Changes in the seasonal cycle of the zebra mussel gonads during its expansion north

The ecological role of the zebra mussel is significant and diverse. It plays a significant role in the nutrition of many benthic-eating fish, as well as waterfowl. The settlement of the zebra mussel in the northern regions of Russia has affected the biology of water bodies and had a negative impact on the cooling system of electric and thermal power plants, including nuclear power plants (atomic power plants), etc., causing serious interference in their operation. In the world, a cheap and reliable method of combating this mollusk has not yet been found; mechanical and chemical methods are used. The effectiveness of measures against zebra mussels is currently clearly insufficient and is associated with mechanical and chemical methods. It is believed that there is a lack of a biological component, since the biology of this mollusk has not been sufficiently studied. The gonads of the zebra mussel from the Rybinsk reservoir and the cooling ponds of the Kalinin NPP were examined. The mollusks were collected in the autumn-winter period, when the reservoir was under ice, and the cooling ponds are not covered with ice due to the increased temperature regime. Histological methods were used. The mollusk was fixed in 10% formalin, the thickness of the paraffin sections was 7 μm, stained with iron hematoxylin according to Heidenheim. Studies on the study of the seasonal cycle of the gonads of the zebra mussel showed a change in the seasonal cycle of its gametogenesis in natural reservoirs, whereas with a change in the hydrological regime, which is typical for the cooling ponds of the Kalinin NPP, the seasonal cycle of gametogenesis turned out to be different. Evolution in the new northern homeland of the zebra mussel will go in the direction of growth, adaptation to the habitat. For this, after some time, their stage of post-spawning autumn depletion of the gonads will probably be restored. The time spent on this restoration will be quite long in duration.