SELECTIVITY IN THE NATURAL DIETS OF ACARTIA-TONSA DANA (COPEPODA, CALANOIDA) - COMPARISON OF JUVENILES AND ADULTS

Selective feeding in nature was compared for adults and two stages [Na uplius VI (NVI) and Copepodite I (CI)] of juvenile Acartia tonsa Dana collected from the northern Gulf of Mexico, Florida, USA. High perform ance liquid chromatography (HPLC) was used to compare the concentratio ns of four carotenoid pigments from copepods in incubating chambers to those from the surrounding water column. Adult copepods ingested sign ificantly more pigment than the juveniles, however no difference was f ound between the relative proportions of pigments ingested by the thre e stages. Adults were shown to feed selectively in 50% of the experime nts, while juvenile stages fed selectively in 75%. The results suggest that conclusions derived from studies on natural feeding of adult cop epods cannot always be extrapolated to juveniles of that species.