Seasonal variations in plankton trophic structure under highly eutrophic conditions

Abstract

The plankton trophic structure of a hypereutrophic tropical estuarine system was evaluated in the dry and wet seasons, as well as during the dry–wet transition period, over 1 year. Correlations between micro- and mesozooplankton abundance and composition and both size-fractioned phytoplankton biomass and abiotic variables were investigated in order to understand seasonal variations in plankton interactions and provide a conceptual trophic model for the plankton community. Rainfall is the main environmental forcing factor for this system, and the plankton community responded accordingly, with different structures during each season sampled. The resulting trophic model shows a multivorous food web, where both longer microbial and shorter herbivore food webs occur simultaneously. Microzooplankton play a crucial role in this ecosystem, linking both small and large phytoplankton to the mesozooplankton. These results have important implications for estuarine management practices, particularly under highly eutrophic conditions.

Evaluating a river's ecological health: A multidimensional approach

“…Thus, the index of biological integrity (IBI) has become a vital method for assessing the overall health of water ecosystems, as it synthesizes various biological indicators [ [25] , [26] , [27] ]. Plankton, as the foundation of the aquatic food web, exerts a profound influence on the growth and reproduction of other aquatic organisms, making it essential for the proper functioning of ecosystems and the provision of ecological services [ 28 , 29 ]. They are typically small, have a relatively short lifespan, and are sensitive to environmental changes [ 24 ].…”