Efeito da contaminação da água por petróleo sobre a fauna de invertebrados aquáticos associada à Salvinia auriculata Aublet (Salvineaceae) e seu uso como bioindicadora de poluição ambiental

Abstract

The effect of the exposition of aquatic invertebrates of a white water lake of the Amazonian basin to petroleum was analyzed on different concentrations (control, 0.05, 0.5, 5 ml/l) and on six times of exposition (10 min, 60min, 6hs, 24hs, 3 days and 10dias). The collections occurred between the months of March and November of 2007 having contemplated the regional hydrologic cycle, to allow the detection of seasonal variations in the populations of the invertebrates. The analyses of data had shown a reduction of 39% in richness of taxa in the highest concentration of oil, but this effect was not detected in lower concentrations. The taxa that showed greater sensitivity to the oil were Diptera, Acari, Ostracoda and Cladocera of the Simocephalus genus and of the Chydoridae family. In contrast, the groups Anelida (Oligochaeta), Cladocera of the genus Diaphanosoma and Copepoda of the sub-order Cyclopoida were well represented but had not presented significant reductions in the presence of oil, indicating that they are tolerant or relatively tolerant groups to this pollutant. Both, the richness of taxa and the population density of each tax had strong seasonal variations. Due to this variation and the resistance of some groups, the effect of the oil on the aquatic communities must be established with caution so that studies with bioindicators present greater exactness.