Objectives:   The National Status and Trends (NS&T) Program is designed to monitor the present status of and to detect temporal changes in the environmental quality of our Nation's Great Lakes, estuarine and coastal waters. One component of the NS&T Program is the Mussel Watch Project. This project is designed to monitor the status of and temporal changes in metal and organic contaminants in Great Lakes, estuarine and coastal waters using bivalve molluscs as sentinel organisms. Measured contaminants include a suite of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides and trace elements. Mussel Watch also monitors the health of these bivalve populations through the measurement of a variety of biological indices such as condition index, size frequency, stage of reproductive development, and prevalence and intensity of diseases, parasites and pathologies. The sites for this program are selected to be representative of general conditions in Great Lakes, estuarine and nearshore waters, away from point source waste discharges. Target bivalve species include the mussel Mytilus edulis and the oyster Crassostrea virginicaon the East coast, C. virginica on the Gulf coast, C. rhizophorae in the Caribbean, M. edulis complex and M. californianus on the West coast and in Alaska, and the zebra mussel, Dreissena polymorpha, and quagga mussel, D. bugensis, in the Great Lakes. In all, over 100 sites are sampled once yearly during the winter months, except dreissenid mussels collected in late August through September.

Work elements:  The Haskin Shellfish Research Laboratory coordinates the biological component of Mussel Watch and conducts all of the biological analyses. Besides condition index, size frequency, and stage of reproductive development, these analyses include a full histopathological analysis designed to enumerate the prevalence and intensity of a variety of diseases such as MSX and Dermo disease in oysters, pathologies such as digestive gland atrophy, tumors and inflammatory processes, and parasites such as cestodes, trematodes, nematodes and ciliates. Mussel Watch is the first large-scale monitoring program to use a quantitative approach to histopathological analysis including the direct enumeration of parasites and the development of semiquantitative scales for disease intensity and extent of pathological condition.

  Analyses of chemical contaminants in bivalve tissues are conducted by chemists at the TDI-Brooks International (formerly at the Geochemical and Environmental Research Group) and the Department of Oceanography, Texas A&M University. TDI-Brooks International is also responsible for sampling and final data analysis. Methods of chemical analysis developed during the Mussel Watch Project are now accepted as state-of-the-art. In addition, Mussel Watch has established a nationally-recognized laboratory intercalibration program to assure the comparability of contaminant analyses among different analytical laboratories. All data collected by the NS&T Mussel Watch monitoring program are stored on-line in the NOAA NS&T office in Silver Spring, MD.

Status:   The Mussel Watch Project is currently (as of March 2006) in its 21st year. During this time, Mussel Watch has documented significant changes in contaminant body burdens and population health on all three coasts of the United States. As examples, significant declines in tributyl tin and certain chlorinated pesticides have been documented following regulations limiting their use in the environment. Disease and condition index of oysters have been shown to follow the El Niño cycle in the Gulf of Mexico with declines in health associated with El Niño-associated changes in climate, particularly rainfall. Latitudinal gradients in contaminant body burden in oysters have been identified and correlated with latitudinal changes in reproductive activity, size, and condition. The Mussel Watch monitoring program will continue at least until the year 2009, at which time it will be one of the largest, longest running monitoring programs ever conducted and will have produced an unparalleled time series relating bivalve population health and contaminant body burden to changes in climate and human activities in every significant Great Lakes, estuarine and coastal water body in the U.S.