Anemonefish personalities influence the strength of mutualistic interactions with host sea anemones

Abstract

The anemone–anemonefish mutualism is one of the most iconic marine mutualisms. For decades, anemonefishes have been known to protect anemones from predators, while anemones provide safe havens for anemonefishes. More recently, it has been suggested that the number of anemonefish influences the survival, growth, and asexual reproduction of anemones. Here, we build on those findings, investigating the effect of four variables (fish number, fish biomass, fish shyness, and anemone colony area), on anemone growth and asexual reproduction. The interaction between Amphiprion percula and Entacmaea quadricolor was used as a tractable system in a controlled aquarium setting. Fish and anemones were monitored in 60 tanks for 18 months, and we recorded all variables at 6-month intervals. We performed single-measure analyses and found that fish shyness, defined as the time spent in the vicinity of the anemone, significantly predicts anemone growth over the entire experiment. Further, we performed repeated-measure analyses and found that both fish shyness and initial anemone colony area significantly predict anemone growth per time period. These data suggest that behavioral variation among individual fish may be an important driver of anemone growth. More generally, this study highlights the importance of behavioral traits in mediating the strength of interspecific interactions such as mutualisms and suggests that such effects should be accounted for when investigating the dynamics of interacting populations.