APPLICATION OF SHANNON- WIENER INDEX AND OTHER PARAMETERS AS A MEASURE OF POLLUTION IN A DRINKING RESERVOIR

Many diversity indexes have been developed extensively to characterize a variety of biological communities. Since 1967, Wilhm and others suggested the widely used ShannonWiener diversity index (H) as a means for establishing water-quality parameters. The usefulness of this diversity index for assessing water quality is based on the assumption that clean streams have high diversity indexes, because clean streams contain many species of relatively equal numbers of individuals per species (Wilhm and Dorris, 1968).In contrast, polluted streams are interpreted to have low diversity indexes because many pollution-sensitive species are eliminated from the community and only a few pollution-tolerant organisms flourish in the absence of competition and in the presence of an abundant food supply. According to Wilhm (1970), "H usually varies between three and four in clean-water stream areas and is usually less than one in polluted-stream areas." Zooplankton organisms are basic food for fishes that live in fresh water ecosystems; besides, they include indicator species that determine water quality, pollution and the state of eutrophication. For this reason many researches have been conducted in terms of both taxonomical and ecological aspects on zooplanktonic organisms. We used the composition of zooplankton species (rotifers, cladocers and copepods) and their specific tolerance to abiotic factors in Bovilla reservoir, like saprobic index, in the way of classifying the trophic state of reservoir that is used as drinking water storage for at least 800 000 inhabitants. Composition of zooplankton showed a total from 44 taxons (26 for rotifers, 11 for cladocers and 7 for copepods), but the total abundance is quite opposite. The total numbers of copepods (where copepodit and nauplii larva’s are most dominant), goes for more half percent of the total found in the two years of sampling. We had this low diversities species because the reservoir has young age, and the eutrophication process is not to be considered. In contrary the trophic status of these waters (most of the time were oligotrophic) should be maintained in low values as much as it possible, because of its use as drinking water. Saprobiological analysis showed that species of zo oplankton using as indicator are not in high concentration along typical species that are also cosmopolitan species. The investigated area during these periods had values from 1.2 to 2.5, which correspond to I, and I- II water category.