Impacto de um trecho de vazão reduzida nas comunidades demacroinvertebrados bentônicos

• Ano de defesa: 2010
• Autor(a) principal: Daniel Marchetti Maroneze
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Conteúdo estomacal; Peixes; Amostradores; Soleiras vertentes; Vazão reduzida; Represas; Bentos; Ecologia; Fauna Bentônica; Vazão de Água; Vertente
• Link de acesso: http://hdl.handle.net/1843/BUBD-B8WHQE

Currently the construction of dams is a major threat to freshwater biodiversity. Flow modification by impoundments causes habitat degradation, negatively affecting the production, range and richness of riverive species. The objective of this study was to evaluate the effects of a reduced and constant flow on benthic macroinvertebrate communities along a segment of the Araguari river (MG) that is partially regulated by rock weirs. In addition, it was compared fish stomach contents with benthic taxonomic inventories. Macroinvertebrates and fishes were collected at six sampling stations along a 9 km segment downstream of the Amador Aguiar I Dam (MG) before (lotic phase) and after (semi-lentic phase) flow reduction. Discharge decreased by an average of 98% (346 m3.s-1 to 7 m3.s-1). There were no changes in the number of taxa, diversity and total biomass. Densities per m2 of Ablabesmyia, Tanytarsus, Leptoceridae and Polycentropodidae were significantly higher in the first year following discharge reduction (ANOVA; p < 0.05). Analysis of similarity (ANOSIM) suggested statistically differences in community composition but lotic and semi-lentic groups werestrongly overlapped (R = 0.32; p < 0.01). In both phases, the macroinvertebrate communities colonizing the river were dominated by tolerant taxa (e.g., Chironomidae, Ceratopogonidae and Oligochaeta) and an alien mollusk (Corbicula fluminea) suggesting that they hadbeen previously modified or degraded. Because of the presence of Corbicula fluminea, it is recommend that biomonitoring be continued to verify whether this species expands its range and increases its numbers. Since 1980, Araguari river has been continuously modified byhuman activities (proliferation of dams, urbanization, deforestation and agricultural land use) that probably caused biodiversity loss and, consequently, altered the ecosystem functioning. The fishes, especially Leporinus amblyrhynchus, Iheringichthys labrosus and Pimelodusmaculatus, consumed a wide variety of benthic macroinvertebrates. Some taxa recorded in their stomachs were not found in sediment samples collected with a Van Veen dredge. Thus, fishes can be used as an additional sampling method for macroinvertebrates, and the analysisof their stomach contents is an efficient technique to complement taxonomic inventories obtained by traditional sediment samples.