Dataset Information

Diatom aggregation when exposed to crude oil and chemical dispersant: Potential impacts of ocean acidification.

ABSTRACT: Diatoms play a key role in the marine carbon cycle with their high primary productivity and release of exudates such as extracellular polymeric substances (EPS) and transparent exopolymeric particles (TEP). These exudates contribute to aggregates (marine snow) that rapidly transport organic material to the seafloor, potentially capturing contaminants like petroleum components. Ocean acidification (OA) impacts marine organisms, especially those that utilize inorganic carbon for photosynthesis and EPS production. Here we investigated the response of the diatom Thalassiosira pseudonana grown to present day and future ocean conditions in the presence of a water accommodated fraction (WAF and OAWAF) of oil and a diluted chemically enhanced WAF (DCEWAF and OADCEWAF). T. pseudonana responded to WAF/DCEWAF but not OA and no multiplicative effect of the two factors (i.e., OA and oil/dispersant) was observed. T. pseudonana released more colloidal EPS (< 0.7 ?m to > 3 kDa) in the presence of WAF/DCEWAF/OAWAF/OADCEWAF than in the corresponding Controls. Colloidal EPS and particulate EPS in the oil/dispersant treatments have higher protein-to-carbohydrate ratios than those in the control treatments, and thus are likely stickier and have a greater potential to form aggregates of marine oil snow. More TEP was produced in response to WAF than in Controls; OA did not influence its production. Polyaromatic hydrocarbon (PAH) concentrations and distributions were significantly impacted by the presence of dispersants but not OA. PAHs especially Phenanthrenes, Anthracenes, Chrysenes, Fluorenes, Fluoranthenes, Pyrenes, Dibenzothiophenes and 1-Methylphenanthrene show major variations in the aggregate and surrounding seawater fraction of oil and oil plus dispersant treatments. Studies like this add to the current knowledge of the combined effects of aggregation, marine snow formation, and the potential impacts of oil spills under ocean acidification scenarios.

SUBMITTER: Genzer JL

PROVIDER: S-EPMC7340286 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Diatom aggregation when exposed to crude oil and chemical dispersant: Potential impacts of ocean acidification.

Genzer Jennifer L JL Kamalanathan Manoj M Bretherton Laura L Hillhouse Jessica J Xu Chen C Santschi Peter H PH Quigg Antonietta A

PloS one 20200707 7

Diatoms play a key role in the marine carbon cycle with their high primary productivity and release of exudates such as extracellular polymeric substances (EPS) and transparent exopolymeric particles (TEP). These exudates contribute to aggregates (marine snow) that rapidly transport organic material to the seafloor, potentially capturing contaminants like petroleum components. Ocean acidification (OA) impacts marine organisms, especially those that utilize inorganic carbon for photosynthesis and ...[more]

PMID: 32634146

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Project description:The Deepwater Horizon oil spill of 2010 raised concerns that dispersant and dispersed oil, as well as crude oil itself, could contaminate shellfish and seafood habitats with hazardous residues that had potential implications for human health and the ecosystem. However, little is known about the effects of crude oil and dispersant on the human fecal microbiota. The aim of this research was to evaluate the potential effects of Deepwater Horizon crude oil, Corexit 9500 dispersant, and their combination on human fecal microbial communities, using an in vitro culture test system. Fecal specimens from healthy adult volunteers were made into suspensions, which were then treated with oil, dispersant, or oil-dispersant mixtures under anaerobic conditions in an in vitro culture test system. Perturbations of the microbial community, compared to untreated control cultures, were assessed using denaturing gradient gel electrophoresis (DGGE), real-time PCR, and pyrosequencing methods. DGGE and pyrosequencing analysis showed that oil-dispersant mixtures reduced the diversity of fecal microbiota from all individuals. Real-time PCR results indicated that the copy numbers of 16S rRNA genes in cultures treated with dispersed oil or oil alone were significantly lower than those in control incubations. The abundance of the Bacteroidetes decreased in crude oil-treated and dispersed-oil-treated cultures, while the Proteobacteria increased in cultures treated with dispersed oil. In conclusion, the human fecal microbiota was affected differently by oil and dispersed oil, and the influence of dispersed oil was significantly greater than that of either oil or dispersant alone compared to control cultures. IMPORTANCE There have been concerns whether human health is adversely affected by exposure to spilled crude oil, which contains regulated carcinogens, such as polycyclic aromatic hydrocarbons. In this study, we determined the effect of BP Deepwater Horizon crude oil and oil dispersant on the human intestinal microbiota, since there is the potential that low-level residues of petrochemicals could contaminate seafood. The results of this study will increase our understanding of the ecophysiological changes in the microbial communities of the human gastrointestinal tract with respect to crude oil exposure.

Project description: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??g liter-1 polycyclic aromatic hydrocarbon [PAH]), whereas significant decreases in metamorphosis were observed at 13% WAF (13.9??g liter-1 PAH). The CWAF and dispersant treatments were more toxic, with decreases in metamorphosis identified at 0.8% (0.58??g 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??g 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.

Project description:Ocean acidification is one the biggest threats to marine ecosystems worldwide, but its ecosystem wide responses are still poorly understood. This study integrates field and experimental data into a mass balance food web model of a temperate coastal ecosystem to determine the impacts of specific OA forcing mechanisms as well as how they interact with one another. Specifically, we forced a food web model of a kelp forest ecosystem near its southern distribution limit in the California large marine ecosystem to a 0.5 pH drop over the course of 50 years. This study utilizes a modeling approach to determine the impacts of specific OA forcing mechanisms as well as how they interact. Isolating OA impacts on growth (Production), mortality (Other Mortality), and predation interactions (Vulnerability) or combining all three mechanisms together leads to a variety of ecosystem responses, with some taxa increasing in abundance and other decreasing. Results suggest that carbonate mineralizing groups such as coralline algae, abalone, snails, and lobsters display the largest decreases in biomass while macroalgae, urchins, and some larger fish species display the largest increases. Low trophic level groups such as giant kelp and brown algae increase in biomass by 16% and 71%, respectively. Due to the diverse way in which OA stress manifests at both individual and population levels, ecosystem-level effects can vary and display nonlinear patterns. Combined OA forcing leads to initial increases in ecosystem and commercial biomasses followed by a decrease in commercial biomass below initial values over time, while ecosystem biomass remains high. Both biodiversity and average trophic level decrease over time. These projections indicate that the kelp forest community would maintain high productivity with a 0.5 drop in pH, but with a substantially different community structure characterized by lower biodiversity and relatively greater dominance by lower trophic level organisms.

Dataset Information

Diatom aggregation when exposed to crude oil and chemical dispersant: Potential impacts of ocean acidification.

Publications

Diatom aggregation when exposed to crude oil and chemical dispersant: Potential impacts of ocean acidification.

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