EFFECT OF HABITAT SELECTION ON THE DIETARY PATTERNS OF 2 TRIGLID SPECIES

The distribution patterns and feeding habits of 2 triglids, Trigloporu s lastoviza and Lepidotrigla cavillone, were investigated for fish col lected in experimental trawl surveys carried out along the Cretan cont inental shelf over 4 yr. Despite their distribution overlap, depth and temperature selection differs considerably between species. T. lastov iza tended to select shallow depths and warm temperatures among those available, whereas L. cavillone was distributed throughout the exploit ed area and no significant temperature selection was found. Furthermor e, no evidence of any size-depth relationship in either fish species w as detected. Stomach content analysis revealed that both species were carnivores, feeding mainly on benthic invertebrates, and that each spe cies consumed a narrow range of prey species with no significant dieta ry overlap. Classification and ordination of the gravimetric and numer ical contributions of prey species in their diets demonstrated that th e dietary samples of the 2 species were distinct. Interspecific dietar y overlap was less than intraspecific overlap between size classes and between months. Trophic diversity was higher for T. lastoviza and inc reased significantly with fish size, while no effect of size on the lo w dietary breadth of L. cavillone was found. Species differences in pr eference and utilization of prey are related to their distribution pat terns. In particular, T. lastoviza exhibited the most restricted distr ibution and appeared to have a broader trophic niche than L, cavillone , which occurs in a wider depth range. The results suggest that the ab ility of these species to exploit particular habitats and/or specific prey characteristics is an important feature of predator foraging that allows them to segregate their feeding niche at the depth range at wh ich they co-occur.