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The head morphology and feeding habits of pairs of characin species (family Characidae) that coexist in four different coastal rainforest streams were analysed. Coexisting species differed in size, but were very similar in eco-morphological attributes. Gut analyses revealed differences in feeding preferences for each coexisting species, indicating resource partitioning. A pattern of organization in species pairs that was repeated in the four studied streams was noticed. The pattern consisted of one slightly larger species with a feeding preference for items of allochthonous origin and another smaller species with a preference for autochthonous items. The hypothesis that small morphological differences enable the current coexistence of those species pairs was proposed. Furthermore, the results show ecological equivalence among different species in the studied streams. [ABSTRACT FROM AUTHOR]

The effects of riparian forest removal on a neotropical stream fish assemblage were assessed in the Mata Atlântica. Fish assemblage structure and fish feeding patterns were quantified at three sites along a pristine-to-deforested gradient in a Serra do Mar stream: (1) a pristine site fully covered by canopy with no light penetration and transparent waters, (2) an intermediate site with partially removed forest and (3) a fully removed forest site with no canopy and full light penetration where siltation and turbid waters predominate. Fish assemblage structure, fish densities and their feeding patterns differed widely among sites. Whilst the same five fish species occurred at the three sites, forest removal favoured the occurrence of sediment-tolerant iliophagous benthic species at the deforested site. At the pristine site, invertebrate prey predominated in water column fish diet and feeding overlap among species was low. Severe shifts in the feeding patterns were noticed in both deforested sites. Invertebrates were replaced by detritus, organic matter and algae at both sites and feeding overlap increased markedly. The overwhelming feeding adaptability of these neotropical fishes appeared capable of buffering the deleterious effects of forest removal on stream quality in terms of increased light penetration, siltation and water turbidity. Forest cutting in this Mata Atlântica stream clearly caused strong functional changes associated with forest clearance through important modifications in the assemblage organization and trophic patterns of the main species, but did not eliminate species. [ABSTRACT FROM AUTHOR]

Feeding behaviour and diet of Bryconamericus microcephalus differed between canopy conditions. At the open canopy site, a behavioural modification, grazing on algae, was observed. This was also reflected in gut content analysis and suggests behavioural plasticity in response to resource availability. [ABSTRACT FROM AUTHOR]

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Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)