Hierarchical effect of local factors on zooplankton species diversity

We investigated the hierarchical importance of local factors including lake area, macrophyte cover, and phytoplankton chlorophyll a (Chl-a) influencing zooplankton diversity (i.e., number of species) and the response of planktonic and littoral zooplankton species to these factors in 23 lakes in a Neotropical floodplain. Results of a regression tree clustered 4 groups of lakes separated according to the following factors in order of importance: percentage of macrophyte cover (environmental complexity), lake area (size of environment), and phytoplankton Chl-a (food resource). Macrophytes were significantly related to species diversity, as found by simple regression, whereas area and Chl-a were not significantly related to total zooplankton diversity. Planktonic species diversity correlated positively with area and Chl-a but negatively with macrophyte cover. By contrast, the opposite occurred for the littoral species, which correlated positively with macrophyte cover but negatively with lake area and Chl-a. We conclude that, in tropical shallow lakes, macrophytes are the most important factor influencing total zooplankton diversity; thus, maintenance and management of macrophytes should increase and promote conservation of aquatic biodiversity in these lake