Uso de macrófitas aquáticas no controle da produtividade primária fitoplanctônica

Abstract

Eutrophication, caused by increased nutrient inputs in aquatic ecosystems (e.g., effluents), enhances the primary productivity of algae and cyanobacteria, negatively affecting biodiversity. One strategy to control these blooms is the use of nature-based solutions (NBS). A wide range of organisms, such as aquatic macrophytes, have been used for this purpose. Our objective was to investigate how different species of floating macrophytes influence ecosystem trophic status and phytoplankton biomass, measured as chlorophyll-a. We hypothesized that macrophytes, through nutrient competition, reduce phytoplankton primary productivity. The experiment was conducted using eutrophic mesocosms classified according to the trophic state index, with treatments consisting of three macrophyte species (Pontederia crassipes, Salvinia auriculata, and Pistia stratiotes). Principal component analysis (PCA) revealed a clear separation between the beginning and the end of the experiment, indicating significant changes in environmental conditions over time. The presence of Salvinia auriculata significantly influenced chlorophyll-a, dissolved oxygen, and trophic state index. The temporal factor showed a significant effect on all environmental variables. Therefore, we conclude that floating aquatic macrophytes play an important role in controlling phytoplankton primary productivity, even under conditions of high nutrient availability