MEPS 173:275-288 (1998)  -  doi:10.3354/meps173275

Effect of habitat selection on the dietary patterns of two triglid species

Mary Labropoulou1,*, Athanasios Machias2

1Department of Biology, University of Crete, PO Box 2208, GR-71409 Iraklion, Crete, Greece
2Institute of Marine Biology of Crete, PO Box 2214, GR-71003 Iraklion, Crete, Greece
*Present address: National Center for Marine Research, Agios Kosmas, GR-16604 Hellinikon, Greece. E-mail:

ABSTRACT: The distribution patterns and feeding habits of 2 triglids, Trigloporus lastoviza and Lepidotrigla cavillone, were investigated for fish collected in experimental trawl surveys carried out along the Cretan continental shelf over 4 yr. Despite their distribution overlap, depth and temperature selection differs considerably between species. T. lastoviza tended to select shallow depths and warm temperatures among those available, whereas L. cavillone was distributed throughout the exploited area and no significant temperature selection was found. Furthermore, no evidence of any size-depth relationship in either fish species was detected. Stomach content analysis revealed that both species were carnivores, feeding mainly on benthic invertebrates, and that each species consumed a narrow range of prey species with no significant dietary overlap. Classification and ordination of the gravimetric and numerical contributions of prey species in their diets demonstrated that the dietary samples of the 2 species were distinct. Interspecific dietary overlap was less than intraspecific overlap between size classes and between months. Trophic diversity was higher for T. lastoviza and increased significantly with fish size, while no effect of size on the low dietary breadth of L. cavillone was found. Species differences in preference and utilization of prey are related to their distribution patterns. In particular, T. lastoviza exhibited the most restricted distribution and appeared to have a broader trophic niche than L. cavillone, which occurs in a wider depth range. The results suggest that the ability 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 which they co-occur.

KEY WORDS: Triglidae · Depth selection · Temperature selection · Ontogeny · Prey selection · Resource partitioning · Niche

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