Many seabirds feed around Alaska during the northern summer. An 'ectothermic vice' squeezed the birds' food supply "A massive die-off of planktivorous Cassin's auklets occurred from Central California to British Columbia in the winter of 2014-15, a marked increase in mortality of was noted in Southern California, and an unusually large die-off of baleen whales occurred in the Gulf of Alaska in 2015–16," they wrote in their paper, published today in PLOS ONE. The blob was up to 6 degrees Celsius above typical maximum temperatures in places and extended to a depth of 200 metres, and more than 3,000 kilometres up the US coastline into Alaska.Īs well as the huge seabird die-off, the researchers believe the marine heatwave caused the mass mortality of a suite of other fish, mammal and bird species during 2014–17.ĭuring the period that the blob persisted off the coast of the US, production of phytoplankton or microscopic algae dropped, and "the largest harmful algal bloom in recorded history" stretched from California to the Gulf of Alaska in 2015, the researchers said. Now a major study has concluded that the die-off was the result of a huge disruption to energy flow through food webs, precipitated by "the blob" - an unprecedented mass of warm, nutrient-poor water that emerged off the Pacific coast of the US from 2013. Researchers think it was the largest seabird die-off in recorded history.Ĭompounding the deaths, at least 22 colonies completely failed to produce any offspring over several breeding seasons. Only a fraction of the dead birds made it to shore, and the total number of deaths was estimated to be close to a million birds.
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