Factors of Dynamics of Plankton Crustacean Communities under Eutrophic Conditions

Resumo

It has been shown that the main drivers of the dynamics of cladoceran and copepod abundances can be predators (fish), the quantity and/or quality of food in terms of the contents of eicosapentaenoic acid, phosphorus and nitrogen in the seston under eutrophic conditions. In experimental mesocosms under eutrophic conditions, we found that, fish did not affect the quantity and quality of food resources for crustaceans. In the second half of experiments, however, dominance shifted from copepods to cladocerans. This was due to the improvement of the food quality for cladocerans in terms of the carbon-to-phosphorus ratio in the seston rather than to fish predation. Under eutrophic conditions, fish reduced the biomass of both cladocerans and copepods without changing the ratio between them.