Native predator chemical cues induce anti-predation behaviors in an invasive marine bivalve

The ability of non-native prey to detect native predators and respond with effective anti-predation behaviors may be an important factor mediating invasion success and biotic resistance. However, our current understanding of how native predator cues influence invasive prey is greatly limited. In estuaries and coastal seas-among the most heavily invaded ecosystems-olfaction of chemical cues is a primary mechanism by which sessile and sedentary organisms evaluate predation risk. We tested the hypothesis that chemical cues from a suite of predators native to southern California, USA, estuaries induce anti-predation behaviors in an invasive bivalve, the Asian nest mussel Arcuatula senhousia. In a laboratory experiment, we manipulated chemical cues from injured conspecifics and a functionally and taxonomically diverse group of native predators that may represent important agents of biotic resistance. We then measured several potential anti-predation behaviors that may be key to Arcuatula survival due to its modest structural defenses. As predicted, Arcuatula changed behaviors in response to cues from predators and injured conspecifics. Interestingly, however, Arcuatula was able to discriminate among cues from different native predators: mussels fed less when exposed to cues from snails and stingrays, burrowed deeper in the presence of cues from injured conspecifics and lobsters, and increased aggregation in response to snail cues. Our findings demonstrate that native predators can induce potentially-defensive behavioral changes in an invasive marine bivalve. The ability for Arcuatula to detect and selectively respond to novel predators may play a role in their invasion success in southern California and other regions globally.