Influence of pollution on fish reproduction in the southern waters of Lake Ladoga

Abstract

The southern waters of Lake Ladoga have important fishery significance - as a place for spawning, feeding and fishing. The hydrological features of this water area, combined with the location of sources of pollution, contributed to the creation of an increased level of anthropogenic load - massive toxicosis of fish and disruption of the process of natural reproduction, which was noted in the eighties of the last century.  The period of early ontogenesis of fish is the most sensitive in the life cycle of fish, and this especially affects salmon and whitefish, which are especially sensitive to anthropogenic impacts, including toxicological factors. As studies have shown, the impact of pollutants has also had a negative impact on other fish species whose spawning grounds are located in this water area. Recent ichthyopathological studies of fish in this water area, which includes three bays: Shlisselburgskaya, Volkhovskaya and Svirskaya, showed massive damage to fish by toxicosis, which prompted a study of early juvenile fish in the littoral areas of the bays. It was shown that in the surveyed water areas from 30 to 70% of early juveniles (larvae, fry) are affected by toxicosis with visual manifestations of the pathological process in the bone tissue, visual, circulatory system, etc. Typical anomalies are craniofacial defects, spinal anomalies, eye defects, of cardio-vascular system. It has been shown that the bone, circulatory, and visual systems are very sensitive to the effects of toxicants in the early stages. Population reproduction is an integral expression of the influence of the combined action of environmental factors and the fish organism itself. The results of the studies showed a pronounced disruption of the natural reproduction of fish, which negatively affects the productivity of the reservoir. Preventive measures for fish reproduction are associated with the reclamation of polluted spawning grounds and factory reproduction of valuable fish species. Typical anomalies are craniofacial defects, spinal anomalies, eye defects, and cardiovascular system defects. It has been shown that the bone, circulatory, and visual systems are very sensitive to the effects of toxicants in the early stages. Population reproduction is an integral expression of the influence of the combined action of environmental factors and the fish organism itself.