This summer, ocean temperatures have been extraordinarily warm and that has led to a lot of discussion about climate change and its impacts on marine life. One of those impacts that isn’t exactly related to temperature, but is related in another somewhat tricky way is acidification. Acidification is the increasing acidity or pH of the ocean water. It is the result of a number of factors including increases in carbon dioxide in the atmosphere that gets absorbed into the water.

Climate change includes a large set of variables and is a large problem to address. In Maine, the Governor’s Climate Council is tackling the issue and has been working hard with a team of policymakers and scientists to come up with strategies to adapt to changes in the ocean. Specifically, the Coastal and Marine Working Group of the Maine Climate Council (MCC) has been looking at things like impacts to local fisheries and changes to habitat along with impacts to working waterfront areas. The released a set of draft strategies at the beginning of the summer and are now gathering public input on those strategies in order to determine next steps (https://climatecouncil.maine.gov/).

On a smaller scale – sometimes a very small scale – one aspect to focus on is the marvel that is a seashell. Many ocean animals rely on shells to protect them from their environment and from predators. That’s because many of them are invertebrates, which means that they have no bones inside of their bodies. But, it doesn’t mean they don’t have bones of a different sort. Instead, these animals put their energy into building an external “skeleton”. That might be a crab or a lobster with a segmented shell. Or, it might be a periwinkle with its delicately whorled shell. Regardless, all of these animals need certain ingredients to build their shells. And, they have to find these ingredients in the environment they live in.

So, exactly what ingredients do they need? The requirements are similar to those that humans need for their bones – calcium being one of the major ones. We get our calcium from foods like dairy and other dietary sources. But, the way that sea creatures get theirs is a little different. While some sea creatures eat their shells as a way of recycling the minerals they need to build a new shell, they have to absorb most of what they need right out of the water. The two critical components are calcium and bicarbonate and sea creatures combine them to make carbonate, the material of shells.

Then, you have the essential mixture, but how does it work? The growth of a snail shell is one of the most fascinating. If I were a stellar mathematician, I could explain it much better. But, it has something to do with the golden ratio that starts with a small spiral and grows logarithmically, repeating itself over and over again. Fibonacci numbers fit in there somewhere as well. These are the same number sequences that dictate the growth patterns of a sunflower or a pattern of a sunflower or a pinecone. The snail lays down layers of calcium carbonate according to this specific pattern. This is, of course, different for other shell-building marine animals.

But, let’s get back to the connection to ocean conditions. The increased carbon dioxide in seawater binds to carbonate ions, using them up so they are no longer available to shell-building animals that combine them with calcium to form calcium carbonate – the stuff they need for their shells. Temperature also plays a role because higher temperatures can mean that even when calcium and carbonate come together, the result isn’t very stable so the two parts don’t always stay together. Without enough of both of these, shell-building creatures are left with weaker building blocks with which they have to make due. That results in structurally weak scaffolding that isn’t as tough against both the environment and predators. This is particularly true for the youngest, most vulnerable shelled creatures. In addition, the acidity of the water can erode a shell even after it has formed.

That aside, when you pick up that tiny whorl, don’t focus too much on the chemical equation or the mathematical trajectory of its building. But instead, wonder at the art of natural construction and the creation of a curve that is so perfect regardless of whether it had the perfect mixture of ingredients.