Intraspecific variation in a marine predator shapes community diversity by altering habitat structure

Gina M. Contolini, Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA; California Sea Grant, Eureka, CA and Eric P. Palkovacs, Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA

Background/Question/Methods
Intraspecific variation is an important form of biodiversity that can alter community and ecosystem properties. While recent work shows the ecological importance of population-level trait variation in freshwater ecosystems, debate exists about its importance in marine ecosystems; marine populations are traditionally viewed as open and highly connected, preventing strong local trait differentiation. Here we test the hypothesis that intraspecific foraging differences among populations of mussel-drilling dogwhelks differentially alter intertidal communities by reshaping mussel bed structure. We conducted a nine-month field experiment in which we exposed intertidal mussel communities to predation from three different dogwhelk predator populations. At the end of the experiment, we measured mussel bed structure, species diversity, and community composition.
Results/Conclusions
We found that dogwhelks from the different populations consumed different sizes of mussels, thereby differentially altering mussel bed structure. This change in habitat structure, in turn, reshaped the diversity and abundance of algae, grazers, scavengers, and detritivores within the mussel bed. Our results extend the ecological importance of predator intraspecific variation into marine ecosystems.