Presentation
Sensitivity of six species of Atlantic scleractinian corals to petroleum hydrocarbons
SessionWildlife - Impacts
DescriptionCoral reefs are keystone coastal ecosystems frequently at risk of exposure to petroleum hydrocarbons from a range of sources, including oil spill incidents and chronic runoff. They are usually one of the highest-valued natural resources for protection in Net Environmental Benefit Analysis (NEBA)/Spill Impact Mitigation Assessment (SIMA) of response methods and environmental impact. Partially due to the lack of standardized toxicity testing methods, many previous studies evaluating the effects of oil exposure on shallow-water corals have not resulted in clear characterization of impacts or relative sensitivity, and this is an important knowledge gap in oil spill preparedness. This article presents the cumulative results of a collaborative multi-year research program designed to characterize the relative sensitivities of six Atlantic coral species to single hydrocarbons (toluene, 1-methylnaphthalene, phenanthrene), MC252 oil, and chemically dispersed oil. A total of 23 separate 48-h dose response assays were conducted, using a standardized approach that integrated acute toxicity thresholds (mortality) with metrics emphasizing sublethal effects on the coral holobiont, including physical/behavioral changes, photosynthetic efficiency, and differential gene expression.
A range of stress responses to hydrocarbon exposure were observed, including significant changes in coral physical condition, with less significant effects on the photosynthetic efficiency of the dinoflagellate symbiont. Significant transcriptomic changes occurred at hydrocarbon exposure concentrations 4-8 times lower than those resulting in significant sublethal physical changes. No latent effects were observed, and corals which survived exposures recovered to baseline condition within 1-4 weeks. The Atlantic staghorn coral Acropora cervicornis, listed as endangered under the Endangered Species Act (ESA), was found to be the most sensitive species tested and should be given priority consideration in the NEBA or SIMA decision-making process. Overall, however, healthy corals were found to be relatively resilient to hydrocarbon exposure compared to other coastal marine species, although further work is needed to assess the influence of seasonal temperature and/or light changes on coral sensitivity.
Our results provide a framework for a comprehensive understanding of petroleum impacts on scleractinian corals, and an improved capacity to predict oil spill impacts on the coral animal and related habitats. These new data provide the required inputs for improved modeling of the predicted effects of different spill response methods, including dispersant use, and supports science-based oil spill response decision-making in sensitive coral reef environments.
A range of stress responses to hydrocarbon exposure were observed, including significant changes in coral physical condition, with less significant effects on the photosynthetic efficiency of the dinoflagellate symbiont. Significant transcriptomic changes occurred at hydrocarbon exposure concentrations 4-8 times lower than those resulting in significant sublethal physical changes. No latent effects were observed, and corals which survived exposures recovered to baseline condition within 1-4 weeks. The Atlantic staghorn coral Acropora cervicornis, listed as endangered under the Endangered Species Act (ESA), was found to be the most sensitive species tested and should be given priority consideration in the NEBA or SIMA decision-making process. Overall, however, healthy corals were found to be relatively resilient to hydrocarbon exposure compared to other coastal marine species, although further work is needed to assess the influence of seasonal temperature and/or light changes on coral sensitivity.
Our results provide a framework for a comprehensive understanding of petroleum impacts on scleractinian corals, and an improved capacity to predict oil spill impacts on the coral animal and related habitats. These new data provide the required inputs for improved modeling of the predicted effects of different spill response methods, including dispersant use, and supports science-based oil spill response decision-making in sensitive coral reef environments.
Authors
Director, Regional External Affairs
Event Type
Paper
TimeWednesday, May 15th8:40am - 9:00am CDT
Location278-280
Remediation