Small dams also change the benthic macroinvertebrates community in rocky rivers

Leticia De Mattos,Gilmar Perbiche-Neves,Ana Lucia Suriani Affonso,Larissa Dal Molin Kruger,Sidnei Pressinatte Junior

doi:10.1590/s2179-975x5316

Leticia De Mattos, Gilmar Perbiche-Neves + Show 3 more

Open Access

https://doi.org/10.1590/s2179-975x5316

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Abstract

Abstract Aim: Here we analyzed some basic ecological attributes (richness and density) of the benthic community in a stretch of a rocky river under the influence of a small dam of a meter in height, forming a small reservoir of run-of-river type. Methods Sediment samples were taken with a Petersen collector at three different periods and in three sites: upstream from the dam (site 1), close to the dam (site 2) and downstream from the dam (site 3). Organisms were separated in large groups and Chironomidae genera. Results The particle size analysis indicated that the sites 1 and 2 are dominated by fine sediments, in contrast to site 3, composed of medium and coarse sediments. A total of 23 taxa of benthic macroinvertebrate groups and 31 genera of Chironomidae were found. Richness and density were different among sampling sites, and for large groups and Chironomidae its attributes increased towards downstream, probably explained by the sediment composition and the originally lotic conditions in site 3, confirmed by all statistical analysis used. In the dam site (2) there was a richness decrease. Non metric multidimensional analysis showed a clear spatial separation of large groups of macroinvertebrates and chironomid genera between sampling sites, indicating that there are typical taxa of each spatial compartment. Canonical correspondence analysis correlated only rubble sediment with the abundance of large groups, and for Chironomidae genera only the granules type was correlationed, with two groups of taxa in the anlysis: one with sites 1 and 2, and other with site 3. Conclusions Even very small dams in rocky rivers as in the present study alter the environmental variables and ecological attributes of benthic macroinvertebrates.

Highlights

Water reservoirs have been constructed since ages ago for water supply, hydropower generation, leisure, fish production, among other uses (Diomande et al, 2013)
In order to demonstrate the ecological effect of even small size, depth, and very low water retention time reservoirs, this study aimed to detect if even a small dam without lateral expansion in the shape of arms, can significantly alter some basic ecological attributes of benthic macroinvertebrates
Water flow, size, area and volume of the reservoir, water retention time and human activities in the watershed tend to influence the presence of these spatial compartments

Summary

Introduction

Water reservoirs have been constructed since ages ago for water supply, hydropower generation, leisure, fish production, among other uses (Diomande et al, 2013) These environments transform lotic in lentic environments, causing reduction of water flow and more deposition of fine sediment, increase of deep and water transparency, modifying the physical and chemical conditions and the structure of biological communities (Tundisi, 1986; Palmer et al, 2000). The structure of insect community and other aquatic invertebrates can be modeled in relation to the natural and anthropic changes (Silveira, 2004) They are an efficient bioindicators due to different tolerances to environmental variables, longer life cycle and low spatial mobility compared to plankton and fishes (Metcalfe, 1989; Queiroz et al, 2008). Some organisms are typical of environments with good water quality, as nymphs of Plecoptera and Trichoptera larvae (Callisto et al, 2001)

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