Influências espaciais e temporais na dinâmica do fitoplâncton em trecho do Baixo rio Doce pós rompimento de barragem
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Data
2022-11-11
Autores
Batista, Amanda Martins
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Universidade Federal do Espírito Santo
Resumo
With the importance of river systems attributed to the multiple uses of water, life quality promotion and maintenance of interconnected continental ecosystems, limnological studies integrated with freshwater biot are priority for the knowledge of phytoplankton organisms that are sensitive to environmental variability. Thus, fluvial phytoplankton varies strongly between different water bodies and time periods, considering some factors such as hydrological regime, abiotic properties, availability of resources and anthropic interventions. That said, the approach of the present study is based on the taxonomic and functional biases of phytoplankton, aiming to analyze the influence of spatial and temporal patterns on the dynamics of the community and functional groups, as well as environmental variables, investigating which of these factors are the main controllers of phytoplankton organisms in the stretch of the Lower Doce river. The study integrated the dry and rainy periods in four sampling stations, with data collected in the years 2018 to 2022, after the dam rupture in Mariana (MG) with the passage of a high volume of mining tailings to the sea. The structural attributes and the biovolume of the phytoplankton community, functional groups and environmental variables were evaluated. There was considerable temporal variation between abiotic factors, however, few varied spatially. There wasn’t spatial separation between the functional groups, nor for the structural attributes of the phytoplankton community. In temporal scales, the greatest diversity and dominance were attributed to the dry and rainy seasons, respectively. The functional groups were mostly typical of meso-eutrophic waters (A, B, C, D, F, J, K, Lo, MP, Nᴀ, P, S1, SN, Tʙ, Tᴄ, Tᴅ, W1, W2, X1 and X2), with A, J and Tʙ common to the dry season, while K and Lo are characteristic of the rainy season under high metal content, mainly total iron. The most important variables for the dynamics of the functional groups were dissolved inorganic nitrogen, suspended particulate matter, total iron and temperature. The most representative classes were Bacillariophyceae, Chlorophyceae and Cyanophyceae. The species Trachelomonas volvocina and Raphidiopsis raciborskii were associated with temperature, turbidity, total phosphorus and phosphate, while Monoraphidium contortum with chlorophyll a. The study contributes to the knowledge of phytoplankton dynamics and abiotic variables of this river ecosystem, revealing that the environmental variability played an important role in structuring the phytoplankton community and functional groups.
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Abordagem Funcional , Algas , Lótico , Nutrientes