Bivalves and Eutrophication

Collaborators:  Kyle Emery (UC Santa Barbara), Mike Pace (UVA), Mark Brush (VIMS), Jennie Rheuban (WHOI), and Iris Anderson (VIMS)

Driven by the rapidly growing industry and the increasing interest in the use of bivalves to meet regulatory water quality goals, we investigated the influence of clams on ecosystem functioning.  We used a modeling approach to assess the role clam aquaculture plays in C and N cycling within a small shallow estuary, Cherrystone Inlet.  Our study highlights the importance of considering impacts of bivalve aquaculture in an ecosystem context, particularly when determining its influence on eutrophication.


Although the clam beds occupy only 3% of the ecosystem’s surface area, clams filtered 7-44% of the systems’s volume daily, consumed an annual average of 103% of the phytoplankton production, creating a large flux of particulate C and N to the sediments.  Annually, N regenerated and C respired by clam and microbial metabolisms were 3- and 1.5-fold higher, respectively, than N and C removed through harvest.  Due to the short water residence time, the low watershed N load, and the close vicinity of clam beds to the mouth of Cherrystone, cultivated clams are likely subsidized by phytoplankton from the Chesapeake Bay.  So, the N released by mineralization at the clam beds would not be present in the system without bivalve facilitation and the macroaglae that are fueled by this N represents a eutrophying process resulting from aquaculture.

Read more:

A.E. Murphy, K.A. Emery, I.C. Anderson, M.L. Pace, M.J. Brush, J.E. Rheuban. 2016. Quantifying the effects of commercial clam aquaculture on carbon and nitrogen cycling: An integrated ecosystem approach. Estuaries and Coasts. DOI 10.1007/s12237-016-0106-0