- Scientific name: Patella caerulea
- Habitat: The Mediterranean Sea
- Conservation status: Extant
- Threat to existence: Ocean acidification
- Fun fact: Limpets are actually a form of aquatic snail!
Additional source: Wikipedia
Image source: Chris Taklis
Ammonites and Graptolites have shown us that evolution is not always fair, but they were millions of years ago. So what about now? How have we changed the rules of evolution? One of the most obvious answers is carbon emissions. When one hears about carbon emissions, the first things that come to mind are global warming and the greenhouse effect. But there is another consequence of emissions equally as deadly and often overlooked: ocean acidification.
Kolbert takes us to the Mediterranean to a specific project studying the effects of ocean acidification. At a place called Castello Argonese there is a unique underwater feature: a vent that is spewing small bubbles of carbon dioxide around the clock. This vent is acidifying the surrounding waters, and the farther from the vent the lesser the acidification effect. This allows researchers to see what the underwater community looks like at varying acid levels. The findings are sobering. Acidification affects everything: metabolism, enzyme activity, nutrient availability, light and sound propagation, microbial community composition, and calcification.
That last one is what immediately threatens the vast group of creatures known as calcifiers, including our Mediterranean Limpet. As acid levels increase, the shells and structures built by calcifiers dissolve away. On top of this, the calcifiers cannot rebuild because the lower pH has robbed them of the necessary ions. The result is calcifiers disappeared completely from the area closest to the vent. The farther from the vent you got, the more you could find, but they look leprous and sickly as the acid eats away at their shells. We’ve seen how a meteor strike can change the rules of evolution, but here we see a subtler catastrophe. Scientists suggest that the effects of carbon emissions are “likely to leave a legacy of the Anthropocene as one of the most notable, if not cataclysmic events in the history of our planet” (124).