute and subacute effects (gross morphological changes, photosynthetic efficiency, mortality, and histologic cellular changes) were evaluated during pre-exposure (4 wk), exposure (48 h), and post-exposure recovery (4 wk) periods. Coral condition scores were used to determine a 48-h median effective concentration of 7442 μg/L. Significant physical and histological changes resulted from exposure to 640 μg/L and 5427 μg/L 1-methylnaphthalene, with a 1-d to 3-d delay in photosynthetic efficiency effects (ΔF/Fm). Pigmented granular amoebocyte area was found to be a potentially useful sublethal endpoint for this species. Coral mortality was used to estimate a 48-h median lethal concentration of 12 123 μg/L. Environ Toxicol Chem 2017;36:212-219. © 2016 SETAC.