SUBSTRATE UTILIZATION IN A MEDITERRANEAN LITTORAL FISH COMMUNITY

Substratum use and spatial relationships in a littoral fish assemblage (families Blenniidae, Tripterygiidae and Gobiidae) were studied along the coast of northeastern Spain, All the species considered displayed a clear preference for a specific substratum type, and that preferenc e was unrelated to substratum availability in the environment. Both th e number of species and species density were distinctly higher for ble nnies and threefin blennies at depths of less than 1 m. Larger numbers of species and higher density levels were observed in areas where roc k and blocks were abundant as opposed to areas in which sand, gravel, or Posidonia oceanica beds predominated. The gobiids, in contrast, did not exhibit any clear tendency over the depth range considered. The r esults on the disjunct distributions, changes in niche breadth Values for sympatric and allopatric distributions of species pairs, and varia tions in niche breadth and overlap with species richness appear to sug gest that substratum occupancy by most species has no adverse effect o n the other species present.