Survival, metamorphosis and growth of larvae from four penaeid species fed six food combinations

Abstract

Survival, metamorphosis and growth of four larval shrimp species, Penaeus aztecus, P. setiferus, P. vannamei and P. stylirostris, were compared after feeding six food combinations. The food combinations consisted of the diatoms, Skeletonema costatum and Chaetoceros gracilis, or the phytoflagellates, Isochrysis sp. and Tetraselmis chuii, alone or in combination with live Artemia nauplii. Post-larval survival, within each algal food type, was not improved by feeding Artemia beginning at the second protozoeal versus the first mysis substage. In addition, larvae fed only algae survived as well as their counterparts fed Artemia, P. stylirostris was the only species tested which survived significantly better to the post-larval stage when fed diatoms rather than phytoflagellates, regardless of treatment. Except for P. stylirostris fed phytoflagellates, metamorphic rates to the post-larval stage were not improved by feeding Artemia beginning at the second protozoeal versus the first mysis substage. All larval species fed phytoflagellates only rather than diatoms only were delayed metamorphically. Only for P. stylirostris did all the diatom treatments result in better metamorphic rates when compared with their phytoflagellate counterparts. Post-larval dry weights, for the four shrimp species studied, were improved when fed Artemia at the second protozoeal substage regardless of algal food type. Except for P. aztecus, growth was significantly better for all species fed the diatom treatments versus their phytoflagellate counterparts. Larval growth, in terms of biomass rather than survival and/or metamorphic rates, is a better measurement of the nutritional value of a larval diet.