Modelos de distribuição de crustáceos decápodes dulcícolas em uma área de mineração na Amazônia brasileira

Abstract

The Carajás Mosaic is a complex of conservation areas located in the southeast of the Brazilian Amazon and recognized for the presence of important mineral resources. The region is considered strategic for the exploitation of iron ore, with the majority of mining activities conducted legally by VALE S.A., however, the presence of illegal mining in the region continues to represent a challenge. Given this context, this study aimed to analyze the composition of freshwater decapod crustacean communities and their relationship with the metals and metalloids found in sediment samples, as well as assessing the influence of water temperature. The samples were collected in 2022 at four locations in the Itacaiúnas River basin and four locations in the Parauapebas River basin, both located in the Carajás Mosaic, with two locations in each basin classified as impacted due to contamination by mining tailings and illegal mining and two considered unimpacted, during two different seasonal periods: rainy and dry. The relationship between crustacean communities and environmental variables was analyzed using multiple linear regressions, considering species richness and abundance as dependent variables, evaluating the influence of the sediment contamination threshold for the metals Al, Fe, Pb and Mn, the metalloid As and water temperature. During the two campaigns, ten species of crustaceans were identified, including shrimps and crabs. Analysis of the physicochemical variables in relation to the periods indicated that high concentrations of As, Fe, Pb and Mn were recorded in the rainy season, while the highest values for temperature and Al occurred in the dry season. The composition of the crustacean assemblages did not change significantly in relation to the period, basin or impact factor. Non-impacted areas showed greater abundance, while temperature variation was associated with a reduction in alpha and beta diversity, indicating negative impacts on the health of aquatic communities.