Experiment on Prey-Switch of Hemigrapsus takanoi towards a native and non-native gammarid species

We conducted two experiments to assess the predation of female H. takanoi (a non-native species in the Baltic) on a native gammarid (Gammarus duebeni) and a non-native analogous gammarid (Gammarus tigrinus). The experiments were conducted at the GEOMAR Helmholtz Centre for Ocean Research Kiel. Crabs were sampled in the innermost part of the Kiel Fjord, Germany (59°19'44N, 10°08'55.5E) during the summer of 2021. This experiment covered a prey-switching trial where both prey species were offered simultaneously in varying densities (2:14, 4:12, 6:10, 8:8, 10:6, 12:4, 14:2; n = 6 replicates per ratio); once again, the amount of consumed prey per species was assessed after 6 hours of feeding by H. takanoi. All remaining parameters were the same as described for Experiment No. 1.