Bodega Bay tide pools show effects of climate change

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On a sunny afternoon in mid-April, Professor Eric Sanford crouched in a tide pool off Bodega Bay and turned over algae-covered rocks in search of a chocolate porcelain crab, a dime-size crustacean with blue speckles.

The creature has been spotted in small numbers around Bodega Bay for decades. But five years ago a severe marine heat wave, dubbed “the blob,” caused a sharp increase in its numbers north of the Golden Gate, says Sanford, a marine ecologist who researches climate change and coastal ecosystems at UC Davis’ Bodega Marine Lab.

“I look at how organisms adapt to climate change,” says Sanford, who regularly publishes articles in scientific journals on how life between the Northern California tides is changing. “We’re now seeing chocolate porcelain crabs and dozens of other species migrating north.”

Northern California’s rugged coast, thick fog and nutrient-rich waters have created one of the most diverse ecosystems on the planet. The state’s intertidal zone — the 9-foot-wide band of coast between the highest of high tides and the lowest of low tides — is home to an intricate web of marine life that evolved over millions of years but remained largely static since that last Ice Age — until recently.

Tide pools are revealed at low tide at the Bodega Marine Reserve in Bodega Bay, Calif. on Wednesday, April 17, 2019. UC Davis marine biologist Eric Sanford is researching the impacts that climate change is having within intertidal zones.

Tide pools are revealed at low tide at the Bodega Marine Reserve in Bodega Bay, Calif. on Wednesday, April 17, 2019. UC Davis marine biologist Eric Sanford is researching the impacts that climate change is having within intertidal zones.

Paul Chinn / The Chronicle

From the southern tip of Baja California to southeast Alaska, the range of sea creatures has pushed northward as water has warmed. Some creatures are expanding their range as they migrate north by holding on to their southern frontier. Others are disappearing from their historical homes.

For instance, intertidal zones in Monterey Bay are starting to reflect what was once seen only around Morro Bay (San Luis Obispo County), and Bodega Bay’s ecosystems are looking more like Monterey’s — with creatures like the small chocolate porcelain crab and sunburst anemone increasing in number or taking up permanent residence.

In March, Stanford published a paper in Nature’s Scientific Reports detailing a northward shift of 67 species, including bottlenose dolphins and olive ridley sea turtles, during the marine heat wave that occurred between 2014 and 2016. It is the most extreme shift of its kind on record, he says. The paper confirmed speculations that changing global temperatures, including short-term spikes, are reshaping the marine environment.

“The intertidal zone is a barometer of change for what’s going on out in our oceans,” Sanford said. “These communities are changing dramatically, not over the scale of centuries but over the scale of the 14 years I’ve been here.”

And what’s going on in the ocean off the California coast is deeply concerning: Gray whales are washing up dead on California shores in concerning numbers this year — 37 as of June, according to the National