Radioactive contamination causes only minor effect on fluctuating asymmetry of two fish species from the Chernobyl area

Abstract

Summary The western part of the Bryansk region (Russia) was seriously contaminated with radioactive isotopes by the Chernobyl disaster in 1986. Contamination level of this area is similar to contaminated regions in Ukraine and Belarus. We studied the fluctuating asymmetry of two cyprinid species, roach Rutilus rutilus and bleak Alburnus alburnus, to assess the effect of radioactive contamination on developmental stability. Fluctuating asymmetry represents random deviations from perfect, usually bilateral symmetry, and is often used to assess developmental stability. Fish were collected in summer 1992 from the Desna and Iput rivers of the Bryansk region with similar hydrological characteristics but with differing levels of radioactive contamination. Contamination in the Desna River exceeded the background level of non-contaminated areas, but was considerably lower than in the Iput River. Roach were 3–5 years old and bleak 1–2 years old. In total, 78 specimens were analyzed, with 13 roach and 26 bleak from each location. We examined 39 meristic and 18 morphometric characters in cranial bones of roach and 23 meristic and 13 morphometric characters in bleak. No significant differences in meristic or morphometric characters were found between roach from the contaminated and reference locations. In bleak, we found significantly higher fluctuating asymmetry in meristic (P test, P < 0.05), but no differences in morphometric characters.