Shellfish are a keystone species, studied by water quality
investigators to determine the health of a water body. Clams,
oysters, mussels and other bivalves filter seawater and, in the process,
can accumulate environmental contaminants in their tissues. Polluted
shellfish beds are often an early warning to a larger problem, upland
in the watershed, that needs immediate attention.
Bivalve shellfish also play an important role in the food web.
These grazers of the sea filter copious amounts of phytoplankton rich
water, converting it into a delectable dish — just as cows
grazing in a pasture convert grass into steak. The role of shellfish in
this transformative position within the marine ecosystem is essential
in the cycling of nutrients in our marine waters. By converting
phytoplankton into tissue and shell, the shellfish are able to improve
light penetration in the water column, reducing overall turbidity
and benefiting larger aquatic plants such as eelgrass.