Clam Leukemia

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Gene expression during development of clam leukemia: interactive effects of temperature and ocean acidification on viral loading and onset of disease

Charles Walker, Professor of Molecular, Cellular and Biomedical Sciences, UNH (603.862.2111); Michael Lesser, Research Associate Professor, Department of Biological Sciences, UNH (603.862.3442); and Kenneth La Valley, Assistant Director, UNH Cooperative Extension (603.862.4343)

The soft-shell clam fishery is an important recreational activity in N.H. and is a multi-million dollar commercial fishery in neighboring states. In 1997, researchers estimated a harvestable soft-shell clam population in Hampton/Seabrook Harbor, N.H., of 25,000 bushels, but that number has since fallen to only 5,400 bushels. This decline in clam abundance results in part from changes in water temperature and pH (e.g., ocean acidification). These environmental conditions coincide with clam leukemia that impacts these organisms when they first become reproductive at age two. Linkages between animal cancer and specific environmental parameters are often difficult to demonstrate. Analysis of genes that produce proteins known to be involved in clam leukemia could provide information on potential interactions with genes governing environmental responses that exacerbate the decline in clam populations in New England.

Charles Walker and his colleagues will inoculate clams with filtered hemolymph from clams with leukemia and follow the differential expression of genes known to be involved in clam leukemia and also stress from temperature, pH and viral infection. Researchers will use genetic markers to determine the effects of ocean temperature and/or acidification on clam mortality or product quality. This information will allow bivalve aquaculturists to improve their decision-making related to clam seeding, harvest and remediation. 

The results of this research will highlight unique gene expression patterns recognized as leukemia is initiated and advances that may be traced to the environmental stressors of seawater temperature and ocean acidification. Researchers plan to develop outreach programs to transfer critical habitat information from this study regarding the linkage between environmental stressors and shellfish productivity to resource managers, conservation biologists and coastal communities.