Áreas úmidas e indicadores ambientais de planície flúvio estuarina na Amazônia Oriental.

Abstract

The most extensive floodplains in the world occur in the Amazon River basin. In these locations, along the largest rivers, pulses of periodic flooding produce seasonal and dynamic connectivity between the smaller channels and the adjacent wetlands. Wetlands play a vital role in water quality, in addition to providing coastal stabilization and erosion control, aquifer recharge, serve as important habitats. The present study aimed to elaborate, based on environmental indicators, the characterization and classification of an estuarine fluvial plain in a humid area, and to evaluate its degree of environmental impact using bioindicators as an analysis tool, considering a gradient of water bodies. The present study took place in the municipalities of Barcarena and Abaetetuba, having an important and significant role, economic-financial, socio-cultural and migratory and ecological-environmental for the region and for the Amazon as a whole. In the present study, it was divided into two stages, considering the hypothesis and specific objectives. The first stage of characterization and classification of the region as wetlands, and the second stage was the use of biological indicators as a way of measuring the environmental quality of the areas. The indicators used for stage I were altimetry, rainfall, hydrography and land use and coverage, and such information was processed in a GIS environment. Additionally, the Topographic Index of Wet Areas (ITU) was used, and the method of map reclassification (topography, land use and precipitation) was proposed, generating product through map algebra, then defining areas with Potential for Formation of Wet Areas (PFAU). The second stage, was carried out after the classification of PFAU’s, using macrozoobenthos as an indicator of environmental quality. Sampling in the main drainages distributed in three sectors with different potential impacts. The sectors were: i) high impact sector ii) medium impact sector iii) low impact sector. In general the region of the present study predominates low altimetric values, the pluviometric precipitation for the annual accumulated, varied from 3594 mm to 4844 mm, not being a marked difference, more than 50% of the soil is characterized as area of agriculture and fields, being directly linked to the modified environments either by the occupation of the industrial pole, or by the use of land with buildings. It was possible to delimit the areas with the potential to form wetlands, being directly linked to the topographic processes and the main drainages. The results indicated that the structure of the community of benthic macroinvertebrates in the drainages surrounding the industrial port complex, shows a loss of environmental quality, with extreme effects of a fall in abundance and diversity. More tolerant taxa (Namalycastis caetensis, Cirolana sp., Pseudosphaeroma sp., Tubificidae and Chironominae) and sensitive (hydropsychidae and Eteone sp.) Impact conditions were identified and evaluated as potential bioindicators for monitoring.