Effect of land use on the composition, diversity and abundance of insects drifting in neotropical streams.

B C G Gimenez,F A Lansac-Tôha,J Higuti

doi:10.1590/1519-6984.03914

B C G Gimenez, F A Lansac-Tôha + Show 1 more

Open Access

https://doi.org/10.1590/1519-6984.03914

Copy DOI

Abstract

Streams may exhibit differences in community structure of invertebrate drift, which may be a reflex of variation in environmental factors, able to change in conditions of anthropogenic interventions. The aim of this study was to analyze the composition, diversity and abundance of insects drifting in two neotropical streams under different land use and to identify the environmental factors involved in determining such patterns. 54 taxa of aquatic insects were identified in urban and rural streams. The results indicated significant differences in species composition due to the replacement of specialist species by generalist species in the urban stream. Higher diversity of taxa was recorded in the rural stream, with high levels of dissolved oxygen and high water flow, which favored the occurrence of sensitive groups to environmental disturbances, such as Ephemeroptera, Plecoptera, Trichoptera and Coleoptera taxa, that living mainly in clean and well oxygenated waters. On the other hand, a higher density of insects drifting, especially Chironomidae, was observed in the urban stream, where high values of pH, electrical conductivity and nitrogen were observed. These larvae are able to explore a wide range of environmental conditions, owing to their great capacity for physiological adaptation. Despite observing the expected patterns, there were no significant differences between streams for the diversity and abundance of species. Thus, the species composition can be considered as the best predictor of impacts on the drifting insect community.

Highlights

Lotic ecosystems, such as streams, are those with unidirectional and continuous water flow responsible for maintaining several process, such as organic matter transport, sediment deposition and formation of longitudinal gradients within drainage basins (Vannote et al, 1980)
This study aimed to analyze the composition, diversity and abundance of insects drifting in two neotropical streams under different land use and to identify the environmental factors involved in determining such patterns
Significant differences were detected to pH (t = 5.04; p

Summary

Introduction

Lotic ecosystems, such as streams, are those with unidirectional and continuous water flow responsible for maintaining several process, such as organic matter transport, sediment deposition and formation of longitudinal gradients within drainage basins (Vannote et al, 1980) These factors, in addition to changes in current velocity, may have direct or indirect influence on local biological communities (Ward et al, 1995). The fluvial continuum of these environments allows the dispersion of immature stages of aquatic invertebrates, and the colonization of river reaches downstream from their original habitats (Callisto and Goulart, 2005) This dispersion process occurs through downstream transport of invertebrates suspended in the water column, in a very common phenomenon in stream ecosystems, known as drift (Brittain and Eikeland, 1988). Several authors have reported that there is no pattern of taxonomic composition, among organisms derived from benthic communities, immature forms of insects represent the dominant group in the composition of the drift (Waters, 1972)

Objectives

Methods

Results

Conclusion