Respuesta de la biomasa zooplanctónica a los gradientes de estado trófico y precipitación de un embalse tropical

The distribution of the zooplankton biomass in the spatial (longitudinal- vertical) and temporal scales based on the gradients of trophic status, algae biomass and the rainfall was analyzed in the photic zone of the reservoir Riogrande II. Cladocerans dominated the biomass due to the large contribution of Bosmina freyi, followed by copepods and rotifers. Biomass of species of microcrustaceans was associated to the most eutrophic sampling station related to highest algae biomass, whereas biomass of species of rotifers was linked to stations of lower trophic status. Highest biomass of microcrustacean was in the season of greatest trophic status whereas highest biomass of rotifer was related to the strongest rainfall season. In the vertical gradient, lowest biomass of all groups occurred in the subsurface. This zone tended to be avoided by most species during the sampling seasons. The expression of zooplankton biomass in the longitudinal axis and the temporal scale mainly responded to the gradient of trophic status and algae biomass, and in the vertical axis possibly responded to predation. Although, this response did not depend on the trophic habit of the species probably due to the diverse trophic offer of the reservoir and the alimentary plasticity of these species, it was clearly different between microcrustaceans and rotifers.