ISSN 1063-0740, Russian Journal of Marine Biology, 2007, Vol. 33, No. 2, pp. 125–132. © Pleiades Publishing, Ltd., 2007.
Original Russian Text © Yu.A. Reunova, N.A. Aizdaicher, N.K. Khristoforova, A.A. Reunov, 2007, published in Biologiya Morya.
Selenium levels in the world’s oceans vary, but lie in
the range of the maximum permissible concentration
(0.001 mg/liter), or are lower (the MPC is given after
). However, selenium content in the upper water lay-
ers of the oceans and seas may exceed the MPC. In
upwelling areas, the surface water is selenium rich due
to selenium carried by the rising deep water [11, 15].
Increased selenium contents in aquatic environments
can be due to human economic activities as well. The
sources of high selenium concentrations in upper oce-
anic waters, especially in estuarine and coastal zones,
are industrial discharges (ore mining and processing,
metallurgy, chemical and electronic industries), as well
as domestic sewage and agricultural drainage waters [8,
14, 18, 29]. For example, the concentration of selenium
in lakes in Finland varies between 0.00227 mg/liter and
lower values, with the upper ﬁgure being two times as
great as the MPC . The toxic concentration of sele-
nium (100 mg/liter) in the Kesterson Reservoir (Cali-
fornia, USA) was attributed to the input of selenium-
polluted agricultural drainage water [17, 21, 24].
Increased contents of this element in bottom sediments
have also been reported for Russia. Thus, at the mouth
of the Tumen River that ﬂows into the Peter the Great
Bay (in the Sea of Japan), the selenium content in bot-
tom sediments (2.25
g/g, dry wt) was 9 times greater
than the background level (0.25
g/g, dry wt), and in
Zapadnaya Bay (3.18
g/g, dry wt) the background
value was exceeded by 12.7 times [2, 4].
Phytoplankton plays a key role in the biotransforma-
tion of selenium in aquatic ecosystems [10, 13, 16, 23].
However, ultrastructural alterations in microalgal cells
at high selenium concentrations have been poorly stud-
ied . The selenium concentrations that initiate alter-
ations in cell ultrastructure, the nature of such cell dam-
age, and the concentrations leading to the total destruc-
tion of the cell are not known yet.
This paper deals with the effects of selenium on the
growth of the marine unicellular alga
and uses electron microscopy and morphometry to
examine the ultrastructural alterations in microalgal
cells exposed to different concentrations of selenium.
MATERIAL AND METHODS
The cells of the marine unicellular alga
Teod. (Chlorophyta) used were 5–29
m wide. A unialgal culture of
was grown in Goldberg’s medium  prepared using
ﬁltered and pasteurized seawater (32‰). Microalgae
were cultured at a temperature of 20
(3000–3500 lx at the surface of ﬂasks) was provided
from luminescent lamps over a 12 h light : 12 h dark
The experiment was run for 14 days in two replicas in
conical Erlenmeyer’s ﬂasks containing 200 ml of the cul-
ture medium. Selenium (0.01, 0.5, 1, 5 and 10 mg/liter)
was added to the ﬂasks containing the microalgae every
Effects of Selenium on Growth and Ultrastructure of the Marine
Yu. A. Reunova
, N. A. Aizdaicher
, N. K. Khristoforova
, and A. A. Reunov
Institute of Marine Biology, Far East Division, Russian Academy of Sciences, Vladivostok, 690041 Russia
Far Eastern State University, Vladivostok, 690950 Russia
Received February 23, 2007
—This study examines the effects of selenium in concentrations of 0.01, 0.5, 1, 5, and 10 mg/liter on
the growth and ultrastructure of the microalga
Selenium in concentrations of 0.01 and
0.5 mg/liter stimulated cell population growth, while the number of ultrastructural alterations was the same as
in the control cells. At a selenium concentrations of 1 mg/liter, cell population growth slightly decreased by the
end of the experiment, and there was some increase in the number of cells with damaged organoids and in the
number of completely destroyed cells. As well, the excretory function of cell vacuoles was suppressed, and the
autophagic activity of these vacuoles was activated to destroy the cytoplasm and nucleus. Concentrations of
5 and 10 mg/liter were toxic to
, suppressing cell population growth and promoting extensive destruc-
tive changes. The threshold concentration of selenium for
was 1 mg/liter, which is 1000 times greater
than the maximum permissible concentration (MPC). The fact that the microalga was able to survive for several
days in this concentration is indicative of its high resistance to selenium.
, selenium, ultrastructure, morphometry.