Drowning in Acid: The Effects of Ocean Acidification
Joyce Xi
Hillcrest Middle School
Floor Location : J 226 V

The oceans are a precious natural resource for organisms, home to over 1 million known species of flora and fauna, and possibly millions more. For billions of years, they have absorbed vast quantities of carbon dioxide and has retained its important role in the carbon cycle. Acid regulation had always been in control, with the ocean's waters never going below the pH of 8, until the humans came along and started destroying the planet with our greenhouse gas emissions, which some scientists say have been in higher concentrations than ever before in earth's history. While some may talk about problems with air pollution and global warming, a much more silent killer is on the loose: ocean acidification, also known as climate change’s evil twin. Increased absorption of carbon dioxide into the oceans forms carbonic acid, which in turn lowers the pH of the oceans. What sort of effects will this have on marine life? In this experiment, I see how this affects various bivalves, mainly in terms of mass loss.
I randomized 36 (empty) shells into groups of 4, each containing 3 of each variety of bivalve I chose to use (manila clam, mussel, and varnish clam). I then obtained 4 glass jars and filled 3 of them with seawater. However, I mixed vinegar into two of those seawater jars and measured one's pH to about 7 (projected pH of oceans in year 2100) and the other to about 5 (pH of oceans in year 2500). The remaining jars were the control jar (regular seawater, pH 8) and the negative jar (regular tap water, pH 7). I predicted the manila clam shell would lose the most mass after one month because it is composed mostly of calcium carbonate (which dissolves easily when it makes contact with acid). I believed the mussels would keep together for a longer period of time due to the proteins contained in its shell. As for the varnish clam, I believed it would be a combination of both the mussel and manila in terms of mass loss.
In the end, I found the manila clams had the most physical and visual changes, with most of the weight loss in the acidic jars being attributed to those shells. The mussels had no weight loss, which I discovered was due to a special protein binding carbonate molecules together. The varnish clam had no significant weight changes, but a lot of its protective covering was missing in the acidic jars.
Overall, my observations and results show the end result of carbonate-dependent creatures being exposed to acidic conditions. Climate change action MUST be taken now, or else we will be leaving these innocent creatures to drown in a sea of acid.