Zooplankton Latitudinal Richness in South American Shallow Lakes

LACEROT, G., CASTELO BRANCO C., PAGGI, J., JOSÉ DE PAGGI, S. & L. SOUZA

Montreal, Canada

Congreso; 30th Congress of the International Association of Theoretical and Applied Limnology .; 2007

International Association of Theoretical and Applied Limnology

The question how climate may influence the diversity and size structure of freshwater zooplankton communities has so-far been addressed largely by pulling data together from different studies reported in the literature. Such comparisons have their methodological difficulties. To address these issues we sampled 83 shallow lakes of similar size along a large climatic gradient in South America (5 degrees-55 degrees S) in a one-time mid-summer census. We analyzed the influence of temperature, aquatic vegetation, trophic state and fish community structure on the zooplankton community. We found that zooplankton species richness values peaked at mid-latitudes (22 degrees -35 degrees S), corresponding to subtropical and tropical climates. The apparent effect of other variables differed among zooplankton groups: macrophyte-PVI positively influenced rotifers and cladoceran richness, whereas trophic state played a more relevant role for copepods. The number of large-sized species was low in the tropics and increased towards polar areas. Large Daphnia was found in some of the tropical lakes studied, but disappeared after the 22 degrees S.