Density and temperature dependent feeding rates in an established and an alien freshwater gammarid fed on chironomid larvae

Abstract

We compared feeding rates of the well-established, non-invasive amphipod Gammarus roeselii with those of the invasive

Size matters: predation of fish eggs and larvae by native and invasive amphipods

“…The generally positive association between size and resource consumption is in accord with previous empirical work with amphipods (Maier et al 2011;Dodd et al 2014) and, given the predator-prey body size ratios in the present experiment, more general theoretical work (Brose 2010;Rall et al 2012). Metabolic rate scales positively with size (Kleiber 1932).…”

“…We also predict larger D. villosus will consume more food than the smaller amphipods in both FR and electivity experiments (Woodward et al 2005;Maier et al 2011;Rall et al 2012). In electivity experiments, we predict that D. villosus will show a stronger tendency than G. pulex to consume fish eggs and larvae given the known predatory tendencies of the invader (e.g.…”

“…We conducted our experiments in temperatures around which trout (7°C) and carp (14°C) eggs develop in the field (Alabaster and Lloyd 1982). As ectotherms, amphipod metabolism and activityincluding predation-will likely be reduced at lower temperatures (Sutcliffe et al 1981;van der Velde et al 2009;Maier et al 2011). Low per capita predation rates on trout larvae do not negate the potential for substantial mortality in the field, however.…”

“…Temperatures were within the range at which both amphipod species will feed (Sutcliffe et al 1981;van der Velde et al 2009;Maier et al 2011). Each amphipod was allowed to feed for a set period: 24 h on carp eggs or larvae, or 48 h on trout because preliminary experiments indicated that predation rates on trout were much lower.…”

Dynamics and population structure of native Echinogammarus stammeri (Karaman, 1931) (Crustacea: Amphipoda) and non-native Gammarus roeselii Gervais, 1835 (Crustacea: Amphipoda) occurring in sympatry in Northern Italy

“…The diet plasticity of gammarids is one of the main reasons for their success in colonising various types of freshwater habitats (Mayer et al 2009;Maier et al 2011); moreover, their high reproductive capacity guarantees a rapid adaptation to environmental changes (Bruijs et al 2001;Wijnhoven et al 2003). These traits amongst others, such as high tolerance for salinity, temperature and oxygen deficit, or efficient self-defence mechanisms against novel predators, have allowed gammarids to become one of the most successful invaders in freshwater ecosystems (Hesselschwerdt et al 2008;Stoffels et al 2011).…”