Diet of round sardinella, Sardinella aurita, larvae in relation to plankton availability in the NW Mediterranean

Abstract

The present study analyses for the first time the diet of larvae of the clupeid Sardinella aurita in the NW Mediterranean. Gut contents of larvae from first feeding (3.9 mm) to early postflexion stages (14.7 mm) were analysed. The type and abundance of ingested prey were related to the plankton composition in the environment in order to determine prey-type selectivity. The feeding incidence observed was among the highest reported for clupeid larvae, with higher values during the day (68.6%) than at night (7.7%), indicating that Sardinella aurita larvae are diurnal predators. The mean number of ingested prey was 3.3 (±2.51). The width of the prey increased from <30 to 410 μm with the development of the larvae, but the niche breadth did not vary with the size of the larvae. The diet was based on different stages of copepods (nauplii and postnauplii) and cladocerans (mainly Evadne spp.), though the preference for each type of prey varied, with higher preference for copepod nauplii in larvae <8 mm and a higher preference for Evadne spp. in larvae ≥8 mm. The copepod based diet of S. aurita larvae is very similar to that reported for Engraulis encrasicolus larvae in the Mediterranean, indicating a possible competition for food between the first-feeding larvae in situations of low prey abundance. © The Author 2008. Published by Oxford University Press. All rights reserved.