Patterns of benthic community traits in neotropical streams: relationship to mesoscale spatial variability

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Abstract: Previously tested in temperate ecoregions, the River Habitat Templet concept provides a framework for relating the characteristics of species (i.e. traits indicating species ecological functions) to habitat attributes. As species traits are comparable among most faunal groups, they can be used to examine community patterns in ecological functions at a large spatial scale, even across areas that differ in the taxonomic composition of their communities. If local physical attributes produce similar trait patterns on a global scale, the River Habitat Templet can serve as a general predictive tool of community characteristics regardless of geographical zones. We studied eight biological traits in 82 neotropical taxa: i) food, ii) feeding habits, iii) respiration, iv) maximum body size, v) body fl exibility, vi) body form, vii) specifi c adaptation to fl ow constraints and viii) mobility and attachment to substratum. A multivariate approach was used to examine taxonomic and functional (trait) differences in macro-invertebrate assemblages among study sites. Proportions of trait modalities were examined in relation to Froude number, substratum roughness and benthic organic matter availability at mesohabitat scale. Even if communities differed taxonomically, they were functionally similar. Thirty of 46 trait modalities of neotropical aquatic taxa were signifi cantly related to at least one selected environmental attribute. The results clearly support the habitat templet as a major driver of macroinvertebrate community structure in neotropical running waters. But the observed ‘trait/habitat’ relationships did not suffi ciently match those from temperate areas for us to confi rm the existence of gene-ral rules organizing functional trait structure among benthic invertebrate communities that would be applicable in different climatic regions.