Use of L-DOPA and soluble bacterial products to improve set of Crassostrea virginica (Gmelin, 1791) and C. gigas (Thunberg, 1793)

Solutions of L-dihydroxyphenylalanine (L-DOPA) and culture supernatants of the marine bacterium Shewanella colwelliana were used to treat competent Crassostrea larvae before transferring them to setting tanks. Setting trials were done in laboratory containers and on a larger scale in a Chesapeake Bay hatchery. Hatchery results showed a consistent and repeatable improvement in set of C. virginica after treatment with either L-DOPA or bacterial supernatants. Laboratory results were more variable, and differences between treatments were less pronounced. Pretreatment of larvae with theophylline led to a more rapid onset of settlement behavior in L-DOPA treatments but not in supernatant treatments, and had no clear effect on over-all set on cultch.