Ocean acidification is complicated, case in point

I once wrote about the complicated way in which ocean acidification is mostly really bad for marine creatures with calcium carbonate shells/skeletons. Well, today, while reading a book I thought had nothing to do with ocean acidification, I came across a report of one such creature for whom the change is apparently for the better. (I’d expected to find all kinds of interesting information in Embryos in Deep Time, but this was a surprise…)

Dupont et al. (2010) studied common sun stars (above; Bernard Picton, habitas.org.uk), following the larvae right up to metamorphosis under current CO2 and pH values of their home seas, and also under a near-future predicted scenario with higher CO2 concentration and lower sea pH. Surprisingly, the larvae in the “future” tanks survived just as well, grew better, and showed no obvious defects in development or calcification compared to the control group.

The authors speculate that this might be related to the reproductive strategy of these animals. While the larvae of many echinoderms have very little yolk in their eggs and have to feed the moment they look vaguely like an animal, sun star larvae are provided with a lot of yolk that can sustain them until they’re ready to metamorphose. So they don’t have to face the burdens of hunting for food; all their energy can go towards growing, which might make them more resilient to harmful environmental effects.

I’m not sure I buy such a simplistic explanation – first, other echinoderms with a similar developmental strategy suffer quite badly in similar conditions; and second, they only examined one species during the early stage of its life cycle. In fact, the authors point out these exact same caveats. (Plus the creatures not only resisted acidification, they thrived.)

Whatever the mechanism, though, Dupont et al.‘s data show that there is at least one animal for which ocean acidification may be a boon. Considering that this guy happens to be a top predator in its ecosystem, that could have major consequences for said ecosystem.

Also, they are incredibly pretty. Echinoderms rock.

***

Reference

Dupont S et al. (2010) Near future ocean acidification increases growth rate of the lecithotrophic larvae and juveniles of the sea star Crossaster papposus. Journal of Experimental Zoology 314B:382–389

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