PRIMARY RESEARCH PAPER
Crowded waters: short-term response of invertebrate drift
to water abstraction
Jose
´
M. Gonza
´
lez
.
Marı
´
a Recuerda
.
Arturo Elosegi
Received: 11 December 2017 / Revised: 11 April 2018 / Accepted: 16 April 2018 / Published online: 24 April 2018
Ó Springer International Publishing AG, part of Springer Nature 2018
Abstract Water abstraction modifies the environ-
mental conditions of stream ecosystems, which can
affect invertebrate assemblages by altering drift. We
examined this issue with a before–after–control–
impact design experiment in which we diverted 90%
of the natural flow from a headwater stream. We
measured flow-reduction effects on drift densities
(animals/m
3
), total drift rates (animals leaving the
reach per hour) and net balance of invertebrates
entering or leaving the Impact reach. We also iden-
tified the specific taxa and traits that drove these
responses. The sudden decrease in flow promoted a
12-fold increase in overall drift density at the Impact
reach, which was primarily driven by filterers, shred-
ders and taxa associated with fast velocities, such as
simulids. By contrast, drift densities of other abundant
taxa, such as Baetis, Esolus and chironomids,
increased less than what could be expected from the
magnitude of flow reduction. While drift rates
remained unchanged after water abstraction, the
Impact reach became a net invertebrate exporter
indicating that many taxa drifted actively as a response
to stressful conditions rather than passively, which
would be reduced by water abstraction. Therefore, our
results suggest that water abstraction influences drift,
with potentially important consequences for the
invertebrate assemblages and ecosystem processes
further downstream.
Keywords Flow regulation Á Reduced flow Á
Invertebrate assemblages Á Ecological traits
Introduction
The rapid rise of human population and per capita
consumption during the last century resulted in a great
increase in the appropriation of natural resources,
including fresh water (Hoekstra & Wiedmann, 2014).
This has resulted in widespread water scarcity in rivers
across the world (Hoekstra et al., 2012), which may be
exacerbated by climate change. For instance, the
frequency of severe droughts is predicted to rise in
certain zones, including regions in southern Europe
currently without a summer dry season (Alcamo &
Olesen, 2012). Moreover, higher air temperatures may
increase water demand for irrigation, which will
promote water abstraction from surface waters and
aquifers, leading to lower base flows during summer
Handling editor: Vero
´
nica Ferreira
J. M. Gonza
´
lez (&) Á M. Recuerda
Superior School of Experimental Science and
Technology, Rey Juan Carlos University, C/Tulipa
´
n s/n,
28933 Mo
´
stoles, Spain
e-mail: jose.gonzalez@urjc.es
A. Elosegi
Faculty of Science and Technology, University of the
Basque Country, PO Box 644, 48080 Bilbao, Spain
123
Hydrobiologia (2018) 819:39–51
https://doi.org/10.1007/s10750-018-3620-1
@Phil_Robichaud
@deepthiw
@JoseServera