RAPID Response in Gulf of Mexico: Sediment Trap Investigations

Woods Hole Oceanographic Institution, Woods Hole MA

Investigators

Abstract

Intellectual Merit: In September 2009, two time-series sediment trap and current meter moorings were deployed in the northern Gulf of Mexico to investigate biogenic fluxes settling to the seafloor (and larval recruitment) at two well-characterized and significant sites of combined deep-water coral and chemosynthetic tube-worm colonies (Fisher et al., 2007). Each of these traps, set just above the seabed and in water depths of 400-450m, have been collecting a new sample of settling material every two weeks since 11 September 2009 and will continue to do so until 2nd July 2010 when their last sample bottle will be rotated shut and the traps will await recovery as part of an already-funded field program (NOAA-MMS) scheduled for November. Serendipitously, however, these two traps are located just 32 nmiles to the NE and 81 nmiles to the WSW of the recent Deepwater Horizon incident and continuing oil release from the seafloor. Continuous monitoring by NOAA has shown that at least one of these two study sites became overlain by oil discharge at the ocean surface by the end of April and that both sites are now overlain by at least light to medium concentrations of hydrocarbons ± dispersant. What remains unestablished at this point, however, is what is happening at depth and what impacts there may be at the Gulf of Mexico seafloor and, specifically, its pristine and unique deepwater coral/ chemosynthetic tube-worm colonies. The purpose of this proposal, therefore, is two-fold. First we seek to join a rapid response research cruise to the area to deploy two additional short sediment trap and current meter moorings to ensure that we maintain continuity in the sampling that began 6 months before the incident and remains ongoing at each of the two sites that we had previously targeted as being of most significance in terms of deepwater coral/chemosynthetic tubeworm ecosystems. If we do not achieve that, our time series will end on July 2nd. Second, and anticipating that there will be a wealth of additional studies that many other PIs will wish to pursue, we seek sufficient funds to conduct initial characterization from these samples (plus those from our earlier deployments) as soon as they are recovered (already-funded cruise in November 2010). Specifically, we anticipate generating a suite of archived samples with coregistered information on mass and biogenic flux (to include inorganic and organic carbon content) and preliminary ?finger-printing? of any hydrocarbon signatures present in each sample. Broader Impacts: The emerging environmental impact in the Gulf of Mexico is of great societal concern and has implications for both future deepwater resource extraction and energy supply for the nation. But the majority of the attention currently being paid to the GoM system is, of necessity, focused on the shallow upper ocean where data is most readily obtained. Serendipitously, this work represents a project that can shed unique light on the effects that may be being imparted upon remarkable and formerly pristine deepwater ecosystems in close proximity to the Deepwater Horizon well-head. Because our combined analyses will only require a small fraction of the samples we collect we will archive the remainder of each sample carefully for broader investigations and, further, we will publicize our results widely and promptly to engender such value-added research. For example, this work will clearly be of relevance and potential to other projects also being developed by (e.g.) R.Camilli (WHOI) and C.Fisher (Penn.State). Our group stands ready to work with all such interested scientific parties and is also in contact with a film team (Mike deGruy, based in Santa Barbara) interested in a response effort (although we have no commitments to them should another team prove more suitable for that work).