Sur­vival tac­tics

Can sea life adapt to sour­ing oceans?

The Star Malaysia - Star2 - - ECOWATCH - By Craig WelCh And that’s when things work well.

The vi­o­let bot­tom-dwelling, prickle-backed spheres wrig­gling in the tank in Gretchen hofmann’s lab aren’t re­ally known for their speed.

But these lowly sea urchins adapt so quickly they’re help­ing an­swer a ques­tion that’s key to un­der­stand­ing ocean acid­i­fi­ca­tion: as fos­sil-fuel emis­sions dis­rupt ma­rine life, will evo­lu­tion come to the res­cue?

Like Darwin’s finches or Bri­tain’s pep­pered moths, these hedge­hogs of the sea in­creas­ingly em­body na­ture’s stun­ning ca­pac­ity for re­silience. A num­ber of plants and an­i­mals threat­ened by sour­ing seas, in­clud­ing some mus­sels, abalone, rock oys­ters, plank­ton and even a few fish, ap­pear likely – at least at first – to ad­just or evolve. But few seem as wired as these salt­wa­ter pin­cush­ions to come through the next sev­eral decades un­scathed.

Yet, work with urchins, as well as other species, sug­gests that acid­i­fi­ca­tion sooner or later may still push these and other ma­rine or­gan­isms be­yond what they can tol­er­ate.

“evo­lu­tion can hap­pen, and it can hap­pen quickly,” said hofmann, a ma­rine bi­ol­o­gist at the Univer­sity of Cal­i­for­nia, Santa Bar­bara (UCSB), who has stud­ied urchins for years. “But con­cerns about ex­tinc­tions are very real and very valid. Bi­ol­ogy can bend, but even­tu­ally it will break.”

The oceans are ab­sorb­ing a quar­ter of the car­bon diox­ide emit­ted by burn­ing coal, oil and nat­u­ral gas. That, re­searchers say, is caus­ing sea chem­istry to change faster than it has for tens of mil­lions of years. Which plants and an­i­mals can ac­com­mo­date these more cor­ro­sive seas – and for how long – will de­pend on many fac­tors, from where they live to their pop­u­la­tion sizes to the depth of stress they face from other forces, such as warm­ing tem­per­a­tures and pol­lu­tion. Sur­vival will vary species by species. Not ev­ery­thing will make it.

“This kind of change is not free; evo­lu­tion is not a gen­tle sport,” said Stephen Palumbi, an evo­lu­tion­ary ecol­o­gist at Stan­ford Univer­sity, who also works ex­ten­sively with urchins. “When evo­lu­tion hap­pens, it’s be­cause the un­fit are dy­ing. It’s pretty bru­tal.”

In the late 2000s, com­mer­cial urchin fish­er­man Bruce Steele feared things would not go so well. And for good rea­son. Urchins graze on al­gae, drive out kelp and are eaten by sea ot­ters, sun­flower stars and hu­mans.

Steele, a scuba diver, had made his liv­ing since the 1970s scoop­ing the spiny del­i­ca­cies off the sea floor to sell to sushi restau­rants as uni. But when he read a re­search paper about acid­i­fi­ca­tion, he saw right away what it could mean for his busi­ness – and for the ocean he loved.

“When you start knock­ing out the very bot­tom of the food chain, it’s in­cred­i­bly ter­ri­fy­ing,” Steele said. “But that’s what the re­search is show­ing us.”

In­creas­ing CO not only makes oceans more cor­ro­sive, it re­duces car­bon­ate ions, which ev­ery­thing from scal­lops to crabs, co­ral and sea urchins need to build shells or skele­tons. So Steele di­aled up hofmann, his lo­cal univer­sity ex­pert on spiky echin­o­derms.

“She thought it was a crank call or some­thing, be­cause ... I don’t know,” Steele said. “I guess peo­ple fig­ure a sea urchin diver’s not go­ing to be read­ing a whole bunch of science.”

hofmann dis­missed Steele at first, but quickly called back and started in­ves­ti­gat­ing his con­cerns. She ex­posed sea urchin lar­vae to high-CO wa­ter and made a trou­bling dis­cov­ery: their bod­ies of­ten got smaller.

ad­just­ing to change: a fe­male skin-diver in Ja­pan dis­plays a sea urchin col­lected from the sea off the coast of Shima in Mie pre­fec­ture. re­searchers at the Univer­sity of cal­i­for­nia-Santa bar­bara are study­ing the crea­ture’s adap­ta­tion to ocean acid­i­fi­ca­tion. — aFP

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