Acidifying oceans could dramatically impact the world's squid species, according to a new study led by Woods Hole Oceanographic Institution (WHOI) researchers and soon to be published in the journal PLOS ONE. Because squid are both ecologically and commercially important, that impact may have far-reaching effects on the ocean environment and coastal¹ economies, the researchers report. "Squid are at the center of the ocean ecosystem² -- nearly all animals are eating or eaten by squid," says WHOI biologist T. Aran Mooney, a co-author of the study. "So if anything happens to these guys, it has repercussions³（反响，影响） down the food chain and up the food chain."

 

Research suggests that ocean acidification and its repercussions are the new norm. The world's oceans have been steadily⁴ acidifying for the past hundred and fifty years, fueled by rising levels of carbon dioxide (CO2) in the atmosphere. Seawater absorbs some of this CO2,turning it into carbonic acid and other chemical byproducts that lower the pH of the water and make it more acidic. As CO2 levels continue to rise, the ocean's acidity⁵ is projected to rise too, potentially affecting ocean-dwelling species in ways that researchers are still working to understand.

 

Mooney and his colleagues -- lead author Max Kaplan, then an undergraduate student from the University of St. Andrews in the U.K. and now a WHOI graduate student, and WHOI scientists Daniel McCorkle and Anne Cohen -- decided⁶ to study the impact of acidifying seawater on squid. Over the summer of 2011, Mooney and Kaplan gathered male and female Atlantic longfin squid (Loligo pealeii) from the waters of Vineyard Sound and transported them to a holding tank in the WHOI Environmental Systems Laboratory. When these squid mated and the females laid their egg capsules -- each of which can contain 200 to 300 fertilized⁷ eggs -- the researchers transferred some of the capsules to one of two smaller tanks filled with Vineyard Sound seawater.

 

These two smaller tanks represented two environments: today's ocean, and the more acidic oceans of the future. One was continuously exposed to air pumped in from outside, to simulate the ocean's current interaction with the atmosphere. The other received air enriched with higher CO2 levels that made the seawater about three times more acidic, a level of acidity that models predict will be widespread a hundred years from now.

 

The researchers watched as the eggs hatched and the squid began to develop in each of the two tanks, and measured their time to hatching, body length and other parameters⁸ as they grew.

 

"Amazingly, we found effects or changes in all those parameters," Mooney says. "Animals raised in high CO2 took longer to develop, which is a big deal when you're basically this egg mass on the bottom of the ocean and fish can just pop along and eat you."

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