ISSN 1067-4136, Russian Journal of Ecology, 2007, Vol. 38, No. 4, pp. 253–261. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © B.G. Kotegov, 2007, published in Ekologiya, 2007, Vol. 38, No. 4, pp. 274–282.
Research on the present-day state of ecosystems of
small rivers is becoming especially relevant, as increas-
ing anthropogenic pressure may soon cause consider-
able changes in the structure of their biological commu-
nities. Studies on the species composition and ecologi-
cal structure of ﬁsh populations in small rivers
undergoing anthropogenic transformation contribute to
the accomplishment of various tasks in the ﬁeld of
nature conservation. Within the scope of the biodiver-
sity conservation program, the small rivers of Russia
are studied as long-term refugia for isolated popula-
tions of some rare ﬁsh and ﬁshlike species included in
red data lists, such as the western brook lamprey, brook
trout, grayling, bystryanka, and freshwater sculpin
(Sokolov et al., 2001; Tylik, 2001; Ruchin et al., 2004).
In some regions, special monitoring of the ichthyo-
fauna is performed and ichthyocadasters of small rivers
are created in order to integrate all information on the
state of ﬁsh populations of these water bodies and to
use it for planning and implementing nature conserva-
tion measures (Vnutskikh and Zinov’ev, 1997;
Zinov’ev and Baklanov, 2000a; Vechkanov et al., 2001;
Tsepkin et al., 2001).
The state of the ichthyofauna of small rivers is also
regarded as an indicator of anthropogenic transforma-
tion of freshwater ecosystems (Sorokin and Sorokina,
1997; Kozlovskii and Antonov, 2001; Kotegov and
Kholmogorova, 2001). In comparison with medium-
sized and large rivers, small rivers have a lower self-res-
toration potential and are less resistant to the impact of
external factors from terrestrial landscapes. As a conse-
quence, they are highly sensitive to anthropogenic
inﬂuence and promptly respond to it by changing their
abiotic and biotic parameters. In particular, this con-
cerns the structure of the ﬁsh component of biological
communities (Baklanov, 2002; Slyn’ko and Kiyashko,
2003). These changes depend on the type of anthropo-
genic impact and may have a directed, successional pat-
tern (Nikolaev, 1985, 1989).
The purpose of this study was to reveal speciﬁc fea-
tures in the species composition of the ichthyofauna
and the structure of ﬁsh communities in small rivers
ﬂowing in different natural and anthropogenic land-
scapes of the Udmurt Republic.
STUDY AREA, MATERIAL, AND METHODS
The study was performed in the central, eastern, and
northern parts of the Udmurt Republic, in the landscape
subzones of southern taiga and mixed broadleaf forests.
The density of the river network reaches 0.6–0.7 km/km
with the modulus of ﬂow being 6.5–8.5 l/c · km
1995). All rivers belong to the basin of the Kama River
and ﬂow directly into it or are tributaries (of different
orders) of three other large rivers, the Cheptsa (501 km),
Izh (270 km), and Siva (206 km) (Fig. 1).
The ichthyological material was collected in 2003
and 2004 in small rivers, up to 100 km long (
, 1988), and in the upper reaches of some
medium-sized rivers, no more than in 100 km from the
source. Altogether, 36 nonregulated stretches of small
rivers were surveyed. Each stretch was assigned a rank
8) depending on the distance from the river
1, 0–10 km;
2, 11–20 km;
3, 21–30 km;
5, 41–50 km;
6, 51–60 km;
7, 61–70 km;
Special Features of Fish Species Composition and Community
Structure in Small Rivers of the Udmurt Republic
B. G. Kotegov
Udmurt State University, ul. Universitetskaya 1, Izhevsk, Udmurt Republic, 426034 Russia;
Received June 20, 2006
—The composition and species richness of ichthyofauna have been studied in 36 stretches of small
rivers in the Udmurt Republic to estimate the dependence of species richness on the distance from the river
source and the level and type of anthropogenic load. Some speciﬁc features of modiﬁcation of the ﬁsh commu-
nity structure under the inﬂuence of agriculture, urbanization, and industry (oil production) have been revealed.
Basic trends in the change of dominant complexes of ﬁsh species with an increase in the distance from the river
source are described for small rivers ﬂowing in different natural and anthropogenic landscapes of the Udmurt
: ichthyofauna, small rivers, species richness, community structure, anthropogenic load.