| Popis: |
The wide geographical distribution of the Norway lobster, Nephrops norvegicus, results in a delay, with latitudinal decrease, in the larval season from spring to winter. Newly hatched larvae of the species may therefore be exposed to suboptimal levels or types of prey and face intermittent periods of starvation at low latitudes. This work investigated the feeding response of the first two zoeal stages of N. norvegicus under variable prey densities, prey types, feeding histories, and photoperiods. Both zoeae (Z) I and II increased the number of consumed prey with increasing food levels. ZI preferred Artemia sp. nauplii over larger metanauplii, while in ZII, higher ingestion was observed only for metanauplii at higher food concentrations. The number of prey ingested by larvae previously starved or under low food conditions was always higher than that of larvae exposed to high food levels. These findings seem to indicate that larvae may maximize prey ingestion in the presence of plankton patches with higher food abundance and minimize the deleterious effects induced by previous periods of intermittent starvation or unsuitable prey densities or types. Extreme photoperiods (24 and 0 h of light) did not improve larval feeding ability and are not a suitable option for larviculture. |
