SANTA CRUZ -- Researchers at a Pacific Grove laboratory have found a potential explanation for why thousands of Humboldt squid washed up on county shores last week -- they were victims of poisoning.
Since the stranding, researchers at Stanford University's Hopkins Marine Station have been looking for an explanation for why Aptos beaches ended up covered with large red cephalopods Dec. 10. By sifting through massive amounts of ocean data, one researcher spotted a pattern, possibly the first clue in solving a bizarre marine mystery.
"There was a cycle of spikes in the amount of domoic acid in the water," said R. Russell Williams, a graduate researcher at the lab.
Domoic acid is a naturally occurring neurotoxin. The spikes coincide with mass squid deaths that happen about every three weeks, though usually in far smaller numbers. Prior to the Dec. 10 event, there were strandings reported on Nov. 20 and Oct. 30, Williams said.
The December stranding was unusually large, and was concentrated on a highly trafficked beach area. In the aftermath, dogs and seagulls hovered near piles of red mantles, while a few good Samaritans tried to rescue the squid that were found alive. Humboldts can reach about 5 feet in length and weigh up to 100 pounds.
While relatively common, the reason for the strandings is still a mystery. One theory is that since the 10-tentacled creatures don't normally call Monterey Bay home, the alien invaders simply became disoriented and beached themselves en masse.
But why? The squid's spectacular stranding has given scientists another chance to look for more clues. State Department of Fish and Game officials even took samples for testing.
Williams works with noted squid researcher William Gilly. The possible link to domoic acid may support the Gilly's theory about disorientation -- more than just finding themselves in a strange place, the squid were intoxicated.
Similar to glutamine, domoic acid in larger doses can cause confusion and even caused brain damage in mammals. Its effect on squid is not well-understood, and is something scientists want to explore further.
Though the overall levels of domoic acid were extremely low -- a human would need to drink thousands of gallons of seawater to get any effect -- the spikes were statistically significant.
Domoic acid is also produced by harmful algae blooms known as red tides, though Williams cautioned that it was too early to link red tides to squid deaths.
Gilly was on a research trip to Mexico and could not be reached, but the fact that there is a local lab focused on a species not native to the region speaks to the scientific fascination with Humboldt squid.
"Basically, they're like mini-giant squid, but we actually get to see them," Williams said.
The Humboldts in Monterey Bay are believed to be visitors, and researchers don't think they've established a population here.
However, Williams said strandings can be a sign that a species is about to do just that. Humboldts were first seen in Monterey Bay during an El Niño event in 2002, but until recently they had not been seen since La Niña returned in 2010.
While Humboldts prey on small lanternfish, Williams said local specimens appear to eat smaller market squid as well.
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