One of the most formidable predators in the Pacific ocean, the Humboldt squid, may become more vulnerable to attacks from other marine beasts as changing water conditions make them more sluggish swimmers, a study has found.
As human activities increase the level of carbon dioxide in the atmosphere, the level in the oceans also rise. Scientists believe this will make the squid lethargic, and so less able to outswim their own predators, including sperm whales that feed heavily on the creatures.
Humboldt squid (Dosidicus gigas) can grow up to 2m long and hunt in shoals of more than a thousand. Scientists have recorded the creatures, which are found in waters from Alaska to Patagonia, swimming at more than 20kmh (13mph).
In the daytime, the squid are forced to dive deep to prey on lantern fish, but because deeper waters are starved of oxygen, the squid must return to the surface at night to recover.
Rui Rosa at the University of Lisbon netted Humboldt squid off the coast of California and transferred them to water tanks aboard the team’s research vessel to examine how they coped with different levels of carbon dioxide in water.
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Ian Sample, guardian.co.uk, 16 December 2008. Full article.
