Structure and dynamics of the phytoplankton community and its relationship with environmental variables at the Mãe-Bá lagoon, Espírito Santo State, Brazil - DOI: 10.4025/actascibiolsci.v31i3.1266

Abstract

The present study aimed to evaluate the structure and dynamics of the phytoplankton community and its relationship with environmental variables at the Mãe-Bá lagoon. Four samples were taken fortnightly during the rainy and dry seasons, in the limnetic zone of two sampling sites, subjected to different environmental conditions. Richness, total density, abundance, dominance, diversity and equitability of phytoplankton were analyzed. The environmental variables studied were: temperature (air/water), transparency, euphotic zone, depth, pH, dissolved oxygen, turbidity, electrical conductivity, total dissolved solids, total suspended solids, salinity, concentration of nitrate, nitrite, ammonia nitrogen, total nitrogen, orthophosphate, and total phosphorus. A total of 138 taxa were found and the Class Cyanophyceae was the most representative both qualitatively and quantitatively. The total phytoplankton density was high, showing the highest values in the dry season and in the point 1, considered more impacted. The lack of dominance and abundance of few species explained the values of diversity and equitability. The Mãe-Bá lagoon was characterized as a shallow environment, with slightly acidic to alkaline water, high values of temperature, dissolved oxygen, euphotic zone and transparency, and low concentrations of nutrients. The structure of phytoplankton community was influenced mainly by precipitation, transparency and water temperature, and possibly limited by nitrate and ammonia nitrogen.