Alaska waters are showing effects of increasing acidity faster and more severely than lower latitudes because cold water is richer in carbon dioxide and melting sea ice and glaciers are worsening the problem.
That’s the verdict in the 2019 report by the Alaska Ocean Acidification Network which updates the science going on around the state.
The off kilter ocean chemistry reduces the amount of minerals sea creatures need to build and maintain their shells.
At Sitka, researchers are testing the effects of acidification and ocean warming on the earliest life stages of herring; early signs point to warming as the bigger threat. At the Alutiiq Pride Shellfish Hatchery at Seward, studies on razor clams indicate they are hurt by increasing acidity.
The tiny swimming sea snails called pteropods are already showing extensive shell corrosion in both the Gulf of Alaska and Bering Sea. Pteropods make up 40 percent of the diet of pink salmon.
The Alaska Network has modeled 40 years of ocean changes in the Gulf and is doing the same for the greater Arctic.
The 2019 report also updates the monitoring being done since 2017 by the ferry Columbia as part of an Alaska/Canada project to learn how increasing ocean acidity affects fisheries.
Wiley Evans is with the Hakai Institute and program technical lead –
“The fantastic thing about this vessel is it’s going from Bellingham to Skagway and back every week. That’s a 1,600-kilometer run. Nowhere in the world is there a ferry system that’s outfitted with CO2 sensors that’s running that scale of a transit. This is really exciting.”
The 418-foot ferry sucks up water samples every two minutes and has produced more than 700,000 measurements.
Early data point to an extremely variable seascape in which the surface water is more corrosive in fall and winter, representing the most vulnerable time for species that are sensitive to acidity. When spring arrives, the phytoplankton bloom removes CO2 from the water through photosynthesis, and the water gets warmer making conditions more favorable for shell production.
So far, only a limited number of Alaska’s commercially important species have been studied for their response to increasing acidity.
Laine Welch, Alaska Fish Radio, 30 December 2019. Article.
