Blue mussels are filter feeders and are useful for monitoring contaminants found in the ocean environment.
When compared to other parts of the U.S., Sitka National Historical Park’s intertidal zone has relatively clean waters. While some pollutants, including mercury, synthetic chemicals, petroleum, and organic fuels are present, they occur at comparatively low levels. However, private boat and cruise ship traffic appear to be increasing in waters adjacent to the park. As these and other human activities in the area expand, so does the potential for contamination.
While we still have a lot to learn about the effects of many pollutants on the marine ecosystem, research has already revealed some sobering results. Studies have shown that chronic exposure to low doses of certain synthetic chemicals, such as PCBs, hinders reproductive and immune systems, and exposure to high levels can kill wildlife.[1] The presence of mercury in marine animals disrupts kidney function, the central nervous system and reproduction.[2] Oil destroys the insulating effects of fur and bird feathers, causing hypothermia and impairing an animal’s ability to fly or swim. Oil can also smother small fish and invertebrates.[3]
In order to document and track the condition of marine waters in Sitka and other Southeast Alaska national parks, the National Park Service has launched a Marine Contaminants Monitoring Program. To conduct the study, researchers collect bay mussels and test them for hydrocarbons, persistent organic pollutants (such as pesticides and flame retardants), and heavy metals. Mussels are used because, as filter feeders, they ingest and retain whatever contaminants are present in the water.
The program began in 2007 by collecting enough mussels to establish baseline marine contaminant levels in each park. Regular, biennial mussel sampling began in 2009. Since that time the park service has joined the National Oceanic and Atmospheric Administration’s Mussel Watch Program. Through this program, park researchers will continue to collect samples, while NOAA conducts lab analysis and reports and manages data.
This long-term monitoring program provides critical data to understand trends and detect potential changes in marine contaminant levels. It will also serve as an invaluable reference should a catastrophic event, such as a chemical or fuel spill, occur in these increasingly well-traveled waters.
