Segregação espaço-temporal das assembléias de peixes em ambientes de entremaré não vegetado e canal subtidal de um estuário de macromaré no norte do Brasil

Abstract

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.