Bye-Bye Bivalves
BY FARRAH LEONE
What covers 75% of the earth and has the ability to deteriorate CaCO3, the same material our bones are made up of? Our oceans!
Here’s the chemistry crash course you didn’t ask for: Acidity is measured in pH on a scale of 0 (most acidic/least basic) - 14(most basic/least acidic). Each number on the scale indicates a 10x difference in acidity or alkalinity. Something with a pH of 1 is 10x less acidic than something with a pH of 0. Liquids become more acidic with the presence of positive Hydrogen Ions (hydrogen with less electrons).
As you’ve probably been told, fossil fuels from cars, factories, and more send out carbon dioxide at a rate which is too high for the earth to recycle. This over abundance of carbon dioxide in the atmosphere acts as a blanket on earth, holding in too much heat for the earth to handle safely. The ocean attempts to balance this scale by working as a sponge for carbon dioxide from the atmosphere, called “a carbon sink”. It sinks the carbon dioxide into the water where it interacts with water (hydrogen dioxide) to create Carbonic Acid. This acid then breaks down into hydrogen ions (what makes the ocean more acidic) and Bicarbonate. Bicarbonate cannot combine with calcium in order to form shells. Shells are made up of calcium and carbonate to create ‘Calcium Carbonate’ a.k.a. CaCO3. This impacts many different species that use CaCO3 in their bodies such as clams, corals, crabs, and more. The ocean has absorbed about 550 billion tonnes of carbon dioxide into the ocean out of the 2 trillion we have released into the atmosphere over the past two centuries.
What uses Calcium Carbonate you ask? Shellfish and corals which provide ecological, recreational, and economic services!
Models by WHOI have predicted that by 2100, there can be a 20% decrease in coral density in parts of the Coral Triangle. Coral reefs constantly thicken their skeleton in order to protect and repair the damage of the species that live around them. Weaker coral leads to more breakage and less habitat, protection from predators, and available food for the entire ecosystem. Not only does it impact the skeleton, but Ocean Acidification has been proven to impact the fertilization of new coral. The highest sperm concentration in these experiments showed that with a moderately acidic environment, fertility would decrease 7%. But in a high acidic environment, it had the potential to decrease up to 12%. The same research also notes that excess carbon is linked to a decrease in flagellar motility. Urchins and some corals will release eggs and sperm into the water with hopes that they will find each other for fertilization. A decrease in flagellar motility means that the tail sperm use to swim with (flagella) is not moving efficiently and is having a difficult time reaching eggs to be fertilized. After analysis of all other factors, it is estimated that an acidic environment could lead to a 52-73% decrease of coral larvae settling and thriving. In the United States alone, coral reefs have been attributed with a commercial value of $100 million! I’m horrible with numbers so let’s frame it like this; all of Taylor Swift’s homes are worth $81 million dollars. With that kind of money you can buy 5.8 of Taylor Swift’s luxury Watch Hill, RI mansions (worth $17 million) on the water.
In a 2017 study on Blood Clams, an economically important species found in Asia, exposure to lower pH levels lead to a decreased aerobic metabolic rate, feeding activity, and integrity of the outside of the shell. In another study on Mussels, the timing of larval exposure to low pH impacts hinge development, however there is no evidence that it impacts internal fitness at this moment.
In an experiment on the Long Island Sound, Oysters exposed to lower pH levels were significantly lighter in weight than those of normal water levels. Multiple sources have listed that acidic water has a corrosive impact on shell-bearing animals. Take a look at the video on this case study: The Puget Sound. If you thought buying 5.8 of Taylor’s houses was ridiculous, the USA the shellfish industry is worth $340 million! That’s 20 Watch Hill houses!
Ocean acidification has the ability to impact all of us: from the creatures of the sea to your business. If we want to protect our resources and our livelihood, we need to start taking action against ocean acidification and the other debilitating side effects of climate change.