Tropical Species Moved Hundreds of Miles North During Marine Heatwave

Species rarely or never seen in Northern California until the 2014-2016 marine heatwave.

Species rarely or never seen in Northern California until the 2014-2016 marine heatwave. Roger Harshaw, Eric Sanford, and Jacqueline Sones.

Between 2014 and 2016, parts of the eastern Pacific Ocean warmed as much as 7 degrees Fahrenheit above average during what has been characterized as the worst marine heatwave on record. During the event, scientists began discovering a record number of tropical sea species along the northern California and Oregon coasts, more than 700 miles north of their usual range.

The scientists published their findings this week in the journal Scientific Reports, reporting that of 67 rare, warm-water species found by University of California, Davis researchers and citizen scientists, 37 had never been documented so far north. “It’s perhaps a glimpse of what Northern California’s coast might look like in the future as ocean temperatures continue to warm,” UC Davis ecologist Eric Sanford, lead author of the new study, said in a statement.

The striated sea butterfly, for example, had never before been recorded north of Baja California, Mexico, but was found in the area between Point Reyes and Point Arena in northern California during the marine heatwave, also commonly known as “The Blob” for the patch of extremely warm Pacific Ocean water. Pelagic red crabs, usually found off the coast of central or southern Baja, were seen as far north as Newport, Oregon. Spiny lobster were identified in Bodega Bay in Sonoma County. Some species, such as nudibranchs, disappeared as soon as water temperatures cooled. But others — including sunburst anemones, chocolate porcelain crabs, and some barnacle species — have established new permanent populations in northern waters.

“Before our very eyes, we’re seeing the species composition shift to more warm-water southern animals in just the 14 years I have been at the Bodega Marine Laboratory,” Sanford said. “That’s a barometer of change for these ecosystems.”