ISSN 10630740, Russian Journal of Marine Biology, 2010, Vol. 36, No. 2, pp. 86–92. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © I.V. Motylkova, N.V. Konovalova, 2010, published in Biologiya Morya.
The Izmenchivoye Lagoon Lake is located in the
southeast part of the Sakhalin Island. In hydrological
terms the Izmenchivoye Lake is a typical sea bay of the
lagoon type, separated from the Mordviniov Bay (the
Sea of Okhotsk) by an accumulative spit. The basin has
an ellipsoid form, with a length of 4.2 km and a width
of 2 km . The lake is small in area (9.5–13.0 km
and average in depth (5–7 m), saline (25.8–32.8‰)
and is a semiclosed lagoon . The riverine drain is
extremely insignificant. As consequence of this, the
lake hydrology depends basically on tide phenomena
in the Sea of Okhotsk and on water exchange capacity
through the channel.
Being subjected to effect tidal currents, the lagoon
represents a specific ecosystem formed mostly by sea
communities. However, the existence of such an eco
system is unsteady, which is caused, first of all, by the
functioning or periodic degradation of the channel
providing water exchange with the Sea of Okhotsk.
Thus, at the end of the summer of 2006 the channel
was blocked by sand deposits and its communication
with the sea was interrupted. A similar phenomenon in
the history of the waterways development was also
observed in 1963, therefore the hydrobiological status
of the waterway changed and the lagoon transited into
an isolated phase. The absence of water exchange with
the sea resulted in a structure change of its biocenosis,
The article was translated by the authors.
thanks to the complete disappearance of sea organisms
in the lagoon (unpublished data of SakhNIRO).
Successful completion of comprehensive hydrobi
ological studies by SakhNIRO staff for 2004–2007
enabled us not only to develop modern ideas on the
condition of the communities and structural parame
ters of zoo and ichthyoplankton [21, 23], and macro
zoobenthos , but also to track their changes con
nected with the termination of water exchange with
the sea [11, 12, 22, 23]. No data on the phytoplankton
of Izmenchivoye Lake was available in the literature.
The objective of our research was a study of the sea
sonal dynamics of phytoplankton number and biom
ass in the Izmenchivoye Lake during the functioning
of the lake channel (January 2005–January 2006).
MATERIAL AND METHODS
Bathometric samples of phytoplankton were taken
monthly from January, 2005 up to January, 2006
(Fig. 1). From May until November the samples were
taken from two layers (surface and bottom), except for
the shallow water station 1 located in the channel; the
remaining of the time the samples were taken only
from the surface layer.
In all, 72 samples of phytoplankton of volume 1.3–
1.5 l were taken. The samples were concentrated by
reverse filtration through lavsan nucleopore mem
branes with a pore diameter of 3
m . The sample
Seasonal Dynamics of Phytoplankton in a LagoonType Lake
Izmenchivoye (Southeast Sakhalin)
I. V. Motylkova and N. V. Konovalova
Sakhalin Research Institute of Fisheries and Oceanography (SakhNIRO), YuzhnoSakhalinsk, 693023 Russia
Received November 19, 2009
—The seasonal changes in taxonomic structure, dynamics of number, and biomass of phytoplankton
in the Izmenchivoye lagoon lake (southeast Sakhalin) were studied. In all, 266 species and intraspecies taxa
of microalgae were revealed. The greatest species diversity (according to the Shannon index) was observed in
May, August and October (H = 2.76–2.89), the least (H = 0.5–0.86), in April and January of 2006. The
monthly average number varied from 997 up to 84 282 cells/l, and biomass from 18.98 up to 878.62 mg/m
The average annual number of phytoplankton and its biomass were 32 650 cells/l and biomass 172.13 mg/m
respectively. The maximum number was registered in August, 2005, and maximum biomass was recorded in
January, 2006. Winter, spring and summer peaks of number coinciding with those of biomass were registered.
For the first time, winter bloom of phytoplankton was registered in inland waters of the Sakhalin Island. In
the winter and spring the basic input to formation of the parameters was composed of diatoms; in summer
and autumn it was composed of by flagellates (dinophyta and cryptophyta).
phytoplankton, seasonal development, Sakhalin, Izmenchivoye Lake.