Oyster Contaminants

Full Title: Use of elemental signatures to detect and trace contaminant entry to the northern Gulf of Mexico coastal food web: managing multiple stressors

Lead Investigator (Institution): Ruth Carmichael (Dauphin Island Sea Lab, University of South Alabama) rcarmichael@disl.org

Technical Monitor: Dennis Apeti (dennis.apeti@noaa.gov)

Award Amount: $231,671

Award Period: June 1, 2017 – May 31, 2020

Summary: Oysters can serve as a record of water conditions at a particular site because they are stationary filter feeders with a hard shell that continually grows. The shell can even serve as a long-term recorder of water conditions in the past that may remain after the animal has died. This project will measure the trace element profiles in oyster shell and compare them to the trace element profiles in oil and other contaminants. These experiments will make it possible to link the chemical fingerprint in oyster shell back to exposure of that oyster to a contaminant. Because oysters live in waters that vary in salinity, particularly on the Gulf of Mexico coast where freshwater discharge can be very high, this link will be tested under different salinities. Understanding this linkage will make it possible to use historical oyster shell and tissue samples to assess past contaminant exposure at different sites. The trace element profiles in the shell of oysters exposed to contaminants will also be compared to measures of the biological condition of the oyster such as its growth rate to develop an indicator for the condition of oysters at a particular site following contaminant exposure. Using data on mortality and abundance at active oyster restoration sites, this project will also assess whether current or previous exposure to contaminants is related to the status of a restore reef. Overall, the results of this work will benefit the recovery of oysters reefs and the economic and ecosystem services they provide by determining how past oil contamination has impacted current oyster health in the Gulf of Mexico.