PRIMARY RESEARCH PAPER Comparison of the propensity to drift for three invertebrate taxa: a laboratory study Elorri Arevalo . Aitor Larran ˜aga . Margaret Lang . Etienne Prevost . Agne `s Bardonnet Received: 17 September 2017 / Revised: 10 December 2018 / Accepted: 17 December 2018 / Published online: 1 January 2019 Ó Springer Nature Switzerland AG 2019 Abstract Invertebrate drift is an important ecolog- ical process but factors affecting the downstream transport of invertebrates are difficult to assess. The influence of water velocity on drift entry rates is still unclear and has rarely been quantified. In this study, conducted in spring and autumn, we investigated the drift propensity for different sizes of Baetis, Simulium and Chironomus larvae which, over a 24-h period, were subjected to low, moderate or high water velocities (14, 30 and 40 cm s -1 , respectively) in either fine or coarse gravel beds. Interspecific differ- ences were detected: Baetis drifted the most, Chi- ronomus showed intermediate values and Simulium drifted the least. Chironomus was the only taxon that responded to water velocity. Baetis and Simulium were only slightly constrained to drift by the experimental conditions, while, in contrast, Chironomus larvae were very sensitive to flow increase. Substrate size (fine/coarse gravel bed) had no effect on any taxa. Small Simulium and Chironomus drifted more than larger ones. A seasonal effect was also detected, with Baetis drifting more in fall and Simulium drifting more in spring. Results suggest that community structure may be as or more important than hydraulics as a determinant of drift rates. Keywords Aquatic invertebrates  Water velocity  Substrate size  Invertebrate size  Season Introduction Invertebrate drift is defined as the downstream trans- port of benthic invertebrates in suspension (Mu ¨ller, 1954) and it is an important ecological process in lotic systems (Brittain & Eikeland, 1988). It increases the stream carrying capacity for drift-feeding fish (e.g. Hayes et al., 2016), and contributes to the dispersal of invertebrate species across the aquatic network allow- ing for connection between habitats and facilitating recolonisation processes. Since the 1960s, ecologists have divided invertebrate drift into categories such as ‘‘behavioural’’, ‘‘constant’’ or ‘‘catastrophic’’ drift Handling editor: Marcelo S. Moretti Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10750-018-3870-y) con- tains supplementary material, which is available to authorised users. E. Arevalo (&)  E. Prevost  A. Bardonnet ECOBIOP, UMR 1224, INRA, Univ Pau & Pays Adour, Aquapo ˆle, 64310 Saint-Pe ´e-sur-Nivelle, France e-mail: elorri.arevalo@gmail.com A. Larran ˜aga Lab of Stream Ecology, Dept. of Plant Biology and Ecology, Univ. Basque Country, UPV/EHU, 48080 Bilbao, Spain M. Lang Environmental Resources Engineering, Humboldt State University, Arcata, CA 95521, USA 123 Hydrobiologia (2019) 830:243–254 https://doi.org/10.1007/s10750-018-3870-y