Change in the Life Cycle Strategy of Fish under the Effect of Chronic Water Pollution

Fish of a polymorphic and evolutionarily young species Coregonus lavaretusfrom a subarctic lake that has been polluted for more than 60 years are used as an example for analyzing principal trends in the dynamics of structural and functional organization of fish populations. It is shown that fish exposed to sublethal doses of toxic substances for a long time have a smaller body size, the period of their sexual maturation becomes more variable, and the frequency of spawning and life span decrease. The biochemical and bioenergetic mechanisms of variation in populations are analyzed. The ecological expediency of change in the life cycle strategy corresponding to r-selection (conversion to a short reproductive cycle) is substantiated.