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Long term ecological impacts of oil spills: comparison of Exxon Valdez, Hebei Spirit and Deepwater Horizon
Citation:
Barron, M. Long term ecological impacts of oil spills: comparison of Exxon Valdez, Hebei Spirit and Deepwater Horizon. Alaska Marine Science Symposium, Pensacola Beach, Florida, January 28 - February 01, 2019.
Impact/Purpose:
The purpose of this presentation is to compare and contrast similarities and differences in three of the worlds great oil spills: in terms of their dynamics, environment, clean up, and ultimate ecological impacts and recovery. The impact of this presentation is that it is a highly prestigious invited talk at the Alaska Marine Science Symposium commemorating the 30th Anniversary of the Exxon Valdez oil spill. The presentation's significance to EPA includes acknowledgement and visibility that Agency science and scientists are recognized as important in the global field of oil spills. EPA will benefit from participation from both the visibility of Agency oil science, and from Dr. Barron continuing to be expand his knowledge and network in oil spills as the EPA's oil toxicology expert.
Description:
Prior to the Exxon Valdez oil spill (EVOS), ecological impacts were generally thought to be short-term and controlled by the mono-aromatic and less persistent components of oil. The long term ecological impacts of EVOS were compared to two other extensively studied and more recent large spills: Deepwater Horizon (DWH) and the Hebei Spirit oil spill (HSOS). Each of the three spills differed in magnitude and duration of oil released, environmental conditions and ecological communities, response and clean up measures, and ecological recovery. The EVOS began on March 24, 1989 and released 42 million liters of Alaska North Slope crude oil into the cold pristine environment of Prince William Sound, Alaska. EVOS oiled wildlife and rocky intertidal shorelines and exposed early life stages of Pacific herring and salmon to embryotoxic levels of PAHs. Long term impacts following EVOS were observed on seabirds, killer whales, subtidal communities, along with catastrophic reductions in Pacific herring populations. Small pockets of residual oil continue to be observed in Prince William Sound, and one subpopulation of cetaceans has never recovered. The DWH spill began on April 10, 2010 and released 507 million liters of light Louisiana crude oil from 1600 m on the ocean floor into the Gulf of Mexico over a four-month period. In contrast to EVOS, the Gulf of Mexico is a region with warmer surface waters and intense oil production and multiple oil seeps. Approximately 7 million liters of chemical dispersants were used during DWH to disperse oil at the surface and at the well head. The DWH spill exposed a diversity of complex aquatic communities in the deep ocean, offshore pelagic areas, and coastal environments. Large scale persistent ecological effects were observed during DWH, including impacts to deep ocean corals, failed recruitment of oysters over multiple years, damage to coastal wetlands, reduced dolphin, sea turtle, and seabird populations, and likely cascading impacts on menhaden and other coastal species from disruption of predator-prey relationships. The HSOS began on December 7, 2007 and released approximately 12 million liters of Middle Eastern crude oils into ecologically sensitive areas of the Taean area of western Korea. In contrast to EVOS and DWH, extensive initial cleanup of HSOS oil stranded on shorelines limited long-term impacts to changes in composition and abundance of intertidal benthic communities. Environmental conditions, including high tidal energy and wind direction, also affected oil distribution and persistence. Comparison of EVOS, DWH, and HSOS show the importance and complexity of the interactions among environment, spill dynamics, and clean up. Understanding how they interact to determine ecological impacts and ecosystem recovery are critical to preparing for and responding to future spills.