Anchor down or hunker down: an experimental study on zebra mussels' response to predation risk from crayfish
Predation cues influence the strength of byssal attachment in bivalves. In zebra mussels, Dreissena polymorpha, anchorage increases in response to nonforaging roach, Rutilus rutilus, but decreases in response to artificially crushed conspecifics, and it remains unaltered by nonforaging crayfish. Given that anchorage to hard substrata protects against dislodgement by predators, the defensive value of its weakening under predation threat is unclear. Our first experiment examined changes in the byssal attachment of zebra mussels in response to active predation by the spinycheek crayfish, Orconectes limosus. We found that zebra mussels decreased their attachment strength when exposed to cues released as crayfish foraged on conspecific mussels. Our second experiment tested whether crayfish have a capacity for chemosensory detection of live zebra mussels. We exposed hungry crayfish resting in shelters to water with or without cues from live mussels. The cues stimulated abandonment of shelters. Our results agree with recent findings that zebra mussels reduce filter feeding in response to predation cues that contain odours of crushed conspecifics. We suggest that this response helps zebra mussels to evade odour-navigating predators (e.g. crayfish) by suppressing the emission of disclosing metabolites, and that a consequence of this physiological suppression is a predator-mediated decrease in byssal attachment.
|Publication Title||Animal Behaviour|
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