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      Effects of deforestation on headwater stream fish assemblages in the Upper Xingu River Basin, Southeastern Amazonia

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          Abstract

          ABSTRACT The expansion of the Amazonian agricultural frontier represents the most extensive land cover change in the world, detrimentally affecting stream ecosystems which collectively harbor the greatest diversity of freshwater fish on the planet. Our goal was to test the hypotheses that deforestation affects the abundance, richness, and taxonomic structure of headwater stream fish assemblages in the Upper Xingu River Basin, in Southeastern Amazonia. Standardized sampling surveys in replicated first order streams demonstrated that deforestation strongly influences fish assemblage structure. Deforested stream reaches had twice the fish abundance than reference stream reaches in primary forests. These differences in assemblage structure were largely driven by increases in the abundance of a handful of species, as no influence of deforestation on species richness was observed. Stream canopy cover was the strongest predictor of assemblage structure, possibly by a combination of direct and indirect effects on the provision of forest detritus, food resources, channel morphology, and micro-climate regulation. Given the dynamic nature of change in land cover and use in the region, this article is an important contribution to the understanding of the effects of deforestation on Amazonian stream fish, and their conservation.

          Translated abstract

          RESUMO A expansão da fronteira agrícola amazônica representa a mais ampla mudança na cobertura e uso da terra no mundo contemporâneo, e ameaça a integridade de ecossistemas de riachos que abrigam a maior diversidade de peixes de água doce do planeta. Nosso objetivo foi testar as hipóteses de que o desmatamento afeta a abundância, a riqueza e a estrutura taxonômica de assembleias de peixes em riachos de cabeceira na bacia do alto rio Xingu, no sudeste da Amazônia. Por meio de amostragens padronizadas realizadas em riachos de primeira ordem, demonstramos que o desmatamento influencia fortemente a estrutura das assembleias de peixes. Riachos em áreas desmatadas tiveram o dobro da abundância de peixes que riachos em áreas florestadas. Essas diferenças na estrutura das assembleias foram em grande parte causadas pelo aumento na abundância de algumas poucas espécies, já que nenhuma influência do desmatamento na riqueza de espécies foi observada. A cobertura de dossel sobre os riachos foi o mais forte preditor da estrutura das assembleias, possivelmente por uma combinação de efeitos diretos e indiretos relacionados à provisão de detritos florestais, recursos alimentares, morfologia dos canais, e regulação micro-climática. Dada a natureza dinâmica da mudança na cobertura e uso da terra na região, este artigo é uma contribuição importante para a compreensão dos efeitos a longo prazo do desmatamento nos peixes de riachos amazônicos e, portanto, para sua conservação.

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          Most cited references56

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          Global biodiversity scenarios for the year 2100.

          Scenarios of changes in biodiversity for the year 2100 can now be developed based on scenarios of changes in atmospheric carbon dioxide, climate, vegetation, and land use and the known sensitivity of biodiversity to these changes. This study identified a ranking of the importance of drivers of change, a ranking of the biomes with respect to expected changes, and the major sources of uncertainties. For terrestrial ecosystems, land-use change probably will have the largest effect, followed by climate change, nitrogen deposition, biotic exchange, and elevated carbon dioxide concentration. For freshwater ecosystems, biotic exchange is much more important. Mediterranean climate and grassland ecosystems likely will experience the greatest proportional change in biodiversity because of the substantial influence of all drivers of biodiversity change. Northern temperate ecosystems are estimated to experience the least biodiversity change because major land-use change has already occurred. Plausible changes in biodiversity in other biomes depend on interactions among the causes of biodiversity change. These interactions represent one of the largest uncertainties in projections of future biodiversity change.
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            THE ECOLOGY OF INTERFACES:Riparian Zones

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              Stream biodiversity: the ghost of land use past.

              The influence of past land use on the present-day diversity of stream invertebrates and fish was investigated by comparing watersheds with different land-use history. Whole watershed land use in the 1950s was the best predictor of present-day diversity, whereas riparian land use and watershed land use in the 1990s were comparatively poor indicators. Our findings indicate that past land-use activity, particularly agriculture, may result in long-term modifications to and reductions in aquatic diversity, regardless of reforestation of riparian zones. Preservation of habitat fragments may not be sufficient to maintain natural diversity in streams, and maintenance of such biodiversity may require conservation of much or all of the watershed.
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                Author and article information

                Contributors
                Role: ND
                Role: ND
                Role: ND
                Journal
                ni
                Neotropical Ichthyology
                Neotrop. ichthyol.
                Sociedade Brasileira de Ictiologia (Maringá, PR, Brazil )
                1679-6225
                1982-0224
                January 2019
                : 17
                : 1
                : e180099
                Affiliations
                [1] São Paulo São Paulo orgnameUniversidade de São Paulo orgdiv1Instituto de Biociências orgdiv2Departamento de Ecologia Brazil ilha@ 123456ib.usp.br
                [3] São Paulo São Paulo orgnameUniversidade de São Paulo orgdiv1Escola de Artes, Ciências e Humanidades orgdiv2Gestão Ambiental Brazil lschiesa@ 123456usp.br
                [2] Canarana Amazonas orgnameInstituto Nacional de Pesquisas da Amazônia Brazil
                Article
                S1679-62252019000100201
                10.1590/1982-0224-20180099
                7cf66043-9334-4646-ab77-5e49623bf42a

                This work is licensed under a Creative Commons Attribution 4.0 International License.

                History
                : 27 July 2018
                : 08 November 2018
                Page count
                Figures: 0, Tables: 0, Equations: 0, References: 77, Pages: 0
                Product

                SciELO Brazil

                Categories
                Original Article

                Land use,Canopy,Arc of Deforestation,Ictiofauna,Dossel,Cobertura vegetal,Uso da terra,Ichthyofauna,Vegetation cover,Arco do Desmatamento

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