Impact of Deepwater Horizon spill on food supply to deep-sea benthos communities

• Published in: Estuarine, coastal and shelf science coastal and shelf science, 2016-02, Vol.169, p.248-264
• Main Authors: Prouty, N.G., Campbell, P.L., Mienis, F., Duineveld, G., Demopoulos, A.W.J., Ross, S.W., Brooke, S.
• Format: Article
• Language: English
• Subjects: Biomarkers; Biomass; Brackish; Deep-sea benthos; Deepwater Horizon spill; Gulf of Mexico; Sediment trap
• ISSN: 0272-7714; 1096-0015
• DOI: 10.1016/j.ecss.2015.11.008

Deep-sea ecosystems encompass unique and often fragile communities that are sensitive to a variety of anthropogenic and natural impacts. After the 2010 Deepwater Horizon (DWH) oil spill, sampling efforts documented the acute impact of the spill on some deep-sea coral colonies. To investigate the impact of the DWH spill on quality and quantity of biomass delivered to the deep-sea, a suite of geochemical tracers (e.g., stable and radio-isotopes, lipid biomarkers, and compound-specific isotopes) was measured from monthly sediment trap samples deployed near a high-density deep-coral site in the Viosca Knoll area of the north–central Gulf of Mexico prior to (Oct-2008 to Sept-2009) and after the spill (Oct-10 to Sept-11). Marine (e.g., autochthonous) sources of organic matter (OM) dominated the sediment traps in both years, however after the spill, there was a pronounced reduction in marine-sourced OM, including a reduction in marine-sourced sterols and n-alkanes and a concomitant decrease in sediment trap organic carbon and pigment flux. Results from this study indicate a reduction in primary production and carbon export to the deep-sea in 2010–2011, at least 6–18 months after the spill started. Whereas satellite observations indicate an initial increase in phytoplankton biomass, results from this sediment trap study define a reduction in primary production and carbon export to the deep-sea community. In addition, a dilution from a low-14C carbon source (e.g., petro-carbon) was detected in the sediment trap samples after the spill, in conjunction with a change in the petrogenic composition. The data presented here fills a critical gap in our knowledge of biogeochemical processes and sub-acute impacts to the deep-sea that ensued after the 2010 DWH spill. •Suite of geochemical tracers from sediment traps document sub-acute impacts to the deep-sea after the 2010 DWH spill.•Reduction in marine-sourced OM after the spill suggests reduction in surface ocean primary production.•Sediment trap samples contain a petrogenic component from both natural sources and accidental spills.•OM is primarily from marine algae from C3 vascular plants rather than a mixture of terrestrial C3 plus C4 plants.