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Biomonitoring for the Georgia Coast: Oysters as Sentinels of Coastal Water Quality

PIs: Marc Frischer (Skidaway Institute of Oceanography, Savannah, GA) and Keith Maruya (Southern California Coastal Water Research Project Authority, CA)

Support: Georgia Coastal Management Program (through a Coastal Incentive Grant)

Timeframe: 2005 - 2006 (ongoing)

Project Objective:
To initiate an environmental observation system for coastal Georgia water quality based on a widely distributed, abundant, easily accessible, and ecologically relevant indicator species – the filter-feeding oyster (Crassostrea virginica).

An initial survey (with respect to land use patterns) of contaminant and bacterial burdens of oysters in coastal Georgia has been completed. This survey included:

  • nineteen sampling expeditions in 6 Georgia coastal counties (May-September 2005)
  • weekly sampling at the Priest Landing site
  • a bioassay study to investigate the relationship between Enterococci bacteria water quality indicators and oysters.

At each field collection a wide range of physical, chemical, contaminant, and microbiological characteristics were determined. These included: exact location, temperature, pH, dissolved oxygen, specific conductance, salinity, and water depth. Microbiological assays included: total and fecal coliform bacteria, enterococcus, and bioluminescent bacteria. Trace organic and metal analyses of oyster tissue are ongoing.


Correlation analyses of water column bacteria loads and those in oysters suggests a significant positive correlation between fecal coliform bacteria, but not between enterococci, total coliform, or bioluminescent bacteria.
Strikingly, enterococci levels detected in oyster tissue and compared on a volume to volume equivalent with water were several orders of magnitude higher in oyster tissues. These observations suggest that oysters may be a significant source of enterococci contamination of coastal waters. If this is the case it may have significant implications for the use of enterococci in coastal waters as indicators of sewage contamination.

Presentations [PDF posters, each opens in new window]:

Presented at SETAC conference, November 2005, Baltimore, Maryland
(The Society of Environmental Toxicology and Chemistry)

Presented at ASLO conference, February 2006, Honolulu, Hawaii
(The American Society of Limnology and Oceanography and The Oceanography Society co-sponsor this meeting.)

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This page was updated October 13, 2006