West Coast
Pelagic red crabs, normally found in warm waters off Mexico, began washing up on beaches in California in 2015. [Photo: Kevin Sullivan/Digital First Media/Orange County Register/Getty Images]

CA - How warming West Coast waters changed the marine ecosystem

The shifts in temperature and species can provide lessons for how fluctuating temperatures might change ecosystems.

Land–based heatwaves have a less obvious though equally important sibling: marine heatwaves. In 2013, the largest marine heatwave on record began when an unusually warm mass of water formed in the Gulf of Alaska. By the next summer, the warm water spread south, raising average water temperatures along the United States west coast by 3.6 to 7.2 degrees Fahrenheit (2-4 Celsius). In 2015, a strong El Niño event strengthened the marine heatwavefurther.

And so “the Blob,” as oceanographers have dubbed this huge body of warm water, was born.

This satellite image from fall 2014 shows the beginnings of the Blob, where red colors represent unusually warm water temperatures. [Image: NOAA/Wikimedia Commons]

Interestingly, a number of species moved northward to places along the west coast of the U.S. where the water had previously been too cold for them.

We are a marine evolutionary biologist and a marine ecologist, and are currently studying these recent arrivals to the northern California coast. Through our work, we hope to understand what has allowed species to not only move with the Blob, but persist after the water cooled.

WITH WARM WATER CAME NEW SPECIES

The Blob changed weather as well as ocean currents, led to the deaths of thousands of marine mammals and birds, and caused harmful algal blooms. Animals also moved during the years of warm water with the Blob. Species that usually live in more southern, warmer waters expanded their ranges into northern California and Oregon.

Pelagic red crabs, usually found off the Baja California peninsula, washed up by the hundreds on beaches north of San Francisco. Keen naturalists were surprised to find that populations of bright green sunburst anenomes, giant owl limpets and pink volcano barnacleshad in some places increased by the hundreds. Ecologists even discovered a new population of angular unicorn snails over 150 miles north of their original range edge.

The Blob was not destined to last forever. It eventually faded away and water temperatures returned to normal.

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