1067-4136/05/3604- © 2005 Pleiades Publishing, Inc.
Russian Journal of Ecology, Vol. 36, No. 4, 2005, pp. 266–270. Translated from Ekologiya, No. 4, 2005, pp. 294–299.
Original Russian Text Copyright © 2005 by Domnin, Korsak, Mosharov.
The increasing anthropogenic impact on natural
ecosystems makes it necessary to study and forecast the
ecological consequences of chemical pollution of the
environment, including the hydrosphere. The ability of
aquatic ecosystems to maintain homeostasis is limited,
and a further increase in anthropogenic load may result
in their irreversible transformation and degradation.
The state and development of an aquatic ecosystem
depend on a combination of different environmental
factors, among which a major role belongs to pollution
with heavy metals, pesticides, and petroleum products.
Exposure to these pollutants may have different conse-
quences, depending on the stage of seasonal succession
in the planktonic community (Phillips
Mauser, 1998; Tarkpea
, 1998). To prevent or
reduce ecological damage, it is necessary to determine
the periods when ecosystems are most vulnerable. This
information is very important for estimating economic
damage from accidental environmental pollution and
determining the seasons in which industrial activities
will be less hazardous in ecological terms. An impor-
tant task of specialists in ecology, including aquatic
toxicology, is to develop the concept of the assessment
of critical changes in natural systems under the effects
of anthropogenic factors.
PROBLEMS IN ECOLOGICAL TOXICOLOGY
Methods for assessing the vulnerability of biologi-
cal systems at the ecosystem level have not yet been
developed. Traditional toxicological methods based on
the responses of individual test organisms to toxic
action are not fully applicable to the natural communi-
ties of aquatic organisms and whole ecosystems (Wun-
, 1997; Molchanova
, 1996; Shadrina,
1997). The responses of different taxonomic groups
(species) of planktonic organisms to toxicants differ,
and the general stability of the planktonic community
varies depending on seasonal changes in both the com-
munity structure and the functional activity of different
groups of algae.
A feasible experimental approach to this task is to
study the functioning of ecosystems under almost criti-
cal conditions, i.e., at a concentration of toxicants in an
aquatic medium that approaches a certain threshold, but
where the changes they cause in the ecosystem are
reversible. The concentrations exceeding this threshold
cause irreversible changes and degradation of the
Phytoplanktonic organisms, as the main primary
producers of organic matter in an aquatic ecosystem,
are a key element providing for ecosystem stability. The
conditions critical for the phytoplanktonic community
are considered to be critical for the ecosystem as a
whole. Therefore, it is essential to formulate the princi-
ples of assessment of ecosystem resistance to chemical
pollution as applied primarily to the phytoplankton.
Seasonal succession in aquatic ecosystems has cru-
cial transitional periods when one community replaces
another, which actually determine the subsequent
course of succession. If the impact of pollutants
exceeds the above threshold at this transitional stage,
irreversible changes will occur in the ecosystem struc-
ture, and its development will follow a different path-
On the Problem of Assessing the Resistance
of Planktonic Community to Adverse Influences
S. G. Domnin*, M. N. Korsak*, and S. A. Mosharov**
*Federal Center of State Sanitary Epidemiological Inspection,
Ministry of Public Health and Social Policy of the Russian Federation,
Varshavskoe sh. 19a, Moscow, 117105 Russia
**Shirshov Institute of Oceanology, Russian Academy of Sciences,
Nakhimovskii pr. 36, Moscow, 117851 Russia
Received January 20, 2004
—An experimental–analytical method for assessing the vulnerability of aquatic ecosystems under
conditions of anthropogenic pollution is considered. Such data are very important for estimating economic
damage from accidental environmental pollution and determining the seasons in which industrial activities will
be less hazardous in ecological terms. A feasible approach to this problem is based on the study of ecosystem
behavior under critical conditions. Phytoplankton, being the main primary producer of organic matter in the
aquatic ecosystem, is the key element providing for its stability.
: ecosystem, stability, planktonic community, seasonal succession of phytoplankton.