Características biológicas y espectro trófico durante el otoño de dos poblaciones simpátricas de "blennius fzuviatilis" y "micropterus salmoides" en un embalse pequeño

Abstract

Therc exist strong differences in size frequency distribution, fecding habits and in habitat use between the populations of "Blennius fluviatilis" and "Micropterus salmoides" coexisting in a small reservoir in NE Spain. Blcnnies are short-sizcd than largemouth bass, its diet is based upon benthic invertebrates, mainly chironomids larvae and inayfly nimphs, and use a habitat without vegetation, madc of large bedrocks and situated in a precise point in the study site. Largemouth bass, on the contrary, use mainly the rcservoir vegetated edges -from which exclude the rest of the fish spccics-, feeds on water coluinn invertebrates (chironomids pupae and zigopterans ninfae) and fishes and are much larger than blennies. These facts, togethcr with a similar behavior of blennies in a ncar site, which lacks largemouth bass (Matarrafia river), make us to suppose the Iack of strong interactions between both species, in the sense that one of them were displaced from his optimun habitat. Nonethcless, the presence oí' young largcmouth bass in blennies habitat rnay be the cause of an inversion in the fceding rriicrohabitat of thc last specics.