CLIMATE COCKTAIL:
The Veliger
Ocean Acidification

OCEAN ACIDIFICATION

Most of us don’t think about the chemistry at work in a great-tasting cocktail, we trust the bartender to get things just right. But the chemistry of our oceans should get our full attention because it's gotten way out of balance, which threatens marine critters big and small that we love, and depend on.

Our world’s oceans are giant carbon sinks. They soak up more CO₂ from the atmosphere than they release, but they can't suck up an infinite amount, and the equilibrium atmosphere to ocean -- is getting increasingly out of whack, hence -- ocean acidification.

Baby Oysters Up Close

Baby Oysters develop in the open ocean as tiny winged shells called veligers. They make their shells fast and cheap, using a type of calcium carbonate called aragonite that easily dissolves. If they survive, veliger shells become the adult oyster's inner shells once they metamorphize.

When seawater becomes more acidic from too much C0₂, its carbonate chemistry fluctuates and makes veliger shells even more prone to dissolve.

On the U.S. west coast and around the world, ocean acidification storms are caused by poor water quality, increasing acidity so much that veligers and other critters cannot develop properly. These tiny creatures are the bottleneck for the entire west coast oyster farming industry, so ocean acidification is a direct threat. Other mollusks, and in fact all ocean animals with shells, are similarly impaired by acidification all over the world.

Seagrass and Kelp
to the Rescue?

While it's unclear how humans can mitigate the impact of ocean acidification on ocean life forms in deep waters, in coastal areas there are some promising signs that kelp and seagrass can help oysters adapt, at least on a small scale that could benefit Northwest coastal communities.

Just as forests of trees soak up CO₂ via photosynthesis to mitigate climate change on land, scientists with the Puget Sound Restoration Fund₁ in Oregon and Washington are studying whether they can use photosynthesis to soak up carbon in seawater to mitigate ocean acidification. Their research focuses on whether multi-acre, fast-growing sugar kelp forests can reduce pH levels in coastal waters enough to keep oysters healthy and provide safe habitat for other marine species. Since Puget Sound waters' pH levels often dip to 7.8 (highly acidic), they are a good testing ground for whether kelp forests will bring pH levels up to more normal levels.

Similarly, researchers in Oregon have discovered that seagrass may be another effective way to keep ocean acidification under control. Seagrass, like kelp, converts carbon to energy through photosynthesis but goes one better: unlike kelp, which must be harvested each year to prevent CO2 from being released back into the ocean, seagrass sequesters and stores carbon long-term in its roots.

While research is ongoing, some promising practical applications have emerged. If you're a Veliger cocktail enthusiast or simply a fan of oysters, you'll be happy to know growing oyster aquaculture beds with seagrass growing around and amongst them produces immediate reductions in seawater pH and, as a result, a healthy oyster harvest and a potential lifeline for coastal communities that have relied on oyster production for generations.

FEATURING

_REFERENCES

_{¹ Puget Sound Restoration Fund. Retrieved at https://restorationfund.org/}