Ecotoxicological diagnosis of Aratu Bay, Bahia, Brazil: a new approach to validate a reactive short-term toxicity end-point by comparison with intertidal benthic activity

Abstract The Aratu Bay ecosystem (12°48′S; 38°28′W), located in an industrialized area, was compared with a similar but undisturbed ecosystem, Iguape Bay, in order to determine the impact of industry on water quality during the last forty years. Comparison was based on simple and low cost methodologies using bioassays on oyster embryos, validated by a survey of a benthic activity index. A bioassay method based on oyster embryo development was used to compare water quality from the study areas. A high percentage (93.2 and 97.3) of abnormal oyster embryo development was observed in water samples from one area (south and southeast) of the bay where, besides receiving heavy discharges of industrial effluents, water circulation is restricted. At the north end of the bay where the area is shallow, and some industrial discharges are present, water quality data indicated that the area was stressed. Little effect of industrial impact has been noted around the Cotegipe channel, a deep area where the water circulati...