ISSN 10674136, Russian Journal of Ecology, 2009, Vol. 40, No. 7, pp. 543–546. © Pleiades Publishing, Ltd., 2009.
Today, it is an established practice to supplement
the diagnosis of a species with data on its ecology.
Experimental studies on the responses of species to
certain environmental factors are often performed in
order to estimate their potential for expansion.
There is a variety of ways to obtaining such charac
teristics of species and present the corresponding data.
A welldeveloped and popular method for estimating
the boundaries of population or species survival is the
method of temperature tolerance polygons.
Fry et al. (1942) were the first who proposed to use
tolerance polygons for characterizing the responses of
species to ecological factors. Such polygons are con
structed by plotting the upper and lower limits of tol
erance to a certain factor within the whole range of its
values at which acclimation is possible. In fact, the tol
erance polygon not only reflects the dependence of
tolerance on the conditions of acclimation but also
shows the zone of potential tolerance, i.e., the range of
factor values to which a given organism (species) can
As a rule, tolerance polygons are trapezium or
parallelogramshaped. In particular, such are the
polygons presented in studies on temperature toler
ance (Fry et al.,1946; Hart, 1952; McLeese, 1956) and
salinity tolerance (Khlebovich and Kondratenkov,
1973; Khlebovich, 1981; Filippov, 2004) of fishes,
invertebrates, and infusorians (Smurov and Fokin,
2001). Polygons plotted for a certain factor are stable
and retain their shape even in cases of its interaction
with other factors (McLeese, 1956).
To date, temperature tolerance polygons have been
plotted for more than 100 species, whereas the number
of species with available polygons of salinity tolerance
is small and obviously insufficient for an adequate
The purpose of this study was to plot and analyze
the salinity tolerance polygon of
These mollusks were chosen because they are highly
euryhaline, form dense colonies on the sandy littoral
of the White Sea, and can be easily cultivated under
laboratory conditions. Moreover, they were the objects
of studies that have already become classic (e.g., Khle
bovich and Kondratenkov, 1971). In addition, we esti
mated the feasibility of the polygon method for pre
dicting the spread of this species over a natural salinity
MATERIAL AND METHODS
The study was performed at the O.A. Skarlato
White Sea Biological Station, Zoological Institute,
Russian Academy of Sciences, from June to August
4–6 mm in size were
collected on the sandy littoral of Cape Ivanov Navolok
in the Chupa Inlet of Kandalaksha Bay, the White Sea.
Freshly collected mollusks were placed in aquariums
with aerated sea water (26‰ salinity) kept in an iso
thermic room at 10
C. They were fed
algae ground in a mortar. The water in aquariums was
replaced every day, with its salinity remaining
unchanged. The mollusks were allowed one week for
adaptation to conditions before being used in experi
ments. Experimental media were prepared by diluting
or evaporating natural sea water and measuring the
resultant salinity with a Atago S/Mill refractometer
(Japan). No less than 100 mollusks were tested at each
salinity, taking daily counts of dead individuals.
Salinity Tolerance Polygon of
(Pennant, 1777) (Mollusca: Hydrobiidae)
A. Yu. Komendantov and A. O. Smurov
Zoological Institute, Russian Academy of Sciences,
Universitetskaya nab. 12, St. Petersburg, 199034 Russia
Received February 21, 2008
—To estimate the capacity of the White Sea littoral mollusk
(Pennant, 1777) for
adaptation to changes in ambient salinity, the range of its tolerance to increased and decreased salinity was
determined experimentally. The results were used to plot the salinity tolerance polygon. On this basis, it was
can live in a salinity range of 6–85‰.
, potential tolerance, tolerance polygon, salinity.