Aquatic macrophyte distribution in relation to water and sediment conditions in the Itaipu Reservoir, Brazil.

摘要: Aquatic macrophyte community distribution along the eastern shoreline of Itaipu Reservoir (one South America’s largest impoundments) is described in relation to limnological and sedimentological factors. The central body reservoir mesotrophic, while arms (flooded influent river valleys) shore may be oligo-mesotrophic eutrophic, depending on time year sub-catchment characteristics. Macrophyte composition species cover were surveyed at 30 sites four arms, sediment total P organic matter; underwater light regime; water Kjeldahl N concentration, alkalinity, conductivity, depth pH. Seventeen euhydrophyte six emergent recorded. Large stands Egeria najas dominated vegetation, together with free-floating weed (Pistia stratiotes Linn., Salvinia auriculata Aublet Eichhornia crassipes (Mart.) Solms.). Canonical Correspondence Analysis data showed that two sets variables important predictors aquatic structure. Floating assemblage was closely related concentration nutrients both sediment, penetration strongest predictor submerged occurrence. Although a large number potential nuisance present, dense growths restricted shallower areas Reservoir, causing localised problems. possibility increasing interference by these plants fisheries, recreational use, transport hydroelectricity generation suggests need for continued monitoring abundance, investigation appropriate management measures.