#1: Farmed clams and oysters are native species grown in their natural habitat and have a critical role in tidal ecology.
The quahog or hard clam Mercenaria mercenaria and the eastern oyster, Crassostrea virginica are common native species on the tidal flats of Cape Cod. They are co-evolved with other local salt marsh organisms and we grow them at densities that are similar to those of historical populations of these species. The ability of healthy populations of clams and oysters to act as estuarine filters, taking in large volumes of water has a positive impact on the nitrogen budget of a tidal flat (Rice, 2001). Phytoplankton, which take up nitrogen from the water, are consumed by shellfish which incorporate the nitrogen into their body tissue in the form of protein. When the shellfish are harvested nitrogen is removed from the local system which helps maintain a healthy nitrogen balance in the bay (too much nitrogen in tidal waters leads to eutrophication and oxygen depletion). Furthermore bivalves deposit organic nitrogen in the sediments enhancing denitrification by sedimentary bacteria. Bivalves can also reduce turbidity by filtering phytoplankton from the water which increases light penetration to ecologically important sea grasses and micro algae on the bottom (Newell, 2004). In our growing area we are nurturing healthy bivalve populations that contribute to the overall well being of the tidal ecosystem.
Newell, R.I.E, 2004. Ecosystem influences of natural and cultivated populations of suspension-feeding bivalve mollusks: a review. J. Shellfish Research. Vol. 23, No. 1, 51-61.
Rice, M.A. 2001. Environmental impacts of shellfish aquaculture: filter feeding to control eutrophication. pp. 76-86 In: Marine Aquaculture and the Marine Environment. January 2001, Cape Cod Press, Falmouth, Massachusetts.