1067-4136/01/3201- $25.00 © 2001
Russian Journal of Ecology, Vol. 32, No. 1, 2001, pp. 56–57. Translated from Ekologiya, No. 1, 2001, pp. 61–63.
Original Russian Text Copyright © 2001 by Stepanova.
The bacterioplankton of the Black Sea is a bioasso-
ciation sensitive to ecological disturbances (Bird and
Karl, 1991; Gutveib, 1990; Stanev, 1989). In 1994, I
began studies on some morphological characteristics
and the distribution of marine bacteria and viruses in
the microplankton and bottom sediments of Sevastopol
bays, which have been performed systematically since
then. The present communication describes the results
obtained between 1994 and 1998.
Samples were taken from the upper water column at
different stations in Sevastopol bays, before noon. Ini-
tially, sea water was ﬁltered through membranes with a
pore size of 0.45
m to remove larger fractions of
microplankton and other suspended particles; thereaf-
ter, ﬁltration through Sartorius nitrocellulose mem-
branes with pore sizes of 0.2 and 0.01
m was used.
The ﬁrst ﬁlter retained mainly marine bacteria (bacteri-
oplankton), and the second retained viruses and bacte-
riophages (femtoplankton) (Sieburt
, 1978). After
staining with acridine orange, microorganisms were
counted using epiﬂuorescent microscopy.
In the summer of 1997, samples of bottom sedi-
ments were taken from a vessel at 43 stations in Sevas-
topol bays using a portable
dredge. A 20-g part of each sample was transferred to a
sterile ﬂask using a sterile spatula, and 10 ml of sterile
saline were added. After intensive shaking for 5 min,
the resulting suspension was allowed to settle for 1 h.
The supernatant was ﬁltered through the membrane
with a pore size of 0.45
m and investigated using epi-
ﬂuorescent microscopy. The data on 1 ml of the suspen-
sion were recalculated per gram of bottom sediment.
The results were processed by conventional statisti-
cal methods (Lakin, 1973).
With respect to the pollution level, the Sevastopol
bays were conventionally subdivided into polluted,
ecologically endangered (pollution levels III–V), and
relatively pure and safe (pollution levels I–II) (Guseva
, 1998; Kiryukhina
, 1985). The averaged
parameters of bacterio- and femtoplankton abundance
in 1994 to 1998 are shown in Table 1.
The number of marine bacteria in the microplankton
varied within the range of (2–5.2)
agrees with the results obtained by other authors (Bird
and Karl, 1991; Stanev, 1989). The bacteria were
mainly represented by rodlike cells. Round and oval
forms were more frequent in spring and summer,
accounting for more than 50% of the bacterial abun-
dance in the ecologically safe Sevastopol bays. The
prevalence of round forms in the microplankton is an
indication of relative water purity (Grigor’eva, 1975).
Representatives of femtoplankton, whose average
per milliliter, included rod-
like (short, rounded, and thin, pointed rods), rounded,
hairlike, and clavate forms. The ratio of their abun-
dance to the total number of bacteria averaged 0.6,
reaching a peak (1.1) in spring and decreasing to a min-
Marine Bacteria and Viruses in the Water
and Bottom Sediments of Sevastopol Bays
O. A. Stepanova
Kovalevskii Institute of the Biology of Southern Seas, National Academy of Sciences of Ukraine, pr. Nakhimova 2,
Sevastopol, 99011 Ukraine
Received June 24, 1999
: marine bacteria, marine viruses, ecology, the Black Sea
Seasonal abundance of bacterioplankton and femtoplankton in Sevastopol bays (1994–1998)
Season of sampling
Abundance ratio of femto- to
of bacterioplankton (
cells) of femtoplankton (
Winter 2 1 0.5
Spring 2.5 2.7 1.1
Summer 4.5 1.5 0.3
Autumn 5.2 2.8 0.5
Seasonal average 3.6