Co-feeding microparticulate diets with algae: toward eliminating the need of zooplankton at first feeding in larval red drum (Sciaenops ocellatus)

The effect of adding algae to the culture water used to rear red drum larva e was evaluated in terms of growth, survival and digestive enzyme activity. Red drum larvae were subjected to one of the following dietary regimes fro m first feeding (day 3 post-hatch) to day 14: (1) zooplankton supplemented with algae (L-A), (2) zooplankton without algae (L-NA), (3) a microparticul ate diet with algae (M-A) and (4) the microparticulate diet alone (M-NA). T he presence of algae in the rearing tanks improved growth of red drum larva e for both types of feeds. Growth was significantly higher (P < 0.05) in la rvae reared in the presence of algae (L-A and M-A) than in larvae raised in the corresponding treatments without algae (L-NA and M-NA). Red drum larva e raised on the microparticulate diet and algae (M-A) grew as well as the z ooplankton treatment with no algae (L-NA), and were not significantly diffe rent from the L-A treatment. The larvae fed the microparticulate diet in th e absence of algae (M-NA) were significantly smaller than the other three t reatments. These results were consistent for two separate feeding trials. F inal survival was highly variable in all treatments; nevertheless, mean fin al survival values were 30% higher in treatment L-A compared to L-NA (14.1 and 10.1%, respectively) and 42% higher in M-A than for M-NA (6.2 and 4.0%, respectively). Significantly higher trypsin and aminopeptidase activity wa s observed in the presence of algae, which may have influenced the digestio n of the diet. Our results demonstrate that red drum larvae may be raised o n a microparticulate diet from first feeding without the use of zooplankton . (C) 2000 Elsevier Science B.V. All rights reserved.