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6029536 
Journal Article 
Performance of a New Ecotoxicological Index to Assess Environmental Impacts on Freshwater Communities 
Camargo, JA 
1990 
If an aquatic organism is not adapted to thrive in an environmental disturbance, its ability to grow, reproduce, or compete in the biological community will be affected negatively, being substituted for another one more resistant and better adapted to environmental stress. The performance of a simple ecotoxicological index to assess environmental impacts produced by man 's activities on freshwater communities was derived by totaling the species deficit index and a new species substitution index. The first index measures the percentage difference between the number of species occurring above and below the disturbance point. The second index measures the species substitution percentage between both places. A sample of the benthic riffle macroinvertebrate community was taken at each of five sampling stations using a cylinder sampler. All samples were preserved in Formalin until their separation, determination , and counting. The following biological parameters and indices were calculated: the number of species or species richness, the organism density, the number of common species, the Margalef 's diversity index, the Shannon 's diversity index, the species substitution index, and the ecotoxicological index. The highest value of the ecotoxicological index corresponded with the smallest diversity because effects of dam and industrial effluent act simultaneously on the benthic macroinvertebrate community at the third sampling station. However, the rank of environmental impact decreased with the distance to disturbance points. The taxonomic identification of species is perhaps the only and major problem in using this index. (Brunone-PTT) 
Water Resources Abstracts; Data interpretation; Ecological effects; Ecotoxicology; Toxicology; Water pollution effects; Benthic environment; Biological studies; Diversity index; Ecosystems; Macroinvertebrates; Mathematical equations; Population density; Sample preparation; Species diversity