Use of response surface methodology to determine optimum diets for Venerupis corrugata larvae: effects of ration and microalgal assemblages.

Microalgal quantity and quality are major factors affecting bivalve larval growth. Effects of ration using bi-specific diet assemblages with varying proportions of the flagellate Isochrysis galbana and the diatom Chaetoceros neogracile were evaluated on Venerupis corrugata larval development. Response surface methodology was used to determine the optimal ration and better proportions of flagellate and diatom in the microalgal diet at different phases of larval development (early larva (< 190 μm, 10 days), 12 days, early pediveliger (15 days) and young postlarvae (26 days)). Maximum growth was obtained on day 10 for a diet of 22.5 cells μL − 1 of I. galbana , which suggests that C. neogracile was not ingested or digested by early larvae. On day 12 a maximum in the experimental domain was predicted for a diet of 22.5 cells μL − 1 of I. galbana and the lowest concentration of C. neogracile tested (30 cells μL − 1 ), as C. neogracile reduced growth of the larvae at higher concentrations. On day 15, maximum growth was found at 42.6 cells μL − 1 of C. neogracile and 27.9 cells μL − 1 of I. galbana . During metamorphosis and early postlarval growth optimal ration was 70 cells μL − 1 of a bi-specific diet in similar proportions to that previous stage of development. This novel approach to study bivalve larval nutrition allows the quality and quantity of the optimal diet to be determined. Statement of relevance This study is really relevant to the field of bivalve larval production because it defines the quality and quantity of the optimal diet for larvae of the clam Venerupis corrugata . The information provided in this paper has great applicability for clam larval production in commercial hatcheries. [ABSTRACT FROM AUTHOR]