Anomalies of the Axial Skeleton in Juvenile Leuciscid Fish (Leuciscidae) of Saratov Reservoir

Data on the diversity and occurrence of anomalies in the development of the axial skeleton are presented for juveniles of six cyprinid fish species of Saratov Reservoir: roach (Rutilus rutilus Linnaeus, 1758), bleak (Alburnus alburnus Linnaeus, 1758), ide (Leuciscus idus Linnaeus, 1758), bream (Abramis brama Linnaeus, 1758), rudd (Scardinius erythrophthalmus Linnaeus, 1758), and white bream (Blicca bjoerkna Linnaeus, 1758). In total, 4 main types of axial skeletal abnormalities of varying severity and localization were diagnosed: scoliosis, lordosis, kyphosis, and underdevelopment of the caudal spine. The proportion of individuals with spinal disorders ranged from 0.5% in bream to 2.3% in bleak. The proportion of axial skeletal anomalies among other detected disorders ranged from 2.0% in bream to 9.9% in bleak, while the total proportion of abnormal individuals in the studied samples varied from 23.4 to 38.4%. There is a tendency of increasing the frequency of occurrence of axial skeleton anomalies in juvenile of the Saratov Reservoir with an increase of the anthropogenic load at different stations of the Reservoir.