What makes shellfish unhappy? Ocean acidification

Ecology staff carry out ocean monitoring and data collection projects.

By Eli Levitt & Rhonda Hunter

In the 1990s, scientists started to investigate where carbon dioxide pollution from burning fossil fuels was going, since only about half of it was showing up in the atmosphere.

They found that about 50 percent of carbon dioxide is absorbed by the world’s oceans. Absorption of increasing levels of carbon dioxide alters the ocean’s natural state – making the ocean more acidic (this move toward the lower end of the pH scale is called ocean acidification).

Our actions affect critters with shells

Excess carbon dioxide emissions from humans burning fossil fuels such as oil and coal are causing ocean water to grow more acidic. Studies indicate that ocean acidity has increased about 25 percent since the start of the industrial age (more details are in Ecology’s FAQ on ocean acidification).

And it turns out that more acidic sea water will likely have a negative impact on ocean species – especially those that form shells such as corals, oysters, and plankton.

Higher than normal acidity prevents shelled critters from forming their shells, and a shell-less ocean critter is less likely to survive. Plankton floating in ocean water have small shells, and these plankton are the basis of the ocean food chain. Other shelled species such as oysters, mussels, and corals are also at risk from acidification.

Acidification can harm Washington's oysters

The disturbing part is that on Washington’s own coast, scientists are seeing impacts that could be due to ocean acidification. For the last six years, Pacific oysters in Willapa Bay have not reproduced (see the story in The Seattle Times). Although the cause has not been determined, acidic waters may have contributed to the recent declines in oyster survival. As scientists work quickly to learn about the potential impacts, the data they have found so far has been put to use by hatcheries. Oyster hatcheries now monitor pH and actively seek out noncorrosive water to use and the larvae are back this year.

And scientists working on a study in Neah Bay recently confirmed that coastal shellfish such as mussels and barnacles are also showing signs of weakened shells – see a new video on the project. The research and monitoring by scientists is crucial to determining the threat. Developing ways to adapt to changing conditions and sharing information among the various groups involved will be key, too.

The time to take action is now!

Ocean acidification is very concerning to people in coastal communities, scientists, and those working in the shellfish industry in Washington. Of course, more research and monitoring needs to be done. But the evidence is growing: ocean waters are becoming more acidic. The big question that still needs to be answered is: what will be impacted and how quickly?

There are many reasons to work hard to slow climate change and avoid the worst impacts. And now, the health of our planet’s oceans makes the case to accelerate our response to climate change. Ocean acidification is a growing concern in Washington state and a compelling reason to take action.

If you want to track what our state is doing about climate change, sign up with our listserv to receive updates. And get involved at the local level to show your concern. See Ecology’s Ocean Resources webpage for more information.

---