Scale-dependency of macroinvertebrate communities: Responses to contaminated sediments within run-of-river dams

Abstract

Due to their nutrient recycling function and their importance in food-webs, macroinvertebrates are essential for the functioning of aquatic ecosystems. These organisms also constitute an important component of biodiversity. Sediment evaluation and monitoring is an essential aspect of ecosystem monitoring since sediments represent an important component of aquatic habitats and are also a potential source of contamination. In this study, we focused on macroinvertebrate communities within run-of-river dams, that are prime areas for sediment and pollutant accumulation. Little is known about littoral macroinvertebrate communities within run-of-river dam or their response to sediment levels and pollution. We therefore aimed to evaluate the following aspects: the functional and structural composition of macroinvertebrate communities in run-of-river dams; the impact of pollutant accumulation on such communities, and the most efficient scales and tools needed for the biomonitoring of contaminated sediments in such environments. Two run-of-river dams located in the French alpine area were selected and three spatial scales were examined: transversal (banks and channel), transversal x longitudinal (banks/channel x tail/middle/dam) and patch scale (erosion, sedimentation and vegetation habitats). At the patch scale, we noted that the heterogeneity of littoral habitats provided many available niches that allow for the development of diversified macroinvertebrate communities. This implies highly variable responses to contamination. Once combined on a global 'banks' spatial scale, littoral habitats can highlight the effects of toxic disturbances.

Functional diversity: a review of methodology and current knowledge in freshwater macroinvertebrate research

“…There is no doubt that Rao's quadratic entropy has become the most frequently used measure of functional diversity by occurring in 19 of 40 papers that defined functional diversity mathematically (e.g. Peru & Dolédec, 2010;Vandewalle et al, 2010;Colas et al, 2011;Gallardo et al, 2011;Buendia et al, 2013;Graeber et al, 2013;Paillex et al, 2013;Reynaga & Dos Santos, 2013). In 2014, almost all reviewed papers used Rao's quadratic entropy for measuring functional diversity of freshwater macroinvertebrates (e.g.…”

Vers une démarche graduée d'évaluation écotoxicologique des sédiments fluviaux : présentation et premiers tests

“…Il faut par conséquent procéder par comparaison à une référence relative présentant des caractéristiques comparables aux sites tests, à l'exception de la contamination. Nous n'avons pas observé de structuration longitudinale dans les retenues étudiées [Colas, F. et al 2011], ce qui légitime l'utilisation d'une référence relative à l'amont des retenues. Pour la bioamplification, l'interprétation fait appel aux NQE-biote ou à des seuils de toxicité tissulaire (CBR).…”

Synergistic impacts of sediment contamination and dam presence on river functioning

“…Macroinvertebrates in reservoirs were sampled using an original protocol (Colas, Archaimbault & Devin, 2011), whereby reservoirs were subdivided into three zones, termed 'tail', 'middle' and 'dam', reflecting their various hydraulic and hydro-morphological conditions. Macroinvertebrates in reservoirs were sampled using an original protocol (Colas, Archaimbault & Devin, 2011), whereby reservoirs were subdivided into three zones, termed 'tail', 'middle' and 'dam', reflecting their various hydraulic and hydro-morphological conditions.…”

“…Macroinvertebrates were sampled during the spring campaign (2010) following two protocols. Macroinvertebrates in reservoirs were sampled using an original protocol (Colas, Archaimbault & Devin, 2011), whereby reservoirs were subdivided into three zones, termed 'tail', 'middle' and 'dam', reflecting their various hydraulic and hydro-morphological conditions. Communities of the banks and of the channel were sampled separately.…”