Composição e estrutura trófica de assembleias de peixes em praias de lago da Amazônia Central e suas relações com variáveis ambientais locais

Abstract

In order to check the influence of environmental variables on the taxonomic composition and trophic guilds of fish assemblages, collections were made in thirteen beaches in lakes associated with the Amazon River, Central Amazonia, during the dry season, between the months of October and December 2011 and October 2012. 6,790 specimens of fish were captured belonging to nine orders, 27 families, 103 genera and 173 species. The results of Canonical Correspondence Analysis suggested that, despite the environmental variables being strongly correlated with the distribution of species, as indicated by the Pearson correlation, the short gradient, indicating little environmental variability, a pattern of species distribution among the beaches could not be estabilished, and the same was observed for trophic guilds. Analysis by guilds caught a little better the structure of the assemblies than taxonomic analysis, taking into consideration the amount of explanation of the axes, since dealing with fewer categories, these being more homogeneous, the ACC can better capture the existence of a variation. In addition, the taxonomic composition was influenced predominantly by limnological variables, which could be reflecting the physiological limits of the species in the occupation of environments. On the other hand, the depth and transparency seem to have stronger relationships with the functional characteristics of fish assemblages, as shown by several authors. However none of the relationships mentioned above was significant, which may have been the result of at least three types of factors: insufficient sampling of the assemblies, the effects of environmental variables not measured, or low variability in environmental factors measured between the beaches.