Important mesopredator restricts feeding in response to risk cues from a new invasive predator

Abstract

Invasive predators can alter community structure and dynamics in their invaded communities through direct consumption of prey and by inducing prey to alter traits, such as behavior or morphology, to avoid predation. These changes can modify the strength or even the direction of species interactions which can have cascading effects throughout a community. On rocky shores in the Gulf of Maine, an important mesopredator, the whelk Nucella lapillus, alters its feeding behavior when it detects waterborne chemical cues of a long-established invasive crab, Carcinus maenas, potentially impacting the abundance and distribution patterns of sessile species and energy flow through the food web. A more recent invasive crab, Hemigrapsus sanguineus, has become a dominant predator in the southern Gulf of Maine rocky intertidal, but our understanding of its impacts on community structure and dynamics remains incomplete. I examined whether chemical cues from Hemigrapsus alter the feeding behavior of Nucella to better understand how native fauna are responding to this relatively new invasive predator and its potential impacts on the community. Nucella exhibited a risk-induced change in feeding behavior by significantly reducing its feeding rate on blue mussels (Mytilus edulis) when Hemigrapsus cues were detected. These findings demonstrate the capacity for rapid behavioral responses to new invasive species and highlight the potential for such interactions to alter community structure and dynamics.