Interspecific Interactions of Amphipods Gammarus lacustris
and Gmelinoides fasciatus

N. A. Berezina

Zoological Institute, Russian Academy of Sciences, Universitetskaya nab. 1, St. Petersburg, 199034 Russia;

e-mail: nber@zin.ru

Received January 10, 2007

Abstract—Experimental studies of interactions between two amphipod species (Gmelinoides fasciatus and
Gammarus lacustris) showed that predation is the basic mechanism accounting for their mutual exclusion in
nature. Mortality from predation among similar-sized specimens of both species at an equal abundance ratio
was similar (24–25% in G. lacustris and 27–30% in G. fasciatus). The displacement of G. lacustris by G. fas-
ciatus was observed when the latter was dominant. Adult G. fasciatus and G. lacustris successfully preyed on
juveniles of their competitors and did not differ significantly in daily food consumption as a percentage of body
weight: 6–24% at a fresh body weight of 18–24 mg in both species. The potential for rapid population growth
under new conditions contributed to the success of the invasive Baikal species G. fasciatus in displacing
G.lacustris from many water bodies of Russia.

DOI: 10.1134/S1067413609020027

Key words: amphipods, interspecific interactions, predation, competition, diets, introduced species.

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