Behaviorally Mediated Indirect Interactions in Marine Communities and Their Conservation Implications

The importance of density-mediated indirect effects (e.g., keystone predators) in marine communities has been widely recognized. Behaviorally mediated indirect interactions (BMIIs) may be equally important in marine systems, but have received relatively little attention. BMIIs occur when a change in an “initiator” species causes a behavioral shift in a “transmitter” species that, in turn, affects a “receiver” species. BMIIs between initiator and receiver species can be described by the ecological relationships between initiator and transmitter, and between transmitter and receiver (i.e., predator and prey, competitors, or no relationship), and the nature of the indirect effect on the receiver (i.e., positive or negative). We review published examples of BMIIs in marine communities, showing that BMIIs may create, enhance, ameliorate, or even reverse the sign of the direct interactions between species. Models that only include direct interactions or density-mediated indirect ones cannot predict some of these effects. BMIIs are likely to be ubiquitous in marine communities and have important implications for both understanding community dynamics and managing these systems. A thorough understanding of BMIIs is particularly important for conservation and management, as humans may play the role of an initiator, transmitter, or receiver of these effects in a variety of marine communities. Corresponding Editor: F. R. Adler. For reprints of this Special Feature, see footnote 1, p. 1081.