A vegetação ripária natural e sua importância para a manutenção e conservação da biodiversidade dos peixes da Bacia do Rio Piratini, RS, Brasil

Abstract

The problem of survival of fish in the present world still requires much studied, and immediate conservation efforts to support characterization studies and biomonitoring of aquatic biodiversity should be a priority, and in this way contribute to the knowledge base and clear guidelines for monitoring for the conservation of fauna and aquatic ecosystems of the Rio Grande do Sul state and Brazil. Currently lacks detailed studies that relate the influence or effect of natural riparian vegetation of streams with aquatic biodiversity. The fish are considered good indicators of long-term effects and habitat conditions in a broad scale fish have longer life cycles (3-10 years) than other organisms traditionally used as bioindicators. The determination of the influence of natural riparian vegetation on the composition and structure of the fish community, assessing the environmental integrity of the aquatic ecosystem in the water systems of the Piratini river basin are the target of this study. The study area covers six cities of Rio Grande do Sul state, totaled 50 sampling stations. Data were collected into six periods during the year 2012. The fish fauna survey was conducted in sampling stations with sampling effort of 40 min per station. Around stations was measured linear strip of natural riparian vegetation. Of the 50 sampled points, it was found that only 13 were regular and 37 (74%) were irregular, according to the Brazilian Forest Code - Law 12727/2012. Were identified 67 species belonging to 16 families. Through logistic regression (LOGIT) was found significance of some environmental factors. Of the 67 species, 47 showed a significant percentage of factors with the description of the occurrence. The categories analyzed had average power of description: 43.71% for water quality, 31.58% for habitat structure and 20.47% on the substrate type and 17.62% for riparian vegetation. The riparian vegetation was found to be closely related to other environmental factors such as temperature, dissolved oxygen, refuge for fish, shading and width of the water course.