Diversity and distribution of freshwater copepods (Crustacea) in southeastern Mexico

Plankton and littoral samples were obtained from several ponds and lagoons of different environments in the Mexican state of Tabasco. These systems ar e located in the Grijalva-Villahermosa or the Usumacinta basins. Twenty-two copepod species were recorded, most of them cyclopoids with neotropical an d Caribbean affinities. Physical and chemical data associated with the spec ies, as well as morphometric parameters of the surveyed systems were measur ed and analyzed. A correlation was found between diversity and parameters r elated to the productivity and the shoreline development (D-L) of the syste ms; therefore the littoral heterogeneity could be used to predict the speci es number in shallow tropical systems. At a regional level, the Tabasco cop epod fauna is similar to that known from the Yucatan Peninsula, but differe nt from the faunal associations of central Mexico. Distributional patterns differed slightly between both basins and appear to be correlated with clim atic variations. This first survey of the freshwater copepod fauna in the s tate of Tabasco shows it to be constituted mainly by neotropical forms.