1063-0740/05/3101- © 2005 Pleiades Publishing, Inc.
Russian Journal of Marine Biology, Vol. 31, No. 1, 2005, pp. 1–6.
Original Russian Text Copyright © 2005 by Biologiya Morya, Morozova, Orlova.
In its biogeographical features, Peter the Great Bay
is thought to be one of the most favorable areas in the
Russian Far East for commercial cultivation of aquatic
organisms. Monitoring of phytoplankton is important
for successful operation of sea farms because it helps
not only to evaluate the food resources in the investi-
gated area, but also to reveal and forecast changes in the
marine ecosystems. It is known that, in performing the
vital functions, cultivated invertebrates, particularly
mollusks, have an appreciable effect on microalgae [7,
8, 11, 16, 25]. Outbreaks of harmful and toxic microal-
gae are often observed in areas of the sea occupied by
mariculture installations [27, 28, 32]. The abundant devel-
opment of noxious algae frequently causes mortality of
marine invertebrates and ﬁsh and is a hazard to humans
and poikilothermal animals [15, 18, 22, 23, 29, 31].
In 1982, a small experimental farm with an area of
2.5 ha was organized in Vostok Bay for cultivation of
the Paciﬁc mussel
. In 1991, the Tikhii
Okean Fishing Collective Farm set up in the bay culture
grounds 10 times as great as the previous experimental
plots. However, since the late 1990s these culture
grounds have been reduced to the size of the year 1982.
The ﬁrst long-term studies of planktonic microalgae of
Vostok Bay performed in 1975–1976 and 1978 
showed the richness of species composition and the
large temporal nonuniformity of the qualitative and
quantitative characteristics of phytoplankton in this
bay. The study of phytoplankton at the time when the
sea farm was in operation (1985–1995) revealed
changes in the species composition of microalgae and
increased eutrophication of the water around maricul-
ture installations [8, 10]. In the course of these investi-
gations, data on the composition and dynamics of
potentially toxic species of microalgae were collected
The aim of this research is to study the species com-
position and seasonal dynamics of phytoplankton of
Vostok Bay and to analyze possible changes in the
structure of phytoplankton as a result of sea farming.
MATERIALS AND METHODS
Planktonic surveys were made at a monitoring sta-
tion situated in the inner part of Vostok Bay near the
hydrotechnical structures for mussel cultivation
(Fig. 1). Samples were taken with Molchanov’s bottle
sampler (4-liter) at the water surface twice a month
from July 2001 to May 2002. Material was ﬁxed with
Utermöhl’s solution to achieve a light-yellow color and
concentrated by the precipitation method or by reverse
ﬁltration through 2-
m nucleopore ﬁlters. Cells were
counted in Nojotte’s chamber with a volume of 0.05 ml
for nannoplankton and 1 ml for microplankton. The
biomass of algae was estimated by the volume method.
Original and literature data on cell volume were used
additionally for each species [2, 6]. A species was
regarded as a dominant if its biomass made up at least
20% of the total density of phytoplankton . Mar-
galef’s index was used as the measure of species diver-
= , where
is the total numbers of a com-
is the number of species .
Monitoring of Phytoplankton
in the Area of a Sea Farm in Vostok Bay (Sea of Japan)
T. V. Morozova and T. Yu. Orlova
Institute of Marine Biology, Far East Division, Russian Academy of Sciences,
Vladivostok, 690041 Russia
Received June 22, 2004
—The qualitative and quantitative composition of phytoplankton in the area of a sea farm in Vostok
Bay (Sea of Japan) was investigated from July 2001 to May 2002. The overall numbers of phytoplankton were
0.008 to 5.3 million cells/liter, and the biomass was 0.02 to 20.5 g/m
. The maximum density and biomass of
phytoplankton were observed in summer, fall, and winter. Ten species known to be toxic were recorded. Of
(Whedon et Kofoid) Balech, and
(Subrahmanyan) Hara et Chihara were found in Vostok Bay for the ﬁrst time. For the dia-
(Greville) Cleve, which is an indicator of extremely eutrophic waters, the cell den-
sity was positively correlated with the area of the culture site.
phytoplankton, monitoring, mariculture,
, Sea of Japan.