Morphological abnormalities in juveniles of common fish species in Koltsovo-Mordovinskaya floodplain of the Saratov reservoir

Ponds of the floodplain Koltsovo-Mordovinskaya of the Saratov reservoir are extensive spawning grounds for most common species of cyprinid fish (fam. Cyprinidae), the most numerous of which roach (Rutilus rutilus Linnaeus, 1758), ide (Leuciscus idus Linnaeus, 1758), bleak (Alburnus alburnus Linnaeus, 1758), silver bream (Blicca bjoerkna Linnaeus, 1758), common bream (Abramis brama Linnaeus, 1758) and rudd (Scardinius erythrophthalmus Linnaeus, 1758). However, over the past decades among larvae and fingerlings of fish, a high proportion of individuals with various morphological irregularities, which we attribute to contamination of the water reservoir as a major component of the complex influence of negative anthropogenic factors. Despite the relative remoteness from large settlements, the water - streams, floodplain lakes and large bays in this part of the Saratov reservoir are constantly experiencing some impact of negative factors with anthropogenic in nature. Embryonic and larval development stages of young fish are very sensitive to even minor exposure to sub-lethal concentrations of toxicants, adaptation processes over time is rapidly evolving into a pathological process, which causes various abnormalities of the morphology and the death of individuals. As a result, young fish from the study area throughout the study period found numerous morphological anomalies, which we attribute to the eight major groups, and greatly weakens the viability of individuals. A similar distribution of the discovered types and groups of morphological anomalies in fry of different mass species of fish of Koltsovo-Mordovinskaya floodplain indicates the nonspecific nature of these violations and the possibility of using this index as a biomarker of the morphological and physiological state of populations of different species of fish. The decrease to zero of the proportion of abnormal individuals among young fish with age, expressed in all the examined species, evidence of the lethal nature of all detected morphological violations. A large proportion of individuals with morphological anomalies among young fish of Koltsovo-Mordovinskaya floodplain associated with an increased level of complex pollution of the investigated area of the Saratov reservoir.