Trophic Specialization of Sympatric Forms of Dolly Varden Salvelinus malma (Salmonidae) from Lake Azabachye, Kamchatka.

The sympatric complex of the northern Dolly Varden Salvelinus malma from the basin of Lake Azabachye is represented by four forms with a narrow long-term trophic specialization. Lake–river predators feed mainly on three-spined stickleback Gasterosteus aculeatus. Lake–river benthivorous are differentiated into two trophic groups; one of them (group G) feeds on amphipods and the other (group A) consumes mollusks (Mollusca) and caddis fly larvae (Trichoptera). Brook chars feed on amphibiotic insects (Insecta). The long-term food segregation of Dolly Varden forms is confirmed by differences in the degree of infection by parasites and in the ratios of stable isotopes, ¹⁵N/¹⁴N and ¹³C/¹²C, in the muscles. The indicator parasites are Eubothrium salvelini and Dibothriocephalus spp. for lake–river predators, Cystidicola farionis and Crepidostomum metoecus for lake–river benthivorous of group G, Diplostomum spp. for lake–river benthivorous of group A, and Salmonema ephemeridarum and Cucullanus truttae for brook chars. Predators and benthivorous of group G are characterized by high values of the ¹⁵N/¹⁴N ratio in the muscles, benthivorous of group A by high ¹³C/¹²C values, and brook chars by low values of ¹⁵N/¹⁴N and ¹³C/¹²C. Lake–river predators and benthivorous live together and are distributed throughout the lake and lake channel; brook chars inhabit tributaries. The sympatric complex of S. malma in the basin of Lake Azabachye is the second most diverse complex after the char complex in Lake Kronotskoe. [ABSTRACT FROM AUTHOR]