California’s vital ocean current will soon experience major disruptions. Here’s what’s at stake

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Huge disruptions are predicted for the California Current marine ecosystem, which stretches along the west coast and is considered one of the richest and most abundant ocean regions in the world.

With human-caused climate change, some of the most important species that live in this area will experience major changes by the end of the century, in some cases with a reduced chance of survival by 25%, according to a new study. .

“Everything from plankton and algae to fish, marine mammals and birds all depends on the health or state of the California Current system,” said study co-author Terrie Klinger at the University of Washington.

All of these species will face immense challenges.

The study took into account the expected changes in water temperature, oxygen and carbon dioxide expected by the end of the century and examined how these differences will affect a total of 12 important species – including including Dungeness crab, anchovy, red sea urchin and kelp – both in their ability to survive, as well as their ability to grow, move, oxygenate and consume food.

The California Current refers to both the flow of water from British Columbia to the Mexican border as well as the area that extends 1,900 miles north to south and 220 miles seaward around this running. The researchers aggregated data from many previous studies, including using high-resolution information available off the coasts of Oregon, Washington and part of Vancouver Island. But the findings apply to the entire West Coast, Klinger said.

By comparing conditions from 2002-2004 to 2094-2096, they came up with a complex picture that includes both positive and negative outcomes for marine life.

“Even though you see positive and negative responses, when you dig into what they look like, you see there is going to be ecological change,” said lead author Jennifer Sunday of McGill University. Importantly, she says, “whenever survival was examined, it was either neutral or decreasing..”

The study also looked at results for pink salmon, razor clam, sablefish, Alaskan pink shrimp, ocher sea star, several types of rockfish, and seagrass. The species with the lowest predicted survival rates were razor clam, red sea urchin, Dungeness crab, and kelp. Yet many of these species should also see increased movement and metabolic rates.

Although survival rates are usually most important, being able to predict other biological changes among different species could help scientists predict changes in the food web – for example when a predator might quickly devour another population because that his metabolic rate increased, Sunday said.

And while the research could help fish and wildlife managers make planning decisions, the only real solution is to reduce fossil fuel consumption to halt further global warming, the authors say.

Not all the news was bad. For example, the kelp forest, an important habitat for many types of marine mammals, fish and crustaceans, is expected to grow faster as the ocean absorbs more carbon dioxide, although its growth is also halted when the ocean is warming.

“The question then becomes, when you have these kinds of competing pressures, good, bad – what ultimately wins out?” said Elliott Hazen, an ecologist at the Southwest Fisheries Science Center in Monterey, a division of the National Oceanic and Atmospheric Administration, who was not involved in the study.

Some will depend on how quickly certain conditions change and if wildlife has a chance to adapt. For example, if its habitat changes slowly enough, the Dungeness crab could theoretically move to new, better areas, Hazen said.

“What tends to be more difficult are the rapid episodic changes that come with this slow change,” he said. “If you all of a sudden have a low oxygen event, you’re going to have the potential for more deaths because the Dungeness crab can’t get out fast enough..”

An example of rapid change that recently occurred in the California Current was a 2014-16 marine heat wave, which led to the destruction of 95% of the kelp forest on the Sonoma-Mendocino coast, said Hazen.

Climate change will have the greatest impact in the northern portion of the California Current due to comparative changes in source water chemistry in the north, but that does not detract from the implications for the rest of the West Coast, Klinger said. .

That’s partly because everything is connected by the California Current, in which food resources, ocean temperatures, and even tiny larvae are dispersed between Washington and southern California.

“It’s a bit like living along a river,” Klinger said. “We are all connected along this river or sea highway.”

Tara Duggan is a staff writer for the San Francisco Chronicle. Email: [email protected]: @taraduggan

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