Comunidade zooplanctônica de reservatórios expostos a diferentes graus de urbanização no Nordeste do Brasil

Abstract

The influence of different types of land use and occupation detracts from water quality around water bodies. Such uses may lead to changes in the chemical and physical variables of water and consequently in the structure of the aquatic community, modifying zooplankton diversity, richness and composition. For the purpose of testing whether i. zooplankton biodiversity of tropical reservoirs is negatively affected by anthropogenic changes in land use; ii. Whether the effects of eutrophication and organic pollution alter zooplankton composition in reservoirs of tropical areas. For this, six reservoirs were selected in the northern forest zone of Pernambuco, three with the greatest influence of urbanization and three located in rural areas with less influence. Samples were collected at 12 points in the limnetic zone of each reservoir. Samples were obtained by filtering 100L of subsurface water through a plankton net (45 μm). To define the types of land use, classifications were made by mapping the surroundings of aquatic environments with a delimitation of 500m and the types of land use were deforested area, forested area and monoculture. 108 zooplankton taxa were recorded, 59 from Rotifera, 41 from Cladocera and 12 from Copepoda. The six environments studied have different richness and diversity (p <0.05). The highest richness (S = 46 species) was recorded around the reservoir most filled with native vegetation and the highest diversity was recorded for the reservoirs most impacted by deforestation (H = 8,644). The reservoirs are different from each other in terms of environmental descriptors (chlorophyll a, phosphorus, pH, conductivity, turbidity, transparency, dissolved oxygen, and total solids). Of these, four (Carpina, Goitá, Guararema and Tapacurá) were described as hypereutrophic and two (Cursaí and Siriji) as oligotrophic. Significant differences in zooplanktonic community structures were observed between reservoirs (PERMANOVA: F = 32,598; P = 0.001). Oligotrophic showed a dominance of microcrustaceans while hypereutrophic presented a community with greater rotifer predominance (RDA, p <0.05). From the zooplankton community were accepted. In this way reservoirs can be used as a model to help reveal how species diversity is affected by landscape configuration.