Paper Reviewed
Peck, V.L., Oakes, R.L., Harper, E.M., Manno, C. and Tarling, G.A. 2018. Pteropods counter mechanical damage and dissolution through extensive shell repair. Nature Communications 9: 264, DOI: 10.1038/s41467-017-02692-w.

Marine calcifying organisms inhabiting polar oceans are expected to be among the most vulnerable species to the predicted effects of ocean acidification. In this regard, the sea butterfly (Limacina helicina) has taken center stage in much of the discussion and debate over ecosystem vulnerability, with several studies suggesting that this microscopic pteropod will experience net shell dissolution under future seawater pH predictions and become the first casualty of ocean acidification just a few short decades from now.

But just how sure is this fate? According to the recent work conducted by Peck et al. (2018), it's not as likely as previously thought.

In coming to such a conclusion, this team of five researchers used micro-computed tomography to analyze the shells of L. helicina specimens that were collected during a research expedition into Arctic waters during 2012. This analysis revealed that this species has the ability to maintain shell integrity, even repairing it from predatory damage, when exposed to waters that are undersaturated with respect to carbonate (i.e., waters that favor shell dissolution). With respect to this latter incredible feat (repairing damaged shells), it was accomplished via an extensive thickening of the animal's inner shell wall, which thickness was observed to be up to 4 times that of the normal exterior shell thickness.

Commenting on their findings, Peck et al. state that "the ability of L. helicina to repair shell damage in naturally undersaturated conditions indicates that this species has more potential to counteract the deleterious effects ocean acidification may have on their shells than previously considered." Furthermore, they say it adds "to the growing body of evidence that many polar calcifiers, exposed to undersaturated waters, can withstand and repair damage to their shells, perhaps on account of natural exposure to heightened physical and chemical variability, which have resulted in organisms developing or exhibiting an inherent resilience strategy."