ISSN 1067-4136, Russian Journal of Ecology, 2007, Vol. 38, No. 2, pp. 128–130. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © O.P. Bazhenova, 2007, published in Ekologiya, 2007, Vol. 38, No. 2, pp. 141–143.
The Irtysh is the largest tributary of the Ob. A cas-
cade of the Bukhtarma, Ust’-Kamenogorsk, and
Shul’ba hydroelectric power plants in its upper reaches
considerably affects hydrologic conditions in the river.
Studies of phytoplankton as the ﬁrst link of the trophic
chain that largely determine the functioning of aquatic
ecosystems and the quality of their waters are important
for solving the problem of monitoring the ecological
state of the Irtysh ecosystem.
This paper deals with the results of studies on phy-
toplankton of the Bukhtarma Reservoir (September
2002 and May 2003) and Shul’ba Reservoir (July 2003)
and the middle reaches of the Irtysh (1998–2003)
within Omsk oblast. Phytoplankton was sampled and
treated using standard hydrobiological methods (
The phytoplankton of the Bukhtarma Reservoir has
been studied regularly since the ﬁrst days of its ﬁlling
(Votinova, 1970; Noskov, 1971; Bazhenova, 1978,
1981). Eutrophication of the reservoir began in the late
1970s (Bazhenova, 1980). Since then, new facts con-
cerning structural rearrangement in its phytoplankton
have been revealed. In particular, 263 species and vari-
eties of algae belonging to seven phyla were recorded
Euglenids and yellow-green algae, as well as some
chrysophyte species of algae, were found in the phy-
toplankton of this reservoir for the ﬁrst time. Most
euglenids and all yellow-green algae are distributed in
the lake part of the reservoir. Such an invasion of
euglenids is indicative of organic pollution in the lake
part of the reservoir.
As previously, blue-green algae play an important
role in the summer–autumn period. Considerable trans-
formations have occurred in the composition of Cyano-
phyta, which are a component of the dominant group of
phytoplankters. In previous years, algal bloom was
Phytoplankton Structure and Water Saprobity
in the Upper and Middle Irtysh
O. P. Bazhenova
Omsk State Agrarian University, Institutskaya pl. 2, Omsk, 644008 Russia;
Received October 12, 2005
: phytoplankton, species composition and structure, saprobity, upper and middle Irtysh.
Taxonomic composition of phytoplankton from the Upper and Middle Irtysh (numbers of species and infraspecific taxa)
1978 2002–2003 2003 1955* 1998–2003
Cyanophyta 38 36 24 31 38
Cryptophyta – – 6 – 2
Chrysophyta 4 10 9 6 16
Bacillariophyta 94 45 41 31 48
Xanthophyta – 6 2 – 7
Euglenophyta – 28 10 4 30
Chlorophyta 122 136 99 85 160
Total 260 263 193 158 302
* According to Skabichevskii (1952, 1957).