Characterizing the Impact and Response of Deep Sea Benthic Foraminifera to the Deepwater Horizon Event in the Northeastern Gulf of Mexico

Sediment cores were collected from the Gulf of Mexico to assess the benthic foraminifera (BF) community structure changes in response to the Deepwater Horizon (DWH) event. Short-lived radioisotope geochronologies (210Pb and 234Th), organic geochemical toxicity assessments, and redox metal concentrations were determined to relate changes in sedimentation rate, toxicity levels, and redox conditions with BF abundance. Records from December 2010 document a community-wide decrease in abundance in the upper 10 mm relative to the down-core mean. There is also depletion in the δ13C and Δ14C records of BF calcite (relative to down-core values) that is synchronous with the timing of the community decline in the surface sediment. This suggests that petroleum hydrocarbons were incorporated into the BF tests. Preliminary mass balance calculations infer that 0.1-7% of the test calcite is composed of petroleum hydrocarbons. Integrating records of BF abundance with other sedimentary chemical records has shown to be effective in quantifying the benthic response and will be valuable in determining the long-term impacts of the DWH event on the benthic habitat on larger spatial scale.