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Chitons Facing Ocean Acidification Grit Their Teeth and Prosper

Paper Reviewed
Sigwart, J.D. and Carey, N. 2014. Grazing under experimental hypercapnia and elevated temperature does not affect the radula of a chiton (Mollusca, Polyplacophora, Lepidopleurida). Marine Environmental Research 102: 73-77.

Writing in the journal Marine Environmental Research, Sigwart and Carey (2014) say that Polyplacophoran molluscs or chitons are a type of marine grazer that possesses a radula with enlarged scraping teeth that extend more than half the length of its body, the anterior feeding teeth of which (when largely eroded) "are shed and replaced with a new row." And they thus began to wonder what would happen to the creature's ability to produce new teeth (which are essential for its survival) when this happens in an acidified ocean. The next step of the two scientists, therefore, was to try to find out for themselves via experimental means.

Sigwart and Cary thus obtained chitons from the bottom of Sweden's Gullmar Fjord, which they transferred to aquaria where the molluscs were housed on stones and shell debris taken from the collection sites within flow-through fjord-bottom seawater that was maintained at either elevated pCO2 (~ 2000 µatm, pH 7.5) or control pCO2 (~400 µatm, pH 8.0) in one of three temperature treatments (10, 15 or 20°C) for a period of four weeks, after which the molluscs were dissected and their radulae examined. And what did the team of two thereby learn?

Sigwart and Carey report "there was no significant difference in the number of new teeth or total tooth row count in any treatment," as well as "no differences in microwear or breakage on the feeding cusps." And they add that "the shell valves also showed no signs of dissolution," which observations probably account for the fact that the species they studied belongs, in their words, "to a lineage that has persisted for over 300 million years," and why they also conclude that it "may be able to overcome even anthropogenic climate change."

Posted 6 April 2015