Does the invasive marine crab (Carcinus maenas) experience a novelty advantage across different intertidal communities?

Background/Question/Methods

Global redistribution of invasive species by human activity is increasingly bringing organisms into contact that have no shared evolutionary history. The capacity of native community members to recognize and respond to invasive predators with appropriate antipredator defenses can considerably influence the impact and success of an invasive species.  Antipredator defenses may take the form of morphological defenses or behavioral responses to waterborne predator cues.  Populations of native prey differ in their responses to invasive predators in the following ways: native prey may be unable to detect the invasive predator, native prey may detect the invasive predator regardless of previous experience, or the capacity to recognize the invasive predator may develop as an evolved or acquired trait.  In this study, we explored the above possibilities using the invasive, marine European green crab (Carcinus maenas).   Carcinus was introduced to Australia and eastern North America over 100 years ago.  Consequently, some populations of native, intertidal prey have been exposed to Carcinus for over 100 years and some populations of some have never experienced the crab (western Tasmania and Newfoundland). 

Results/Conclusions

In a series of laboratory experiments we found that native whelks collected from “experienced” and “naïve” populations reduced foraging in response to waterborne cues from Carcinus.  Thus, even whelks that shared no evolutionary history with Carcinus recognized the invasive crab’s waterborne cues.  However, native whelk populations did not consistently show induced morphological defenses (shell thickening) in responses to Carcinus.  These results suggest that Carcinus does not benefit from a “novelty advantage” in invaded communities.