Supplementary Material 1: Notes on samples and sites included in this study and
taxonomic resolution
Invertebrate assemblage responses and the dual roles of resistance and resilience to drying in
intermittent rivers
Aquatic Sciences
Catherine Leigh*, Núria Bonada, Andrew J. Boulton, Bernard Hugueny, Scott T. Larned, Ross Vander
Vorste and Thibault Datry
*catherine.leigh@irstea.fr. Irstea, UR MALY, centre de Lyon-Villeurbanne, 5 rue de la Doua-CS
70077, F-69626 Villeurbanne cedex, France.
Site and sample selection
In this study, there are two samples only per site (one collected before and one after the dry period),
both collected during flow. For the ‘before’ and then again for the ‘after’ sample (respectively T1 and
T2), we only included samples collected on the same date across sites within a river (±3 days to cover
the time involved in sampling multiple sites within rivers). For example, if there were five sites
sampled in a river after a dry period, but flow commenced in one in August (with the T1 sample
collected later that month) and in the other four in November (with the T2 samples collected later that
month), then we only included the data from the four sites sampled in November because these had
consistent sampling dates and experienced similar flow conditions. For sites with more than one
replicate sample collected per date, we composited taxon lists across replicates (following methods
outlined previously in the appendix to Datry et al. 2014) to generate one taxon list per site per date.
(Note: only presence-absence data was used in this study, not abundance [count, density etc.] data.)
Again, this procedure increased consistency across datasets.
When there were many sites sampled along a longitudinal flowpath, we discarded the closest adjacent
sites that differed in flow regime (i.e., an I and P site) and, in some cases, the site farthest upstream or
downstream to limit longitudinal differences in habitat and maintain balance between the numbers of I
and P sites across the combined dataset. In Sycamore Creek, multiple samples were collected from one
site through time (Grimm et al. 2007). Consulting the accompanying flow data for this stream (USGS
2007), we were able to isolate a discrete dry period in one year of the time series and selected samples
before and after this event from within the stable flow period, avoiding samples collected during high
flow periods and spates as these are known to affect the composition of invertebrate communities in
this stream (e.g., Sponseller et al. 2010). The original Albarine, East Glen and West Stronghold
Canyon datasets each included more than one set of T1-T2 sample pairs. The T2 sample from the first
pair in both the East Glen and West Stronghold Canyon datasets was the same as the T1 sample for the
second pair, therefore we only used the first T1-T2 sample pair from both datasets. The T1-T2 sample
pairs from the Albarine were independent but the first pair included a winter sampling period; no other
samples from any other rivers were collected in winter, therefore we only included the second pair in
our analysis to retain consistently.
Periods between ‘before’ (T1) and ‘after’ (T2) samples
For the intermittent (I) sites, T1 and T2 samples were temporally separated by three periods: a flow
period from T1 until the site went dry; a dry period until flow resumed at the site; and a post-dry
period of flow until T2. For the perennially flowing (P) sites, there was one continuous flow period
between T1 and T2. For all sites, the number of days between T1 and T2 is known, calculated directly
from the sampling dates provided with each dataset. For I sites, the dates of the transitions between
1
periods are unavailable. However, information provided by the studies’ authors (via personal
communication), in their datasets and published studies and/or from nearby flow-gauge stations were
used to estimate when the periods transitioned and thus the duration, in months, of each period. For
example, the sampling site on the Fuirosos dried around the end of June 2001and flow resumed in late
September 2001 (Acuña et al. 2005). T1 and T2 samples were date June and October 2001,
respectively. This indicates the streambed was dry for ~ 3 months and the post-dry flow period prior to
T2 lasted ~ 1 month. For Sycamore Creek, for example, the duration of the post-dry flowing period
was calculated directly from the flow time series (USGS 2007).
Invertebrate sampling protocols used at the selected sites and rivers
Albarine River, France. Invertebrates were collected from riffles at I and P sites before (May 2010)
and after (October 2010) the I sites dried. At each site and each sampling date, two invertebrate
samples were collected at each of two riffles. Invertebrates were collected with a Hess sampler (0.125m2 area, 200-μm mesh) and preserved with 96% ethanol. Most aquatic insects and all molluscs were
identified to genus or species, and crustaceans, annelids and mites to genus, family or order. For more
details on invertebrate sampling and processing, see Datry (2012).
Asse River, France. Invertebrates were collected from riffles at I and P sites before (March 2009) and
after (October 2009) the I sites dried. At each site and sampling date, two invertebrate samples were
collected at each of two riffles. Invertebrates were collected using a Hess sampler (0.125-m2 area, 200μm mesh) and preserved with 96% ethanol. Most aquatic insects and all molluscs were identified to
genus or species, and crustaceans, annelids and mites to family, order or genus.
East Glen River, UK. Invertebrates were sampled from riffle-run-glides at an I and P site before (July
2008) and after (August 2008) the I site dried. At each site and sampling date, four replicate samples
were collected using a Surber sampler (0.1-m2 area, 1000-μm mesh). Samples were preserved in 4 %
formaldehyde solution. Most aquatic insects and molluscs were identified to species, genus or family,
and crustaceans, annelids and mites to order or coarser levels of resolution. For more details on
invertebrate sampling and processing, see Stubbington (2011) and Stubbington et al. (2011).
Fuirosos River, Spain. Invertebrates were sampled from the riffle habitat at one I site before (June
2001) and after (October 2001) it dried. On each sampling date, four replicate samples were collected
from cobbles (~0.078-m2 area), sand (0.012-m2 area) and leaf substrata (0.015-m2 area) and sieved
(250-μm mesh). Samples were preserved in 4% formaldehyde solution. Most invertebrates were
identified to genus or family, except for nematodes and mites which were left at their respective group
levels (i.e., Nematoda, Hydracarina). For more details on invertebrate sampling and processing, see
Acuña et al. (2005).
Little Stour, UK. Invertebrates were collected from riffle-runs at I and P sites between late August and
early September before (1996) and after (1997) the I sites dried. At each site and sampling date,
samples were collected using two-minute kick-samples with a handnet (250-μm mesh) and preserved
with 4% formaldehyde. Most aquatic insects and molluscs were identified to species, genus or family,
and annelids and mites to order. For more details on invertebrate sampling and processing, see Wood
and Armitage (2004).
Nahr-el-Kahb, Lebanon. Invertebrates were sampled from I and P sites before (June 1979) and after
(November 1979) the I sites dried. Invertebrates were collected using a Surber sampler (0.125-m2 area,
600-μm mesh). Most taxa were identified to genus. For more details on invertebrate sampling and
processing, see Khalaf and Lahoud (1983).
Orari River, New Zealand. Invertebrates were collected from riffles at I and P sites before (October
2007) and after (February 2008) the I sites dried. At each site and sampling date, four replicate
samples were collected with a Surber sampler (0.09-m2, 250-μm mesh). Samples were preserved in
2
70% isopropyl alcohol. Most aquatic insects and all molluscs were identified to genus or species.
Crustaceans, annelids and mites were identified to family or order.
Selwyn River, New Zealand. Invertebrates were collected from riffles at I and P sites before
(November 2003) and after (October 2004) the I sites dried. At each site, four replicate samples were
collected with a Surber sampler (0.09-m2 area, 250-μm mesh). Samples were preserved in 70%
isopropyl alcohol. Most insects and all molluscs were identified to genus or species. Crustaceans,
annelids and mites were identified to family or order. For more details on invertebrate sampling and
processing, see Arscott et al. (2010).
Sycamore Creek, USA. Invertebrates were collected from the sandy-run habitat at one reach of the
spatially intermittent creek before (April 1986) and after (April 1987) a period of zero flow, as
indicated by flow records from the nearby USGS gauge (USGS 2007). At each sampling date, five
replicate samples were collected with a PVC core (0.008-m2 area, 250-μm mesh) or Surber sampler
(0.092-m2 area, 250-μm mesh) and preserved with 95% ethanol. Most insects and molluscs were
identified to species, genus or family, and non-insects to class or phyla. For more details on
invertebrate sampling and processing, see Grimm et al. (2007).
West Stronghold Canyon, USA. Invertebrates were sampled from riffles at I sites before (April 2004)
and after (March 2005) they dried. Kick-samples were collected from all sites with a handnet (1000μm mesh net) after disturbing a 0.25 m2 area of streambed. Samples were preserved in 95% ethanol
and identified as far as practical, usually to genus or species for insects and family, order or class for
non-insects. For more details on invertebrate sampling and processing, see Bogan and Lytle (2007).
Taxonomic resolution applicable to this study
Table S1. Invertebrate taxa and their levels of resolution represented in this study’s dataset compiled
across 42 I and P sites in Mediterranean and temperate rivers and across 26 I sites in arid,
Mediterranean and temperate rivers (see Table 1 for more detail). p: phylum; c: class; o: order; sf:
superfamily; f: family.
Taxonomic resolution
Hirudinea
Oligochaeta
Hydracarina
Amphipoda
Isopoda
Copepoda
Ostracoda
Coleoptera
Hemiptera
Diptera
Ephemeroptera
Lepidoptera
Megaloptera
Odonata
Plecoptera
Trichoptera
Hydrozoa
Bivalvia
Gastropoda
Nematoda
Platyhelminthes
I and P
Level (number)
c(1)
c(1)
c(1)
o(1)
o(1)
o(2)
c(1)
f(8)
f(2)
f(10)
f(8)
sf(1)
f(2)
f(2)
f(5)
f(10)
c(1)
f(1)
f(7)
p(1)
p(1)
I only
Level (number)
c(1)
c(1)
c(1)
o(1)
o(1)
o(2)
c(1)
f(7)
f(12)
o(1),f(6)
sf(1)
f(1)
f(1)
f(5)
o(1),f(7)
f(1)
f(6)
p(1)
p(1)
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