Relationship between the structure of zooplankton community and the water level in a floodplain lake from the Pantanal, Mato Grosso

ABSTRACT. The hydrological condition of floodplain systems alters the structure and dynamic of aquatic communities. We suggest that the structure of zooplankton community changes according to the flood phases and connectivity. This study was carried out in a floodplain lake located in the Northern Pantanal (Brazil). Zooplankton density varied considerably over time, although the sampling stations presented similar densities. The densities ranged from 2,000 ind. m-3 in the high water phase to more than 2,300,000 ind. m-3 during the low water phase when the lake remains isolated. The densities of the groups also presented a temporal variation. Rotifers described the community mainly in the low water phase and microcrustaceans during the high water phase. Variations in the total zooplankton and groups densities were significantly correlated to the PCA 1 axis (negatively composed by water depth and positively by turbidity) and to the food availability (phytoplankton)