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Habitat degradation and trout stocking can reinforce the impact of flash floods on headwater specialist Alpine bullhead Cottus poecilopus – A case study from the Carpathian Mountains



In freshwater streams, flooding is a typical source of natural disturbance that plays a key role in the dynamics of animal populations and communities. However, habitat degradation and fish stocking might increase the severity of its impact. We tested the effects of a flash flood on the abundance of three size classes of headwater dwelling Alpine bullhead, Cottus poecilopus, in the streams of the Carpathian Mountains in the Czech Republic, that are stocked with hatchery-reared brown trout, Salmo trutta. We showed that the overall abundance of Alpine bullhead was highest at the sites with the least degraded habitat (i.e., natural habitat) and we caught almost no Alpine bullhead at the sites with the most degraded habitat. The flash flood had a strong negative effect on the abundance of the largest individuals of Alpine bullhead. Abundance of small and medium size Alpine bullhead was negatively affected by the abundance of adult stocked brown trout before as well as after the flash flood. However, negative effect of adult brown trout abundance on abundance of large Alpine bullhead was not significant before the flash flood, and it became significant after the flash flood. This could indicate an accumulation of negative impacts of trout stocking and flash flood on this size class. Overall, our results suggest that stocking of hatchery trout and habitat degradation can reinforce the impact of flash floods on the population of Alpine bullhead in the streams of the Carpathian Mountains.
J Appl Ichthyol. 201 8;1–9.  
© 2018 Black well Verlag GmbH
Floods are an important phenomena in the freshwater stream eco-
system, as they form the stream habitat and connect streams with
the riparian zone. During floods, streambeds process and transfer
a large amount of sediment (Kondolf, 1997). This temporary distur-
bance of the bottom habitat is especially challenging for benthic
organisms and thus benthic animals display an array of adaptations
for high flow (Naiman, Decamps, & McClain, 2005). Alpine bullhead,
Cottus poecilopus, is a benthic species that is able to hold its position
in the fas t flowing water (Coom bs, Anderson, Braun, & G rosenbaugh,
2007). Adaptations of the Alpine bullhead for fast flowing water
include morphological traits such as a low body height, flat head and
body, as well as a large caudal peduncle depth (Kerfoot & Schaefer,
2006). Alpine bullhead also display behavioural adaptations like shel-
tering in the less exposed floodplain and tributaries during floods
(Bayley, 1991; Sato & Yoshimura, 2014).
Over the last hundred years, most European rivers have un-
dergone significant morphological changes associated with an-
thropogenic modifications of channels and floodplains, which has
resulted in serious habitat degradation (Kondolf, 1997). The artificial
changes have made streams straighter, incised, and insulated from
the floodplains. These changes in the morphology of stream chan-
nels, together with climate change, have increased the frequency
  Accepted:7Februa ry2018
DOI: 10.1111/jai.13682
Habitat degradation and trout stocking can reinforce the
impact of flash floods on headwater specialist Alpine bullhead
Cottus poecilopus – A case study from the Carpathian
M. Kubín1,2 | M. Rulík1| S. Lusk3| L. Závorka4
1Department of Ecology and Environmental
Sciences, Faculty of Science, Palacký
University Olomouc, Olomouc, Czech
2Nature Conservation A gency of the Czech
Republic, Chodov, Czech Republic
4CNRS, UMR 5174 EDB, Université Toulouse
3 Paul Sabatier, Toulouse, France
Miroslav Kubín, Department of Ecology and
Environmental Sciences, Faculty of Science,
Palacký University Olomouc, Olomouc,
Czech Republic.
Funding information
IGA_PrF_2016_019 Project of Palacky
University in Olomouc
In freshwater streams, flooding is a typical source of natural disturbance that plays a
key role in the dynamics of animal populations and communities. However, habitat
degradation and fish stocking might increase the severity of its impact. We tested the
effects of a flash flood on the abundance of three size classes of headwater dwelling
Alpine bullhead, Cottus poecilopus, in the streams of the Carpathian Mountains in the
Czech Republic, that are stocked with hatchery- reared brown trout, Salmo trutta. We
showed that the overall abundance of Alpine bullhead was highest at the sites with
the least degraded habitat (i.e., natural habitat) and we caught almost no Alpine bull-
head at the sites with the most degraded habitat. The flash flood had a strong nega-
tive effect on the abundance of the largest individuals of Alpine bullhead. Abundance
of small and medium size Alpine bullhead was negatively affected by the abundance
of adult stocked brown trout before as well as after the flash flood. However, nega-
tive effect of adult brown trout abundance on abundance of large Alpine bullhead
was not significant before the flash flood, and it became significant after the flash
flood. This could indicate an accumulation of negative impacts of trout stocking and
flash flood on this size class. Overall, our results suggest that stocking of hatchery
trout and habitat degradation can reinforce the impact of flash floods on the popula-
tion of Alpine bullhead in the streams of the Carpathian Mountains.
   KUBÍN et al.
and severity of sudden natural phenomena like flash floods (Brunetti
et al., 2006). Such events can arise due to heavy precipitation over
several hours, followed by a quick and usually short- term rise of the
flow (Doswell, Brooks, & Maddox, 1996). Flash floods are associ-
ated with fast flow rates and significant geomorphological changes
in the streambed, which can have a substantial negative effect on
fish communities in mountain streams (Foulds, Griffiths, Macklin, &
In addition to degradation of stream habitats, frequent stock-
ing of hatchery reared salmonids like brown trout, Salmo trutta, has
become a common practice in many streams worldwide since the
mid- 19th century (Stankovic, Crivelli, & Snoj, 2015). Stocking hatch-
ery brown trout is known to have a negative impact on the growth
and survival of various stream dwelling species (Buoro, Olden, &
Cucherousset, 2016). Alpine bullhead are less abundant at sites with
a high abundance of S. trutta (Baran et al., 2014). However, the ef fect
of habitat degradation and trout stocking on the capacity of Alpine
bullhead populations to resist natural disturbances like flash floods
has not been addressed.
This study compares the abundance of three size classes of
Alpine bullhead at 15 stretches of three streams in the Carpathian
Mountains in the Czech Republic, before and after a flash flood. The
aim of this study was to examine how the populations of Alpine bull-
head respond to flash floods across a range of habitats varying in
quality and abundance of stocked hatchery brown trout.
2.1 | Study locality
The headwaters of the Rožnovská Bečva River are located in
the Beskydy Landscape Protected area in the Czech Republic
Mountains. It is a typical torrential gravel- bed stream with a length
of 37.6 km and basin area of 254.3 km2. The mean annual dis-
charge of the Rožnovská Bečvariversis2.72m3/sat Rožnovpod
bedrock of the study area is composed of flysch Cretaceous rocks
dominated by Quaternary sediment (Menčík & Tyráček, 1985).
The widespread vegetation in the upstream section is spruce for-
est, which alternates with willow, alder vegetation and meadows
downstream. Fifteen sampling stretches were chosen at the three
FIGURE1 MapshowingthewatershedoftheRožnovskáBečvaRiverandthreemaintributaries(Starozuberskýstream,Dolnopasecký
KUBÍN e t al.
habitat description). The abundance of brown trout in the stud-
ied streams is maintained above its natural level due to periodical
stocking by the Czech angling association, which is performed in
2 year cycles. Adult brown trout (2+) are captured every second
year and juveniles (0+) are stocked of with about 3.5 thousand of
individuals per km. Torrential precipitation caused a flash flood in
(precipitation of 145.4 mm was recorded on May 16). Consequently,
the water flow in the observed streams increased approximately a
hundred times within several hours (for example, the discharge in
Zákopeckýstreamduringthefloodpeakwas10.5m3/s, compared
to the average daily flow in May, which is 0.184 m3/s). The flash
flood rate reached the level of the 5–10 year flood record. In the
other streams, the flow reached approximately the 10- year flood
approximately the 50- year flood level (data source: Czech Hydro-
Meteorological Institute).
2.2 | Data sampling
We selected five 100 m long sampling stretches in each of three
study streams. The mean distance between the stretches within a
stream was 1 km. Sampling of the stretches was carried out before
(from September to November 20 09) and after (from July to October
2010) the flood. Alpine bullhead and brown trout were captured
by two- pass electrofishing using a backpack electroshocker (SEN
[200–240V, straight DC], B ednář, Czech Republic ). The upstream
and downstream edges of the sampling stretches were obstructed
by nets with a mesh size 5 × 5 mm, to prevent sampled fish escaping.
Every fish was measured (total length to the nearest mm). Following
the measurements, all specimens were placed in a recovery tank and
then released back to the place where they were caught. We did
not estimate densities of age 0+ juveniles (>35 mm total length, TL)
due to the low sampling efficiency of electrofishing for this age class
(Bohlin, Hamrin, Heggbergert, Rasmussen, & Saltveit, 1989). The
final estimate of the brown trout and Alpine bullhead abundance in
the investigated sampling sections was done in accordance with the
calculations in Seber and LeCren (1967). Alpine bullhead is defined
as an “endangered” species within the Czech national conservation
legislature (Law no. 114/1992 Coll. on the conservation of nature
and landscapes).
The level of habitat degradation within the sampled stretches
was evaluated before the flash flood following a method pro-
posed by Weiß, Matouskova, and Matschullat (2008) for EU- Water
Framework Directive. The method assesses the eco- hydrological
quality of rivers based on 32 parameters e.g., character of flow,
diversity of microhabitats, human- made changes in flow regime,
occurrence of artificial steps, vegetation, land- use in the flood-
plain, retention of the floodplain, flood protection measures, river
valley type, etc.). The aquatic ecosystem is understood as a terri-
tory formed by mutually interconnected zones: channel, riparian
belt and floodplain. Riverbank features, riparian belt and floodplain
are separately assessed during mapping, but the final assessment
is calculated jointly for both sides. Results in simple point classifi-
cation (points I–V), where (I) corresponds to the reference, i.e., the
natural habitat without human intervention, (II) Slightly changed, (III)
Moderately changed, (IV) Strongly changed, and (V) characterizes
a completely changed habitat. The average water depth was calcu-
lated based on measurements with a calibrated bar at five sites in
each section. The river substratum was sampled using a method de-
vised by Wolman (1954) and quantified according to Bain, Finn, and
Booke (1985). We used the stream substrate classification system:
boulder (>256 mm), cobble (64–256 mm), pebble (16–64 mm), gravel
(2–16 mm), sand, silt (<2 mm).
2.3 | Data handling and statistics
We used generalized linear models (GLM) for count data (i.e.,
Poisson distribution) with positive skewed distribution (i.e., log
link). All models contained a study stream as a covariate to ac-
count for variability between the sampled streams. The first
model was built to test the effect of flash flood and habitat degra-
dation across the size classes of Alpine bullhead. For this purpose,
individuals of Alpine bullhead were split in to three size classes:
small (body length range 40–65 mm), medium (body length range
70–90 mm), and large (body length range 95–125 mm). Alpine
bullhead can start to spawn when they reach a body length of
40 mm, but probability of maturity and number of eggs pro-
duced by females is positively correlated with body size (Freyhof,
Kottelat, & Nolte, 2005). The models contained abundance of
individuals as response variable and the year of sampling (two
levels), size class (three levels), level of habitat degradation (four
levels) as independent variables (see Table 2 for detailed model
structure). The effect of brown trout abundance on bullhead was
tested by models containing bullhead abundance as a response
and bullhead size class, initial abundance (i.e., before the flood) of
juvenile and adult brown trout, the year of sampling (two levels)
as independent variables (see Table 3 for detailed model struc-
ture). Based on a previous study describing growth of brown trout
Slavík, 2013), we considered brown trout smaller than 110 mm as
juvenile and brown trout larger than 110 mm as sub adult or adult.
The effect of the flash flood on the stream channel morphology
was tested using chi- square test for categorical variable (i.e., sub-
strate type) and pair- wise T- test for continuous variables (i.e.,
substrate homogeneity and water depth). To avoid the mistreat-
ment of covariate interaction terms, non- significant interactions
in GLM were removed from models and the model was run again
without them (Engqvist, 2005). The removal was performed by a
step- wise method of selection from the highest non- significant
interaction to the lowest. Model fit was assessed by visual inspec-
tion of distribution of model residuals and plots of fitted values
versus residuals. Differences among categories of fixed factors
were tested using Tukey’s HSD post- hoc test. Statistical analyses
   KUBÍN et al.
TABLE1 Basic characteristics of each sampled river section. Ecological status of sampling sections following Weiß et al. (2008) was used to evaluate the level of habitat degradation
Study streams
section ID
Before flood (2009) After flood (2010)
substrate (%)
depth (m)
Salmo trutta
(ind. per
100 m−1 )
depth (m)
(ind. per
100 m−1 )
Dolnopasecký DP 1 3.2 505 II Boulders 50 0.14 12 Boulders 41 0 .14 9
DP 2 4.3 455 III Pebbles 41 0.12 48 Gravel 55 0.13 19
DP 3 4.5 425 II Pebbles 50 0.15 131 Gravel 40 0.16 43
DP 4 4.2 410 III Pebbles 80 0.15 192 Gravel 45 0.17 33
DP 5 4.0 390 IV Gravel 40 0.17 122 Gravel 60 0.19 15
Starozuberský SZ 1 3.8 500 IPebbles 50 0.1 42 Pebbles 65 0.9 10
SZ 2 3.6 465 IPebbles 55 0.9 41 Pebbles 45 0.10 19
SZ 3 4.5 440 II Pebbles 70 0.11 14 Pebbles 60 0.12 9
SZ 4 4.2 405 III Pebbles 65 0.13 114 Pebbles 80 0.11 23
SZ 5 4.0 365 III Pebbles 60 0.15 88 Boulders 35 0.18 16
Zakopecký ZP 1 3.2 605 IBoulders 60 0.15 75 Boulders 45 0.21 106
ZP 2 4.3 545 III Pebbles 50 0.21 53 Boulders 40 0.23 136
ZP 3 4.5 525 II Pebbles 50 0.14 82 Pebbles 40 0.24 29
ZP 4 4.2 505 III Pebbles 45 0.25 40 Boulders 45 0.27 18
ZP 5 4.0 485 III Boulders 35 0.31 33 Pebbles 50 0.29 34
KUBÍN e t al.
were performed using R software v.3.2.2 (R Development Core
Team, 2015), and multcomp (Hothorn, Bretz, & Westfall, 2008),
car (Fox & Weisberg, 2015), and lme4 (Bates, Maechler, Bolker, &
Walker, 2015) packages.
The flash flood had a strong effect on the abundance of Alpine bull-
head in the studied streams. However this effect differed across the
size classes (χ2 = 12.1; p < .0001; Tables 2 and S1). Total abundance
of bullhead decreased from 781 to 684 individuals, which represents
a reduction of 12.4% of Alpine bullhead abundance before the flash
flood. There were only slight changes in the abundance of individuals
with small (χ2 = 4.0; p = .046) and medium (χ2 = 3.0; p = .084) body
sizes before and after the flash flood. However the number of large
individuals decreased substantially after the flash flood (χ2 = 37.6;
p < .0001; Figure 2).
The abundance of Alpine bullhead was highest at the sites with
the least degraded habitat (i.e., natural habitat) and we caught al-
most no Alpine bullhead at the sites with the most degraded hab-
itat (Figure 3; Table S1). However, abundance of Alpine bullhead at
the sites with natural habitat significantly decreased after the flash
flood, from 207 to 154 individuals (χ2 = 15.4; p < .0001; Figure 3).
In contrast, abundance of Alpine bullhead was not affected by flash
floods at the sites with degraded habitat (Habitat quality II: χ2 = 1.3;
p = .253; Habitat quality III and IV: χ2 = 2.0; p = .155; Figure 3). We
found no significant change in the type of the dominant substrate
(χ2 = 1.866; p = .3934) and substrate homogeneity (|t| = 0.8705;
p = .3987) and only a slight increment (2 cm in average) of the stream
channel depth (|t| = 2.2121; p = .0440; Table 1) after the flash flood.
Initial abundance of adult stocked brown trout (i.e., before
the flash flood) had a strong negative effect on the abundance of
small and medium sized Alpine bullhead, and this negative effect
was consistent between the years before and after the flash flood
(Tables 3 and S1; Figure 4). However, adult trout abundance also
had a significant additive negative effect on the abundance of large
Alpine bullhead following the flash flood. In particular, the nega-
tive slope of the relationship between initial abundance of adult
brown trout abundance and abundance of Alpine bullhead was not
significant before the flash flood (χ2 = 0.8; p = .363), but it became
significant after the flash flood (χ2 = 5.4; p = .020; Figure 4). In con-
trast to the impact of adult brown trout, the effect of abundance
of juvenile brown trout on Alpine bullhead was relatively weak
(Tables 3 and S1; Figure 4). Specifically, we found that there was a
negative relationship between abundance of juvenile brown trout
and abundance of Alpine bullhead only before the flash flood and
only in small (χ2 = 3.9; p = .048) and medium size classes (χ2 = 7. 0;
p = .008).
The overall abundance of stocked brown trout significantly de-
creased after the flash flood in most studied stretches (χ2 = 13.620;
p = .0086), from 1,087 to 519 individuals, which represents are duc-
tion of 52.3% of brown trout abundance before the flash flood.
Several studies have demonstrated the negative effect of floods on
populations of sculpins. For example Cottus pullex in a Japanese river
TABLE2 Generalized linear models (GLM) testing the effects of
habitat degradation and flash flood on abundance of Alpine
Overall model df χ2p
Intercept 1946. 2 <.0 01
Year 112.1 <.001
Stream 2353.8 <.001
Size group 2 75.1 <.0 01
Habitat quality 3107. 2 <.0 01
Size group: Year 2 39.4 <.001
Habitat quality: Year 312.6 .006
Size group 45–65 mm
Intercept 1554.6 <.0 01
Year 14.0 .046
Habitat quality 344.8 <.0 01
Stream 256.4 <.001
Size group 70–90 mm
Intercept 1873.7 <.001
Year 13.0 .084
Habitat quality 33 9. 3 <.0 01
Stream 2193 .5 <.001
Size group 95–125 mm
Intercept 1170.5 <.0 01
Year 137.6 <.001
Habitat quality 351 .9 <.001
Stream 21 57.5 <.001
Habitat quality I
Intercept 1536.9 <.001
Year 115.4 <.0 01
Size group 2 63.7 <.001
Stream 17 7. 3 <.001
Habitat quality II
Intercept 1305.7 <.001
Year 11.3 .253
Size group 2 80.3 <.001
Stream 261.6 <.001
Habitat quality III and IV
Intercept 1492.1 <.001
Year 12.0 .155
Size group 2 146.1 <.001
Stream 2201.1 <.0 01
Interactions in the overall model are decomposed in post- hoc models for
each size group and the level of habitat degradation. Report contains the
independent variables, degrees of freedom, χ2, and level of significance
described by p- value.
   KUBÍN et al.
(Natsumeda, 2003) or Cottus carolinae exposed to severe floods in
Arkansas (Matthews, 1986). In agreement, we found a decrease in
the abundance of Alpine bullhead following the flash flood, which
was especially pronounced in the largest individuals with the high-
est reproductive value (Freyhof et al., 2005). Large Alpine bull-
heads (95–125 mm) often occur in the middle of stream channels
with coarser substrata and deeper water (Davey, Hawkins, Turner,
& Doncaster, 2005; Liefferinge, Seeuws, Meire, & Verheyne, 2005).
These microhabitats provide shelters against predators and can pro-
tect bullhead against increased water flow. However, water energy
at the peak flow during the flash flood transports stream- bed ma-
terial like cobbles and boulders. Therefore, there is an increase in
TABLE3 Generalized linear models (GLM) testing the effects of
abundance of juvenile and adult brown trout and flash flood on
abundance of Alpine bullhead
Overall model df χ2p
Intercept 1715.9 <.001
Initial number of juvenile ST 1 26.0 <.001
Initial number of adult ST 1 21.3 <.001
Year 10.2 .618
Stream 2204.6 <. 001
Size group 2 3 9.4 <.001
Initial number of juvenile ST:
11.2 .279
Initial number of juvenile ST:
Size group
230.8 <.001
Initial number of adult ST:
11.8 .177
Initial number of adult ST:
Size group
21.7 .437
Size group: Year 2 4.7 .096
Initial number of juvenile ST:
Size group: Year
27.2 .026
Initial number of adult ST:
Size group: Year
29.5 .008
Size group 45–65 mm before flood
Intercept 1653.8 <.001
Initial number of juvenile
13.9 .048
Initial number of adult ST 1 33.4 <.001
Stream 210.7 .005
Size group 45–65 mm after flood
Intercept 1671.4 <.001
Initial number of juvenile
11.7 .188
Initial number of adult ST 1 28.1 <.001
Stream 236.0 <.001
Size group 70–90 mm before flood
Intercept 1896.4 <.001
Initial number of juvenile
17.0 .008
Initial number of adult ST 1 27. 2 <.001
Stream 218.8 <.001
Size group 70–90 mm after flood
Intercept 1818.4 <.001
Initial number of juvenile
11.3 .256
Initial number of adult ST 1 40.2 <.001
Stream 292.5 <.001
Size group 95–125 mm before flood
Intercept 195.1 <.001
Initial number of juvenile ST 11.1 .294
Overall model df χ2p
Initial number of adult ST 1 0.8 .363
Stream 2201.1 <.0 01
Size group 95–125 mm after flood
Intercept 12.2 .132
Initial number of juvenile
10.1 .698
Initial number of adult ST 1 5.4 .020
Stream 2201.1 <.0 01
Interactions in the overall model are decomposed in post- hoc models for
each size group and the year before and after flash flood. Report con-
tains the independent variables, degrees of freedom, χ2, and level of sig-
nificance described by p- value.
TABLE3 (Continued)
FIGURE2 Barplot indicates number of Alpine bullhead
(mean ± SD) pooled by three size group (small 40–65 mm, medium
70–90 mm, and large 95–125 mm) before (year 2009) and after
(year 2010) the flash flood. Light grey fill columns represent
numbers of bullheads in 2009, black fill columns represent numbers
KUBÍN e t al.
the mortality of benthic fishes like Alpine bullhead seeking shelter in
the riverbed during such events (Erman, Andrews, & Yoder- Williams,
1988). In contrast, smaller individuals usually live along the edges
of stream channels (Harvey & Stewart, 1991) and have a higher
chance of surviving the flood due to higher habitat complexity, less
water velocities (Leopold, Wolman, & Miller, 1964; Pearsons, Li, &
Lamberti, 1992).
Despite the fact that stream- bed morphology was only margin-
ally affected by flash flood, we cannot exclude the possibility that
the alternation of habitat during the flash flood may have caused
an outmigration of large individuals to less influenced stretches e.g.,
with relatively low water velocities along stream margins (Harvey,
Nakamoto, & White, 1999). We found that the degraded habitat sup-
ported an overall lower abundance of Alpine bullhead than natural
habitat. Their higher abundance in the more natural stretches was
probably due to the higher habitat complexity (Pearsons et al., 1992),
Drozd, 2005; Edwards & Cunjak, 2007), variability of flow velocities
(Grift et al., 2003) and refuge availability (Deboer, Ogren, Holtgren,
& Snyder, 2011).
We found that juvenile brown trout had a relatively low impact
on Alpine bullhead, but all size classes of Alpine bullhead were neg-
atively affected by adult brown trout, suggesting that predation of
juvenile bullheads and competition with adult bullhead can be the
main drivers of the species interaction. Brown trout can have a
negative effect on bullhead populations through interspecific com-
petition (i.e., diet overlap, Louhi, Mäki- Petäys, Huusko, & Muotka,
2014 or niche overlap, Hesthagen, Saksgård, Hegge, Dervo, &
Skurdal, 2004). Adult trout abundance also had a negative effect
on the abundance of large Alpine bullhead especially following the
flash flood. Therefore, we suggest that the overall decrease of large
Alpine bullhead after the flash flood can be explained by a combina-
tion of habitat loss and competition with stocked brown trout (Louhi
et al., 2014).
FIGURE3 Barplot indicates number of Alpine bullhead
(mean ± SD) pooled by level of habitat degradation at the sampling
site (see Table 1 for details) before (year 2009) and after (year
2010) the flash flood. Light grey fill columns represent numbers of
bullheads in 2009, black fill columns represent numbers 2010
FIGURE4 Relationship between the initial abundance of juvenile and adult brown trout (i.e., before the flash flood) and abundance of
Alpine bullhead before (black curves) and after (light grey curves) the flash flood predicted by GLM. Size groups are represented by different
line type: dotdash–small 40–65 mm, dashed –medium 70–90 mm, full line–large 95–125 mm
   KUBÍN et al.
Abundance of brown trout itself was rapidly reduced after the
flash flood, likely because they are unable to keep their position
instreams during increased flow. This result is in agreement with
a previous study on hatchery reared brown trout, which demon-
strated that their abundance was significantly reduced following
massive floods in the Horokiwi stream, New Zealand (Allen, 1951).
Trout population decline during floods may be associated with
reduced heterogeneity of soil riverbed substrate or lack of sub-
mersed wood (Harvey et al., 1999) and available refuges (Deboer
et al., 2011). Likewise, the decrease of trout abundance can be re-
lated to the fact that the hatchery trout are insufficiently adapted
to natural environment (Brockmark, Adriaenssens, & Johnsson,
In conclusion, the results of the present study show that hab-
itat degradation and stocking of hatchery trout, above the nat-
ural occurring population size, imposes a negative effect on the
abundance of Alpine bullhead and reduces their capacity to mit-
igate the negative impacts of natural disturbances such as flash
floods. This was especially true for large bodied individuals with a
high reproductive capacity. Our findings imply that a reduction of
trout stocking and stream restoration may help to protect endan-
gered fish species and increase the stability of fish communities in
mountain headwaters.
Radhoštěm for assistancein thefield. Wearegratefulto Vlastimil
Kostkan,Evžen Tošenovský,VlastimilRaškaandJaromírKudlákfor
comments during the study. The study was supported by the IGA_
PrF_2016_019 project of Palacky University in Olomouc. All of the
experimental procedures comply with valid legislative regulations of
the Czech Republic (Law no. 246/1992, §19, art. 1, letter c and no.
114/1992, §56, art. 1).
M. Kubín
Allen, K . R. (1951). The Horokiwi Stream: A study of a trout population.
The New Zealand Marine Department Fisheries Bulletin, 10, 238.
Bain, M . B., Finn, J. T., & Booke, H . E. (1985). Quanti fying stre am substrate
for habitat studies. North American Journal of Fisheries Management,
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Baran, R., Kubecka, J., Kubin, M., Lojkasek, B., Mrkvicka, T., Ricard, D.,
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How to cite this article:KubínM,RulíkM,LuskS,ZávorkaL.
Habitat degradation and trout stocking can reinforce the
impact of flash floods on headwater specialist Alpine
bullhead Cottus poecilopus – A case study from the
Carpathian Mountains. J Appl Ichthyol. 2018;00:1–9. ht tps://
... Morphologic adaptations like their flat head or caudal peduncle depth enable bullheads to maintain their position in fast-flowing water (Kerfoot and Schaefer 2006;Coombs et al. 2007). However, unusually heavy rainfall events resulting in major flash floods have a strong negative effect on the abundance of adult individuals (Kubín et al. 2017). In heavy flood-modified riverbanks, the number of shallow areas is reduced, and thus, the natural variability of bullhead habitats disappears (Erman et al. 1988;Stráňai and Andreji 2004). ...
... In heavy flood-modified riverbanks, the number of shallow areas is reduced, and thus, the natural variability of bullhead habitats disappears (Erman et al. 1988;Stráňai and Andreji 2004). Change in stream morphology reduces the abundance of bullhead, particularly larger individuals (Freyhof et al. 2005;Kubín et al. 2017). Consequently, technical changes may increase the mortality, movement, and population disturbance of this species. ...
... Extreme flooding events have intense effects on the freshwater aquatic ecosystem, including on the fish population. Several studies have demonstrated the negative influence of floods and the consequent artificial reconstruction of channels on local populations of bullhead (Matthews 1986;Natsumeda 2003;Hajdukiewicz et al. 2018;Kubín et al. 2017Kubín et al. , 2019. ...
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Flash floods represent a serious threat to wildlife, water biota, and human life in pre-alpine regions, particularly in recent historical memory. The alpine bullhead is an established bioindicator of water quality in mountain streams, which can be adversely affected by an increased propensity for flash flooding. The aim of this study was to examine the effect of flash flooding on the variation of chemical elements found in the skull of alpine bullheads, with a focus on inter-annual effects. Their bone tissue reflects an increased concentration of K and Cl and a decreased concentration of biogenic Cr, Zn, and Mo, absorbed mainly through the gills, for up to 2 years following a flood. During autumn, following a summer flash flood, the amount of Mn and Fe present in skull tissues of fish was found to have increased, tapering off again over the following year. These metals are predominantly ingested by bullheads while feeding. The lack of specific types of biogenic concentration in the water may be critical to the definition of presence/absence patterns, as populations were shown to decline 2 to 3 years post-flood. Pre-alpine streams are particularly susceptible to this type of flooding. The decreases in biogenic elements and increase of K and Cl exhibited in bullhead tissues indicate that a negative ecological footprint due to flash floods can still be observed several years following the event.
... In general, human-altered river channels (e.g., by narrowing and straightening, bank reinforcement, removal of instream wood or large boulders) display overall degradation accompanied by lower values of complexity metrics than undisturbed channels within the same geomorphic settings (Elosegi and Sabater, 2013;Polvi et al., 2014;Wyżga et al., 2012). Such increased spatial homogeneity and 'simplification' is usually reflected by the presence of lower biodiversity in invertebrate or fish taxa (Beechie and Sibley, 1997;Hajdukiewicz et al., 2018;Kubín et al., 2018;Wyżga et al., 2014), although some compilation reports did not find a direct response between the increased complexity after river restoration and richness of stream biota (Louhi et al., 2011;Palmer et al., 2010;Turunen et al., 2016). Only a few scientific papers have focused on the consequences of check dams for aquatic and riparian ecosystems. ...
... For steep mountain reaches between individual check dams, we found decreased sediment heterogeneity, which likely resulted in the degradation of some parameters of longitudinal heterogeneity (Long_sqer, Long_conc). However, the presence of high longitudinal heterogeneity in steep headwater streams increases transient storage or retention of organic matter in the channel (Gooseff et al., 2007;Wohl, 2016) and plays a positive role in the abundance of local endangered fish and amphibian species as Alpine bullheads or Alpine newts (Kubín et al., 2018;Vojar et al., 2010). Moreover, the lacks of fine particles near the channel banks owing to the reduced sediment heterogeneity may influence the original structure of riparian vegetation (e.g., Boix-Fayos et al., 2007;Bombino et al., 2009;Zema et al., 2018). ...
Check dams can modify local channel and sedimentological characteristics through sediment deposition in upstream sedimentary wedges and scour processes downstream of individual check dams. However, research focusing on the channel reaches between subsequent check dams (referred to here as intermediate reaches) is limited. We evaluated channel complexity and its selected dimensions (longitudinal and cross-section heterogeneity, sediment characteristics and the presence of instream wood) in 30-m long intermediate reaches (n = 10) between subsequent check dams in comparison with channel reaches that were not treated with check dams (n = 10) in both a stepped-bed stream in a steep confined valley and an originally pool-riffle stream in an unconfined foothill valley. Check dams altered the channel complexity of intermediate reaches when compared with reaches of undisturbed streams. However, in contrast to foothills streams, check dams did not heavily affect longitudinal or cross-sectional heterogeneity of the intermediate reaches in the steep streams. Despite an increase in sediment homogeneity in steep reaches treated with check dams, the presence of coarse bed sediments helped to preserve their stepped-bed morphology. In contrast, the longitudinal profile of the treated foothill stream completely lost its vertical oscillations because of the transformation of pool-riffles to a uniform plane bed morphology. Similarly, cross-sectional heterogeneity in the foothill stream was degraded in comparison with those of untreated reaches. We did not observe differences in instream wood abundance between treated and untreated streams.
... data). Brown trout forms significantly larger sustainable selfreproducing populations than other salmonids in Czechia (Kubín, Rulík, Lusk, & Závorka, 2018;Matěna et al., 2017). Grayling populations are relatively small and brook trout is stocked at significantly lower intensity than rainbow trout (Lyach & Remr, 2019;Turek et al., 2018). ...
In central Europe, both brown trout Salmo trutta and European grayling Thymallus thymallus are threatened native salmonid species with high value in recreational angling and nature conservation. On the other hand, rainbow trout Oncorhynchus mykiss and brook trout Salvelinus fontinalis are intensively stocked non‐native species of high angling value but no value for nature conservation. This study tested if harvest rates of native salmonids are negatively correlated to intensive stocking and harvest rates of non‐native salmonids in inland freshwater recreational fisheries. Data were collected from 250 fishing sites (river and stream stretches) over 13 years using mandatory angling logbooks. Logbooks were collected from individual anglers by the Czech Fishing Union in the regions of Prague and Central Bohemia, Czechia (central Europe) and processed by the author of this study. In result, anglers harvested 200,000 salmonids with total weight of 80 tons over 13 years. Intensive stocking of multiple salmonid species lead to slightly lower harvests of native salmonids. Inversely, intensive harvests of multiple salmonid species lead to slightly higher harvest of native salmonids. Recapture rates of stocked salmonids were relatively low (0.6%–3.7%), proving fish stocking moderately ineffective. Since the effects of non‐native salmonid stocking and harvest rates on native salmonid harvest were significant but not strong, it is suggested that rivers and streams that support fishing for non‐native salmonids still support fishing for native salmonids. However, this idea does not apply for fishing sites with really high intensity of non‐native salmonid stocking – harvest rates of natives were very low on these fishing sites.
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Floods in June 2013 affected significant portions of the Czech Republic (total damages amounted ~600 millions of euro). This study examines the impact of catastrophic flood on the species composition and size of fish prey in the diet of the common kingfisher (Alcedo atthis), a fish-eating bird, nesting and hunting on Botič stream (Prague, Czech Republic) in 2013. Hundred and forty years water (flow 74.5 m3 s−1) caused considerable damage to property and it is likely that the character and size composition of biota, especially fish, changed. This should be reflected naturally in the diet of resident kingfishers. The diet of kingfishers before and after the flood were investigated from the mass of regurgitated pellets, which were collected from the nest tunnel and chamber immediately after the successful breeding period before and after the flood event. Before the flood (normal situation; flow 0.4–1.5 m3 s−1), the average length of fish caught was 6.5 cm LT (total length), average weight 2.6 g, and the index of food diversity was 1.58. After the flood, the average length of fish caught was 7.5 cm LT, weight 4.1 g, and the index of the food diversity was 1.36. It was evident that after the flood kingfishers were forced to hunt significantly larger prey. Six fish species (Gobio gobio, Squalius cephalus, Perca fluviatilis, Scardinius erythrophthalmus, Rutilus rutilus, Pseudorasbora parva) which were hunted both before and after the flood composed 96.5 and 99.8% of the catch (by numbers). Surprisingly, the impact of floods may not always be reflected in the species composition of the diet of fish-eating birds, it mostly depends on the presence of fish broadly occurring in the stream, natural stability of the fish stock and on the composition of the fish assemblage in the upstream catchment area.
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The effect of an extreme flood on fish communities was evaluated in the upper reaches (r. km 78-100) of the Tichá Orlice river. The flood discharge itself lasted 2-3 days in July 1997, the extreme discharges at a level repeating at intervals of 100 years (around 120 m3.s-1) lasted only a few hours. The effect of the flood was evaluated on the basis of quantitative samplings in 4 river sections before and after the flood. The upper reaches of the Tichá Orlice river are populated by a fish community of the Salmo-Thymallus type with predominance of Salmo trutta m. fario. Except in section 1, the effect of the deluge on the numbers of this species was not destructive. As for Thymallus thymallus, the flood had a distinct destructive effect on this species in section 1 and 2. Bottom-dwelling fish species were most distinctly affected by the deluge. The numbers of Lampetra planeri, Barbatula barbatula and Cottus gobio were significantly decreased. The most distinct decrease was recorded in section 1 in which extensive shifts of materials forming the river bed took place. The data obtained indicate that the effect of the flood was different in the particular sections of the river bed. The flow rate is the major decisive factor, decreasing markedly if the water incidentally rises and floods the floodplains beyond the river bed. Another important factor which may significantly affect incidental losses due to the flood is the response of fishes to increased water discharges during the flood. This pertains, above all, to their being capable of seeking flow screens in which to wait until the flood is over and then to return to the river bed after the water level has dropped. There are specific differences in this point.
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An approach to forecasting the potential for flash flood-producing storms is developed, using the notion of basic ingredients. Heavy precipitation is the result of sustained high rainfall rates. In turn, high rainfall rates involve the rapid ascent of air containing substantial water vapor and also depend on the precipitation efficiency. The duration of an event is associated with its speed of movement and the size of the system causing the event along the direction of system movement. This leads naturally to a consideration of the meteorological processes by which these basic ingredients are brought together. A description of those processes and of the types of heavy precipitation-producing storms suggests some of the variety of ways in which heavy precipitation occurs. Since the right mixture of these ingredients can be found in a wide variety of synoptic and mesoscale situations, it is necessary to know which of the ingredients is critical in any given case. By knowing which of the ingredients is most important in any given case, forecasters can concentrate on recognition of the developing heavy precipitation potential as meteorological processes operate. This also helps with the recognition of heavy rain events as they occur, a challenging problem if the potential for such events has not been anticipated. Three brief case examples are presented to illustrate the procedure as it might be applied in operations. The cases are geographically diverse and even illustrate how a nonconvective heavy precipitation event fits within this methodology. The concept of ingredients-based forecasting is discussed as it might apply to a broader spectrum of forecast events than just flash flood forecasting.
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The rainbow trout (Oncorhynchus mykiss) is probably the most widely introduced fish species in the world. Since the first translocation outside of the range of its natural distribution, the species has been introduced into at least 99 countries and has established reproducing populations in many different parts of the world. The present review aims to synthesize the existing information on these translocations, with special emphasis on self-sustaining populations in Europe, where continuous introductions have in general not led to naturalization. Our survey produced a list of more than 130 confirmed or potential self-sustaining populations across 16 European countries. The highest abundance of such populations was observed in the Alpine foothills of central Europe where naturalization is not limited to modified waters less suitable for native salmonids but also occurs commonly in pristine and near-natural waters. There is no consensus on the reasons for the absence of self-sustaining populations of rainbow trout across much of Europe, partly because knowledge of the mechanisms involved is limited, while the data collected here shed new light on the invasion biology of the species.
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The distribution patterns of alpine bullhead Cottus poecilopus in three tributary streams of the Rožnovská Bečva River (Danube basin) were studied with respect to temperature, oxygen concentration and saturation, shading, current, conductivity, total organic carbon (TOC), nitrates and phosphates, biochemical oxygen demand (BOD5), pH, redox potential, bottom grain structure, density of macroinvertebrates and the abundance of brown trout Salmo trutta. Sites with lower abundance per hectare of C. poecilopus differed significantly in dissolved oxygen saturation, density of macroinvertebrates during the autumn period (positive correlation with C. poecilopus) and in abundance per hectare of S. trutta (negative correlation). These results indicate that these factors significantly influence the distribution of this endangered species in the studied catchment and that stocking of S. trutta will impair its recovery.
The structure of fish assemblages in five reaches of a high desert stream in north-central Oregon was determined by snorkeling before and after a summer flash flood and two spring floods. One reach in each of two other streams that were unaffected by the first flood was used as a reference system. Stream reaches varied in habitat complexity as measured by hydraulic retention. Following the floods, hydraulically complex stream reaches lost proportionately fewer fish, had generally higher fish diversities, and had higher fish assemblage similarity than hydraulically simple stream reaches. Fish assemblages were resilient, and certain species such as speckled dace Rhinich-thys osculus were exceptionally good at recoloni/ing disturbed habitats. Successful recruitment of different fish species depended, in part, on flood timing. Young of the year of species that spawn in early spring (e.g., rainbow trout Oncorhynchus mykiss) were more negatively affected by early spring floods than summer floods. Species that spawn later in the season (e.g., cyprinids and catostomids) were more negatively affected by summer flooding. Higher fish diversities in hydraulically complex reaches (lower disturbance intensity) after floods support predictions of the intermediate-disturbance hypothesis and suggest that fish assemblage resistance may be related to overall habitat complexity in these small streams.
The introduction of organisms within the native range of wild conspecifics is a widespread phenomenon and locally modifies patterns in intraspecific diversity. However, our knowledge of the resulting ecological effects, as opposed to those caused by invasion-induced changes in interspecific diversity, is still limited. Here, we investigated the ecological effects of native and non-native invaders across levels of biological organisations and recipient organisms using the global and long history introductions of salmonids. Our meta-analysis demonstrated that the global effects of native species introductions exceeded those induced by non-native invaders. The impacts of native invaders were primarily manifested at the individual level on wild conspecifics, but remained largely unexplored on other native organisms and at the community and ecosystem levels. Overlooked and poorly appreciated, quantifying the impacts of native invaders has important implications because human-assisted introductions of domesticated organisms are ubiquitous and likely to proliferate in the future.
Publisher Summary This chapter describes the various geomorphic and hydrologic processes such as catchments that influence riparian system development and maintenance. Catchments are areas of the land surface in which all the runoff drains to a single point on a stream or river channel, and are bounded by drainage divides; catchments have been known to range from hundreds of square meters in size to millions of square kilometers. Catchment drainage networks may have dendritic, palmate dendritic, or trellised forms, depending on the nature of underlying geology. These networks vary in drainage density and gradient, which affect riparia by impacting flood intensity and stream power, respectively. The most basic geomorphic processes in catchments are erosion, transport, and deposition. These processes operate across all time and space scales but vary in relative importance along drainage networks. Erosive processes dominate headwater regions, whereas deposition processes dominate the bottom of catchments draining to the ocean or into enclosed basins. Transport dominates in the mid-reaches of river systems. Erosion scours and eliminates riparian habitats and occurs when the shear stress imposed by flowing water exceeds the shear strength of the material over which it flows. The dominant forms of erosion include down-cutting and lateral movement of channels and scouring of channels and floodplains. Hydrologic processes strongly influence riparian habitats as the transport medium for sediments, but the presence or absence of water by itself is also an important control on riparian form and function. Flooding is a key process that distributes surface water to riparian environments and sets up gradients that drive surface water-groundwater exchanges. Four characteristics of floods, which are especially important to riparian and floodplain ecosystems are magnitude, frequency, timing, and duration.
In December 1982, widespread, physically catastrophic flooding occurred in the Ozark Mountains of northern Arkansas. In the Piney Creek watershed (Izard County), flooding resulted in an immediate change in rank order abundance of numerically dominant fishes and moderate alteration in composition of the entire fauna. At badly scoured locations, local assemblages of fishes were markedly altered. These changes in the fish fauna of Piney Creek exceeded seasonal changes in the fishes that were found in an earlier, non-flood year. The Piney Creek fish fauna showed rapid recovery from the flood, however, and by August 1983, eight months later, the total fish fauna and the local fish assemblages closely resembled those of August 1982, before the flood. Comprehensive sampling of the watershed in 1972, 1973, 1981 (in part), 1982 and 1983 suggests that the fish fauna was stable (via elasticity) and persistent across years, seasons and a drastic flood.
Where two successive catches, c1 and c2 are taken with the same effort from a population, an estimate of the size of the population, ñ, is given by $\tilde{n}=c_{1}{}^{2}/(c_{1}-c_{2})$ , with a variance ${\rm var}\ [\tilde{n}]=[c_{1}{}^{2}c_{2}{}^{2}(c_{1}+c_{2})]/(c_{1}-c_{2})^{4}$ Estimates from more than two successive catches, from single catches and of mortality rates are discussed and formulae given. Simple mark-recapture experiments can be combined with repeated catch experiments.
The present study examined fish assemblages in ten tributaries with different environmental characteristics in the upper drainages of the Agano River system, northern Honshu, Japan. Seven fish species (five families) were found in the 10 tributaries examined. White-spotted charr Salvelinus leucomaenis and sculpin Cottus pollux were common in almost all tributaries. Masu salmon Onchorhynchus masou masou inhabited the tributaries at relatively low densities despite intensive stocking in the study region. No statistically significant relationships between local environmental factors and the number of species captured were found. However, all seven species, including age-0 fish of each species, were recorded in the tributary with the lowest gradient and second-narrowest stream width, suggesting that small tributaries potentially provide an important habitat for a diverse range of species. The relative density of white-spotted charr in tributaries subject to fishing prohibition was higher on average than that in tributaries not subjected to fishing prohibition, suggesting that fishing depresses the abundance of white-spotted charr.