A poster presentation at the 2014 Ocean Sciences Meeting (23-28 February) provides a reminder that the Exxon Valdez Oil Spill (EVOS) is still affecting the shorelines of some of Alaska’s national parks.
In addition to these beaches, sea otters, orca and many fish species are not yet considered recovered from the event.Scientists from the Alaska Science Center of the US Geological Survey (USGS) have been monitoring the rocky coastline along Shelikof Strait for at least 18 years. On beaches protected by boulders and cobble, they have recovered oil, definitively linked to EVOS by NOAA chemical laboratories and verified by Woods Hole Oceanographic Institution, which is barely weathered. Dr. Gail Irvine of the USGS team compared it to 11-day-old oil.
The results of this ongoing study suggest that cleanup should focus on beach such as these where the oil not exposed to wave action and is, therefore, likely to persist. This is in contrast to studies of less protected beaches where the use of pressurised water to clean resulted in long term damage to invertebrate and plant populations.
The study also showed that some of the oil is moving into the water at two of the six study sites and that subsurface oiling has not changed significantly at 4 sites. The finding of minimally weathered oil suggests one reason for the slow recovery of sea otters. Females, particularly those with dependent pups, spend much of their time foraging in the intertidal zone. During the spring and summer when the pups are very young the mothers prey primarily on clams buried in the sand, potentially exposing them to the subsurface oil directly and to ingestion of contaminated prey.
The long-term effect of EVOS on the environment is the subject of ongoing research by several US government agencies, which started when the cleanup officially ended. Research is funded through the EVOS Trustee Council, which manages the 900 million USD civil settlement funds for recovery and rehabilitation of the region.
Resources:
Irvine, et al. 2014. Exxon Valdez oil after 23 years on rocky shores in the Gulf of Alaska: Boulder armor stability and persistence of slightly weathered oil. Poster presentation abstract. Ocean Sciences Meeting 2014
Bodkin, JL et al. 2012. Long-term effects of the ‘Exxon Valdez’ oil spill: sea otter foraging in the intertidal as a pathway of exposure to lingering oil. Marine Ecology Progress Series 4447:273-287. doi:10.3354/meps09523
Matkin, CO. et al. 2008. Ongoing population-level impacts on killer whales Orcinus orca following the 'Exxon Valdez' oil spill in Prince William Sound, Alaska. Marine Ecology Progress Series 356:269-281. doi:10.3354/meps07273