I was reading this article on WUWT about extinction events that included some claims that ocean acidification would have caused the shellfish to have their shells dissolve. Yes, that old canard.
Never mind that CO2 was several THOUSAND PPM when shellfish evolved. Never mind the megaTONS of metal nodules and carbonates on the ocean bottom that will cause it to stay mildly alkaline against stronger acid insults than CO2. Never mind the tanks of the aquarium hobby where folks do CO2 enrichment to make things grow better, including shell fish… No, all of that is to be ignored in favor of a groundless panic that even a tiny bit less alkaline conditions, and Clams are going to be history…
And I pictured clams… and thought “acid”… that turned into “Acid Rain” and got me thinking about the acid rain (and natural forest floor acid leachate) and, well, Freshwater Clams.
As a kid we would find these in the Sacramento River and contributories. Great fish bait. I don’t know if any of them are ‘natives’ but at least one variety is an introduced one. The Asian Freshwater Clam.
So, I thought, could I find a map of the distribution of Freshwater Clams and one for River pH and see where was the limit on Clams? At just what pH did Clams Die Out? Some lakes and rivers can have a pH down in the 5 ish and even into the 4.x range; so I figured there would be some kinds of limits on range, as that is a significantly acid condition.
Well, I found my maps. I could put a whole lot of words around it, but really is just comes down to one point:
There is no visible limit to clams based on water pH. Even down into that 4.x range.
The limit has more to do with where they have been introduced and perhaps some cold limits up in the Montana / Dakota freezer… So just look at these two maps, ponder, and consider that this sure looks to me like a pretty good “existence proof” that shellfish just don’t give a damn about acidity in water well up into the 4.x range. As crawfish are also found all over those areas too, I think it’s pretty clear that even that kind of shellfish doesn’t care much about pH.
I know, it’s a small map. Just notice that the blue parts are a pH of about 5 to 5.5, while the red / orange areas range down to a pH of 4.1 and in all cases the pH is significantly acid when compared to neutral at 7.0 or the ocean in the low 8.x range which is actually alkaline. And the clams?
Another interesting article on Asian Clams with a slightly different version of the same map.
There are a bunch of different crayfish species, and the USGS has maps for each kind, but I didn’t see a map of “all species” (most likely as it would just be a map of ALL U.S. states). So here’s map, chosen at random, of one species:
You can check out the other species at the USGS maps here:
I wish I could say more about it, but not much more needed. Just: Can you say “existence proof”? Ocean acidification just is not going to cause problems for clams, lobsters, crabs, or any of those like critters. If they don’t mind a pH of 4.3 nothing the ocean does will matter.