Over the past 20 years of work in the deep Gulf of Mexico we have assembled a large database on over 40 sites with chemosynthetic communities and 14 natural sites with extensive cold-water coral development. As a result of the ongoing oil leak at the Deep Water Horizon rig, some of these sites are very likely to be exposed to high concentrations of hydrocarbons and dispersant. Visitation, imaging, and sampling in the very near future at a subset of these sites will provide timely information on any acute impacts on benthic fauna, as well as provide ground-truthing of data suggesting that the oil/dispersant mixture is spreading along density gradients at depth. We propose to revisit sites where we have ongoing studies, including pre-exposure tissue and live coral samples, and well-marked and navigated mosaics of coral and coral/tubeworm communities. A site in MMS lease block VK 826 and another in MC 751 are identified as high-priority sites with extant mosaics, excellent pre-existing macrofauna sample sets, and are currently monitored with time series sediment traps. A third high-priority site is in MMS lease Block MC 294, within 7 miles of the leak site. This site harbors a typical seep community of mussels and tubeworms. Numerous others could be visited if ongoing plume modeling and ground-truthing work suggests other important areas or depths in the Gulf of Mexico for study. At each site visited, we will conduct high resolution imaging of the hard ground megafaunal communities for comparisons to similar imagery collected last year and make a series of macrofauna collections for a suite of analyses. These analyses will include analysis of hydrocarbon load (tissue PAHs), Comet assays to assess DNA damage, analysis of phospholipids fatty acid biomarkers from bacteria in coral mucous, and also experiments with living Lophelia pertusa for growth studies under laboratory conditions. Broader Impacts For the first time in US history, we are dealing with a massive leakage and spread of oil and trial dispersants (potentially much more toxic to life than the oil itself), which have been directly injected at over 1500m into the deep sea. The scale of this disaster dwarfs any previous oil spills and how plumes of these substances will travel in the deep sea and what their effects on the benthos will be is still almost completely unknown. As a result, there is a critical need to assess the impact on deep-sea megafauna communities and communicate those results as soon as possible.
This award supported a research expedition to a deep-water coral community 7 nm from the site of the Deepwater Horizon disaster, which had been discovered less than two months previous to the expedition. The collaborative project included investigators from 4 academic institutions and the USGS, as well as a film crew. The expedition used the deep submergence vehicle Alvin to photo-document the condition of the corals and associated animals, and also take samples for histological, molecular, and hydrocarbon analysis. Figure 1 shows the submarine Alvin on the sea floor at the site at 1470 m depth with impacted corals and attached brittle stars in the foreground. This picture was taken with a time lapse camera deployed at the site. The Autonomous Underwater Vehicle (AUV), Sentry, was also used to explore for other coral communities in the vicinity in order to better understand the potential footprint of the impact from the disaster on deep-water corals in the region. The analysis of the samples and photographs provided the first conclusive evidence of deleterious impact from the spill to a deep-sea animal community. It also documented impact at a greater distance from the spill than previous reports suggested were impacted and at greater depth than models of the deep-water plume suggested might be impacted. Figure 2 shows a coral photographed one month previous to the expedition that had been recently and heavily impacted by the spill and still has it’s commensal brittle star clinging to branches covered with a brown flocculent material that contains hydrocarbons fingerprinted to the Macondo well. These results were reported in the Proceedings of the National Academy of Sciences in 2012 (PNAS, doi: 10.1073/pnas.1118029109). In addition, by conclusively documenting the impact at this early point in time after the spill, this study set the stage for two important and ongoing avenues of research. The first is following the results of the impact to the health of both the individual deep-water corals at the site and the health of the community as a whole. This is only possible because of the very high quality maps and imaging accomplished during this project. The second is determining the footprint of the impact to corals in the region. This is only possible because of the success of the methods developed to find new communities and because we can use the information collected on the primary site over time to recognize impact to corals at communities discovered years after the spill. Figure 3 and 4 are pictures of the same coral taken during the original discovery cruise in 2010 and again during an expedition with the NOAA vessel Oceanos Explorer in March 2012 that show how a coral originally impacted by the spill in the summer of 2010 changed by March 2012.
