Abordagens multivariadas dos determinantes da diversidade e estrutura da comunidade fitoplanctônica do rio Preguiças, Parque Nacional dos Lençóis Maranhenses

Abstract

Beta diversity and functional traits of indicator phytoplankton associated with environmental heterogeneity were studied as descriptors of environmental quality along a tropical sea- river ecosystem. The results showed significant spatial differences in environmental heterogeneity, contributing to biological heterogeneity. Sporadic and recurrent blooms were associated with spatio-temporal variations of the environmental conditions, resulting in a reduction in alpha diversity in the estuarine sector (ES). Beta diversity was related to variations in salinity, pH, turbidity, temperature, dissolved inorganic nitrogen (DIN), and orthophosphate, which acted as environmental filters. Colonial, bloom-forming, harmful and small-size taxa demonstrated relations to silicate concentrations, suspended particulate matter and salinity. Unicellular and larger species showed correlations with higher photic zone depths, orthophosphate concentrations, dissolved oxygen and DIN. This study demonstrated that a possible decrease in beta diversity could cause homogenization of the community, indicating a possible reduction in environmental quality. Integrating information on the functional characteristics of phytoplankton into diversity studies made it possible to observe in greater detail the influence of environmental filters, favoring the identification of species and priority sites for biodiversity monitoring.