The marine heat wave between 2014 and 2016 inspired an unprecedented northward movement of warm-water species, according to a new study.
A new study has found an unprecedented number of warm-water species were observed in the coastal waters of Northern California and the Pacific Northwest during the marine heatwave that stretched from 2014 to 2016.
Scientists at the University of California, Davis, documented dozens of unusual species at their Bodega Marine Laboratory during the heatwave, species -- including jellyfish, crabs, nudibranchs, fish, dolphins and sea turtles -- typically found among the waters of Baja California, Mexico.
Watch 150 Years of Global Mean Temperature Increases Credit UC Berkly
Published in the journal Scientific Reports, scientists documented the 67 rare, warm-water species spotted by marine biologists and citizen scientists. More than half of the species, 37 sightings, had never been seen so far north.
The striated sea butterfly, a swimming sea snail, had never been seen north of Baja, but researchers observed the species for the first time in California waters. Another unexpected visitor was the pelagic red crab, normally restricted to the waters off central and southern Baja, was observed as fart north as Newport, Ore.
"Against the backdrop of climate change, we hope southern species will track northward because that's necessary for their persistence and survival," Eric Sanford, a UC Davis professor of ecology and evolution, said in a news release. "It's perhaps a glimpse of what Northern California's coast might look like in the future as ocean temperatures continue to warm."
The heatwave developed as warm water from the Gulf of Alaska, called "The Blob," drifted southward and merged with a major El Nino event traveling northward. The marine heatwave was one of the hottest and longest on record, raising ocean temperatures between 3.5 to 7 degrees Fahrenheit.
In 2016, as the waters finally cooled, most of the rare species returned to their traditional haunts off the coast of Mexico. A handful of species, however, including the sunburst anemone, chocolate porcelain crab, a brittle star and a few barnacle species, stuck around. Once rare, these species are becoming more common in the waters of Northern California, according to the new paper.
Primary study region in northern California, USA. Inset map (upper right) shows location of study region along the Pacific coast of the United States.
"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."
Professor Sanford explained that marine heatwaves temporarily open a door between lower latitudes and the northern coast.
He said the longer that door is open, the greater the number of southern species that can step through it.
The 2014-2016 event was so long and warm, it allowed southern species to enter California and move northward.
The research team view such geographical shifts as an indication of how marine the communities may continue to respond to warming oceans, as more heatwaves are expected in the future.
