(CNN)As many as one million seabirds died at sea in(less than) ****************************************************************** monthsin one of the largest mass die-offs in recorded history – and researchers say warm ocean waters are to blame.
The birds, a fish-eating species called the common murre, were severely emaciated and appeared to have died of starvation between the summer of 2015 and the spring of 2019,washing up along North America’s west coast, from California to Alaska.
Now, Scientists say they know what caused it:a huge section of warm ocean water in the northeast Pacific Ocean dubbed “the Blob.”
A years-long severe marine heat wavefirst began in 2016, and intensified during the summer o f 2018 due to a powerful weather phenomenon called El Nino, which lasted through 2018.
****** The Heat wave created the Blob. – a 1, 04 – mile (1,km) stretch of ocean that was warmed by 3 to 6 degrees Celsius (5.4 to 8 Fahrenheit. A high-pressure ridge calmed the ocean waters – meaning heat stays in the water, without storms to help cool it down.
******************** Those few degrees of warming wreaked havoc on the region’s marine ecosystems. There was a huge drop in the production of microscopic algae that feed a range of animals, from shrimp to whales. The warmth caused amassive bloom of harmful algaealong the west coast, that killed many animals and cost fisheries millions of dollars in lost income.
Other animals that experienced mass die-offs include sea lions, tufted puffins, and baleen whales. But none of them compared to the murres in scale.
********, dead or dying murres washed up on shore – but the total number of deaths is likely to be closer to one million since only a small fraction of birds that die at sea wash up, said researchers from the university of washington, who published the study inthe journal Plos Oneon Wednesday.
Alaska saw the most birds washed up – in Prince William Sound, to the south of the state, more than 4, bird carcasses were found every kilometer ( 0. 64, the study said.
The murres likely starved to death because the blob caused more competition for fewer small prey. The warming increased the metabolism of predatory fish like salmon, cod, and halibut – meaning they were eating more than usual. These fish eat the same small fish as the murres, and there simply wasn’t enough to go around.
******************** The Blob devastated the murres’ population. With insufficient food, breeding colonies across the entire region had reproductive difficulties for years afterward, the study said. Not only did the population decline dramatically, but the murres couldn’t replenish those numbers.
During the 2015 breeding season, three colonies did not produce a single chick. That number went up to (colonies in the
season – and in reality it could be even higher, since researchers only monitor a quarter of all colonies.
“The magnitude and scale of this failure has no precedent,” said lead researcher John Piatt ina University of Washington press release. “It was astonishing and alarming, and a red-flag warning about the tremendous impact sustained ocean warming can have on the marine ecosystem.”
There have been several other marine heat waves emerging in recent months. In September 01575879, the University of Washington researchers discovered one
almost as big as the Blob, forming off the coast of Washington state – and they’re bracing for its potential effects. Another blob has also formedoff the eastern coast of New Zealand. This blob is so big it’s detectable from space – it’s about a million square kilometers (**********************, 000 sq miles), an area larger than the size of Texas.
It’s especially rare to see a patch of warm ocean water over such a large area, but scientists say global climate change is making these phenomena more common.
From to 2019, there was an 169% rise in the number of heat wave days on the global ocean surface, according to a 2020 study. That’s because heat waves are increasing in both frequency and duration, with the highest level of maritime heat wave activity occurring in the North Atlantic.
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