Settling distances of benthic invertebrates in a sediment mobilization simulation in semi-natural flumes

Abstract

Drift time and distance depend on the ability of the drifting invertebrates to alter their body posture or by swimming, and these behaviors may change according to the local hydraulic environment, resulting in different distances travelled before exiting the drift. Such drift and settlement mediated invertebrate movement determine dispersal processes and ultimately generates distribution patterns within streams. We conducted an experiment in an open-air, artificial flume system directly fed by an Alpine stream, where we disturbed the sediment in the flumes, inducing catastrophic drift in the benthic community, and then assessed the settlement distances of benthic invertebrates. For each flume, we collected drift samples by disturbing the substrate at 1.5 m intervals, at increasing distance from the downstream end, for a total of 7 disturbances and a maximum settling distance of 10 m in each flume, with five replicates (i.e., five flumes) for each disturbance. The disturbances induced a massive catastrophic drift in Ephemeroptera, Plecoptera and Trichoptera, always higher than the behaviorally-occurring basedrift. The Settling Index calculated over the total drift collected at each distance increased with increasing distance, and after 10 m, 90% of the drifting animals had settled. Evenness and taxa richness progressively decrease with increasing settling distance. All drifting taxa were represented mainly by young instars. We used the drift collected at 1 m from the disturbance to standardize the remaining samples, based on the assumption that 1 m is not a distance long enough to allow animals to settle at that water velocity. We calculated the percentage of possible drifters which settled by computing a Settling Index for each taxon. The drifting taxa listed by decreasing Settling Index scores were Epeorus sp., Rhithrogena semicolorata, Isoperla spp., Sericostoma spp., Ecdyonurus spp., Nemoura spp., Leuctra spp., Baetis spp., Hydropsyche spp., Rhyacophila spp. We have shown, in accordance with numerous other studies, that entrained EPT nymphs travel only short distances before returning to the substratum, and that the actual distance travelled while drifting and the total time spent in drift varies between species. The results of this study can provide suggestions to assess taxon-specific availability to colonization which generates distribution patterns within streams and, on a smaller scale (i.e., flume simulations), our results can be extrapolated to other studies conducted in artificial flumes, or to support evidences from field studies.

Downloads

Download data is not yet available.

Author Biographies

Maria Cristina Bruno, Fondazione Edmund Mach - Research and Innovation Centre

Researcher, Limnology and Stream Ecology Group, Sustainable Agro-Ecosystems and Bioresources Department

Mauro Carolli, University of Trento
Post-doc, Department of Civil, Environmental and Mechanical Engineering, University of Trento.
Bruno Maiolini, Fondazione Edmund Mach - Research and Innovation Centre
Retired Researcher, Limnology and Stream Ecology Group, Sustainable Agro-Ecosystems and Bioresources Department
Published
2015-10-21
Section
Original Articles
Supporting Agencies
Fondazione Edmund Mach, Research and Innovation Centre, University of Trento, Department of Civil, Environmental and Mechanical Engineering.
Keywords:
Invertebrate drift, downstream dispersal, EPT, larval settlement.
Statistics
Abstract views: 1693

PDF: 564
HTML: 644
Share it

PlumX Metrics

PlumX Metrics provide insights into the ways people interact with individual pieces of research output (articles, conference proceedings, book chapters, and many more) in the online environment. Examples include, when research is mentioned in the news or is tweeted about. Collectively known as PlumX Metrics, these metrics are divided into five categories to help make sense of the huge amounts of data involved and to enable analysis by comparing like with like.

How to Cite
1.
Bruno MC, Carolli M, Maiolini B. Settling distances of benthic invertebrates in a sediment mobilization simulation in semi-natural flumes. jlimnol [Internet]. 21Oct.2015 [cited 31Mar.2020];75(1). Available from: https://www.jlimnol.it/index.php/jlimnol/article/view/jlimnol.2015.1324

Most read articles by the same author(s)