School of Marine and Atmospheric Sciences
Stony Brook University
Stony Brook, NY 11794-5000

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Bassem Allam

Dr Bassem Allam, Associate Professor

Effect of environmental factors on Quahog Parasite Unknown (QPX) disease development and resulting mortalities in the hard clam, Mercenaria mercenaria

The hard clam or quahog (Mercenaria mercenaria) is one of the fastest-growing marine fisheries on the Atlantic seaboard. In NY, the fishery is worth approximately $15 million per year. In summer 2002, NY hard clam fishery was significantly affected by an epizootic of QPX disease; an infectious disease which has emerged as a significant problem for the clam industry in Massachusetts and Virginia since the 1990's.


Cultured QPX cells


This project is based on our field results showing the seasonality of the infection. It uses laboratory approaches to evaluate the effect of major environmental conditions on disease development and resulting mortalities. In addition to disease status, the effect of environmental factors on general and specific clam defense factors is also being carried out, including factors associated with cellular and humoral immunity and the expression of genes involved in the immune response. Cellular and molecular aspects of clam immune response to the infection, including state-of-the-art genomics tools (micro-aeeay or DNA chips), are now being specifically targeted in the framework of a new externally-funded project. More information can be found here.

Clam shucking (image courtesy NYSDEC)

The disease, also called Chytrid-like disease, is caused by Quahog Parasite Unknown (QPX), an organism that belong to the family called Thraustochytriidae (Phylum Labyrinthulomycota or Labrinthomorpha), a group that has already been associated with mortalities of cultured abalones and infections in wild nudibranchs. Many aspect of the life cycle and the biology of QPX remain unknown but some additional information about the disease can be obtained by reading this fact sheet.

Fresh mount of clam tissues showing 3 QPX cells

This project is a collaboration with Mrs. Debra Barnes (NYSDEC) and Dr Arnaud Tanguy (University of Paris 6, Station Biologique de Roscoff, France)

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Last update: June 2010