hide
Free keywords:
-
Abstract:
Benthic macroinvertebrate communities were studied in the igarapés Saracá, Caranã and Água Fria
near Porto Trombetas, Municipality of Oriximiná, State of Pará, Brazil (1°25' to 1°35'S and 56°15' to
56°W). The main objective was to investigate the potential use of the benthic macroinvertebrates community as indicators of the ecological fragility of the igarapés located in an area of the Amazon basin influenced by bauxite mining. These aquatic ecosystems have low pH (< 4.5); low electrical conductivity (< 90
µS cm-1); low or undetectable total alkalinity; low nutrient concentrations in the sediment, which implies
low primary productivity; low species richness; low secondary productivity; and low rates of organic
matter decomposition. The benthic macroinvertebrates utilize mainly allochthonous organic matter. Some
areas of the ecosystems investigated have been modified by bauxite tailings (especially in their sediment
granulometry), by a dam formed by railroad construction (which altered the hydrodynamics and eliminated
the terra firma vegetation), and by accidental discharges of various minerals from the railroad traffic and
bauxite mining. These factors have drastically modified the local benthic macroinvertebrate communities.
The value of benthic macroinvertebrates as indicators of ecological fragility, the health of the ecosystem
investigated, and water quality is evaluated.
