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Squids may have a harder time breathing with climate change

Print | Comments () Posted by Beth Daley December 16, 2008 02:27 PM

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By Beth Daley, Globe Staff

For several years, scientists have warned that the oceans’ absorption of carbon dioxide from the atmosphere is lowering its ph – an acidic threat to corals and other marine shells.

A jumbo squid (courtesy of the Monterey Bay Aquarium Research Institute

Now, researchers from the University of Rhode Island report in this week’s Proceedings of the National Academy of Sciences ocean acidification could also severely impact Humboldt, or jumbo, squids. The squids, which can grow up to seven feet long are found in Pacific waters and are an important ocean predator as well as food for marine mammals, seabirds, and fish.

They also live an edgy life: The animals must recharge their blood oxygen supply constantly from the waters around them.

According to Brad Seibel, URI assistant professor of biological sciences, and Rui Rosa, a former URI post-doctoral student, squids are active during the night when they feed in oxygen rich shallow waters, but their metabolism dramatically slows during the day when the descend to the low oxygen deep sea. Increasing ocean acidification, along with warming temperatures, is expected to limit the amount of oxygen the squids can get from their nighttime feeding ground waters.

Seibel and Rosa exposed the squids to concentrations of C02 equivalent to those projected to be in the ocean in about a century because of manmade emissions.

The squids took in less oxygen from the high CO2 water and as a result, their activity levels declined about 45 percent. Warmer ocean temperatures, which are expected to rise as global temperatures do, also hold less oxygen, exacerbating the effect.

That means squids could become far more sluggish in shallow waters, making them more vulnerable to predators. The change may also push the species to even shallower waters where they may find new species to feed on, altering the food web – or they may migrate to more northern waters as temperatures warm. While jumbo squids could possibly adjust to the changing ph in oceans over time, they have among the highest oxygen demands of any animal in the world, and it could likely be difficult for the animals to adapt.

tags humboldt, low oxygen, sluggish, squids