Estrutura espaço-temporal da comunidade zooplanctônica do reservatório da usina hidrelétrica de Tucuruí (Pará – Brasil)

Abstract

Reservoirs are a reality in Brazil, such environments are highly dynamic and have strategic importance and are used for various uses, which interfere with water quality, ecosystem functioning and the structure of aquatic communities. These lentic environments are suitable for the development of planktonic populations. The zooplankton community in reservoirs plays an important role in energy transfer and nutrient regeneration, and their composition, structure, dynamics and succession of species are influenced by physical, chemical and biological conditions. Thus, the objective was to characterize the spatio-temporal structure of the zooplankton community and its relationship with the environmental variables in the reservoir of the Tucuruí HPP (Pará, Brazil) in the months of February, July and December 2011. Samples were performed in 10 stations of collection along the reservoir. The samples were collected with 64 µm plankton nets together with the environmental parameters that were measured using a multiparametric probe. Physical-chemical analyzes revealed the formation of an environmental gradient related to the seasonal period. In the assessment of the trophic state, the environment had eutrophic behavior. With 156 taxa of zooplanktonic organisms identified, where the rotifers had the highest species richness with 88 taxons, followed by cladocerans (24) and copepods (13), which is in line with the typical pattern of tropical water bodies. The richness varied significantly in relation to the months, and the Simpson index was significantly higher in February, while the density of organisms did not show significant variation. The density was dominated by the rotifer species K. americana and nauplii, who throughout the study were contributing 50% of the abundance. Cluster analysis showed that the abundance of zooplankton was related to space variation of the UHE of Tucuruí. Canonical redundancy analysis showed that the environmental gradient is related to time and zooplankton is related to space, resembling the cluster. Monostyla sp., Keratella quadratica, Brachionus caudatus austrogenitus were related to December (canal and interior). Thermocyclops sp was related to the interior (February / July). Filinia longiseta, Testudinella patina, Asplancha sp1, A.ovalis, Lecane lunaris, Trichocerca chattoni, Trichocerca sp., Ceriodaphinia cornuta dubia and Holopedium amazonicum, Cyclopoida sp3 were strongly related to the channel (February / July). Demonstrating the formation of specific habitats that structure the zoolanctonic community of the UHE of Tucuruí during the analysed period.