Red Crabs As Sentinel Organisms of Deepwater Horizon Oil in Gulf of Mexico Sediments

Forensic Chemistry
Oral Presentation

Prepared by G. Douglas, B. Liu, W. Wong, E. Litman, J. Hardenstine
NewFields Environmental Forensics, 300 Ledgewood Place, Suite 305, Rockland, MA, 02370, United States


Contact Information: gdouglas@newfields.com; 781-681-5040


ABSTRACT

The Deepwater Horizon (DWH) oil spill is unique because unlike most oil spills, a substantial fraction of the released oil was deposited on deep benthic sediments in the form of particulate, dispersed and floc related oil. From 2010 to 2014 benthic macrofauna were collected from the deep seafloor to determine if there was forensic evidence to indicate biological exposure to the spilled Macondo oil. Polycyclic aromatic hydrocarbons (PAH) and biomarkers (triterpane and steranes) were measured in dissected red crab tissue samples, in order to identify the chemical fingerprint of any oil present within the tissue. Results show that red crabs were exposed to Macondo oil from the DWH oil spill. Specific results include:
(1) The red crab hepatopancreas samples provided the most sensitive and diagnostic chemical fingerprints by which to assess exposure of these animals.
(2) The highest exposures of red crabs to Macondo oil occurred closest to the well although exposures up to 14 km southwest of the well were identified.
(3) Detection of Macondo Oil residuals was consistent with spatial distribution of spill impacted sediments.