Various estuarine environments are hydrologically and ecologically connected and provide
vital functions to several aquatic organisms. Spatial and temporal segregation were observed
in fish assemblages structure (average biomass) in the subtidal channel and intertidal nonvegetated
environments in the estuary of the Marapanim River, North Brazil. Monthly fish
sampling were carried out between August 2006 and July 2007 at the subtidal channel and
intertidal non-vegetated environments using a beam trawl and beach seine, respectively. A
total of 41,496 individuals belonging to 29 families and 76 species was collected. Species
richness in the subtidal channel (71 species) was higher than in the intertidal non-vegetated
environments (51 species). Different associations in the composition of the species and
functional guilds were observed between the subtidal channel and the intertidal non-vegetated
environments, through the Detrended Correspondence Analysis. Significant differences in fish
fauna composition were found between environments, seasons and zones, through Analysis of
similarities (ANOSIM). The fine sediments (silt-clay), sand and salinity were the most
important factors structuring the fish assemblages. In summary, these results can be
associated to the fish tolerance to environmental factors, and to different feeding type.
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