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 when pursuing patchy, ephemeral resources. Such resource dynamics emerge from biophysical coupling in the pelagic ocean, suggesting links from physical forcing to resource distribution to consumers’ production of social information. We tested these hypothesized links using integrated observations of blue whale communication, distribution of their krill prey, and physical oceanographic forcing in their foraging habitat. Physical forcing modulated both prey availability and predator communication across nested temporal scales. Interannually, stronger upwelling led to greater krill abundance and elevated production of blue whales’ foraging-associated calls. At finer scale, episodic upwelling produced denser krill swarms and heightened production of foraging-associated calls. Blue whales’ widely propagating calls thus function as reliable social indicators of patch quality in their vast, dynamic pelagic habitat. These findings demonstrate that biophysical coupling in the ocean shapes predator communication and provide insight into the ecological drivers of social information use.