Freshwater molluscs of the Dyje (Thaya) River and its tributaries - the role of these water bodies in expansion of alien species and as a refuge for endangered gastropods and bivalves

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FRESHWATER MOLLUSCS OF THE DYJE (THAYA)
RIVER AND ITS TRIBUTARIES – THE ROLE OF THESE
WATER BODIES IN EXPANSION OF ALIEN SPECIES
AND AS A REFUGE FOR ENDANGERED GASTROPODS
AND BIVALVES
LUBOŠ BERAN
Agency for Nature Conservation and Landscape Protection of the Czech Republic, Kokoøínsko Protected
Landscape Area Administration, Èeská 149, CZ–276 01 Mìlník, Czech Republic
(e-mail: lubos.beran@nature.cz)
ABSTRACT: The malacofauna of the Dyje River, including the lower sections of its five tributaries, is still rich
and diversified despite the pollution, regulation and building of several dam reservoirs. In total, 42 freshwater
mollusc species (24 gastropods, 18 bivalves) were found at 75 sites. The richest malacofauna (30 species) was
recorded in the lower section of the Dyje. Populations of endangered or rare molluscs Theodoxus danubialis,
Viviparus acerosus,Lithoglyphus naticoides,Unio crassus,Pseudanodonta complanata,Pisidium amnicum and P.
moitessierianum were found. The first three species inhabit only the area under study in the Czech Republic. Es-
pecially the occurrence of Unio crassus corresponds with river sections that were only partly affected by human
activities (long distance below dam reservoirs, less polluted sections, unregulated watercourses). The occur-
rence of five invasive species, four originating from other continents (Potamopyrgus antipodarum,Physella acuta,
Ferrissia fragilis,Sinanodonta woodiana) and one (Dreissena polymorpha) originally Ponto-Caspian, was confirmed
for the Dyje River and its tributaries. The Dyje River formed the main invasion route from the Danube River
into Moravia (eastern part of the Czech Republic).
KEY WORDS: Dyje (Thaya) River, molluscan assemblages, zoogeographical analyses, invasion corridor, Unio crassus
INTRODUCTION
The Dyje (Thaya) River is one of the largest rivers
in the Czech Republic and belongs to the Black Sea
drainage area. The lower section of the Dyje River has
been of interest to malacologists for more than 100
years. The first data are mentioned in ULIÈNÝ (1885),
who studied this area in 1882. Published and unpub-
lished data (e. g. material deposited in the National
Museum in Prague) till 1998 have been summarised
in BERAN &HORSÁK (1998, 1999) who studied
aquatic molluscs of the Dolnomoravský úval lowland,
including the lower stretch of the Dyje. The
macroinvertebrate fauna of the Dyje River down-
stream of the Nové Mlýny reservoir was studied by
HORSÁK (2001). On the other hand, aquatic mollus-
can fauna of the upper part of the Dyje was poorly
known and no published data were available. Little at-
tention was paid to the aquatic molluscs of the lower
sections of its tributaries except for the Kyjovka River
which was studied by BERAN &HORSÁK (1998).
The Dyje River flows into the Morava River at the
Czech-Austrian-Slovak boundary, and both rivers
drain a large part of Moravia (eastern part of the
Czech Republic). The river was partly changed due to
canalisation, dam construction and pollution. To as-
sess how much these changes affected the molluscan
assemblages of the Dyje and its tributaries was one of
the aims of this research, with special reference to
populations of endangered or rare molluscs and, on
the other hand, to invasions of non-native gastropods
and bivalves.
Folia Malacol. 21(3): 143–160
http://dx.doi.org/10.12657/folmal.021.018

MATERIAL AND METHODS
The field work was conducted in 2001–2013. In to-
tal, 41 sites were sampled in the Dyje River, including
the Vìstonice dam reservoir (sites 20–30, one of the
five dam reservoirs). The remaining 31 sites were lo-
cated on five tributaries, and three sites on the cana-
lised Morava River upstream of the inflow of the Dyje
River (Fig. 1, Appendix 1). The main sampling
method for freshwater molluscs was washing vegeta-
tion or sediments on a metal sieve (kitchen strainer,
diameter 20 cm, 0.8 mm mesh), combined with col-
lecting by eye (searching of stone, wood and
anthropogenic material, e.g. plastic bags and bottles,
surface). Unionids were sampled by means of visual
inspection of suitable habitats while wading upstream
and searching for live molluscs or fresh shells (nacre-
ous layer still lustrous, periostracum coloured). Places
with fine sediment were searched by hand. All live in-
dividuals of endangered Unio crassus were measured
and released. In the case of abundant populations the
data were used to study the size structure of the popu-
lation.
Freshwater molluscs were identified concho-
logically or, when identification based only on shells
was impossible, dissected and determined based on
their genitalia. Specimens for dissection were killed
in hot water and then fixed in 70% ethanol. No speci-
men of legally protected species (Unio crassus,U.
pictorum,Anodonta cygnea) was killed. Selected mate-
rial of shells of endangered or rare species is depos-
ited in the author‘s collection. The classification fol-
lows HORSÁK et al. (2010) while WELTER- SCHULTES
(2012) was used for zoogeographical classification.
144 Luboš Beran
Fig. 1. The map of the Dyje River and its tributaries with the geographical distribution of the sampling sites. Drawn by MAR-
TIN DOLEJŠ

STUDY AREA
Dyje
The Dyje (Thaya) River arises from the confluence
of the Austrian Dyje River and the Moravian Dyje
River near Raabs in Austria at the altitude of 410 m
and, after 235 km, flows into the Morava River south
of Bøeclav at the Czech-Austrian-Slovak boundary at
the altitude of 148 m. The annual mean discharge be-
fore the inflow to the Morava River is 43.9 m3/sec
(VLÈEK 1984). The watercourse has been only partly
changed and canalised, but the Vranov, Znojmo,
Mušov, Vìstonice and Nové Mlýny dam reservoirs
have changed the river’s character for a long distance
below the dams and divided it into several isolated
segments. The largest tributaries are the Jihlava and
Svratka rivers which flow into the Dyje River at the
Vìstonice dam reservoir. The Zeletavka, Jevišovka and
Kyjovka rivers are smaller tributaries. The Dyje was
studied at the part between the Czech-Austrian
boundary near Uherèice (average flow rate 8.5
m3/sec, Figs 1, 2) and the inflow into the Morava
River at the Czech-Austrian-Slovak boundary (ca. 208
km). The studied part of the Dyje River was divided
into four sections:
Dyje I – Dyje River between the Czech-Austrian
boundary and the Vranov dam reservoir,
Dyje II – Dyje between the Vranov dam reservoir and
the Mušov dam reservoir,
Dyje III – the Vìstonice dam reservoir,
Dyje IV – Dyje between outflow from the Nové Mlýny
dam reservoir and inflow into the Morava River at
the Czech-Slovak-Austrian boundary.
Zeletavka
The Zeletavka Brook arises near Lesná at the alti-
tude of 660 m and after 56 km flows into the Dyje
River in the Vranov dam reservoir with the average
discharge of 1.1 m3/sec (VLÈEK 1984). The lower sec-
tion of this brook, ca. 18 km long, downstream of
Baèkovice was studied. This part has a relatively natu-
ral character.
Jevišovka
The Jevišovka River is a left-bank tributary of the
Dyje River. It originates in the Bohemian-Moravian
Highlands (Èeskomoravská vrchovina) upland at the
elevation of 560 m and flows for 81 km to Jevišovka,
Freshwater molluscs of the Dyje (Thaya) River and its tributaries 145
Fig. 2. The Dyje River near the Czech–Austrian border in its upper part (Dyje I, site No. 3). Photo: LUBOŠ BERAN

where it enters the Dyje River with the average dis-
charge of 1.1 m3/sec (VLÈEK 1984). The downstream
section, ca. 16 km long, was studied. The watercourse
was hardly changed and canalised (Fig. 3).
Jihlava
The Jihlava River arises near Jihlávka at the alti-
tude of 670 m and after 185 km flows into the
Vìstonice dam reservoir at the altitude of 170 m, with
the average discharge of 11.8 m3/sec (VLÈEK 1984).
The river stretch downstream of the inflow of the
Oslava River, ca. 34 km long, was studied. The water-
course of this section is only partly changed and sev-
eral weirs were built.
Svratka
The Svratka River arises in the Zïárské vrchy Mts.
at the altitude of 760 m and after 174 km flows into
the Dyje River at the Vìstonice reservoir at the alti-
tude of 170 m with the average discharge of 27.2
m3/sec (VLÈEK 1984). The lower, studied section, ca.
5 km long, was canalised and changed into a straight
and slowly flowing canal.
Kyjovka
A small river originating in the Chøiby upland at
the altitude of 512 m; after 86.7 km it flows into the
Dyje River at the altitude of 150 m, with the average
discharge 1.1 m3/sec (VLÈEK 1984). A section about
20 km long was searched. The downstream river
stretch approximately 10 km long flows through a
floodplain forest and has natural character while the
upper studied section was canalised.
146 Luboš Beran
Fig. 3. The canalised part of the Jevišovka River (site No. 50). Photo: LUBOŠ BERAN

RESULTS
MOLLUSCAN ASSEMBLAGES
In total, 42 freshwater mollusc species were found
in the Dyje River and the lower sections of its five trib-
utaries: 24 gastropods and 18 bivalves. The Dyje River
harbours 41 freshwater molluscs. Fourteen species
were recorded in the upper section of the Dyje River
(Dyje I, upstream of the Vranov dam reservoir), while
in the lower section the molluscan assemblages in-
cluded from 24–27 (27 in Dyje II; 24 in Dyje III –
Vìstonice dam reservoir) to 30 (Dyje IV) species (Fig.
4). The lower section of the Dyje River was the richest
studied part while the poorest one was the Zeletavka
Brook, with only eight species. The other four tribu-
taries (Jevišovka, Jihlava, Svratka, Kyjovka) were
found to hold from 20 to 24 species. In the canalised
Morava River above the inflow of the Dyje River only
14 species were recorded. Bithynia tentaculata,Valvata
piscinalis,Radix auricularia,Physella acuta,Ancylus
fluviatilis,Unio pictorum,U. tumidus,Anodonta anatina,
Sphaerium corneum,Pisidium henslowanum,P. supinum,
P. subtruncatum were recorded at more than seven
studied sections or tributaries while Theodoxus
danubialis,Viviparus viviparus,Valvata cristata,
Stagnicola palustris,Physa fontinalis,Gyraulus crista,
Planorbarius corneus,Ferrissia fragilis,Pisidium amnicum
and Dreissena polymorpha occurred in only one or two
studied sections. Dreissena bugensis was not found in
any studied site. Species which prefer slowly flowing
or stagnant water (e.g. Lymnaea stagnalis,Planorbis
planorbis,Anisus vortex,P. corneus,Anodonta cygnea)
dominated in the Vìstonice dam reservoir which was
studied as the only one out of the five reservoirs built
on this river. The lists of studied sites and molluscs
found at particular localities are shown in Appendices
1 and 2 (Tables 1–5).
ZOOGEOGRAPHICAL ANALYSIS
More than half of the recorded species have
Holarctic or Palaearctic distribution ranges (Fig. 5).
Five species are Euro-Siberian and eight are Euro-
pean. Only Th. danubialis,Viviparus acerosus and origi-
nally also L. naticoides and D. polymorpha occur espe-
cially in the Danube drainage area and belong to spe-
cies with Danubial or Pontic (Ponto-Caspian) distribu-
tion ranges. The first three species were recorded
only in the lowest section of the Dyje River (Dyje IV)
and the Kyjovka River, L. naticoides also at site No. 19
Freshwater molluscs of the Dyje (Thaya) River and its tributaries 147
14
27
24
30
8
24
22
20
22
14
0
5
10
15
20
25
30
35
Number of species
Dyje I
Dyje II
Dyje III
Dyje IV
Želetavka
Jevišovka
Jihlava
Svratka
Kyjovka
Morava
Fig. 4. Number of species recorded in particular parts of the Dyje River and its tributaries
Holarctic Palaearctic Euro-Siberian
Europaean Pontic
and Danubial Non-native
Fig. 5. Zoogeographical analysis of molluscs found in the
Dyje River and its tributaries

(Dyje II) upstream of a system of three dam reservoirs
(Mušov, Vìstonice, Nové Mlýny) and V. acerosus also in
the lower section of the Jevišovka River (Fig. 6). The
invasive D. polymorpha was recorded also in the lowest
stretch of the Dyje River and in the Kyjovka.
Potamopyrgus antipodarum,Ph. acuta,F. fragilis and
Sinanodonta woodiana are invasive species originating
from other continents.
ENDANGERED AND RARE MOLLUSCS
More than 50% of the recorded species are com-
mon and widespread, but it is noteworthy that also
several molluscs that inhabit the Dyje River and its
tributaries are rare and endangered species (Fig. 7).
Three prosobranchs (Th. danubialis,V. acerosus,L.
naticoides) occur in the Czech Republic only in the
studied area. The first one is red-listed (BERAN et al.
2005) as Critically Endangered while the other two –
as Endangered. Another endangered mollusc, Unio
crassus, was found in the Dyje River and three of its
tributaries. Probably abundant populations were re-
corded in two sections of the Dyje River (Dyje I, Dyje
II), scattered populations were found in the Jevišovka
and Jihlava, and some specimens were found in the
lower section of the Dyje (Dyje IV) and the Zeletavka
Brook (Appendix 2: Tables 1–5). An especially abun-
dant population was found in site No. 18, with 78
specimens per 10 m2in a shallow place with sandy bot-
tom. Specimens with shell length of 45–55 mm
148 Luboš Beran
Fig. 6. Distribution of aquatic molluscs with Danubial or Pontic distribution ranges. Drawn by MARTIN DOLEJŠ
Critically
Endangered Endangered Vulnerable
Near
Threatened
Least
Concern Not Evaluated
Fig. 7. Proportion of different species categories of the Red
List

formed more than 60% of the population (Fig. 8).
The estimated abundance of Unio crassus in the other
sites was much smaller, approximately less than 1
specimen per1mofthewatercourse. Pseudanodonta
complanata, a unionid vulnerable or endangered in
many European countries, was occasionally found at
several localities in the Dyje River and in only one site
of the Morava River. Two endangered pea mussels
were recorded only occasionally. Only one specimen
of P. amnicum was found at site No. 8 (Dyje II) while P.
moitessierianum was found at three sites of the Dyje
River (two sites of the Vìstonice reservoir) and two
sites of the Jevišovka River (Fig. 9).
NON-NATIVE MOLLUSCS
Four non-native molluscs were recorded in the
study area (Fig. 10). P. antipodarum, an invasive spe-
Freshwater molluscs of the Dyje (Thaya) River and its tributaries 149
Fig. 9. Distribution of endangered bivalves. Drawn by MARTIN DOLEJŠ
35–40 40–45 45–50 50–55 55–60 60–65 65–70 70–75
Shell length (mm)
Number of specimens
0
5
10
15
20
25
30
35
Fig. 8. Shell length of observed Unio crassus individuals

cies originating from New Zealand, occurs in the Dyje
River except the upper section, and also in the Jevi-
šovka and Jihlava rivers. North American Ph. acuta was
found in the Dyje River where it was one of the domi-
nant species in the Vìstonice dam reservoir and was
also recorded in all the tributaries except the Zele-
tavka Brook. Another North American species, F.
fragilis, was found in only two sites in the Kyjovka River
and in the Vìstonice dam reservoir. S. woodiana, origi-
nally distributed in southeastern Asia, was recorded
from the lower section of the Dyje River (Dyje IV),
Morava River and Kyjovka River. This bivalve was the
dominant unionid in several sites (Appendix 2: Tables
1–5).
DISCUSSION
The Dyje River and the lower sections of its tribu-
taries still harbour rich and diverse molluscan assem-
blages. Although only the main streams of these rivers
were studied, the occurrence of 42 freshwater mollusc
species (24 gastropods, 18 bivalves) was recorded.
This constituted ca. 54% of the total freshwater
malacofauna of the Czech Republic. The lowest
stretch of the Dyje with its 30 species is among the
richest Czech rivers, comparable e. g. with the Labe
(Elbe) River which is the largest river in the Czech Re-
public (BERAN 2005, 2009). One of the possible rea-
sons for the diversity is probably the natural character
of the watercourse (downstream of Bøeclav), com-
bined with the presence of several species which oc-
cur only there in the Czech Republic (Th. danubialis,
V. acerosus,L. naticoides, see below) and also the occur-
rence of invasive non-native species originating from
other continents (P. antipodarum,Ph. acuta,F. fragilis,
S. woodiana) as well as invasive D. polymorpha, origi-
nally a Ponto-Caspian species. This richness is in con-
trast with the canalised section of the Morava River
upstream of the confluence with the Dyje, where only
14 species were recorded.
The comparison with distributional data on fresh-
water molluscs in the Czech Republic (BERAN 2002)
showed that the lower stretch of the Dyje River to-
gether with the lower section of the Kyjovka River are
the only watercourses with the occurrence of molluscs
with Danubial and Pontic distribution ranges (Th.
danubialis,V. acerosus,L. naticoides), except the inva-
150 Luboš Beran
Fig. 10. Distribution of non-native molluscs. Drawn by MARTIN DOLEJŠ

sive D. polymorpha which is originally also Pontic
(Ponto-Caspian) species. Another exception is L.
naticoides which occasionally occurred in the Dyje
River upstream of the system of three dam reservoirs,
and also the population of V. acerosus which was re-
corded in the lowest section of the Jevišovka River and
upstream of these reservoirs (see Fig. 6). The popula-
tions of these species are probably relicts that inhab-
ited (together with Th. danubialis) this river section
before building of the system of three dam reservoirs
(BERAN &HORSÁK 1998). The section of the Dyje
around the inflow of the Jihlava and Svratka rivers
with its extensive floodplain is among the sites with
the highest diversity, not only of freshwater molluscs,
and was damaged by construction of the reservoirs be-
tween 1969 and 1989 (BUÈEK 2012).
The population of Th. danubialis in the Dyje and
Kyjovka rivers is situated on the northern edge of the
species’ range (see e.g. WELTER-SCHULTES 2012). The
species is regarded as a Critically Endangered mollusc
in several countries, e.g. Austria and Germany
(GLÖER 2002, WELTER-SCHULTES 2012), it is endan-
gered in Slovakia (ŠTEFFEK &VAVROVÁ 2006), rare in
Hungary (FEHÉR et al. 2004), while in the southern
part of its range it is common and widespread. In
Croatia it belongs to dominant species, especially in
karstic rivers like Korana (BERAN 2013) or Kupa
(HADBIJA et al. 1995), where it forms the main part of
gastropod biomass. Similarly, the site of V. acerosus is
located on the north-western edge of its geographical
range (WELTER-SCHULTES 2012), except new intro-
duction(s) in northwestern Europe (e. g. SOES et al.
2009).
Building of the five dam reservoirs, combined with
pollution and river canalisation, caused many
changes of the Dyje river and also other studied water-
courses. The situation of the population of endan-
gered thick-shelled river mussel U. crassus is a good
example of how these changes affected the molluscan
asemblages of this river. At present this population is
divided in two (three) subpopulations, one around
the Czech-Austrian boundary in the upper part of the
river (sites No. 1–4, 6). This part has a natural charac-
ter and ends in the Vranov dam reservoir. The second
subpopulation (sites No. 16–18) inhabits the short
part of the river which has also a relatively natural
character and is located about 18 km downstream of
the Znojmo dam reservoir. This part is followed by a
canalised watercourse and a system of three dam res-
ervoirs without populations of U. crassus. This bivalve
was also occassionaly found in the third section of this
river, upstream of the inflow to the Morava River. In
the past, U. crassus was one of the most common and
widespread unionids and was also used as feed for do-
mestic livestock (ULIÈNÝ 1892–1895), so it can be sup-
posed that its occurrence in the Dyje River before
anthropogenic changes was nearly continuous while
now only isolated and mostly scattered populations
live there. Several smaller populations (or only some
specimens) found in the tributaries (Zeletavka,
Jevišovka, Jihlava) are also isolated from the popula-
tions in the Dyje River. The fragmentation of most
populations is another negative effect which can
cause a decrease or extinction of the thick-shelled
river mussel in this region; in Moravia in the Danube
drainage area more numerous populations are
known only from the studied area and also from the
Beèva River, from Malá Beèva canal and from four
mill races (BERAN &DOUDA 2009, DOUDA &BERAN
2009).
Like the U. crassus population, populations of an-
other endangered unionid P. complanata are divided
into subpopulations. The situation is worse due to the
very low density. The scattered occurrence and low
densities of this species in many rivers are common in
the Czech Republic (BERAN 2002), and make survival
of its populations uncertain.
P. amnicum, the biggest pea mussel in the Czech
Republic, was found in the Dyje River at site No. 8.
The species inhabits unregulated and unpolluted
rivers and brooks. In the Czech Republic it belongs to
endangered molluscs (BERAN 2002). Unfortunately,
only one specimen was found and more detailed re-
search is necessary to confirm the existence of the
population. Subfossil shells were found also in the
Jevišovka River. In the studied area P. amnicum is
known also from a small pond in Vranov (LOZEK &
VAŠÁTKO 1997). Other closest sites with the recent oc-
currence of abundant populations are known from
central Moravia in two canals (mill races) of the Beèva
River (BERAN 2003, 2007). The last endangered mol-
lusc is P. moitessierianum. The species inhabits slowly
flowing waters with muddy sediment; it was found in
the Dyje (site No. 18), and surprisingly also in the
Vìstonice dam reservoir (site No. 25, 26) and in the
Jevišovka R. (site No. 49, 50). The species was found
in the studied area for the first time in 1996 (BERAN &
HORSÁK 1998) and this record was the first for
Moravia (eastern part of the Czech Republic).
Finding of an abundant population of V. viviparus
in the upper section of the Dyje River (Dyje I, site No.
3–6) between the Czech-Austrian border and the
Vranov dam reservoir is noteworthy. The species oc-
curs in the Czech Republic only in Bohemia (western
part of the Czech Republic) in the Labe (Elbe) River
basin (BERAN 2002) while V. acerosus is known from the
Dyje River and in the past also from the Morava River
(Danube river basin) (BERAN 2002). The existence of
population of V. viviparus is surprising and no informa-
tion exists on the occurrence of this species in the Dyje
River in Austria or the Moravian Dyje River. The Czech
section of the Moravian Dyje River was studied (BERAN
2008b) and V. viviparus was not recorded. It is possible
that the species was introduced in the Vranov dam res-
ervoir (construction finished in 1934) from the Labe
(Elbe) River drainage area in the past (e. g. during
Freshwater molluscs of the Dyje (Thaya) River and its tributaries 151

building of the dam reservoir). The population lives
115 km away from the nearest population of V. acerosus
(site No. 52, see Fig. 1).
The Chinese pond mussel, S. woodiana was first
found in the Czech Republic in an oxbow of the Dyje
River downstream of Bøeclav in 1996 (BERAN 1997).
This record is also mentioned in BERAN &HORSÁK
(1998) as the only site with the occurrence of this in-
vasive alien species; HORSÁK (2001) did not find it in
any of the five studied sites located on the Dyje River
downstream of the system of three dam reservoirs.
The results confirm the continuing invasion as ob-
served by BERAN (2008a) and show that the Chinese
pond mussel has become a dominant bivalve in some
sites in the rivers Kyjovka and Dyje. DOUDA et al.
(2012) demonstrated that the spread of this alien bi-
valve was not limited by the availability of hosts and
that the temperature conditions in Central European
lowland rivers were suitable for completion of its life
cycle; they also identified potential threats to native
habitats and communities. It is not possible to ex-
clude a negative impact on the populations of com-
mon as well as endangered unionids, together with
water pollution and habitat alteration. On the other
hand, in the lowest section of the Dyje River (site No.
41) where stones are very rare, live specimens and
also empty shells of S. woodiana are often used by criti-
cally endangered Th. danubialis as suitable
microhabitat (Fig. 11).
In comparison with earlier studies (BERAN &
HORSÁK 1998, HORSÁK 2001) P. antipodarum was dis-
covered in three studied sections of the Dyje River.
This non-native species was first found in the Dyje
river basin in the Dyje near Èízov (between sites No. 7
and 8) in 1996 (VOJEN LOZEK, unpublished data).
These findings confirmed its rapid expansion also in
this river. However, the densities were relatively low
and P. antipodarum did not belong among dominant
molluscs. The species was also recorded in the
Jevišovka and Jihlava but it is impossible to confirm
these records with the occurrence in the past because
historical data were not available. The presence of P.
antipodarum does not seem to have an unequivocally
negative effect on the native malacofauna. Another
non-native species, F. fragilis, was known only from the
floodplain of the Morava River (BERAN &HORSÁK
1998, 2007) and in the Dyje river basin it was first dis-
covered during this research in 2008 at site No. 72.
152 Luboš Beran
Fig. 11. Theodoxus danubialis uses living specimens and empty shells of Sinanodonta woodiana in the lowest parts of the Dyje
River where stones and other suitable habitats for Th. danubialis are rare. Photo: LUBOŠ BERAN

Ph. acuta was first recorded in the Dyje river basin be-
tween 1969 and 1971 in a small ditch in the floodplain
of the Dyje River in Lednice (BALÙSEK &VOJTEK
1973) (the nearest studied locality is site No. 32) and
later was recorded also in the Dyje River and its tribu-
taries (BERAN &HORSÁK 1998). The non-native gas-
tropod Gyraulus parvus inhabits only the floodplain of
the Dyje River (BERAN &HORSÁK 2002) and was not
found in the studied rivers. In the future expansion of
other invasive non-native species such as Corbicula
fluminea can be expected; it was already found in the
Danube River in Slovakia (VRABEC et al. 2003) and
Austria (TITTIZER &TAXACHER 1997).
Altogether, four alien species originating from
other continents and the invasive Dreissena polymorpha
which is originally Ponto-Caspian were recorded in
the Dyje River, its tributaries and the surrounding
floodplain. While the Labe (Elbe) River with seven
non-native species (P. antipodarum,Ph. acuta,G.
parvus,Menetus dilatatus,F. fragilis,C. fluminea,D.
polymorpha) is a main corridor for the invasion of alien
molluscs into Bohemia (western part of the Czech Re-
public) (PETRUSEK &BERAN 2006), the Morava and
Dyje rivers are the main route for invasions from the
Danube drainage area into Moravia (eastern part of
the Czech Republic).
The canal connecting the Danube, Odra and Labe
rivers whose building has been discussed for many de-
cades (centuries in the case of the Dunaj-Odra canal)
(KRÁTKÝ &LÖW 2005) would significantly increase
the possibility of invasion of non-native species, simi-
larly as in the case of many European rivers (BIJ DE
VAATE et al. 2002, LEUVEN et al. 2009), as well as con-
sequent changes in the gene pool of autochtonous
molluscs. It would also change the character of the
lower part of the Dyje River, through significant nega-
tive impact to the molluscan assemblages. This would
increase the probability of extinction of populations
of endangered and rare mollusc species.
CONCLUSIONS
The research on the Dyje River and lower sections
of its main tributaries confirmed the existence of rich
molluscan assemblages, including three species oc-
curring in the Czech Republic only in this area. The
malacofauna of the Dyje River was negatively altered
by the construction of several dam reservoirs which
divided the river into several sections, changed the
watercourses below the dams and in the case of the
system of three dam reservoirs (Mušov, Vìstonice,
Nové Mlýny) also damaged one of the richest
floodplains in the Czech Republic. Other negative ef-
fects, such as pollution and regulation, affected also
the tributaries. Despite the negative anthropogenic
impact, isolated populations of endangered or rare
species are still present in several less altered river sec-
tions.
The biodiversity of the Dyje River was affected by
the occurrence of several non-native aquatic
molluscs. The river forms a major route along which
alien fauna disperses to the southern part of Moravia.
ACKNOWLEDGEMENTS
I thank MARTIN DOLEJŠ for preparing the maps
and three anonymous reviewers for their valuable
comments.
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Received: April 4th, 2013
Revised: June 28th, 2013
Accepted: July 2nd, 2013
154 Luboš Beran

APPENDIX 1
LIST OF INVESTIGATED SITES
Data in the list are as follows: site number, geo-
graphical co-ordinates (http://www.mapy.cz/), code
of the mapping grid for faunistic mapping (according
to PRUNER &MÍKA 1996), name of the nearest settle-
ment, description of the site, date of investigation.
Dyje
1–48°53'23''N, 15°38'08''E,7159, Mitrovice, the Dyje
River on the Czech-Austrian border, 28.7.2009;
2–48°53'19''N, 15°39'02''E, 7159, Uherèice, the Dyje
River 400 m upstream of the road bridge Uherèice –
Podhradí nad Dyjí, 13.9.2008;
3–48°53'18''N, 15°39'36''E, 7159, Uherèice, the Dyje
River about the road bridge Uherèice – Podhradí nad
Dyjí, 28.10.2011;
4–48°53'50''N, 15°40'51''E, 7160, Podhradí nad Dyjí, the
Dyje River about 300 m upstream of a weir in
Podhradí nad Dyjí, 28.10.2011;
5–48°53'59''N, 15°41'01''E, 7160, Podhradí nad Dyjí, the
Dyje River near a weir in Podhradí nad Dyjí,
31.8.2008;
6–48°54'50''N, 15°41'30''E, 7160, Podhradí nad Dyjí, the
Dyje River 1 km north of Podhradí nad Dyjí,
31.8.2008;
7–48°53'45''N, 15°48'41''E, 7160, Vranov nad Dyjí, the
Dyje River in Vranov nad Dyjí, 28.10.2011;
8–48°50'08''N, 15°53'32''E, 7161, Lukov, the Dyje River
near the inflow of the Kaja Brook (Kajabach),
3.11.2006;
9–48°50'37''N, 16°03'19''E, 7162, Znojmo, the Dyje River
between the bridge and the monastery in Znojmo,
1.11.2006;
10 –48°50'28''N, 16°03'23''E, 7162, Znojmo, a mill race of
the Dyje River near the monastery, 2.11.2006;
11 –48°50'18''N, 16°04'09''E, 7162, Znojmo, the Dyje
River near the weir in the south-eastern part of
Znojmo, 2.11.2006;
12 –48°50'17''N, 16°04'32''E, 7162, Znojmo, a canal of
the Dyje River near Oblekovice, 3.11.2006;
13 –48°50'31''N, 16°06'54''E, 7162, Dyje, the Dyje River
in Dyje, 19.9.2009;
14 –48°49'23''N, 16°09'59''E, 7163, Hodonice, the Dyje
River near a road between Hodonice and Krhovice,
20.9.2009;
15 –48°48'36''N, 16°10'41''E, 7163, Krhovice, the Dyje
River 500 m southeast of Krhovice, 20.9.2009;
16 –48°48'04''N, 16°11'12''E, 7263, Micmanice, the Dyje
River downstream of the bridge of a road near
Micmanice, 30.8.2011;
17 –48°46'08''N, 16°15'32''E, 7263, Hrádek, the Dyje
River downstream of the road Hrádek-Jaroslavice,
22.10.2011;
18 –48°45'22''N, 16°17'29''E, 7263, Dyjákovice, the Dyje
River south of Dyjákovice, 23.10.2011;
19 –48°49'11''N, 16°28'08''E, 7164, Jevišovka, the Dyje
River near the railway station Jevišovka, 19.9.2009;
20 –48°54'41''N, 16°36'44''E, 7065, Strachotín, the bank
of the Vìstonice dam reservoir east of the inflow of
the Svratka River, 15.7.2012;
21 –48°54'52''N, 16°37'07''E, 7065, Strachotín, northern
edge of the Vìstonice dam reservoir, 2.6.2012;
22 –48°54'34''N, 16°37'59''E, 7065, Strachotín, riprap at
the northern edge of the Vìstonice dam reservoir,
2.6.2012;
23 –48°54'09''N, 16°38'49''E, 7065, Strachotín, riprap at
the northeastern part of the dam of the Vìstonice wa-
ter reservoir, 2.6.2012;
24 –48°53'26''N, 16°38'28''E, 7065, Dolní Vìstonice,
southeastern part of the Vìstonice dam reservoir,
11.8.2012;
25 –48°53'18''N, 16°37'18''E, 7065, Dolní Vìstonice,
southern bank of the Vìstonice dam reservoir,
11.8.2012;
26 –48°53'07''N, 16°36'08''E, 7065, Mušov, southwestern
edge of the Vìstonice dam reservoir, 11.8.2012;
27 –48°53'22''N, 16°35'31''E, 7065, Mušov, western bank
of the Vìstonice dam reservoir, 11.8.2012;
28 –48°54'13''N, 16°35'12''E, 7065, Mušov, northwestern
edge of the Vìstonice dam reservoir, 8.9.2012;
29 –48°54'19''N, 16°35'37''E, 7065, Mušov, northwestern
bank of the Vìstonice dam reservoir near inflow of
the canal, 8.9.2012;
30 –48°54'33''N, 16°36'12''E, 7065, Ivaò, the edge of the
Vìstonice dam reservoir ca. 300 m southwest from
the inflow of the Jihlava River, 8.9.2012;
31 –48°49'37''N, 16°46'11''E, 7166, Bulhary, the Dyje
River upstream and downstream of a weir,
20.10.2012;
32 –48°48'15''N, 16°48'29''E, 7166, Lednice, the
Lednický náhon (man made branch of the Dyje
River) downstream of the weir in Lednice, a)
22.3.2008, b) 24.4.2010;
33 –48°46'17''N, 16°52'48''E, 7267, Bøeclav, the Dyje
River upstream of a weir in Bøeclav, 31.8.2011;
34 –48°45'41''N, 16°53'12''E, 7267, Bøeclav, the Dyje
River downstream of a weir in Bøeclav, 31.8.2011;
35 –48°44'52''N, 16°53'21''E, 7267, Bøeclav, the Dyje
River near the bridge, a) 26.9.2003, b) 22.9.2007;
36 –48°43'25''N, 16°53'07''E, 7267, Bøeclav, the Dyje
River near Pohansko (near a bridge), 3.10.2009;
37 –48°42'29''N, 16°54'28''E, 7367, Bøeclav, the Dyje
River west of Lány castle, 3.10.2009; 38 – 48°40'31''N,
16°54'40''E, 7367, Bøeclav, the Dyje River about 4 km
upstream of the inflow of the Kyjovka River,
4.10.2008;
39 –48°39'34''N, 16°55'23''E, 7367, Bøeclav, the Dyje
River about 1,5 km upstream of the inflow of the
Kyjovka River, 3.10.2009;
Freshwater molluscs of the Dyje (Thaya) River and its tributaries 155

40 –48°38'15''N, 16°55'41''E, 7367, Lanzhot, the Dyje
River about 1,5 km downstream of the inflow of the
Kyjovka River, 4.10.2008;
41 –48°37'05''N, 16°56'21''E, 7367, Lanzhot, the Dyje
River before inflow to the Morava River, a) 20.4.2008,
b) 31.3.2013.
TRIBUTARIES
Zeletavka
42 – 48°58'08''N, 15°35'15''E, 7059, Baèkovice, the
Zeletavka Brook near the bridge in Baèkovice,
29.7.2009;
43 –48°57'17''N, 15°34'25''E, 7059, Danèovice, the
Zeletavka Brook near Šimkùv Mlýn (Mill) east of
Danèovice, 27.7.2009;
44 –48°56'18''N, 15°36'52''E, 7059, Lubnice, the
Zeletavka Brook in Lubnice, 27.7.2009;
45 –48°57'42''N, 15°39'19''E, 7059, Police, the Zeletavka
Brook east of the Bahnùv Mlýn (Mill), 29.7.2009;
46 –48°57'45''N, 15°40'47''E, 7060, Zblovice, the
Zeletavka Brook east of the Svobodùv Mlýn (Mill),
30.7.2009.
Jevišovka
47 –48°50'40''N, 16°16'36''E, 7163, Bozice u Znojma, the
Jevišovka near the road bridge near the seclusion
Mlýnské domky, 19.9.2010;
48 –48°50'27''N, 16°17'23''E, 7163, Bozice u Znojma, the
Jevišovka near the road bridge Bozice –Mackovice,
19.9.2010;
49 –48°49'24''N, 16°22'26''E, 7164, Hrušovany nad
Jevišovkou, the Jevišovka near the railway bridge
Hrušovany nad Jevišovkou –Brno, 27.9.2009;
50 –48°49'24''N, 16°23'57''E, 7164, Hrušovany nad
Jevišovkou, the Jevišovka near the road bridge south
of Hrušovany nad Jevišovkou, 27.9.2009;
51 –48°49'29''N, 16°27'22''E, 7164, Jevišovka, the
Jevišovka 800 m upstream of the road bridge near the
Jevišovka railway station, 2.10.2009;
52 –48°49'27''N, 16°27'59''E, 7164, Jevišovka, the
Jevišovka between the Jevišovka railway station and
village, 27.9.2009;
Jihlava
53 –49°05'48''N, 16°21'47''E, 6964, Ivanèice, the Jihlava
River upstream of the inflow of the Oslava River,
31.7.2011;
54 –49°05'49''N, 16°22'05''E, 6964, Ivanèice, the Jihlava
River at the road bridge Ivanèice – Moravský
Krumlov, 31.7.2011;
55 –49°04'37''N, 16°25'26''E, 6964, Moravské Bránice,
the Jihlava River 1 km upstream of the road bridge
Moravské Bránice – Nové Bránice, 16.10.2010;
56 –49°04'36''N, 16°26'16''E, 6964, Moravské Bránice,
the Jihlava River downstream of the road bridge
Moravské Bránice – Nové Bránice, 16.10.2010;
57 –48°58'04''N, 16°33'19''E, 7065, Pøibice, the Jihlava
River 300 m upstream of the road bridge north of
Pøibice, 28.9.2010;
58 –48°57'49''N, 16°33'41''E, 7065, Pøibice, the Jihlava
River 300 m downstream of the bridge north of
Pøibice, 28.9.2010;
59 –48°56'17''N, 16°34'28''E, 7065, Ivaò, the Jihlava River
about 1 km northwest of Ivaò, 4.10.2009;
60 –48°56'02''N, 16°34'15''E, 7065, Ivaò, the Jihlava River
northwest of Ivaò, 4.10.2009;
61 –48°55'41''N, 16°34'20''E, 7065, Ivaò, the Jihlava River
near the road bridge in Ivaò, 4.10.2009;
62 –48°55'03''N, 16°35'57''E, 7065, Ivaò, the Jihlava River
1 km upstream of the inflow to the Svratka River and
the Nové Mlýny Water Reservoir by the bridge, a)
28.4.2001, b) 15.7.2012;
63 –48°54'48''N, 16°36'15''E, 7065, Ivaò, the Jihlava River
at the inflow to the Svratka River and the Nové Mlýny
Water Reservoir, 15.7.2012;
Svratka
64 – 48°57'01''N, 16°37'05''E, 7065, Vranovice nad
Svratkou, the Svratka River near the road bridge
Pouzdøany –Vranovice, 11.10.2009;
65 – 48°56'17''N, 16°36'21''E, 7065, Pouzdøany, the
Svratka River 2 km downstream of the road
Pouzdøany –Vranovice, 11.10.2009;
66 –48°55'37''N, 16°36'15''E, 7065, Ivaò, the Svratka
River 2 km upstream of the Nové Mlýny Water Reser-
voir, 11.10.2009;
67 –48°55'09''N, 16°36'21''E, 7065, Ivaò, the Svratka
River 1 km upstream of the Nové Mlýny Water Reser-
voir, a) 28.4.2001, b) 2.6.2012;
Kyjovka
68 –48°46'24''N, 17°00'42''E, 7267, Týnec, the Kyjovka
River in Týnec, 4.10.2001, LB+MH;
69 –48°44'40''N, 16°59'10''E, 7267, Kostice, the Kyjovka
River near Kostice, 22.9.2007;
70 –48°43'40''N, 16°58'40''E, 7267, Lanzhot, the Kyjovka
River near the road bridge Lanzhot –Kùty,
31.12.2007;
71 –48°41'49''N, 16°57'34''E, 7263, Lanzhot, the Kyjovka
River near the bridge 3 km south of the church in
Lanzhot, 31.12.2007;
72 –48°39'48''N, 16°55'59''E, 7263, Lanzhot, the Kyjovka
River 2,5 km upstream of its inflow to the Dyje River,
4.10.2008;
Morava
73 –48°40'21''N, 16°58'21''E, 7367, Lanzhot, the Morava
River northwest of Kùty, 10.10.2009;
74 –48°39'22''N, 16°58'01''E, 7367, Lanzhot, the Morava
River west of Kùty, 10.10.2009;
75 –48°39'10''N, 16°58'03''E, 7367, the Morava River
southwest of Kùty, 10.10.2009.
156 Luboš Beran

Freshwater molluscs of the Dyje (Thaya) River and its tributaries 157
APPENDIX 2: Table 1. List of freshwater molluscs recorded at Dyje I and II study sites
Species/Site No. Dyje I Dyje II
12345678910111213141516171819
Theodoxus danubialis (C. Pfeiffer, 1828)
Viviparus viviparus (Linnaeus, 1758) 2 60 200 28
Potamopyrgus antipodarum (Gray, 1843) 3
Lithoglyphus naticoides (C. Pfeiffer, 1828) 3
Bithynia tentaculata (Linnaeus, 1758) 45 18 12 300 180 40 40 200 35 400
Valvata piscinalis (O. F. Müller, 1774) 16
Acroloxus lacustris (Linnaeus, 1758) 210 2 2
Galba truncatula (O. F. Müller, 1774) 32 3 313
Radix auricularia (Linnaeus, 1758) 20 3 12 15 10 1 12 5 3 2
Radix ampla (Hartmann, 1821) 14 70 1 2 3 3 7
Physella acuta (Draparnaud, 1805) 1 18
Anisus vortex (Linnaeus, 1758) 26 2 7 5
Gyraulus albus (O. F. Müller, 1774) 23010 2
Gyraulus crista (Linnaeus, 1758) 1
Hippeutis complanatus (Linnaeus, 1758) 1
Ancylus fluviatilis (O. F. Müller, 1774) 25 40 70 35 15 900 40 40 2 180 90 50 350 350 200 200
Unio pictorum (Linnaeus, 1758) 4 82427
Unio tumidus Philipsson, 1788 3 1814341840
Unio crassus Philipsson, 1788 6 13 3 1 8 3 14 78
Anodonta anatina (Linnaeus, 1758) 20 33713 71 7 26 3153
Pseudanodonta complanata (Rossmässler, 1835) 1221
Sphaerium rivicola (Lamarck, 1818) 12 14
Sphaerium corneum (Linnaeus, 1758) 220 8040 5080 184025 18
Musculium lacustre (O. F. Müller, 1774) 2
Pisidium amnicum (O. F. Müller, 1774) 1
Pisidium henslowanum (Sheppard, 1823) 745 20 2 3 8
Pisidium supinum A. Schmidt, 1851 12
Pisidium subtruncatum Malm, 1855 2256574336
Pisidium nitidum Jenyns, 1832 3 8815 1212 3 2 2 4
Pisidium casertanum Poli, 1791 6
Pisidium moitessierianum (Paladilhe, 1866) 16
Number of species 5 6 10 10 7 9 3 8 10 7 10 11 8 6 10 8 6 7 11
Number of specimens recorded at the sites is given (only estimation in the case of more abundant species). x – only old shells found

158 Luboš Beran
APPENDIX 2: Table 2. List of freshwater molluscs recorded at Dyje III and IV study sites
Species/Site No. Dyje III Dyje IV
20 21 22 23 24 25 26 27 28 29 30 31 32a 32b 33 34 35a 35b 36 37 38 39 40 41a 41b
Theodoxus danubialis (C. Pfeiffer, 1828) 60 4 8 500 22
Viviparus acerosus (Bourguignat, 1862) 300 2 8 14 1 2 1
Potamopyrgus antipodarum (Gray, 1843) 3 8 2 4 30 2 2
Lithoglyphus naticoides (C. Pfeiffer, 1828) 43 33535151517
Bithynia tentaculata (Linnaeus, 1758) 6 200 350 300 600 300 300 150 40 70 5 250 15 28 16 28 40 30 24 25 25 24 20 15 4
Valvata piscinalis (O. F. Müller, 1774) 40 18 20 4 10 8 80 10 35 60 17 30 12 10 6
Acroloxus lacustris (Linnaeus, 1758) 2 3 3 2 2
Galba truncatula (O. F. Müller, 1774) 5 2 40 30 150
Stagnicola palustris (O. F. Müller, 1774) 10
Radix auricularia (Linnaeus, 1758) 15 15 18 8 6 25 8 35 23 3 16 2 14 2 20 20 18 38 2
Lymnaea stagnalis (Linnaeus, 1758) 12 10 7 10 3 5 6 5 1
Physa fontinalis (Linnaeus, 1758) 14
Physella acuta (Draparnaud, 1805) 70 5 4 20 25 15 60 35 150 18 35 40 20 13 8 20 40 45 35 6
Planorbis planorbis (Linnaeus, 1758) 3 6
Anisus vortex (Linnaeus, 1758) 3 2 15 20 10 13 13 10 40 18
Gyraulus albus (O. F. Müller, 1774) 3 6 10 12 2 4 2 3
Gyraulus crista (Linnaeus, 1758) 4
Hippeutis complanatus (Linnaeus, 1758) 10 12 3
Planorbarius corneus (Linnaeus, 1758) 4433 4
Ancylus fluviatilis (O. F. Müller, 1774) 1 80 5 15 8 90
Ferrissia fragilis (Tryon, 1863) 30
Unio pictorum (Linnaeus, 1758) 3 32214 4 65278418216 34
Unio tumidus Philipsson, 1788 3 1 1 7 3 8 100 46 17 6 8 24 3 30 8 7
Unio crassus Philipsson, 1788 x3 x4 x7 x3 2
Anodonta cygnea (Linnaeus, 1758) 2 2 1 1 2 3
Anodonta anatina (Linnaeus, 1758) 8 5 7 3 1219251 409104315318 1
Pseudanodonta complanata (Rossmässler, 1835) 112
Sinanodonta woodiana (Lea, 1834) 36 26 14 35
Sphaerium rivicola (Lamarck, 1818)
Sphaerium corneum (Linnaeus, 1758) 28 15 4 10 4 4 6 3 6
Pisidium henslowanum (Sheppard, 1823) 4 2 3 5 212846
Pisidium supinum A. Schmidt, 1851 7 3 2 12 2
Pisidium subtruncatum Malm, 1855 1 1 4 2
Pisidium nitidum Jenyns, 1832 3 3 2 3 3 1231 2232
Pisidium moitessierianum (Paladilhe, 1866) 2 4
Dreissena polymorpha (Pallas, 1771) 70 6 45 251468 6
Number of species 7855717199131491710112210106151714173714
For explanations see Table 1.

Freshwater molluscs of the Dyje (Thaya) River and its tributaries 159
APPENDIX 2: Table 3. List of freshwater molluscs recorded at Zeletavka and Jevišovka study sites
Species/Site No. Zeletavka Jevišovka
42 43 44 45 46 47 48 49 50 51 52
Viviparus acerosus (Bourguignat, 1862) 200 70 65
Potamopyrgus antipodarum (Gray, 1843) 14 80 130 120 3 8
Bithynia tentaculata (Linnaeus, 1758) 28 35 40 18 30 40
Valvata piscinalis (O. F. Müller, 1774) 21230
Acroloxus lacustris (Linnaeus, 1758) 260
Galba truncatula (O. F. Müller, 1774) 6206
Radix auricularia (Linnaeus, 1758) 28
Radix ampla (Hartmann, 1821) 80
Physella acuta (Draparnaud, 1805) 350 300
Gyraulus albus (O. F. Müller, 1774) 6
Ancylus fluviatilis O. F. Müller, 1774 7 13 6 8 8 10 15 13
Unio pictorum (Linnaeus, 1758) 21308 7
Unio tumidus Philipsson, 1788 65 23 5 10
Unio crassus Philipsson, 1788 2x2 171
Anodonta cygnea (Linnaeus, 1758) 14
Anodonta anatina (Linnaeus, 1758) 3697431818416
Sphaerium rivicola (Lamarck, 1818) 410 8
Sphaerium corneum (Linnaeus, 1758) 60306761566
Musculium lacustre (O. F. Müller, 1774) 23
Pisidium amnicum (O. F. Müller, 1774) x3 x3
Pisidium henslowanum (Sheppard, 1823) 44
Pisidium supinum A. Schmidt, 1851 813 812
Pisidium subtruncatum Malm, 1855 422348
Pisidium nitidum Jenyns, 1832 674 6
Pisidium casertanum (Poli, 1791) 4 2312
Pisidium moitessierianum (Paladilhe, 1866) 11
Number of species 4354412121616815
For explanations see Table 1.
APPENDIX 2: Table 4. List of freshwater molluscs recorded at Jihlava study site
Species/Site No. Jihlava
53 54 55 56 57 58 59 60 61 62a 62b 63
Potamopyrgus antipodarum (Gray, 1843) 4 12 3 35 20 20
Bithynia tentaculata (Linnaeus, 1758) 100 8 14 70 350 15 35 40 4 300 300
Valvata piscinalis (O. F. Müller, 1774) 4 8 25 500 250
Galba truncatula (O. F. Müller, 1774) 3
Radix auricularia (Linnaeus, 1758) 2 10 8 8 12 18
Lymnaea stagnalis (Linnaeus, 1758) 1238
Physella acuta (Draparnaud, 1805) 3 2 40 15 30 12
Planorbis planorbis (Linnaeus, 1758) 216
Anisus vortex (Linnaeus, 1758) 27035
Gyraulus albus (O. F. Müller, 1774) 3 13 160 80
Ancylus fluviatilis O. F. Müller, 1774 60 45 15 10 20 40 35
Unio pictorum (Linnaeus, 1758) 1 1 12 12 15 3
Unio tumidus Philipsson, 1788 55388184012
Unio crassus Philipsson, 1788 4411112
Anodonta cygnea (Linnaeus, 1758) 5

160 Luboš Beran
Anodonta anatina (Linnaeus, 1758) 6582221468234
Sphaerium corneum (Linnaeus, 1758) 387436853 136
Musculium lacustre (O. F. Müller, 1774) 15
Pisidium henslowanum (Sheppard, 1823) 52 2543
Pisidium supinum A. Schmidt, 1851 2122242 1
Pisidium subtruncatum Malm, 1855 1232 2123105
Pisidium nitidum Jenyns, 1832 25 66
Number of species 7 11 8 10 7 9 10 10 11 12 17 14
For explanations see Table 1.
APPENDIX 2: Table 5. List of freshwater molluscs recorded at Svratka, Kyjovka and Morava study sites
Species/Site No. Svratka Kyjovka Morava
64 65 66 67a 67b 68 69 70 71 72 73 74 75
Theodoxus danubialis (C. Pfeiffer, 1828) 1
Viviparus acerosus (Bourguignat, 1862) 60 200 3 2
Lithoglyphus naticoides (C. Pfeiffer, 1828) 200 250 150 2
Bithynia tentaculata (Linnaeus, 1758) 600 800 600 100 300 15 10 15 10 18 150 40 300
Valvata cristata O. F. Müller, 1774 32
Valvata piscinalis (O. F. Müller, 1774) 840308016 5 4
Acroloxus lacustris (Linnaeus, 1758) 4
Galba truncatula (O. F. Müller, 1774) 42
Radix auricularia (Linnaeus, 1758) 110 5 7103516
Radix ampla (Hartmann, 1821) 825 4
Lymnaea stagnalis (Linnaeus, 1758) 82412
Physella acuta (Draparnaud, 1805) 6 30 30 12 8 30 30 40 15 18 60 20
Planorbis planorbis (Linnaeus, 1758) 1
Anisus vortex (Linnaeus, 1758) 30 4 15 2 1
Gyraulus albus (O. F. Müller, 1774) 10 15 12 3
Hippeutis complanatus (Linnaeus, 1758) 2
Planorbarius corneus (Linnaeus, 1758) 1
Ancylus fluviatilis O. F. Müller, 1774 70
Ferrissia fragilis (Tryon, 1863) 50
Unio pictorum (Linnaeus, 1758) 3 825 1 2334
Unio tumidus Philipsson, 1788 35 15 12 6 16 3 8 14 18 8 45
Anodonta cygnea (Linnaeus, 1758) 14
Anodonta anatina (Linnaeus, 1758) 101014 33512428410
Pseudanodonta complanata (Rossmässler, 1835) 1
Sinanodonta woodiana (Lea, 1834) 256 923
Sphaerium rivicola (Lamarck, 1818) 460 3 1
Sphaerium corneum (Linnaeus, 1758) 100 30 25 2 5 2 2 3 35 3 2
Musculium lacustre (O. F. Müller, 1774) 23
Pisidium henslowanum (Sheppard, 1823) 2 14 224
Pisidium supinum A. Schmidt, 1851 8
Pisidium subtruncatum Malm, 1855 2224 21
Pisidium nitidum Jenyns, 1832 31
Pisidium casertanum (Poli, 1791) 3
Dreissena polymorpha (Pallas, 1771) 350 300 500
Number of species 11 10 12 11 16 12 8 8 12 14 13 10 11
For explanations see Table 1.