Abstract

Food and temperature are factors that influence larval growth, development and survival of many marine invertebrates. In this job, the effect of these two factors was studied on the ingestion and digestion process of veligers of the Queen conch Strombus gigas, mollusc of commercial importance in the Caribbean region. Ingestion and digestion were measured by epifluorescence miscroscopy in new hatched larvae, distributed at 400 larvae*l-1. Five microalgal diets were tested: 2 Prasinophycea (Tetraselmis suecica, Tetraselmis chuii), 1 Chlorophyceae (Chlamydomonas coccoides) 1 Haptophyceae (I. aff. galbana) and 1 Bacillariophyceae (Thalassiosira fluviatilis). For each diet three temperatures were tested: 18, 28 and 32ºC. To detect ingestion, larvae were fed for two h, and observed under the epifluorescence microscopy each h. To observe digestion, larvae were sieved and placed in new containers with filtered seawater without food. Digestion was observed each h, during 8 h, and at 24 h after feeding. All observations were done in live larvae. A qualitative estimation of the stomach filling was done and feeding behavior between different diets and temperatures was compared by means of the absolute ingestion index (AII) and the absolute digestion index (ADI). At 18ºC, in all the diets, the AII was ? 90%, except for T. fluviatilis where this index was 15%. At 28ºC and 32ºC the AII varied between 90 and 97%. With respect to digestion, T. fluviatilis was neither digested at 18ºC nor at 28ºC. At 32ºC, this index was 66%. With the other diets, at 18ºC the ADI was < 65%; and at 28ºC and 32ºC this index was between 80 and 86%

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