Spatial and seasonal variation of microphytoplankton community and the correlation with environmental parameters in a hypereutrophic tropical estuary - Maranhão - Brazil

Abstract

Duarte-dos-Santos et al.: Spatial-seasonal variation of microphytoplankton 356 Spatial and seasonal variation of microphytoplankton community and the correlation with environmental parameters in a hypereutrophic tropical estuary -Maranhão -BrazilThe Bacanga River Estuary has a hydrodynamic behavior and its tidal flow is limited by a dam. It is considered as a hypertrophic environment that receives daily high loads of domestic sewage without treatment. This study aimed to evaluate the spatial and temporal variation of phytoplankton community and its relationship with environmental parameters. Bi-monthly sampling campaigns were carried out at six fixed sites between 2012 and 2013. Physical-chemical and biological parameters were collected (chlorophyll a, phytoplankton composition and abundance) to perform the statistical correlations. The results indicate that phytoplankton community is mostly represented by diatoms, with Skeletonema costatum being the dominant species responsible for bloom in April and June of 2012. The dominance of this species is related to the high silicate concentrations, pH and turbidity. Other blooms events as well as the Euglena gracilis and Chlamydomonas sp. were recorded in February 2013, when the total phosphorus concentrations were high and the dissolved oxygen concentrations were higher. Dinoflagellates, cyanobacteria and diatom Thallassiosira sp. were widely distributed in the dry period and highly correlated with salinity, water transparency and nutrients. Hence, the distribution of phytoplankton community is more defined seasonally, rather than spatially. AbstrActDescriptors: Algal bloom, Microalgae, Nutrients.O estuário do rio Bacanga apresenta um comportamento hidrodinâmico com fluxo de marés limitado por uma barragem. Ele é considerado como um ambiente hipereutrófico que recebe diariamente altas cargas de esgoto doméstico sem tratamento. Este trabalho teve como objetivo avaliar a variação espaço-sazonal da comunidade fitoplanctônica e suas relações com parâmetros ambientais. Amostragens bimestrais foram realizadas em seis pontos fixos entre 2012 e 2013, obtendo valores dos parâmetros físico-químicos e biológicos (clorofila a, composição e abundância do fitoplâncton) para realização das análises estatísticas. Os resultados indicam que a comunidade fitoplanctônica é representada por diatomáceas, sendo Skeletonema costatum a espécie dominante responsável por pulsos de florações em abril e junho de 2012. O predomínio dessa espécie está relacionado aos elevados teores de silicato, pH e turbidez da água. Outros eventos de florações como da Euglena gracilis e Chlamydomonas sp. foram registrados em fevereiro de 2013, quando os teores de fósforo total estiveram elevados e as taxas de oxigênio dissolvido foram superiores. Os dinoflagelados, cianobactérias e a diatomácea Thallassiosira sp. apresentaram ampla distribuição no período de estiagem e estão altamente correlacionados com a salinidade, transparência da água e nutrientes. Desta forma, a distribuição da comunidade fitoplanctônica é ...

Structure of microphytoplankton community and environmental variables in a macrotidal estuarine complex, São Marcos Bay, Maranhão - Brazil

“…The ITCZ, during the following months of the year, is much less intense and results in a dry season (Dias et al, 2016;Funceme, 2016). This seasonal pattern was confirmed along the study period and it was in accordance with previous studies for the northeastern region (Azevedo et al, 2008;Rodrigues and Cutrim, 2010;Duarte-dos-Santos et al, 2017).…”

“…Studies addressed the dynamics of phytoplankton community in estuaries along the north coast of Maranhão -Brazil, especially in the São Marcos Bay, are scarce (Teixeira et al, 1988;Lavôr-Fernandes, 1988;Azevedo et al, 2008;Rodrigues and Cutrim, 2010;Duarte-dos-Santos et al, 2017). The analysis of the seasonal and tidal distribution of phytoplankton community and the complex relationships of these distribution patterns with environmental factors in the São Marcos Bay can identify potential indicative species of ecological conditions as well as provide relevant scientific evidence to water quality assessment and pollution control.…”

Mechanism Underlying Flow Velocity and Its Corresponding Influence on the Growth of Euglena gracilis, a Dominant Bloom Species in Reservoirs

“…In recent years, there have been reports of Euglena blooms occurring in other places. A string of reports on Euglena water blooms in various parts of the world have begun to appear, such as in 17 states in the United States [29,30], Poland (in a shallow oxbow lake) [31], Iran (Gorgan Bay) [32], Brazil (Guaiba Lake and the Bacanga River Estuary) [33,34], and China (Luoma Lake and shallow urban lakes in Wuhan) [35,36]. In retrospect, previous research has generally discussed the effects of other algae on nutrient salt consumption and physiological mechanisms.…”