Data from: Predator-free space, functional responses and biological invasions

Predator-prey interactions are mediated by the structural complexity of
habitats, but disentangling the many facets of structure that contribute
to this mediation remains elusive. In a world replete with altered
landscapes and biological invasions, determining how structure mediates
the interactions between predators and novel prey will contribute to our
understanding of invasions and predator-prey dynamics in general. Here,
using simplified experimental arenas, we manipulate predator-free space,
whilst holding surface area and volume constant, to quantify the effects
on predator-prey interactions between two resident gammarid predators and
an invasive prey, the Ponto-Caspian corophiid Chelicorophium curvispinum.
Systematically increasing predator-free space alters the functional
responses (the relationship between prey density and consumption rate) of
the amphipod predators by reducing attack rates and lengthening handling
times. Crucially, functional response shape also changes subtly from
destabilising Type II towards stabilising Type III, such that small
increases in predator-free space to result in significant reductions in
prey consumption at low prey densities. Habitats with superficially
similar structural complexity can have considerably divergent consequences
for prey population stability in general and, particularly, for invasive
prey establishing at low densities in novel habitats.