Frequency of morphological alterations in the fish of Lake Guaíba and its application to environmental monitoring

Flores-Lopes, FábioMarcelo Reuss-Strenzel, Gil

This paper examined the association between the frequency of morphological alterations in fish and the physical and chemical parameters often used in monitoring water quality, with the aim of determining which places show most environmental degradation and which species are most affected. Fish samplings were standardized and carried out seasonally, using seine nets, in eleven locations in the catchment area of the Guaíba Lake. A total of 53,408 specimens were collected. Eight species were found to be constant in the samples and were therefore considered to be potential bioindicators. The highest frequency of morphological alterations was observed in the areas where the quality of water was the worst. Deformations of the opercular bones and of fin rays and spines were the most frequent alterations found. The repeated spatial pattern of the occurrence of deformations of fin rays and spines during two periods of study, points to this alteration as a good indicator of environmental quality.Key words: Guaíba. Environmental impact. Water quality.