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

Abstract

The effect of adding algae to the culture water used to rear red drum larvae was evaluated in terms of growth, survival and digestive enzyme activity. Red drum larvae were subjected to one of the following dietary regimes from first feeding (day 3 post-hatch) to day 14: (1) zooplankton supplemented with algae (L-A), (2) zooplankton without algae (L-NA), (3) a microparticulate diet with algae (M-A) and (4) the microparticulate diet alone (M-NA). The presence of algae in the rearing tanks improved growth of red drum larvae for both types of feeds. Growth was significantly higher ( P<0.05) in larvae 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 larvae raised on the microparticulate diet and algae (M-A) grew as well as the zooplankton treatment with no algae (L-NA), and were not significantly different from the L-A treatment. The larvae fed the microparticulate diet in the absence of algae (M-NA) were significantly smaller than the other three treatments. These results were consistent for two separate feeding trials. Final survival was highly variable in all treatments; nevertheless, mean final 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 was observed in the presence of algae, which may have influenced the digestion of the diet. Our results demonstrate that red drum larvae may be raised on a microparticulate diet from first feeding without the use of zooplankton.