Abnormalities and Bilateral Asymmetry of Otoliths in Arctic Charr Salvelinus alpinus Complex (Salmonidae) from Lakes Lama and Kapchuk, Taimyr

Abstract

Otolith abnormalities and bilateral asymmetry are analyzed in five reproductively isolated forms and natural F1 hybrids between the forms in Arctic charr Salvelinus alpinus complex from lakes Lama and Kapchuk (Norilo-Pyasinskaya water system, Taimyr). Otolith abnormalities are associated with the partial replacement of aragonite (the usual otolithic polymorph of CaCO₃) by vaterite (another less stable crystalline modification of CaCO₃) and their unusual shape. The abnormalities are observed in 11.9% of the specimens and may be induced by technogenic pollution from Nornickel, the world’s largest manufacturer of palladium, nickel, and platinum. The assessment of bilateral asymmetry based on otolith measurements and shape indices does not indicate notable differences in this parameter between the charr forms. However, the shapes of the left and right otoliths described by wavelet analysis are significantly different in two groups: a form of Lake Kapchuk designated as the main form and F1 hybrids. The differentiation of the forms is evaluated using wavelet and linear discriminant analyses of otolith shape. The difference in the topologies of two dendrograms constructed based on the shapes of the left and right otoliths obtained from the same specimens can be explained by the occurrence of bilateral asymmetry.