Defining quantitative stream disturbance gradients and the additive role of habitat variation to explain macroinvertebrate taxa richness

• Published in: Ecological indicators 2013-02, Vol.25, p.45-57
• Main Authors: Ligeiro, Raphael, Hughes, Robert M., Kaufmann, Philip R., Macedo, Diego R., Firmiano, Kele R., Ferreira, Wander R., Oliveira, Déborah, Melo, Adriano S., Callisto, Marcos
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; anthropogenic activities; Applied ecology; basins; Biological and medical sciences; Catchment disturbances; Conservation, protection and management of environment and wildlife; Disturbance indices; ecoregions; Ephemeroptera; EPT assemblages; Fresh water ecosystems; Fundamental and applied biological sciences. Psychology; General aspects; insects; Local disturbances; macroinvertebrates; microhabitats; Plecoptera; Reference condition approach; Stream habitats; streams; Synecology; Trichoptera; watersheds
• ISSN: 1470-160X; 1872-7034
• DOI: 10.1016/j.ecolind.2012.09.004

► Local and catchment disturbance indices were calculated for 40 stream sites in two river basins. ► Those indices were not correlated, and both were associated with reduced EPT richness. ► A single integrated disturbance index summarized the disturbance condition of the sites. ► The influence of habitat on EPT richness varied inversely with the strength of the disturbance gradient. Most studies dealing with the use of ecological indicators and other applied ecological research rely on some definition or concept of what constitutes least-, intermediate- and most-disturbed condition. Currently, most rigorous methodologies designed to define those conditions are suited to large spatial extents (nations, ecoregions) and many sites (hundreds to thousands). The objective of this study was to describe a methodology to quantitatively define a disturbance gradient for 40 sites in each of two small southeastern Brazil river basins. The assessment of anthropogenic disturbance experienced by each site was based solely on measurements strictly related to the intensity and extent of anthropogenic pressures. We calculated two indices: one concerned site-scale pressures and the other catchment-scale pressures. We combined those two indices into a single integrated disturbance index (IDI) because disturbances operating at both scales affect stream biota. The local- and catchment-scale disturbance indices were weakly correlated in the two basins (r=0.21 and 0.35) and both significantly (p