Historical and Potential Future Importance of Marine Megafauna Subsidies to Terrestrial Ecosystems

Francis David Gerraty , Charles A Braman, Jenifer E. Dugan, Kathleen Elder, Kyle A. Emery, Benjamin S. Halpern, Walter N. Heady, Elizabeth H.T. Hiroyasu, Grace B. Lewin, Erica S. Nielsen, Ruth Y. Oliver, Mark Reynolds, Alex Wegmann, Raimy C. Williams, Rae Wynn-Grant, Hillary S. Young, Zoe L. Zilz

Marine megafauna exert tremendous influence on the structure and function of ocean ecosystems, yet mounting evidence shows that their ecological impacts also cross the land-sea interface and modify terrestrial ecosystem dynamics. Marine megafauna connect land and sea by serving as large, calorically-rich food sources for terrestrial consumers and by transferring marine-derived nutrients onto land as carrion, eggs, placentas, and excreta. We synthesize empirical studies from around the world to characterize the broad suite of terrestrial consumers that exploit marine megafauna as food and the ecological impacts arising from these cross-ecosystem resource subsidies. We identified 224 megafauna-consumer species pairs and diverse ecological effects impacting terrestrial consumers, populations, communities, and ecosystems. Given that commercial exploitation has decimated marine megafauna populations globally, land-sea linkages once mediated by these animals have declined from historical periods to the present day, yet megafauna recoveries hold potential to restore these marine-terrestrial connections and reshape coastal ecosystem dynamics.