Variação espaço–temporal da comunidade de zooplâncton e das variáveis ambientais nas águas estuarinas do Rio Anil, São Luís – MA

Abstract

The zooplankton community is increasingly being considered a key element for diagnosing the health of aquatic ecosystems, as they respond quickly to environmental changes, which are reflected in the composition and distribution of these organisms. Therefore, the general objective of the research was to characterize the composition and distribution of the zooplankton community, relating it to environmental variables along the Anil River Estuary, São Luís – MA. The samples were collected through horizontal and surface trawling in the water with the aid of a plankton net, 120 μm mesh, where after this process they were placed in properly labeled plastic bottles and fixed in 4% formaldehyde for qualitative and quantitative analysis of the material. biological in four campaigns (dry x rainy). From the results, it was observed that zooplankton beta diversity and environmental heterogeneity are related to the level of degradation in a macrotidal estuary, in addition, the trophic state associated with the composition and distribution of the zooplankton community along with environmental variables, determined the division into two sectors of the estuary. Alpha diversity pointed to the second sector (SII), the most impacted along the estuary, with a decline when compared to the first sector (SI). Beta diversity, through the calculation of PERMDISP and Jaccard dissimilarity, revealed an environmental heterogeneity defined by significant seasonal differences, contributing to biological heterogeneity between the rainy and dry periods. PERMANOVA showed variations in environmental parameters such as: salinity, pH, SiO3 and NO- , showing significant differences both temporal and spatial (p<0.05). The community was composed of 74 taxa, 75.7% of which were represented by the copepod group, mainly by the Oithonidae and Paracalanidae families with the largest number of species. As for IndVal, it determined 15 taxa, including the copepods Euterpina acutifrons, Clytemnestra scutellata, Debilus swelli and Notodiaptomus sp. nine representing the SI (60%) and six the SII (40%). Therefore, through research it is possible to determine the environmental filters and indicator species that make up the dynamics of the estuary, as well as the current trophic state for diagnosing the ecosystem.