Pacific Ocean

Crab Industry at Odds with Warming Waters

But as rising ocean temperatures threaten to make fishery closures routine, it will be even harder to count on crab for holiday meals—or livelihoods. Over the past decade, warming sea waters have produced harmful algal blooms that contaminate crab meat with domoic acid, a neurotoxin that can cause seizures, memory loss and other serious symptoms and has been blamed for poisoning and stranding scores of sea lions in California every year. State officials delayed three out of the last six crab seasons to protect public health after an unprecedented multiyear marine heat wave, dubbed “the blob,” hit the north Pacific Ocean in 2013.

Pacific West Coast Acidification Rate Larger than Other Oceans

The ocean absorbs carbon dioxide from the atmosphere, which reduces pH levels and concentrations of calcium carbonate, a mineral used by shellfish to calcify their shells. As more carbon is released into the atmosphere, concentrations of calcium carbonate decrease and the shells of organisms like foraminifera get thinner, a trend Osborne saw clearly in the sediment cores she examined.

“The shell thickness record instantly showed a long-term declining trend,” she said. “It was really obvious across entire record.”

Massive Marine Heat Wave Returns

The current expanse of warm water stretches from Alaska to Southern California to Hawaii. It appears similar to conditions five years ago when the original “blob” was first taking shape, federal scientists said, although so far, the warmer-than-normal waters extend down only about 150 feet below the surface, rather than 600 feet five years ago.