The aim of this work was to evaluate ecological aspects of phytoflagellate populations during the rainy and dry seasons of 2000 and 2001 in floodplain lakes in the Araguaia River. The analyses were based on species richness, composition and biovolume of the phytoflagellates, associated with climatic and limnological variables of the water. The Mantel test showed weak spatial patterns for phytoflagellate populations; moreover the Mantel test confirmed the importance of the local component in the structure of these populations. The results of DCA applied to the biological data showed that high- and low-water periods were not strikingly different in 2000 and 2001. Biovolume data indicated that the phytoplankton was dominated by Chryptophyceae (functional group Y) and Euglenophyceae (functional group W1) in 2000 and 2001. Species richness and biovolume responded to the flood pulse. Both high- and low-water had different dynamics in the two years; this seems to indicate the importance of the flood pulse for phytoflagellates.
Araguaia River; floodplain lakes; Phytoflagellates
