Abstract
Abstract: Aim The goal of this study is to examine the composition and richness of caddisfly assemblages in streams at the Serra da Bocaina Mountains, Southeastern Brazil, and to identify the main environmental variables, affecting caddisfly assemblages at the streams with different conditions of land use. Methods The sampling was conducted in 19 streams during September and October 2007. All sites were characterized physiographically by application of environmental assessment protocol to Atlantic Forest streams and by some physical and chemical parameters. Of the 19 streams sampled, six were classified as reference, six streams as intermediate (moderate anthropic impact) and seven streams as poor (strong anthropic impact). In each site, a multi-habitat sampling was taken with a kick sampler net. The sample was composed by 20 units, each one corresponded to 1 m2 of collected substrate, corresponding 20 m2 of sampling area. The material was placed in a plastic container (500 µm of mesh), washed, homogenized and sub-sampled. For each stream, 6 subsamples were randomly sorted. Results Were collected 2,113 caddisfly larvae, belonging to 12 families and 28 genera. Hydropsychidae and Leptoceridae were the most abundant families, and Smicridea was the most abundant genus. Sorensen’s index results showed that the streams studied were grouped according to environmental integrity. The Indicator Species Analysis showed only characteristic taxa to reference streams. Canonical Correspondence Analysis showed that caddisfly assemblage was strongly influenced by nitrate concentration, pH and condition of riparian vegetation. Multiple regression analysis indicated significant correlations to five genera with some environmental parameters, besides total abundance of Trichoptera. Conclusions Ours results showed that degree of environmental impact, mainly the nitrate concentration, pH, and condition of cover vegetation acted as a major factor in determining the Trichoptera assemblages present in the stream of the Serra da Bocaina, separating streams along an environmental gradient.
Highlights
The lotic ecosystems in the Atlantic forest of Southeastern region of Brazil have suffered severe man-induced stress and are threatened by pollution, development of urban areas and loss of riparian vegetation
The aim of the present study was to examine the composition and richness of caddisfly assemblages in streams at the Serra da Bocaina Mountains, Southeastern Brazil, and to identify the main environmental variables, including riparian vegetation, affecting caddisfly assemblages in streams subjected to different conditions of land use
The Serra da Bocaina territory is partly preserved in a conservation unit, the Parque Nacional da Serra da Bocaina (PNSB) with an area of 1 000 km2, located between 22°40’23°20’S and 44°24’-44°54’W), with 60% of native vegetation and the remainder consisting of a 30-y regenerated forest
Summary
The lotic ecosystems in the Atlantic forest of Southeastern region of Brazil have suffered severe man-induced stress and are threatened by pollution, development of urban areas and loss of riparian vegetation. Macroinvertebrate as indicators of human disturbance have a long history for use in evaluating sewage pollution in rivers, among Trichoptera larvae are often a major component of the invertebrate fauna in lotic ecosystems worldwide (Ward, 1992), corresponding about 8-13% of total abundance. They are fundamental components of the trophic dynamics and energy flow in lakes, rivers, and streams, forming a link between basal resources (organic debris and primary production and secondary consumers such as fishes (Resh & Rosenberg, 1984; Angrisano, 1995; Wiggins, 1996)
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