Photo via WHOI
We're familiar with the problem of ocean acidification causing crustaceans' shells to dissolve. The problem has been seen among species such as oysters, clams and mussels. However a new study shows that in several other species such as crabs, shrimp and lobsters, increased acidity can spur a thickening of shells. But having thicker shells doesn't signal that the animals are in a safer position. The Woods Hole Oceanographic Institution (WHOI) scientists have studied the effects of exposure to ocean acidification on 18 crustacean species, and they've found that for seven of those species, exposure causes the animals to grow thicker shells, as reported by TGDaily.
Lead scientist Justin B Ries notes, "Most likely the organisms that responded positively were somehow able to manipulate...dissolved inorganic carbon in the fluid from which they precipitated their skeleton in a way that was beneficial to them," said Ries, now an assistant professor in marine sciences at the University of North Carolina. "They were somehow able to manipulate CO2...to build their skeletons."
But thicker shells don't mean that the animals are safe, since they often prey on other creatures whose shells are thinning and becoming weaker. Conversely, the animals that feed on the crustaceans growing thicker shells will have a harder time cracking through, which potentially means they'll have to find another food source.
As the research team states, "...any possible ramifications are complex. For example, the crab exhibited improved shell-building capacity, and its prey, the clams, showed reduced calcification. 'This may initially suggest that crabs could benefit from this shift in predator-pray dynamics. But without shells, clams may not be able to sustain their populations, and this could ultimately impact crabs in a negative way, as well,' Ries said."
Overall, the study showed that various species react very differently to changes in CO2 levels - some have shells that thin quickly, some that thicken, and some that don't thin until the levels are above 1,000 ppm (we're currently at about 480ppm). But all of them depend on one another and other forms of marine life that are all being affected by ocean acidification.
Here's a great documentary on ocean acidification, well worth taking the 20 minutes to watch how the oceans are becoming more acidic and the impacts it's having all over the globe.