A 40-mile wide bloom of toxic algae stretching from California to Alaska that can cause memory loss in humans has shut down fisheries off the US coast.
Surveyors aboard a National Oceanic and Atmospheric Administration research vessel revealed that the vast bloom is up to 650 feet deep and much bigger than first feared.
It has led to high levels of domoic acid which has worked its way into the food chain which can trigger amnesic shellfish poisoning. In extreme cases, this can cause loss of short term memory in humans.
On Tuesday, Shellfish managers were forced to double the area off Washington’s coast that is closed to Dungeness crab fishing, after tests revealed high toxin levels in crab meat.
This coastal ribbon of microscopic algae, up to 40 miles wide and 650 feet deep in places, is flourishing amid unusually warm Pacific Ocean temperatures.
So-called ‘red tides’ are cyclical and have happened many times before, but ocean researchers say this one is much larger and persisting much longer.
It has caused higher levels of neurotoxins which have led to severe consequences for the Pacific seafood industry, coastal tourism and marine ecosystems.
Dan Ayres, coastal shellfish manager for the Washington Department of Fish and Wildlife, said the area now closed to crab fishing includes more than half the state’s 157-mile-long coast.
It is likely will bring a premature end to this year’s coastal crab season, he believes.
Anthony Odell, a University of Washington research analyst who is part of a NOAA-led team surveying the harmful algae bloom, said ‘We think it’s just sitting and lingering out there.’
‘It’s farther offshore, but it’s still there.’
The survey data should provide a clearer picture of what is causing the bloom which is brownish in color, unlike the blue and green algae found in polluted freshwater lakes.
Marine detectives already have a suspect: a large patch of water running as much as 3 degrees centigrade warmer than normal in the northeast Pacific Ocean, nicknamed ‘the blob.’
Donald Boesch, professor of marine science at the University of Maryland, said: ‘The question on everyone’s mind is whether this is related to global climate change.
‘The simple answer is that it could be, but at this point it’s hard to separate the variations in these cycles.
‘Maybe the cycles are more extreme in the changing climate.’
Pat Glibert, professor at Horn Point Laboratory, University of Maryland Center for Environmental Science, said the number of documented cases is greater now than a decade ago.
He said: ‘There’s no question that we’re seeing more algal blooms more often, in more places, when they do occur, they’re lasting longer and often over greater geographical areas.
‘We’re seeing more events than documented decades ago.’
Odell recently completed the first leg of the survey, mostly in California waters.
On Wednesday, researchers plan to continue monitoring the sea between Newport, Oregon, and Seattle.
The vessel will then go to Vancouver Island, wrapping up in early September.
Another research ship is taking samples off Alaska.
Donald Boesch, professor of marine science at the University of Maryland, said: ‘The question on everyone’s mind is whether this is related to global climate change.
‘The simple answer is that it could be, but at this point it’s hard to separate the variations in these cycles.
‘Maybe the cycles are more extreme in the changing climate.’
Pat Glibert, professor at Horn Point Laboratory, University of Maryland Center for Environmental Science, said the number of documented cases is greater now than a decade ago.
He said: ‘There’s no question that we’re seeing more algal blooms more often, in more places, when they do occur, they’re lasting longer and often over greater geographical areas.
‘We’re seeing more events than documented decades ago.’
Odell recently completed the first leg of the survey, mostly in California waters.
On Wednesday, researchers plan to continue monitoring the sea between Newport, Oregon, and Seattle.
The vessel will then go to Vancouver Island, wrapping up in early September.
Another research ship is taking samples off Alaska.
Associated Newspapers Ltd