Stressors are factors that alter the biological performance or state of an ecosystem. Primary stressors include harmful algal blooms, chemical contaminants, nutrients, and pathogens that impact coastal habitats, resources, and communities, including bivalve species and shellfish aquaculture. Environmental stressors can cause a variety of biological responses in marine organisms, ranging from the biomolecular and biochemical effects at population and community levels. Our projects include short-term indicators, such as biomolecular and biochemical responses, and longer-term ecologically-relevant indicators. These serve to provide measurement endpoints used to determine threshold levels of stressors beyond which impacts on the physiological performance of bivalves are observed.

Biomarkers of environmental stress at lower levels of biological organization can provide direct evidence of exposure to stressors while intermediate-level responses such as histopathological, bioenergetic, immunological, and reproductive changes can help predict stress effects at the individual, population, and community levels.

Responses at higher levels of organization (populations, communities) are relatively insensitive (giving a long-term response) to stressors but have higher ecological relevance and are therefore more directly applicable to Environmental Risk Assessment and Environmental Management processes.

Responses at the lower levels of biological organization have the primary advantage of being relatively sensitive (giving a short-term response) to stressors thus serving as "early warning system" of organisms impaired physiological performance. Biomarkers, however, can not be considered useful indicators of marine organisms health unless they are causally linked to ecologically-relevant responses such as population or community-level endpoints. For the determination of threshold levels, experiments are conducted under laboratory and field conditions.

The BIVALVIANET will provide the science to help managers understand the biological effects of environmental stressors, including contaminants and nutrients, and develop actions over time, or respond quickly to avert a crisis.