Coastal species that were once only seen in Baja, Mexico, are now showing up as far north as the Oregon coast. Scientists say the influx is unprecedented.
A two-year marine heat wave known as “the blob” pushed dozens of southern species into cooler waters in Northern California and Oregon. Researchers in a UC Davis study counted 67 species outside their normal bounds between 2014 and 2016, including a sea butterfly that had never appeared in California before. They also included a red crab normally restricted to Baja, Mexico, which turned up in Newport, Oregon.
But these southern species’ temporary migration is not what surprised the researchers. What did was the sheer number of these creatures migrating north.
Lead researcher Eric Sanford attributes the influx to the blob’s lengthy duration.
“Normally, cold water from Northern California and south-flowing currents along our coast, they tend to block connections between southern waters and Northern California and Oregon,” Sanford said. “However during this marine heat wave, it was a bit like temporarily opening a door between lower latitudes and the northern coast.”
While the heat wave has cooled off, scientists expect similar patterns to continue in the years to come.
“Right before our very eyes we’re seeing the composition of these shoreline communities shift to include more of these southern warm water species,” Sanford said. “And I think that's really a barometer of change that suggests our oceans in a lot of ways are changing quite rapidly.”
Sanford added that extreme weather events like “the blob” have already become more common in the last couple of decades.