Análise de metais pesados em espécies do gênero Trichomycterus da bacia do Rio Iguaçu

Abstract

The increase in human population is threatening life on planet Earth, including aquatic species, because along with it is the increase of waste discharged into bodies of water through human activities. Among several pollutants that affect aquatic ecosystems are essential and nonessential heavy metals. These are also called trace elements, and when in high concentrations pose risks to biota. Heavy metals pose a great danger to the aquatic ecosystem as they are not degradable and can bioaccumulate. Several rivers are already polluted, among them is the Iguaçu river basin, located in southern of Paraná State. The Iguaçu River has several species of endemic fish, that is, that occur only in this river. Among the endemic species found in the Iguaçu River are a specie of Trichomycterus genus, which is being threatened with extinction due to pollution. The use of these endangered species for research is very important, as many do not yet have enough literature, risking extinction without being known. Another consequence that the loss of these species can generate is the imbalance of the ecosystem, as they are part of the ecological interaction that exists in this environment. The genus Trichomycterus, popularly called "candirus" is part of the family Trichomycteridae, which belongs to the order of Siluriformes. The rivers used to collect these individuals were Jirau Alto, located in Dois Vizinhos, São José, Quati River affluent and Pedregulho river, located in Cascavel city, Paraná State. These rivers are tributary of the Iguaçu River. The equipment used to capture the Trichomycterus in Two Neighbors was the ‘covo’. In Cascavel, electric fishing was used. After collection, the identification key of Trichomycterus described by BAUMGATNER(2012) was used. This study aimed to analyze the cadmium, copper, lead, iron, manganese and zinc concentrations in Trichomycterus stawiarski and Trichomycterus sp.1, both located in two different municipalities. For heavy metals analysis the samples were opened dry and the samples were read by atomic absorption spectrometry. Statistical analysis to interpret the results of the concentrations in the species between each other and in the different sites was obtained through the double classification analysis of variance, the Krukal Wallis test and the principal component analysis (PCA). The results showed us that there is a difference in the concentrations of the metals studied in the different species and locations, especially in relation to cadmium and iron. Regarding the site, Cascavel had a higher concentration of identified heavy metals, which polluted the city of Dois Vizinhos. In relation to metal, cadmium was found at high temperatures, generating great ecological concern, as this is one of the most toxic metals even in small quantities. With a lack of limits under Brazilian law and studies have become difficult to interpret the reading of iron concentration and predict what can happen to a species over time.