Our paper addresses how Antarctic echinoderms but specifically sea stars (=starfish) and brittle stars are likely to be vulnerable as the climate changes, creating a more acidic ocean environment.
Here is a quick video that nicely summarizes the broader phenomena of Ocean Acidification (abbreviated OA)
But here is where we add further details-the acidification? affects different kinds of calcium carbonate (the material which composes shells, coral skeletons, etc.) differently...
Most of the shells and skeletons that you read about in the news are usually made either out of different forms of calcium carbonate-either aragonite (wikipedia has a nice summary here) or calcite. Aragonite is usually what's seen as associated with shells, skeletons, etc..
But, of course, echinoderms being echinoderms have something a little different going on... Echinoderms have skeletons with a high concentration of magnesium (Mg).
Their skeletons are composed of Mg-calcite (magnesium calcite)
One can see many recent stories about how aragonite in shells is easily dissolved by ocean acidification.
Mg-calcite is even MORE soluble (and more vulnerable) than aragonite!
Looking at Mg-calcite in Antarctic Echinoderms
Of all the echinoderms? Which had the HIGHEST amount of Mg-calcite by % weight??
Several species of Starfish!
I would note that ophiuroids were not heavily sampled-below but in all liklihood they are just as if not more important here..
Specfically, this very widespread species, Porania antarctica dsplayed among the HIGHEST % weight of Mg-Calcite
|Photo by Dirk Shories at this site.|
This total amount of Mg-calcite was compared relative to OTHER %of Wt. values across different latitudes (0=equator, higher = closer to Antarctica)
2. Mg-calcite is most vulnerable to dissolution. A study on coralline algae (that's algae which builds a skeleton for itself using the mineral Mg-calcite) showed that when 8-12% by wt. of a calcite skeleton is composed of Mg-calcite it becomes HIGHLY soluble.. Look above at the Table 2 from the paper most sea stars have 9 to 10% by wt. Mg-calcite skeletons!