[Long-period endogenous oscillations in fish population size: mathematical modeling].

We present a mathematical model of an aquatic community, where the size-and-age structure of hydrobiont populations is taken into account and the corresponding trophic interactions between zooplankton, peaceful fish and predatory fish are described. We show that the interactions between separate components of the aquatic community can lead to long-period oscillations in fish population size. The period of these oscillations is of the order of dozen years.

[The analysis of commercial fish population size oscillations in Lake Peipus].

With the use of recurrence plots, we show that the irregular oscillations in time, which commercial fish populations in Lake Peipus undergo, are deterministic.

[Mathematical model of invasion of mysids (Mysidacea) into the Naroch Lake system].

We present a mathematical model of the invasion of mysid into the Naroch Lake system. The model is parameterized with the use of field observation data. We show that the mysid invasion can lead to an increase in the time-averaged fish population size, and to a decrease in the time-averaged rotifer population size.

[Resource availability and its role in development of invasion processes].

The state of biotic communities inhabiting different water bodies is analyzed aiming to determination of conditions facilitating development of biological invasions. Mass-balance and dynamic models are used to reveal the factors ensuring the invasion of zebra mussel, Dreissena polymorpha, in Naroch Lakes (Byelorussia), and smelt, Osmerus eperlanus, in Lake Syamozero (Karelia). The results obtained indicate that for invasions leading to trophic chain lengthening, the main factor of successful invasion is the availability of resources that are not utilized by aboriginal species.

[A conceptual mathematical model of aquatic communities in lakes Naroch and Myastro (Belarus)].

A conceptual mathematical model of fish and zooplankton (rotifer) populations inhabiting the lakes Naroch and Myastro has been developed and studied. The parametrization of the model was carried out having regard to the field observation data. The population dynamics was simulated taking into account that the lakes Naroch and Myastro are coupled with each other by a channel.

[Invasion of an intermediate predator: the dynamics of fish populations in the mathematical model of a trophic chain (as applied to the Syamozero lake)].

We present a mathematical model of the dynamics of a spatially heterogeneous predator-prey population system. A prototype of the model system is the Syamozero lake fish community. We study the impact of the invader, an intermediate predator, on the dynamics of the fish community.

[A conceptual model of the dynamics of the Syamozero lake community].

We have developed a conceptual mathematical model of the dynamics of a spatially heterogeneous population system, the prototype of which is the Syamozero lake fish community. Based on the analysis of solutions of the model, we show that interrelations between prey and predator populations in two neighboring habitats (pelagic and offshore zones) can lead to both undamped oscillations and stationary values of the population size. The population density was found to be close to the values oblained in the course of long-term observations of the biota of the Syamozero lake.

Coexistence of triploid and diploid forms of spined loach, Cobitis taenia: a model-based approach.

A tritrophic model of Lotka-Volterra type was developed to describe the dynamics of a unisexual-bisexual complex in fish. The model assumes two genetically isolated forms, bisexual (diploid) and unisexual (triploid), competing for a common resource. The efficiency of food conversion into offspring for the unisexual form is dependent on the availability of the diploid males.