CARACTERIZACION ESPACIO-TEMPORAL DEL NICHO TROFICO DE LA FAUNA ICTICA ANDINA DEL RíO MAULE, CHILE

fluvial systems of central chile show seasonal variations in: caudal, temperature and conductivity. this has influenced the ichthic native fauna, which has been characterized as primitive, with a low number of genera and species. the coexistence on native and exotic fishes in the maule river, chile (35°43°s;71°05°w), is registered since the beginning of the xx century; system in which the ecological interactions between these species have not been adequately evaluated. for this, in between two different seasons of the year 1988, four different locations were selected in the andean zone of the maule river and its tributaries. the ichthic fauna was obtained using total census, with electrofishing equipment, stomach contents of 142 specimens of oncorhynchus mykiss, basilichthys australis and salmo trutta were analized. the principal diet of the fishes analysed was basically benthic organisms, where chironomidae, ephemoroptera and trichoptera were the predominant. horn°s index was used to compare trophic niche overlap among species, finding a high overlap index in all seasons and locations. niche overlap and benthic diversity showed a negative relationship, this may indicate changes in the intensity of ecological interactions caused by changes in the gradient of resources