Abstract
This paper demonstrates the possibilities of detecting changes in populations of animals, based on the analysis of their dynamic phase portrait. This method allowed us to clarify the periodization of the process of naturalization of the Black Sea sprat (Clupeonella cultriventris) in the Rybinsk Reservoir and in detail describe the changes in the main dynamic characteristics of the population. On the example of zander (Sander lucioperca) in Lake Vozhe, the state was observed in which intra-population mechanisms activate which slow the increase in population (distribution of individuals from regions with high density). Use of this method allowed us to describe the new stable state of the population of grayling (Thymallus thymallus), which it entered as a result of increase in sport fishing. The data on time of presence of a population in equilibrium state allowed us to correctly unify the materials used for the analysis of changes in its age group.
Highlights
The ability to resist the external impact or return to the initial state after disturbance is an ability characteristic and necessary for all biological systems at all levels of the organization
The objective of this study was to generalise the experience of using dynamic phase portrait for analysis of populations of fish, revealing the possibilities of the method to reveal additional information about biochanges in them
Relative number of grayling (Thymallus thymallus) was calculated as a value of caught fish per attempt, i.e. number of individuals caught in a standard net of 30 m length during 24 h (Boznak et al, 2019)
Summary
The ability to resist the external impact or return to the initial state after disturbance is an ability characteristic and necessary for all biological systems at all levels of the organization. The analysis of disturbances is an experimental tool which allows one to determine how a complex system functions, because at that time the capabilities of separate elements as well as connections between them manifest more clearly (Begon et al, 1986; Clarke & Warwick, 1998). It is important to note that changes in characteristics of populations occur over a certain time due to consequent alterations. Its reaction to external factors to a large extent depends on inertia (Romanovsky et al, 1975), and is related to complex dynamic systems (Antamonov, 1977). One of effective methods of analyzing such a system is the survey of its dynamic phase portrait (Vol’kenshtein, 1978)
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