SoCal Heat Wave Sent Marine Life North, Study Finds

A Janolus Nudibranch (left) and a violet sea snail are pictured in Bodega Bay, Calif. A new study reports that dozens of warm-weather species of sea slugs, jellyfish and other marine life migrated into the northern California region over an unusually long two-year period of severe heatwaves. (Jacqueline Sones via AP)

(CN) – Two years of severe heatwaves drove dozens of marine species to Northern California from southern waters, a Tuesday study from researchers at UC-Davis shows.

Published in the journal Nature, the study attributes the unusually warm waters between 2014 and 2016 to two factors: a large warm-water anomaly in the Gulf of Alaska in 2013 that was spreading south, and a strong El Nino event on the equator that pushed warm water north in 2015. 

Of the 67 species in the report, including sea slugs, jellyfish and barnacles, 37 species set new traveling records in their migration north. 

Researchers observed an influx to Northern California of 21 primarily southern species such as the pelagic snail. 

While not all the species are choosing to stick around Northern California, the study showed that a species of sea slug that feeds on other sea slugs just may stay around.

More worrisome, the study suggests that these long-term heatwaves and new species moving in can have serious effects on the marine communities.

“Prolonged marine heatwaves and enhanced poleward dispersal may play an important role in longer-term shifts in the composition of coastal communities in northern California and other biogeographic transition zones,” the report says. 

Among other ecological disturbances within the California Large Marine Ecosystem during the heat wave, researchers found that a decline in subtidal kelp that in 2018 caused the shutdown of recreational abalone fishing. 

The report, which focused primarily on regions Pointe Reyes and Pointe Arena, noted that these observations are unprecedented, even though shifts like this are frequently associated with El Nino events.

The average water temperature in Northern California can range between 50 to 55 degrees Fahrenheit, increased up to 7 degrees Fahrenheit. 

The heatwaves are not so rare these days and should be studied accordingly, the study says. 

“Marine heatwaves have increased in frequency and duration over the past century, prompting calls for increased study of their ecological effects,” the report said. 

The report was written by Eric Sanford, Jacqueline Sones, Marisol Garcia-Reyes, Jeffrey H. R. Goddard and John L. Largier.

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