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Mimi: Dissolving Intertidal Organisms & Effects of Ocean Acidification

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Heading out to sample mussels on the Bodega Marine Reserve. Photo by Mimi Pinna

Heading out to sample mussels on the Bodega Marine Reserve. Photo by Mimi Pinna

Ocean acidification is a process in which excess carbon dioxide (CO2) from the atmosphere dissolves in the ocean, creating a lower (or more acidic) ocean pH. One quarter (25%) of the CO2 released from burning fossil fuels is dissolved into the ocean, the world’s largest storage of carbon. While this process of storing carbon has occurred throughout Earth’s history, recent levels of carbon dioxide have been so high that they have changed the ocean’s chemistry beyond “normal” historic ranges. In 2016, carbon dioxide parts in the atmosphere surpassed 400 ppm (parts per million), the highest since the Pliocene epoch, a geological period known for its warm temperatures. Carbon dioxide dissolves in the surface waters first before mixing in the deep ocean. As such, the first organisms to be affected by ocean acidification are in the intertidal or shallow surface waters.

Many animals use calcium carbonate to make their shells, from mussels to limpets. Calcium carbonate is known to break down in higher acidity or low pH environments. This can be a threat to animals who use calcium carbonate to make their shells. Still, these processes are complicated, and laboratory experiments are limited in their ability to make larger claims about the effects of shell-building on the overall marine ecosystem. Over time, even animals who are still able to make their shells will have to use more energy to do so, meaning they will have less energy to dedicate to other important processes like reproduction. This could threaten the larger intertidal and marine ecosystem.

When I worked at the Bodega Marine Lab in the summer of 2015, I was able to help monitor Dr. Emily Rivest’s mussel experiment. We started by collecting mussels from “tuffies” in the rocky intertidal. The tuffies were attractive environments for small organisms to live in. Emily would gather tuffies, filled with tiny mussels, and take them back to the lab to use for the experiment. There, we placed the mussels into tanks and let them grow in different pH environments. 

A small crab from along the Northern California shoreline. Photo by Mimi Pinna.

A small crab from along the Northern California shoreline. Photo by Mimi Pinna.

This work was extremely rewarding and enlightening for me. Strong science is critical at a time when many organisms are struggling to live in their habitats. With science, we can make well-informed decisions about how to help these organisms. Walking along the coast, searching for chitons, limpets, and colorful mussel shells is my favorite hobby. Let’s learn how to preserve this experience for generations to come!

-Mimi Pinna is a current undergraduate student at UC Davis, majoring in International Relations with an emphasis in Marine Environments. You can find her walking the California shoreline in her spare time. 

 

For more on the activities of the Hill Biogeochemistry Lab and students, see below!