T279 Foraminiferal Responses and Recovery from Environmental Stressors

Wednesday, 4 November 2015
8:00 AM - 12:00 PM
Room 315

DOCUMENTING THE SPATIAL AND TEMPORAL RESPONSE OF BENTHIC FORAMINIFERA FOLLOWING SUBSURFACE OIL RELEASES IN THE GULF OF MEXICO

Paper number: T279-2
Program: Technical Sessions
Time: 8:10 AM – 8:30 AM

Authors

Abstract

A series of sediment cores collected from the Gulf of Mexico (2010-2014) were used to assess the spatial and temporal impacts on the benthos, quantify the recovery of benthic foraminiferal (BF) community and shell chemistry (δ13C) following the Deepwater Horizon (DWH) event. A significant decline in BF density (80-93%) and diversity recognized since 2010 has been attributed to both a 2-3-fold increase in polycyclic aromatic hydrocarbon concentrations and increasing reducing conditions in surface sediments. At certain sites, a recovery in density occurred in late 2011, while at other sites density did not recover until 2012. Independent of location, the δ13C record of BF carbonate showed a marked depletion in 2010 that has further intensified through 2012. This suggests that BF not only incorporated petroleum carbon into their shells directly following the DWH event, but that they were continually respiring a petroleum carbon source for more than two years afterwards. Using both δ13C and Δ14C mass balance approaches, 1-2.5% of total respired carbon assimilated into BF carbonate from 2010 to 2012 was comprised of petroleum carbon. BF community change and trophic implications over this time-series will be discussed and compared to the record of recovery in the Southern Gulf of Mexico following the IXTOC event (1979). This continuing research identifies specific biological responses to physical and chemical changes in the sediments and identifies benthic community recovery rates following a deep-water petroleum release.