LABORATORY CULTURE OF ZEBRA (DREISSENA-POLYMORPHA) AND QUAGGA (D-UGENSIS) MUSSEL LARVAE USING ESTUARINE ALGAE

Zebra (Dreissena polymorpha) and quagga mussel (D. bugensis) larvae we re reared through and beyond metamorphosis in the laboratory on diets of the estuarine algae, Isochrysis galbana T-Iso and Pavlova (= Monoch rysis) lutheri. Larvae were successfully spawned and raised in the lab oratory for over 1 year with routine survival to settlement. Some adul t males reared from an August 1994 spawn reached sexual maturity with active sperm by April 1995. Diets of dried Chlorella sp. and Synecococ chus sp. were unable to support larvae. Settlement of pediveligers at 22 degrees C occurred at approximate to 21 days for zebra mussel and 3 2 days for quagga mussels. Saturated fatty, acids predominated in I. g albana and P. lutheri, whereas polyunsaturated fatty acids (PUFAs) pre dominated in Chlorella sp. The process to culture dreissenid larvae in the laboratory is very labor-intensive and requires continuous cultur e of live algae maintained in log growth phase. Larvae are fed every o ther day at a density of 2 x 10(5) cells mL(-1) for the first week, an d then daily densities of 3-5 x 10(5) cells mL(-1) thereafter. Water q uality is critical. Larvae and juveniles should be stocked at densitie s of approximate to 1 mL(-1) and the water must be changed at least 3x wk(-1) in static cultures. Water must be changed at least weekly in t anks holding adult brood stock. Methods of controlling protozoan and r otifer infestation of cultures are also important for successful cultu re.