Cryopreservation offers the opportunity to store embryos and larvae of the hard clam, Mercenaria mercenaria, for extended periods with negligible losses. Objectives for Phase I research include (1) to determine the efficacy of selected cryoprotectants in preserving and storing 2-8 cell clam embryos, (2) to determine survival and developmental competency of 2-8 cell embryos, trochophore and veliger larval stages in selected cryoprotectants, and (3) to assess effective freezing and thawing rates of cryopreserved hard clam embryos and larvae. Techniques previously employed in cryopreservation studies of oyster spermatozoa, embryos and larvae of marine mussels and sea urchins as well as techniques developed for vertebrate embryos will be screened. Selected cryoprotectants and procedures will be applied to test survival and developmental competency of hard clam embryos and larvae. Effective cryopreservation methods will be further tested for applicability in commercial scale culture facilities.
Anticipated Results:Considerable resources are dedicated to broodstock conditioning and maintenance in commercial bivalve culture operations. Atlantic Farms dedicates approximately one- fifth of its hatchery budget to broodstock to insure a constant year-round supply of spawnable adult clams. This system is not only expensive and cumbersome to operate, it also results in variable gamete quality and subsequent variable hatchery production. Cryopreservation technology would allow the consistent supply of required quantities of gametes of known quality to hatchery production. This would result in considerable savings not only in the operation of the hatchery but in the optimization of the entire production system (nursery and growout operations.) In addition, genetic improvements in selected stocks could be more easily realized in commercial-scale operations.
