Laboratories: Laboratory for Behaviour of Lower Vertebrates: Goals and Tasks

LABORATORY FOR BEHAVIOUR OF LOWER VERTEBRATES

Headed by Professor D.S. Pavlov, Dr. Biol. Sci, Academician of the Russian Academy of Sciences

tel. (495)-952-20-88

Tver Floating Biological Station

MAIN GOALS AND TASKS

The head of Laboratory
D.S. Pavlov

Professor B.P. Manteifel

The fundamental studies in the field of the theory of fish migrations in inland waters, anti-predator and foraging relationships among aquatic animals, ecological role of the physical habitat heterogeneity, ethological organization of communities, electroreception and electrocommunication in electric fishes have got further development.

On the basis of long-term studies of fish downstream migrations from the reservoirs with slowed water exchange, the main patterns and mechanisms of the migrations were discovered. A complex factor - ecological zone of water intake, controlling most of the characteristics of downstream migrations, was revealed. A mathematical model that allows to estimate the portion of fish which migrate downstream from the total number of fish in a reservoir with slowed water exchange was developed and tested. On the basis of this approach a methodology of protection of migrant and resident fish species passing through the dams was developed.

The phenomenon of physiological, biochemical and behavioral differentiation was described for juveniles of non-migratory fishes (Cyprinids and Percids), caracterized by formation of two phenotypical groups with different strategies of their dispersion. This differentiation was firstly observed during early embryogenesis and terminated at the stage of the late larvae. It was induced by the effect of metabolites of the neighboring eggs on embryos in the clutch. In the period of early larvae this differentiation is expressed in their migratory behavior. Phenotypical group of migrants bringing about the strategy of downstream migration, while residents stay within the native habitat.

Three types of downstream migration were revealed - non-motivated downstream migration (which was typical of early larvae), motivated downstream migration (which was expressed in the period of early larvae) and externally motivated downstream migration (which played the primary role in late larvae and juveniles of the older age groups). Morphological, physiological, biochemical and behavioral mechanisms of realization of the first two types of migration were found. It was shown that appearance of behavioral differentiation (motor activity, trophic reactions, response on stressors etc.) in overwintered juveniles of salmon could start at the age of 13 months, and first of all influence, on, functional activity of monoaminoergic structures of fish brain. Further on, these differences in progeny became deeper; one part of juveniles after parr smolt transformation migrated to the sea, while the other one remained in the river.

Electrical discharges of the cat-fishes Synodontis shall, registered for the first time in their habitats

The concept of trophic relations in fishes in heterogenous habitats was formulated taking into account conflicting demands of feeding, antipredator, exploratory activities and social interactions. Such important aspects of habitats heterogeneity as visual structuring and aggregated prey distribution allowed fish to use the space non-randomly, i.e. selectively. Selectivity is expressed as an uneven distribution of time/efforts at exploration, feeding, and defense. The important role of physical heterogeneity and stability of environment in the main components of feeding behavior of fishes, searching, selection and consumption, was shown. The main traits of fish behavior and their parasites, controling interactions within the " host-parasite " system were revealed. It was shown that efficiency of defensive behavior of fish against parasites increased when fish form a shoal.

A concept of fish behavior in hydraulically heterogenous environment was developed. The main parameters of heterogeneity such as: average flow velocity, turbulence of the flow and hydrostatic pressure influence on elementary reactions and complex forms of fish behavior. These characteristics determine the choice of optimal hydrodynamic conditions by fishes. The role of hydraulic heterogeneity of environment in migratory, reproduction, feeding, searching behavior, as well as in fish distribution was studied.

The results of studies with hydroacoustic techniques showed extremely high fish concentration in one of the riverbed depressions of the Irtysh River (Gornoslinkinskaya riverbed depression). Local dense fish aggregations of different age and species composition were observed there through the whole year. It did not depend on diel and seasonal variations of fish abundance, changes of size and species composition, and patterns of spatial distribution. The obtained materials radically changed a traditional knowledge about the presence of fish aggregations in riverbed depressions only in winter. In ecological aspects, the riverbed depressions should be considered as multifunctional habitats, playing marked role in juveniles foraging and migrations of breeders. A local strategy of bioresource conservation in the key habitats of the Ob-Irtysh basin was suggested.

The abilities of specialized generation of electric signals in fishes of several, previously unknown taxonomical groups were revealed and studied. In fishes of the order of Siluriformes, the electric discharges were registered for the first time both under laboratory experimental conditions and in the field. Electrosensory neurons were found in the central nervous system of these fishes. Their neurophysiological characteristics were co-evolutionary adapted to reception of weak, species-specific electric signals. The study of electroorientational systems of fishes allowed to develop theoretical basis and design technical means of new generation for underwater location, orientation and communication on galvanic currents.

Previously unknown element of biparental care in cihlids fishes, supply of the juveniles with feed by stirring-up the substrate, was revealed. A hypothesis of evolutionary development of this form of parental behavior was suggested. An interplay of temperament (stable individual differences in behavior) of the fishes with peculiarities of their parental behavior was studied.