Salish Sea providing a ‘window’ into the future of ocean acidification (text & video)

WDFW is currently studying whether crabs could be impacted by ocean acidification, a process some scientists say Puget Sound is particularly susceptible to.

WASHINGTON — The waters of Puget Sound form the backbone of many businesses across the Pacific Northwest. They’re also central to the identity of many coastal towns in western Washington. 

The Washington State Department of Fish and Wildlife (WDFW) says it is the most valuable type of fishing in the state. WDFW is currently studying whether crabs could be impacted by ocean acidification, a process some scientists say Puget Sound is particularly susceptible to.

Aaron Dufault, a Puget Sound shellfish manager with WDFW, works with teams in the department to ensure sustainable management of Dungeness crab.

“We manage these populations using what we call 3S management, which utilizes sex, so we only allow folks to harvest males, we don’t harvest females,” Dufault said. “Then we have size. So, we have a minimum size that we allow folks to target, so we’re protecting juveniles or sub-adults there. But we also have seasons. So we make sure we’re not targeting these, targeting crabs when they’re molting, for example, when they’re vulnerable, to mortality, due to handling and stuff like that.”

They work to understand all of the processes potentially impacting Dungeness crabs, including ocean acidification. So far, based on their monitoring, ocean acidification on its own does not appear to impact adult populations. It does, however, appear to affect juvenile populations.

“Adults don’t seem to be very affected by ocean acidification, they have the ability to regulate their internal fluid, the acid-base regulation is really strong, so adults aren’t typically impacted,” Dufault said. “Juveniles, however, seem to be pretty susceptible to ocean acidification. So this is for juveniles being impacted. It’s not just a common thing to see across crustaceans, but across other taxonomic groups as well.”

At this point, ocean acidification is something WDFW is actively thinking about and needing to consider for the future, but it is not yet something driving their management of shellfish populations, Dufault said. Still, they are tracking a number of changes in the ocean that, together, are impacting several species.

Meanwhile, other research into the impacts of ocean acidification is ongoing, including work being done by oceanographers with the University of Washington.

Researchers are still working to learn how quickly ocean acidification has been increasing. That includes work by graduate researcher Mary Margaret Stoll, studying alongside Gagnon, and using coral found in Puget Sound waters to build a history of ocean acidification in the Pacific Northwest. Using specimens collected in the 1890s on a research cruise and samples of the same type of coral collected over the past year, skeletons serve as time capsules to observe how acidic the ocean was then compared to now. 

“One way we can study our role as humans in ocean acidification is to look back at past acidification, so kind of rewinding to the early 1900s before the Industrial Revolution, before we started burning fossil fuels at a large scale. We really want to know how much seawater chemistry has changed over the past century because of those activities,” Stoll said. “The Salish Sea is sitting at the leading edge of ocean acidification impacts and because of that it provides a window into future changes that might be happening in other areas in future decades.”

Stoll says they are still finishing the project and documenting the findings. Gagnon believes the results will be useful for forward-thinking approaches to anticipating and mitigating ocean acidification. 

“By understanding the pattern and pace of ocean acidification, we can know where to put our conservation resources to best protect the marine systems that we value, such as where to invest in infrastructure to mitigate the changes,” Gagnon said. “Being armed with an idea of what the future’s gonna look like, it will really help us plan appropriately.”

Eric Zucco, King5, 24 February 2022. Full article.

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