Ocean Acidification is Killing our Beloved Shellfish

By Sara Ghandour

As you walk through a fish market, your eyes dart to your favorite section: the shellfish. These nutritious and delicious creatures are mouthwatering, just begging to be bought. However, as you approach them, something deters you. Their shells look different than what you imagined. They are cracked eggs, brittle and white, weak to the touch. As you scan the shelves, you see that not one, but hundreds have the same weakened shells. These organisms are supposed to be robust and dark, so why have they deteriorated so much? The answer is ocean acidification. 

What is ocean acidification? This phenomenon is one of the most abundant threats to marine ecosystems, especially bivalve shellfish. Because of anthropogenic climate change, the carbon dioxide levels in our oceans have skyrocketed–lowering pH levels in the water and increasing its acidity.

At the rate the oceans are acidifying, shellfish are struggling to adapt. Bivalve shells are composed of a chemical compound called calcium carbonate which these organisms produce by extracting calcium and bicarbonate from the waters they reside in. As acidification patterns increase in our oceans, the ability of shellfish to produce calcium carbonate decreases. The result is fragile shells with chipped white flakes that indicate acidification.

Photo Credit: N. Sezer/Istanbul University

This is critical because shellfish play a fundamental role in the ecosystem by providing many protection and filtration services. By organizing themselves in walls, they can block rough waves and turbulent waters from reaching the coastline. However, their strength as a unit is decreasing because of increasing acidification. Thus, the formation that was once a robust castle is now an abandoned cabin, weak and deteriorating. These powerful creatures not only prove to be a strong defense as a unit, but each individual possesses a power: filtration. Bivalves can remove both toxins and nitrogen from our waters. Even though shellfish are minuscule compared to many other organisms, the continuing impact of acidification on them and their environment will be enormous. 

When bivalves lose their filtration abilities, nitrogen levels rise in the oceans and increase eutrophication rates. Eutrophication is the absorption of chemicals such as nitrogen and phosphorus into our oceans.  These chemicals provide nutrients and facilitate the growth of toxic microscopic organisms called harmful algae. When the algae die and decompose, they strip oxygen from the waters, creating a hypoxic condition called the “dead zone.” This affects marine organisms and can also harm the people who depend on these waters. 

Shellfish not only have environmental impacts, but they also play a major role in the lives of people all around us. This is because they are a highly sustainable and green part of the aquaculture industry. But if our acidification patterns continue to increase over time, the predicted cost of shellfish production loss would be over 100 billion US dollars and thousands of jobs (Narita et al. 2012). This is detrimental because, alongside their impacts on the livelihood of many people, shellfish provide excellent nutritional value by having high amounts of iron, zinc, magnesium, and vitamin B12. 

Large-scale environmental issues such as ocean acidification often make us feel hopeless and paralyzed, but we, as individuals, have the power to affect change. Getting involved in local activities that promote climate change conservation is a great way to make a difference! With that, organizations like the National Ocean and Atmospheric Administration (NOAA) gives tips on how to play your part in ocean conservation with articles like 50 Ways To Love Your Ocean And Coast. This is a great source to help you learn about all the opportunities and actions you can take to make a change. These include small individual steps to reduce your carbon footprint, and ways you can reach out and get involved within your community and with fellow activists. If we work together, our environment will show significant improvement and fuel our hope for significant change. By reducing ocean acidification we will not only help shellfish, but the domino effect of our efforts can save so much more.