O sistema nervoso entérico do catfish Rhamdia quelen em ambientes com diferentes tipos de ação antrópica ao longo da bacia do Rio Iguaçu

Abstract

The Iguaçu River has great ecological importance for the preservation of endemic species of fish, it also has socioeconomic relevance, mainly due to the presence of hydroelectric plants. In addition, it is a source of water, food and leisure for the municipalities located on its banks, being considered one of the most important rivers for the southern region of Brazil. The Iguaçu River is subdivided into three basins, exposed to different types of land use and occupation, with emphasis on agriculture for the Baixo Iguaçu region and industrial activities for the Middle Iguaçu and Alto Iguaçu regions. In this research, 70 fish of the endemic species Rhamdia quelen were used, from the Lower and Upper Iguaçu basins and collected at points with diferente types of anthropogenic pollution, derived from the various uses and occupations of the soil in the municipalities of Dois Vizinhos and Curitiba, in addition to animals were collected for negative control in the Environmental Conservation Unit of the Iguaçu National Park. Morphometric and quantitative alterations in the neurons of the Enteric Nervous System, in the cranial portion of the small intestine of the fish, were evaluated by means of evidence with methylene blue, as well as the presence of pesticides in the tributaries from which the individuals were collected. Through the ANOVA test and the chi-square test. It was determined that the pollution present in the tributaries led to cellular alterations, manifested by the increase in the proportion of large neurons and decrease in the density of myenteric neurons in the urban point of Curitiba and to a tendency to the presence of smaller neurons in the fish collected in the rural points of Dois vizinhos and Curitiba, in addition, the multiple residue test identified the presence of two pesticides, they being imidacloprid in the Preserved point of Dois Vizinhos and atrazine in the rural point of Curitiba. The results obtained corroborate the hypothesis that pollution anthropic development is affecting the optimal development of organisms.