Diagnóstico ambiental do médio e baixo rio Araguari para gestão e conservação de peixes, Amapá, Brasil

Abstract

Aquatic ecosystems are vulnerable to the carrying and increase of various types of contaminants, especially inorganic contaminants, from various anthropogenic sources. Thus, the study aimed to: evaluate the composition of vegetation cover the points in the middle and lower courses of the Araguari River as factors influencing the concentration of inorganic contaminants (As, Cd and Hg) in the water, in the muscle of the fish species Plagioscion squamosissimus, in addition to detecting these contaminants in otoliths of the same species. Sampling for water and fish collection was carried out between March and June 2019 in the middle and lower Araguari River, in the state of Amapá. The evaluation of land use was carried out using the Argis software, the quantification of inorganic contaminants in the muscle tissue of the species was performed using the atomic absorption spectrophotometer technique and the detection of inorganic contaminants in otoliths using the plasma spectroscopy technique Laser Induced (LIBS). The stretches of the middle and lower Araguari River indicated higher proportions of forest fragments and expansions of buffalo pastures. The concentrations of Cd and Hg in the water samples in the middle and lower Araguari River presented values in disagreement with the legislation and indicated risks for the preservation of the aquatic biota. The concentrations of Cd in the muscular tissue of P. squamosissimus in the lower Araguari River presented values in disagreement with the Brazilian legislation, indicating risks to human health due to the consumption of its muscular tissue. The bioaccumulation factor indicated that Hg was bioavailable in water. In addition, inorganic As, Cd and Hg contaminants were detected in otoliths in individuals from the middle and lower Araguari River. The highest concentrations of As and Cd in the otoliths were found in specimens sampled in the middle portion of the Araguari River and Hg in the low portion. The results indicated that the Araguari River is undergoing processes of environmental disturbances, requiring projects aimed at the constant monitoring of this water resource, as well as mitigating measures to maintain the local biodiversity.