Gammarus aequicauda is the most abundant amphipod species in the Crimean hypersaline lakes, and is predatory upon other invertebrate species, suppressing their populations. The authors studied a time balance during the feeding of G. aequicauda in the presence of two prey species. The different variants of prey composition were: (1) two Artemia sp., (2) two chironomid larvae, and (3) one Artemia sp. and one chironomid larva. The duration of the experiments differed and continued until both prey were consumed. The experiments were carried out in vessels with and without bottom sediments. The result showed that in vessels with and without sediments in the case of both species of prey, the time to the capture of the first prey did not depend on whether Artemia sp. or chironomid larva was the first prey; the time differences are statistically insignificant. The duration of eating prey in all experimental variants depended on the kind of prey, and those differences were highly significant. The average hourly consumption rate was dependent on prey composition and order of prey capture and eating. The maximum consumption for two prey was when both were brine shrimp. In vessels without sediments and containing both Artemia sp. and chironomid larva the consumption rate was higher if the first caught prey was Artemia sp. rather than сhironomid larva. The order of prey eating did not influence a ration size in vessels with bottom sediments. When both prey were chironomid larvae, the total diet did not practically differ in vessels with or without sediments.
Keywords: Artemia; Gammarus aequicauda; chironomid larvae; feeding; time balance; trophic relation.
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