Biophysical ecosystem variation shapes oceanic predator communication

William K Oestreich , Kelly J Benoit-Bird, Chad M Waluk, John P Ryan

Social information is predicted to be most valuable to consumers when they pursue patchy, ephemeral resources. Such resource dynamics emerge from coupling of physical and biological processes in the pelagic ocean. Integrating these paradigms from behavioral ecology and oceanography motivates the hypothesis that physical oceanographic forcing shapes resource distribution, which in turn alters oceanic consumers’ production of social information. We tested these hypothesized physical-biological-social links using integrated observations of blue whale communication, the distribution of their krill prey, and physical oceanographic forcing in their foraging habitat. Physical forcing modulated both prey distribution and predator communication across nested temporal scales. Interannually, stronger upwelling led to greater krill abundance and more frequent detection of blue whales’ foraging-associated type D calls. At finer temporal scale, stronger upwelling produced denser krill swarms and heightened production of blue whale D calls. Blue whales’ widely propagating D calls correlate with high-quality foraging conditions and thus represent valuable social information for predators searching for patchy, ephemeral krill swarms in this vast, dynamic oceanic habitat. More broadly, these findings demonstrate that physical oceanographic forcing shapes predator communication by modulating the distribution of prey, providing insight into the biophysical drivers of social information use in Earth’s largest living space.