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We assessed the ecological uniqueness of fish and crustaceans in traditional fishing grounds from a tropical shallow marine ecosystem, where bycatch is historically high. Trimestral trawling was carried out between November 2009 and August 2010 in nine sites along 80 km of coastline in South Brazil. We investigated the local (LCBD) and species contribution to beta diversity (SCBD) using beta regression models, disentangling the influence of environmental (water, sediment characteristics) and biotic (S, abundance, diversity, dominance) parameters over LCBD; and species occurrence, total and mean local abundance association with SCBD. The shallow marine areas presented high beta diversity of fish and crustacean. We identified two ecological unique sites for fishes that occurred in colder sites, while the only unique site identified for crustaceans occurred, where crustacean species richness was lower. The ecological unique sites for both taxa were those with lower species richness and abundance, with distinct assemblages’ composition, although the location of the unique sites differed between taxa. Species contribution to beta diversity was mostly driven by species with intermediary–high distribution on the region with high variability in occurrence and abundance. High biodiversity is the general rule when assessing bycatch species, and the singularity of the species composition in the unique sites stems from the occurrence of rare species, which increases the size of the species pool. [ABSTRACT FROM AUTHOR]

Headwater streams subjected to anthropogenic impacts are prone to environmental quality decay, which may affect stream functioning. To investigate the effects of loss of environmental quality in stream functioning, we tested the hypothesis that leaf breakdown is faster in streams with higher environmental quality, and that invertebrate community structure and microbial biomass are negatively affected by habitat simplification resulting from environmental degradation. We submerged Alchornea glandulosa leaves in litter bags in nine streams, in Southern Brazil, in an environmental gradient. We characterized breakdown rates (k), physical in-stream characteristics, abundance of invertebrate taxa, and functional groups and microbial biomass for each stream, with three mesh exclusions (fine, medium, coarse). Breakdown was faster in the most preserved stream (k = − 0.032 ± 0.005) and decreased towards the most disturbed stream (k = − 0.0034 ± 0.001). Breakdown rates were positively associated with underwater habitat complexity, equitability of macroinvertebrate taxa, and abundance of Stenochironomus sp., which together explained 51% of breakdown rate variability. Breakdown rates from the less disturbed streams (n = 7, excluding urban-influenced) were lowest in medium-mesh, intermediate in fine-mesh, and highest in coarse-mesh bags, and the only taxon that differed according to this pattern was the mining-chironomid Stenochironomus sp., which suggests that this taxon had a significant activity of leaf processing. [ABSTRACT FROM AUTHOR]

This study was developed as a research of first order streams fish assemblages located in two Conservation Units in Northwestern Paraná, Brazil, with the purpose of providing information about ichthyofauna composition of these water bodies while they are still under protection. There were captured 2,557 individuals belonging to six orders, nine families and 10 species in three streams. The most abundant species were Phalloceros harpagos (44%) from Conceição stream, Astyanax aff. paranae (14%) and P. harpagos (12%) from Jurema stream, and Melanorivulus apiamici (9%) from Conceição stream. Trichomycterus sp. could not be identified into a specific level, meaning it can represent an undescribed species to science, registered for the first time at the upper Paraná River basin. [ABSTRACT FROM AUTHOR]

The Itajaí-Mirim river basin, SC (Brazil) is a reference in the collection of water for public supply compared to the other basins that make up its territory. However, it presents a greater contribution of sanitary sewage throughout its course. In this context, the objective of the present article is to select streams allocated to different land uses and to understand the influence of land use on water quality, as a provision ecosystem service and preponderant to the health of the population. The methodological steps developed for the choice of streams were geoprocessing and field activity, while for the monitoring of water quality, the analysis of physical-chemical parameters was carried out. The results obtained showed that the use of land influences the quality of water in streams, being negative in rural and urban areas, as a chemical and physical contaminant attribute regarding the discharge of untreated effluents into the watercourse; and positive to the potability of water in forested area. It is important to encourage action by the public power for the development of policies and guidelines aimed at territorial planning, whose essential resource for the provision of human activities is in potential degradation. [ABSTRACT FROM AUTHOR]