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Unprecedented Number of Warm-Water Species Moved Northward During Marine Heatwave

Tropical Species Near San Francisco? New Range Limit Records Indicate Future Face of California Coast

During the marine heatwave of 2014-16, scientists from the University of California, Davis, noticed creatures typically seen only in places like Baja California, Mexico, showing up outside the 嘿嘿视频 Bodega Marine Laboratory. These included warm-water species of jellyfish, crabs, nudibranchs, fish and even dolphins and sea turtles.

in the journal Scientific Reports, documents an unprecedented number of southern marine species moving northward into California and as far north as Oregon. Of 67 rare, warm-water species sightings observed by the authors and citizen scientists, 37 had never been documented so far north before.

Among the 37 with new northern range limits are tropical creatures like the striated sea butterfly, which had not been found north of Baja. This is the first record of them in the state of California. Another unexpected visitor was the pelagic red crab, normally restricted to the waters off central and southern Baja. But during 2014-16, when water temperatures were 3.5 to 7 degrees Fahrenheit warmer than usual, the crabs were seen as far north as Newport, Oregon. And the molt of a spiny lobster 鈥 an important fishery species in Baja 鈥 turned up in Bodega Bay.

Mosaic of ocean species rarely seen in Northern California
Species rarely or never seen in Northern California until the 2014-2016 marine heatwave. Top row from left: Hilton鈥檚 nudibranch, blue buoy barnacle, short-beaked common dolphin, Olive鈥檚 nudibranch. Middle row: Spanish shawl nudibranch, violet sea snail, pelagic red crab, Hopkins鈥 rose nudibranch. Bottom row: brown booby, striated sea butterfly, glass-spined brittle star, scarlet sea cucumber (Brown booby photo by Roger Harshaw; scarlet sea cucumber and striated sea butterfly by Eric Sanford; all others by Jacqueline Sones.)

鈥淎gainst the backdrop of climate change, we hope southern species will track northward because that鈥檚 necessary for their persistence and survival,鈥 said lead author Eric Sanford, a 嘿嘿视频 professor of ecology and evolution. 鈥淚t鈥檚 perhaps a glimpse of what Northern California鈥檚 coast might look like in the future as ocean temperatures continue to warm.鈥

Warm water blob

As 鈥淭he Blob鈥 of warm water moved from the Gulf of Alaska south along the Pacific coast, a major El Ni帽o event worked its way from the equator north to California. Together, these events created unusually warm water conditions and one of the longest marine heatwaves on record.

Marine heatwaves temporarily open a door between lower latitudes and the northern coast. The longer that door is open, the greater the number of southern species that can step through it. The 2014-16 event was so long and warm, it allowed southern species to enter California and move northward. Current reversals, where water flowed northward from Monterey Bay, also aided the species on their journeys. This combination led to the record-breaking number of species moving northward, the study said.

Scientist looks in tidepool of anemones
嘿嘿视频 Professor Eric Sanford looks at a tidepool full of giant green anemones, a common species to the area, on the Bodega Marine Reserve. (Jackie Sones/嘿嘿视频)

New settlers

Most of the visitors were ephemeral. The brightly colored nudibranchs, for instance, disappeared almost as soon as the water cooled. But some seem to have established a foothold in Northern California. These include the sunburst anemone, chocolate porcelain crab, a brittle star and some barnacle species.

Sanford said these southern species were absent or rare from Bodega Bay in the 1970s but are now fairly common in the area.

Chocolate Porcelain Crab
Chocolate porcelain crab. (Jackie Sones/嘿嘿视频)

Barometer of change

The marine ecologists and oceanographers who authored the study view such geographical shifts as an indication of how these communities may continue to respond to warming oceans, as more marine heatwaves are expected in the future.

鈥淏efore our very eyes, we鈥檙e seeing the species composition shift to more warm-water southern animals in just the 14 years I have been at the Bodega Marine Laboratory,鈥 said Sanford. 鈥淭hat鈥檚 a barometer of change for these ecosystems.鈥

The study鈥檚 co-authors include Jacqueline Sones and John Largier from 嘿嘿视频, Marisol Garcia-Reyes from Farallon Institute, and Jeffrey H.R. Goddard from UC Santa Barbara.

Radar data for the study were funded in part by NOAA鈥檚 United States Integrated Ocean Observing System.

Media Resources

Eric Sanford, Bodega Marine Laboratory, 707-875-2040, edsanford@ucdavis.edu

Kat Kerlin, News and Media Relations, 530-750-9195, kekerlin@ucdavis.edu

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