Mass die-offs of sea lion pups are tied to malnutrition — High Country News – Colorado News

Mass die-offs of sea lion pups are tied to malnutrition — High Country News – Colorado News

The effects of warming ocean waters are rippling through marine ecosystems.

 

This story was originally published by Hakai Magazine, and is reproduced here with permission.

Meteorologists had never seen anything quite like it — a mass of abnormally warm surface water that overwhelmed much of the northeastern Pacific Ocean for three years starting in late 2013. They called it the Blob.

Within months, thousands of starving sea lion pups began washing ashore along the west coast of the United States.

At the time, scientists figured the two occurrences were related. But in a new study, a team of researchers describes in detail how warm water and related impacts on ocean productivity hurt the young sea lions.

Scientists believe the Blob began to form in the Gulf of Alaska after the winds that drive the upwelling of nutrient-rich cold water from the seafloor to the surface weakened or died, allowing surface water to grow unusually warm and slowing the production of phytoplankton. At the same time, farther south, El Niño was disrupting ocean circulation. The resulting masses of warm, nutrient-poor water being formed in the north and south joined up, and the so-called Blob settled in for a three-year stay off the coast of California.


A California sea lion basks in the sun at La Jolla Cove, California.

Mick Thompson/Flickr

The Blob hit the sea lions when reduced primary production sent forage fish, such as anchovies and sardines, elsewhere, says study coauthor Karina Acevedo-Whitehouse, a disease ecologist at the Autonomous University of Queretaro in Mexico.

Without their usual prey, hungry sea lions turned to…

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