The effect of chronic volcanic pollution on the morphometric characteristics of juvenile Dolly Varden (Salvelinus malma W.) on the Kamchatka peninsula

Abstract

Salmon rivers that flow from volcanoes on the Kamchatka Peninsula are subjected to chronic pollution by mineral suspensions and dissolved metals. We analyzed the impact of chronic pollution on the body morphology of Dolly Varden parr using linear measurements and geometric morphometrics. Populations from different rivers demonstrated differences in morphology, although our results suggest that contamination is not responsible for the formation of any specific morphological features. The anadromous juveniles from polluted streams are characterized by high variability in external morphology, expressed in the increased standard deviation and coefficient of variation in distributions of morphometric traits. Mean standard deviation of the trait distributions in the samples from polluted rivers is significantly higher than in samples from streams not subjected to volcanic pollution. The increase of morphometric variability occurs gradually with fish age and affects a complex of characters, including the position of fins and their length. Isolation of Dolly Varden in polluted streams has other consequences for external morphology. The landlocked populations are characterized by channelization of the development and acquire novel morphologic features, which are reflected in peculiar values of some morphometric traits (especially upper jaw length and position of dorsal fin) together with reduced dispersion in these traits.