Abstract

Phytoplankton biomass and quality caused variation in the larval life span of queen conch, Strombus gigas. Conch larvae were grown in the laboratory on two sources of natural seawater. Great Bahama Bank and Exuma Sound, and on cultured algae, Caicos Isochrysis and Choetoceros gracilis. Larvae were also fed a continuous supply of natuíal phytoplankton from Bahamian waters in a fieldenclosed mesocosm system. Metamorphic competence was achieved in the shortest time (day 16) in the mesocosm system. In the laboralory larvae were competent by day 26 in the Bank water and day 20 in the cultured algal treatments. Veligers fed Sound waters did not achieve metamorphic competence. Food source was best characterized by cell counts and composition, than Chl a concentrations. Bank and Sound waters had similar Chl a levels, however, Bank water had larger cells, more taxa and higher cell count. Natural foods can be used as an alternative food source for culturing S. gigas larvae. Results from feeding studies using natural foods can also be used to predict dispersal potential in the field.

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