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).
In 2009, I began a study to collect and analyse particles sinking to the seafloor in the northern Gulf of Mexico to understand what supplied the food required to sustain delicate deep-water coral communities at depth, below sunlight, there. One obvious source is sinking of waste organic matter from the sunlit upper ocean (shallower than 200m) where life is abundant. Alternately, nutrient supply might come from exotic chemically-fuelled ecosystems associated with natural hydrocarbon (oil and gas) seeps that are known to occur across the floor of the Gulf of Mexico, in and among the active oil fields. While our project was already underway, the Deep Water Horizon accident occurred and within days oil slicks were mapped north of the Macondo well-head that passed directly over my sampling site. My samples was being collected using a sediment trap which acts as a giant circular funnel with a large surface area at the top (about 3ft diameter) that narrows and empties out into a plastic bottle at its base. Anything solid falling into the top of the funnel gets collected into the sample bottle at the base where, every two weeks, a carousel rotates to line up a fresh sample bottle with the base of the funnel (meanwhile all the other sample bottles are covered so nothing gets in or out). That way, when we analyse the samples, we know how much material arrived at the seafloor in each 2-week period and we can analyse how things vary with time. In this project I extended the original planned sampling so that, instead of our time-series running out while the Macondo well-head was still uncapped, we could compare, on a like-for-like basis, how the amount and composition of material sinking to the seafloor changed, from six months before the DWH accident happened until well beyond when the well-head was finally capped, several months later. What I found, when the samples were analysed in the laboratory was that there was no immediate clear sign of oil input reaching the seafloor at the study site but that there were important results to pay attention to. During the period that the Macondo well head was discharging oil in an uncontrolled way from the seafloor and contributing to surface ocean oil slicks, the results show an increase in the total amount of material sinking back to the seabed at the northern Gulf of Mexico site (about 30 miles NE of Macondo) and, further, that the concentration of organic carbon (which might or might not be oil related) in this material increased with time, too. Two questions then arose that we could not answer from those results alone: 1) Were the increases in mass and carbon flux in 2010 different from what would be expected in the Gulf of Mexico anyway in Spring and Summer where, (just as happens on land after Winter) increased hours of daylight and warmer temperatures can lead to a sudden flourishing of life in the surface ocean, which can also lead to an increase in the fall of waste material to the seafloor? 2) Whether the results observed at the time of the DWH accident were typical or atypical, did they carry any distinctive geochemical signatures that might allow us to "fingerprint" them as being related to the oil spill? In continuing work we have made important progress. By completing similar studies in 2011 we showed that the total amount of material and the carbon content of that material sinking to the same site over the Spring/Summer cycle of 2011 was not significantly different from that of 2010. However, in one measurement that can be made in my laboratory it was found that, by comparing the ratio of carbon [C] to nitrogen [N] in the sinking material, the highest material flux samples with the highest carbon contents at the height of the DWH accident in 2010 appeared to be composed of significantly different material in terms of its C:N ratio. The values in Spring 2010 were what scientists would normally conclude means this was "old" carbon and, hence, these results could be consistent with carbon that had come from an underground oil reservoir. That is as far as this project has been able to pursue the matter within this grant, except that, because we were scrupulous in how we collected our samples and preserved them, we have now been able to hand our remaining samples and data off to the dedicated branch of NOAA who are pursuing the outcomes of the DWH accident. They have now taken my samples and are employing specialist laboratories to scrutinize the samples further to "fingerprint" them and see whether the unusual results reported here are, indeed, a direct result of the Deep Water Horizon accident impacting these fragile deep-water coral communities.
