Ecologia de duas espécies de Pachyurus (Perciformes, Sciaenidae) do rio Tocantins, na região represada pela UHE Serra da Mesa, Goiás

摘要: Pachyurus schomburgkii Gunther, 1860 and P. paucirastrus Aguilera, 1983 occur in the Tocantins-Araguaia basin, where latter is endemic. The species were found upper Tocantins, region it was impounded by Serra da Mesa hydroelectric dam. Fourteen sites sampled but both restricted to two (FU PG) located downstream from Fishes bimonthly captured December 1995 2002 with standardized gillnets. We present data on distribution, diet, physiological condition reproductive status of these species, focus alterations related impoundment. Most specimens adult, number individuals decreased after damming. Species classified as benthic invertivores, feeding mainly immature insects. Niche breadth significantly higher paucirastrus, and, for during pre-impoundment phase. Interspecific diet overlap high; however, resource partitioning more pronounced site immediately dam (FU) than distant (PG). Values relative factor indicated that must have profited effectively available resources environmental changes paucirastrus. Thus, factors might contributed disappearance this beginning power plant operation. seems had a better adjustment changes, persistent area damming; remained site, been occasionally until no longer found, approximately four years closure. Considering many impoundments are planned rio we recommend further studies about other stretches order evaluate conservation species.