Marker-assisted selection of hard clams for resistance towards QPX

Marker-assisted selection of hard clams for resistance towards QPX

qpxhisto

QPX cells (dark spheres) in clam mantle tissues. QPX disease remains the most significant infection affecting the hard clam in the Northeastern US.

The hard clam or northern quahog, Mercenaria mercenaria, is one of the most valuable seafood products in the Northeast representing the first marine resource in several states. Since the 1990’s, several Northeastern states have suffered severe losses in aquacultured hard clam stocks due to a fatal disease caused by a protistan parasite called Quahog Parasite Unknown (QPX).  The extensive scale of these mortality events resulted in the loss of several dozens of Millions of aquacultured market-size clams and significant impact on aquaculture operations. The overall objective of this proposal is to conduct a research program that employs molecular genetics tools towards providing the commercial aquaculture industry with improved clam stocks. Previous work demonstrated that clam susceptibility to QPX depends upon the geographic origin of the broodstock suggesting a genetic basis for clam resistance.  The central hypothesis is that clam resistance to QPX is genetically dictated and can be predicted using selected genetic markers. We will combine marker-assisted selection with traditional selection methods in conjunction with field and laboratory disease transmission studies to identify clam stocks that are resistant to QPX disease. The selection for QPX-resistant clam strains would allow the development and expansion of the hard clam aquaculture industry.  Information on genetic variation in clam broodstocks as related to disease resistance and growth will be widely diffused through our robust extension and outreach plan providing direct benefits to shellfish breeders and farmers.  Improved germplasm is expected to substantially reduce losses to QPX disease and enhance yields.  The growth of shellfish aquaculture can provide ecologically sustainable economic growth in coastal communities and decrease pressure on over-exploited capture fisheries.