Ontogeny of pancreatic enzymes in larval red drum Sciaenops ocellatus

The growth, survival and trypsin, lipase and amylase activities of red drum larvae were measured in two experiments. For the first trial, a group was fed live prey only (L) and another group was fed a combination of a micropa rticulate diet (MPD) and live food (L-MP). For the second growth trial a gr oup fed the MPD only (MP) and a starvation group (ST) were examined in addi tion to the L and L-MP treatments. Enzyme activities of live prey were meas ured to estimate their possible contribution to larval digestion. No signif icant (P > 0.05) differences in final size and survival were observed betwe en treatments L and L-MP. Larvae subjected to starvation or fed the MPD die t alone were smaller than treatments fed live prey and did not survive past days 5 and 14, respectively. Trypsin, lipase and amylase activities were d etectable at hatching. No significant differences (P > 0.05) in total enzym e activities among treatments were observed before day 14. Specific activit y of trypsin, lipase and amylase peaked on day 3 (prior to first feeding) a nd subsequently decreased. For trypsin, the percentage of enzyme activity p otentially attributable to ingested prey increased with age to a maximum of 17%. For lipase and amylase this fraction was less than 5% throughout the study, except on day 8 (12% and 24%, respectively). The lack of significant differences observed in the activity of digestive enzymes among treatments suggests that dietary regime, availability of prey and possible effects of exogenous enzymes did not significantly influence enzyme activity. Therefo re, the lower growth rate observed in the L-MP, MP and starved treatments c annot be attributed to low digestive enzyme production of the enzymes measu red. It is more likely that the MPD failed to supply the required nutrients for adequate development.