Avaliação ambiental do estuário do Capibaribe por intermédio da fauna planctônica: estrutura e indicadores biológicos da qualidade da água

Abstract

The general objective of this work was to evaluate a heavily polluted estuary (Capibaribe) through the zooplankton community and verify its potential use as a bioindicator of water quality. To test the hypothesis that in the Capibaribe estuary, the water quality condition is eutrophicated to the point of sustaining (i) a zooplankton community formed by species indicative of abundant particulate organic matter, low oxygenation and high turbidity and (ii) the establishment of small populations dominated mainly by rotifers, the campaigns were carried out in the urban area of the river in the city of Recife (Pernambuco), in three sectors based on the salinity gradient: Euhaline, Polyhaline, Meso-oligohaline and 9 collection stations. Six campaigns were carried out, always during low tide. Data regarding environmental variables were measured from a Horida U-52 probe. Zooplankton samples were collected by filtering a minimum of 100 L through a plankton net (45 µm) and a graduated bucket and fixed with 4% saline formaldehyde. The bioindication of taxa was evaluated by the Indication Value (IndVal) method, where ten species belonging to the Rotifera group, Copepoda and Polychaeta larvae were found. For the zooplankton community, 46 taxa belonging to the groups Rotifera, Annelida (Polychaeta), Mollusca (velliceroy of Gastropoda), Crustacea (Copepoda, Cladocera, Decapoda, Cirripedia), Chaetognatha and Chordata (fish larvae and eggs) were recorded. Rotifera was the most frequent group, especially Brachionus angularis (81.48%), the mean density was 625.4+-731.8 ind. L-1. The highest richness was in the Euhaline (dry) and Meso-oligohaline (rainy) sectors, the rotifer dominance and diversity were higher in the Meso-oligohaline sector for both periods. The study proved the hypotheses that the estuary is dominated by smallsized species and bioindicators of abiotic factors that indicate pollution, showing that the Capibaribe River estuary is being affected by anthropic disturbance and that bioindicator species can be used for water quality monitoring.