Connections among Land Use, Water Quality, Biodiversity of Aquatic Invertebrates, and Fish Behavior in Amazon Rivers

DE SOUSA, RODRIGO SILVA; SILVA, GILMAR CLEMENTE; BAZZAN, THIAGO; DE LA TORRE, FERNANDO; NEBO, CAROLINE; SIQUEIRA-SILVA, DIÓGENES HENRIQUE; CARDOSO-SILVA, SHEILA; POMPÊO, MARCELO LUIZ MARTINS; DE PAIVA, TERESA CRISTINA BRAZIL; DA SILVA, FLÁVIO TEIXEIRA; DA SILVA, DANIEL CLEMENTE VIEIRA RÊGO

Toxics

MDPI Publishers

Año: 2022 vol. 10

Rivers in the Amazon have among the greatest biodiversity in the world. The XinguRiver, one of the tributaries of the Amazon River, has a length of 1640 km, draining 510,000 km2in one of the most protected regions on the planet. The Middle Xingu region in Brazil has beenhighly impacted by mining and livestock farming, leading to habitat fragmentation due to alteredwater quality. Therefore, comparing two rivers (the preserved Xingu River and the impacted FrescoRiver) and their confluence, the aims of the present study were to (1) assess the land uses in thehydrographic basin; (2) determine the water quality by measurements of turbidity, total solids, andmetals (Cd, Cu, Fe, Mn, Pb, Zn, and Hg); (3) compare the zooplankton biodiversity; and (4) toevaluate the avoidance behavior of fish (Astyanax bimaculatus) when exposed to waters from theXingu and Fresco Rivers. Zooplankton were grouped and counted down to the family level. For theanalysis of fish avoidance, a multi-compartment system was used. The forest class predominatedat the study locations, accounting for 57.6%, 60.8%, and 63.9% of the total area at P1XR, P2FR, andP3XFR, respectively, although since 1985, at the same points, the forest had been reduced by 1.3%,25.7%, and 27.9%. The Xingu River presented almost 300% more invertebrate families than the Fresco River, and the fish population preferred its waters (>50%). The inputs from the Fresco River impacted the water quality of the Xingu River, leading to reductions in local invertebrate biodiversity and potential habitats for fish in a typical case of habitat fragmentation due to anthropic factors