In the Amazon, aquatic herbaceous are found in all types of water, but its abundance can be influenced by the limnological conditions of each environment. This study aimed to evaluate the influence of habitat conditions on the structure of aquatic herbaceous in the Catalão Lake region, Manaus, AM. We evaluated seven transects in white water environments (AB), nine in decanted water (AD), and seven in mixed water (AM). In each transect, aquatic herbaceous were identified, relative coverage and frequency of occurrence were measured, and turbidity, conductivity, pH and depth variables were evaluated. Variation in depth indicated that the environments of AD and AM were deeper than AB, yet lower conductivity and more acidic waters were recorded in AM. We recorded 32 taxa of aquatic herbaceous, being the most frequent Paspalum repens, Salvinia auriculata, Pistia stratiotes and Lemna valdiviana. Among the species recorded, 50% were common to all three environments. On the other hand, some species occurred exclusively in AB, in AD or AM environments. In AB, floating forms were more frequent, and this environment had the highest coverage; in AD and AM environments, emerged forms showed higher frequency and coverage. AM had greater richness of aquatic herbaceous compared to other environments. Variations recorded indicate that limnological conditions of white and black water rivers can determine the structure of aquatic herbaceous community, even at small spatial scales.
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