Extreme storms can limit the expansion of the invasive species Caulerpa cylindracea in the rocky shore.

Abstract

Abstract Invasive species constitute a major environmental concern worldwide and extreme events, favoured by climate change, are expected to enhance their invasibility, however more scientific evidence is needed to better understand this interaction. We tested manipulatively in the rocky shore how the invasibility of the alga Caulerpa cylindracea, one of the most deleterious exotic species worldwide, was affected as storms become more extreme. We found that low intensity storms with a high frequency enhanced the invasibility of C. cylindracea, while extreme storms, limited the invasibility of this alga. These effects did not only occur on the short-term, but also after several months after the disturbance, suggesting legacy effects. C. cylindracea having a low attachment capacity is expected to need other canopy-forming algae to facilitate its attachment to the substrate, while large bare rock patches may leave C. cylindracea too exposed to the wave effect on rocky shores hindering its survival in this habitat. This study suggests that extreme events do not necessarily enhance the invasibility of exotic species and can have contrasting effects depending on the habitat. Thus, the effects of extreme events on the invasibility of exotic species needs to be particularly studied in different habitats, so optimized management strategies can be adapted to each habitat in pursuit to mitigate as much as possible the effects of climate change.