Diet of invertebrates sampled in leaf-bags incubated in a tropical headwater stream

Emerson M De Carvalho,Virgínia S Uieda

doi:10.1590/s1984-46702009000400014

Abstract

The diet of macroinvertebrates sampled in leaf-bags incubated in a tropical stream was analyzed on a spatial scale (one forested and one deforested area) and on a temporal scale (dry and rainy seasons). The macroinvertebrates were mostly represented by detritivores specialized in fine detritus (69%), followed by generalist detritivores (10% with a diet based on fine and coarse detritus), carnivores (10%), omnivores (8%), and one detritivore genera specialized on coarse detritus (3%). The detritivores exhibited a broad spatial and temporal distribution and were represented mainly by Ephemeroptera, Trichoptera and Diptera. Phylloicus sp. (Trichoptera) consumed mostly coarse detritus (CPOM) and can be classified as the unique specialist shredder in this stream. Carnivores were represented by Anacroneuria sp. (Plecoptera), Hetaerina sp. and Heteragrion sp. (two Odonata). Omnivory was observed for Anacroneuria sp. and Smicridea sp. (Trichoptera), which evidently varied spatially and temporally in the proportion of the food consumed. The high diversity and the wide distribution of the taxa that used organic matter as food resource demonstrated the great importance of this food item to the macroinvertebrates community in this tropical stream.

Highlights

Headwater streams are influenced by the riparian vegetation, which provides shade and organic inputs (CUMMINS 1973, VANNOTE et al 1980)
The macroinvertebrates were mostly represented by detritivores specialized in fine detritus (69%), followed by generalist detritivores (10% with a diet based on fine and coarse detritus), carnivores (10%), omnivores (8%), and one detritivore genera specialized on coarse detritus (3%)
The macroinvertebrates community sampled in leaf-bags was composed mostly by Insecta, represented by seven orders, which are normally found associated to leaf litter (CRISCI-BISPO et al 2007)

Summary

Introduction

Headwater streams are influenced by the riparian vegetation, which provides shade and organic inputs (CUMMINS 1973, VANNOTE et al 1980). A considerable fraction of the litter entering streams is retained within the channel (POZO 2005) and becomes available as food resource for the vast majority of detritivores and microbial decomposers (DOBSON 2005). This litter can be colonized by a great number of macroinvertebrates (UIEDA & GAJARDO 1996) that can use it as food and as shelter. We compared the diet of macroinvertebrates sampled in two consecutive areas of the same stream, one forested and other deforested (spatial scale), on the dry and rainy seasons of 2004 (temporal scale)

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