Sea Ducks Rode Out the Pacific Marine Heatwave Because Their Prey Did

The Pacific marine heatwave of 2014–2016 was an intense, long-lasting disturbance across the North Pacific. Marine mammals and seabirds that depend on open-water prey such as forage fish declined on a large scale — in many cases for years afterward — most likely because those fish became scarce.

But not every species suffered. A study of birds that feed on the seafloor found them largely unharmed.

The study

From 2006 to 2022, researchers surveyed marine birds along the coast in summer and winter in two national parks in the northern Gulf of Alaska. They tracked benthivorous birds — those that eat bottom-dwelling invertebrates, mainly sea ducks and shorebirds — accounting for season and region. They also measured how much of that invertebrate prey was available.

What they found

Why it matters

The results support the idea that each predator's fate in the heatwave depended on what happened to its prey. Where the food web ran through forage fish, predators crashed; where it ran through seafloor invertebrates — part of the nearshore web built on seaweed (macroalgae) — predators held on.

Knowing which species are vulnerable to which kinds of disturbance matters more as marine heatwaves and other human-caused stresses are expected to become more frequent.

Sources

Based on "The Pacific marine heatwave did not impact all marine bird species equally," National Park Service, summarizing B. Robinson, H. A. Coletti, B. Ballachey, J. L. Bodkin, K. Kloecker, S. B. Traiger and D. Esler (2023), "Lack of strong responses to the Pacific marine heatwave by benthivorous marine birds…"; a work of the United States government in the public domain.