Industrial impacts on eastern Amazon streams assessment with benthic EPT community, leaf litter decomposition and...

Stream ecosystems are highly sensitive to land-use changes driven by industrialization, which can disrupt their physical habitat, biological communities, and functioning. While this is a global phenomenon, impacts on tropical streams are relatively unknown. To understand these impacts, we assessed several structural and functional indicators in ten rivers of the eastern Amazon, half of them flowing through areas affected by a complex of industrial activities including mineral processing, port infrastructure, transportation, and urban development and the other half in unimpacted (control) areas. We examined benthic macroinvertebrate communities (by means of Ephemeroptera, Plecoptera and Trichoptera; EPT), leaf litter decomposition of the native plant species Goupia glabra, and the relative role of microbes and associated fauna in the decomposition process, in two different seasons (dry and rainy). Industrial streams exhibited lower EPT abundance than control streams. Microbial decomposition was similar between treatments, whereas total decomposition was higher in control streams at advanced stages of the process, suggesting a key role of associated fauna. Industrial streams showed reduced colonization of leaf litter in terms of macroinvertebrate abundance and richness. Although these trends seemed to persist across seasons, many were significant only during the dry season. Our findings highlight the detrimental effects of multiples anthropogenic pressures particularly those related to industrial expansion, unregulated urbanization, and inadequate sanitation infrastructure on tropical streams. These results underscore the need for integrated conservation and management strategies that account for the cumulative impacts of diverse land-use changes to preserve stream biodiversity, ecological functioning, and ecosystem services.