Freshwater ecology in the Mato Grosso, Central Brazil

Summary

Five meander lakes in the valley of the Rio Suiá Missú were sampled during September to the end of November 1968. A total of 26 species of Cladocera were identified in the samples. The lakes were arranged in a sequence of presumed age, size and depth. The associations of Cladocera in the youngest and deepest lakes were dominated by planktonic Cladocera, such as Holopedium amazonicum and Bosmina hagmanni. The older and shallower lakes had a greater variety of Cladocera, and the associations were dominated by chydorids and macrothricids. The diversity of species was greatest in the lake in the middle of the sequence. More species were found in all the lakes than would be expected from MacArthur's broken stick model with non-overlapping niches. The majority of the species (62%) in the samples were cosmotropical, a further 23% were cosmopolitan and the remaining 15% were species known only from America.