title: Metabolic activity and behavior of the invasive amphipod Dikerogammarus villosus and two common Central European gammarid species (Gammarus fossarum, Gammarus roeselii): Low metabolic rates may favor the invader.
abstract: The Ponto-Caspian amphipod Dikerogammarus villosus is one of the most successful invaders in Central European rivers. Contrary to studies on its ecology, ecophysiological studies comparing the species' physiological traits are scarce. In this context, in particular the metabolic activity of the invasive species has rarely been considered and, moreover, the few existing studies on this species report strongly deviating results. The purpose of this study was to assess the metabolic activity and behavior of D. villosus and other common European amphipod species (Gammarus fossarum, Gammarus roeselii) in relation to temperatures covering the thermal regime of the invaded habitats. Based on direct calorimetric measurements of metabolic heat dissipation at three temperature levels (5°C, 15°C and 25°C), we found the routine metabolic rate of D. villosus to be significantly lower than that of the other studied gammarid species at the medium temperature level. The estimated resting metabolic rate indicated a similar trend. At 5°C and 25°C, both routine and resting metabolic rate did not differ between species. Compared to G. fossarum and G. roeselii, D. villosus exhibited lower locomotor activity at the low and medium temperatures (5°C and 15°C). In contrast, its locomotor activity increased at the high experimental temperature (25°C). G. fossarum and G. roeselii were apparently more active than D. villosus at all studied temperatures. We conclude that D. villosus has both physiological and behavioral adaptations that lead to a reduction in metabolic energy expenditure, which is assumed to be beneficial and might contribute to its invasive success.
authors.affiliation: Department of Biology, Institute of Integrated Natural Sciences, University Koblenz-Landau, Universitätsstrasse 1, 56070 Koblenz, Germany; Department of Animal Ecology, Federal Institute of Hydrology, Am Mainzer Tor 1, 56068 Koblenz, Germany. Electronic address: jochenbecker@uni-koblenz.de.
authors.forename: Jochen
authors.initials: J
authors.lastname: Becker
authors.affiliation: TA Instruments, Helfmann Park 10, 65760 Eschborn, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Ortmann
authors.affiliation: Department of Biology, Institute of Integrated Natural Sciences, University Koblenz-Landau, Universitätsstrasse 1, 56070 Koblenz, Germany; Department of Animal Ecology, Federal Institute of Hydrology, Am Mainzer Tor 1, 56068 Koblenz, Germany.
authors.forename: Markus A
authors.initials: MA
authors.lastname: Wetzel
authors.affiliation: Department of Biology, Institute of Integrated Natural Sciences, University Koblenz-Landau, Universitätsstrasse 1, 56070 Koblenz, Germany; Department of Animal Ecology, Federal Institute of Hydrology, Am Mainzer Tor 1, 56068 Koblenz, Germany.
authors.forename: Jochen H E
authors.initials: JHE
authors.lastname: Koop
mesh_terms: D033304:Amphipoda / Q000378:metabolism* / Q000502:physiology*; D000818:Animals; D001481:Basal Metabolism / Q000502:physiology*; D002151:Calorimetry; D006003:Glycogen / Q000378:metabolism; D006358:Hot Temperature; D058865:Introduced Species; D011235:Predatory Behavior / Q000502:physiology*; D013045:Species Specificity; D014280:Triglycerides / Q000378:metabolism
chemical_list: D014280:Triglycerides; D006003:Glycogen
keywords: Dikerogammarus villosus; Gammarus fossarum; Gammarus roeselii; Glycogen; Heat production; Invasive species; Locomotor activity; Metabolic rate; Triglyceride