1063-0740/02/2802- $27.00 © 2002
Russian Journal of Marine Biology, Vol. 28, No. 2, 2002, pp. 94–99.
Original Russian Text Copyright © 2002 by Biologiya Morya, Morozova, Orlova, Selina.
The areas of aquaculture industries are prone to
environmental changes that affecting both benthic and
pelagic organisms [3, 5, 17, and others]. The inverte-
brates that were cultured, among them mollusks, pro-
duce a profound effect on the phytoplankton [11, 13,
28, and others]. The changes induced in the plankton
communities, in turn, negatively affected the cultivated
invertebrates. Thus, intense toxic and harmful algae
development may result in mass mortalities of marine
ﬁsh and invertebrates [25, 32]. Toxins produced by
some microalgal species accumulate in the mollusk tis-
sues in the course of ﬁltration, posing a threat to
humans and warm-blooded animals [22, 26, 32, 34].
In Minonosok Bight, where one of the largest Pri-
morye aquaculture farms is situated, bivalve mollusks
have been cultivated for ~30 years. This long-term
activity is becoming increasingly harmful to the bight
ecosystem. One of its consequences is the repeated
mass mortalities of scallop larvae and spat in the bight
. The impact of bivalve cultivation on the local plank-
ton phytocenoses has been poorly studied [7, 11, 13].
The paper presents the results of seasonal studies of
the qualitative and quantitative compositions of phy-
toplankton in Minonosok bight. The studies were
aimed at elucidating the possible impact of the mollusk
population cultured on the bight phytoplankton. Spe-
cial efforts were focused on monitoring studies of the
composition and dynamics of potentially toxic and
harmful microalgae. Such studies are obligatory for
aquaculture farms specializing in ﬁsh and marine inver-
tebrate culture in Europe, the United States, Canada, and
countries of the Asian–Paciﬁc region [21, 32,
MATERIALS AND METHODS
The material was collected during plankton surveys
in Minonosok Bight, where suspension-feeding scallop
cultivation installations are situated and occupy ~8 ha
and ground scallop rearing is performed to commercial
sizes. The samples were collected at three stations
(Fig. 1) one to three times a month from April until
October 1997 and every ten days from June until Sep-
tember 1999. Stations 1 and 2 were situated close to the
bight entrance points of Fedorova and Kreiserok,
respectively. According to the scheme of major bight
currents , station 1, which is situated near Fedorova
Point, was exposed to the open waters of Pos’et Bay
and was the control station. Station 2, situated near Kre-
iserok Point, and station 3, situated in the center of the
area occupied by scallop suspension-feeding installa-
tions in the innermost part of the bight, were exposed to
waters coming from the area of scallop culturing.
One-liter bathometric samples were ﬁxed with Uter-
mel’s solution to a light-yellow color and concentrated
by sedimentation. Micro- and nanoplankton cells were
counted in Nojott chambers with a volume of 1 and
0.05 ml, respectively.
The algal biomass was estimated volumetrically
using our original and literature data on measurements of
the cellular volume of each algal species found [6, 10].
The species that were considered dominant ate those
whose density was not less than 20% of the total phy-
toplankton density .
The water trophic level was estimated based on the
classiﬁcation system by Yamada
[35, 36] using
data on the total phytoplankton density and on the spe-
cies used as indicators of the water trophic level.
Phytoplankton in the Scallop Culture Area in Minonosok Bight
(Pos’eta Bay, Sea of Japan)
T. V. Morozova, T. Yu. Orlova, and M. S. Selina
Institute of Marine Biology, Far East Division of the Russian Academy of Sciences, Vladivostok, 690041 Russia
Received December 18, 2000
—The species composition and quantitative characteristics of the phytoplankton in Minonosok Bight
were studied in the spring and fall of 1997 and 1999. One hundred thirty-three algal species and intraspecies
taxa were identiﬁed. The cell density of the phytoplankton varied from 0.03 to 19.6 million cells/l, and its bio-
mass ranged from 0.02 to 19 g/m
. Both the density and biomass were at a maximum in June and August. Nine
potentially toxic species were found, among which the genera
Ehr. predominated. The density of these genera exceeded the reportedly harmul level during the
phytoplankton, toxic microalgae, aquaculture, mollusks, Pos’eta Bay.