Diversity assessment of benthic macroinvertebrates, yeasts, and microbiological indicators along a longitudinal gradient in Serra do Cipó, Brazil

M Callisto,C A Rosa,P Moreno,M Goulart,A O Medeiros

doi:10.1590/s1519-69842004000500003

Abstract

The main goals of this study were: 1) to evaluate the structure, diversity, and functional trophic group composition of benthic macroinvertebrate communities; 2) to characterize water quality in the headwaters of the Doce river watershed, based on physical, chemical, and biological parameters (benthic macroinvertebrates, fecal coliforms, heterotrophic bacteria, and yeasts); and 3) to contribute to the knowledge of the structure and function of longitudinal gradients in lotic ecosystems in Brazil. A total of 60 benthic macroinvertebrate taxa were identified, the dominant group being the aquatic insects, with 50 families distributed in 8 orders. The dry period presented higher values of taxonomic richness and total density of benthic macroinvertebrates. A decreasing gradient was observed in these variable values from the 3rd order stretch down to the 6th order stretch. The highest Shannon-Wiener diversity values were found in the rainy period in the 3rd order stretches, which presented well-developed riparian forest. Besides the 3rd order stretches, the Pielou evenness index values were also high in the 6th order stretch. The collectors, together with the scrapers, predominated in the benthic macroinvertebrate communities in all river stretches, except in the 2nd, 4th, and 5th order stretches in the rainy period, where communities were dominated by filterers. The shredders and predators presented low densities for all river stretches. All microbiological variables presented low levels. Due to the high counts of heterotrophic bacteria and coliforms, the studied river stretches presented inadequate potability but adequate balneability levels. The results suggest that the structure, diversity, and composition of the benthic macroinvertebrate communities are influenced by the trophic resource availability, seasonality, and sediment heterogeneity. The microbiological results of this study allow inferring that the waters from Serra do Cipó have excellent potential for recreational use and as future sources of water for human consumption.

Highlights

Within recent decades aquatic ecosystems have been altered at different scales, and registered as negative consequences of anthropogenic activities
Diversity, and functional trophic group composition of the benthic macroinvertebrate communities along the longitudinal gradient, the results indicated that, as verified in other studies, the major influences were seasonality (Oliveira et al, 1997; Bispo & Oliveira, 1998), habitat and microhabitat diversity (Galdean et al, 2000, 2001; Callisto et al, 2001b), and the canopy cover of the riparian vegetation along the river bed (Aguiar et al, 2002)
A decrease in taxonomic richness and total density of benthic macroinvertebrate communities was observed in the rainy period in almost all river stretches

Summary

Introduction

Within recent decades aquatic ecosystems have been altered at different scales, and registered as negative consequences of anthropogenic activities (e.g., mining, dam construction, artificial eutrophication, river canalization, and recreation). Biological indicator use in monitoring programs provides a more exact measure of anthropogenic effects on aquatic ecosystems (Callisto & Esteves, 1995; Callisto et al, 2001a). Microbiological monitoring of organisms important in determining water contamination levels is usually done by fecal pollution indicators, represented by bacteria counts of coliform groups (Ceballos et al, 1995; Lutterback et al, 2001). This parameter is used by government agencies to classify water bodies as to use and sanitary levels (balneability and potability). Species within the genera Cryptococus, Debaryomyces, and Rhodotora are characteristically found in nonpolluted waters, while Candida and Saccharomyces species can be frequently found in eutrophic waters (Hagler et al, 1986; Rosa et al, 1995)

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