The Natural Cycles in the Gulf of Alaska Accentuate Ocean Acidification
According to new study from the University of Alaska Fairbanks, changes in major wind and ocean circulation systems can briefly accelerate or reverse the rate of ocean acidification in the Gulf of Alaska.
According to Claudine Hauri, a researcher at the UAF International Arctic Research Center, ocean acidification is typically viewed as a slow push on the environment that gradually affects the carbon chemistry in the seawater.
The findings from the study, stated by Hauri, demonstrates that the chemical circumstances faced by marine organisms may fluctuate on a daily and seasonal basis. Despite a long-term trend of ocean acidification due to an ongoing rise in atmospheric CO2 levels, this variation occurs. The most recent study also reveals massive cycles that occur every 5 to 10 years.
Chemical pollution levels in offshore areas will deteriorate for a long time before settling or possibly improving,” according to co-author Andrew McDonnell of the University of Alaska Fairbanks College of Fisheries and Ocean Sciences. “We don’t know how the organisms will react to that.” Some bacteria, on the other hand, are often sensitive to changes in environmental factors.
Hauri and her colleagues used a model that incorporates biogeochemical, physical, and hydrological ocean models to simulate past Gulf of Alaska conditions from the years 80 to 2013.The study discovered natural decadal changes in chemical conditions caused by the strength of the North Pacific subpolar gyre.
This gyre is a massive system of circulating ocean currents driven by wind that influences the Gulf of Alaska. When the gyre is powerful, it brings more carbon-rich deep water to the ocean’s surface. This can hasten ocean acidification, resulting in extreme events that stress delicate microorganisms. When the gyre is weak, significantly less carbon is transferred to the surface, reducing or reversing the ocean acidification consequence.
From 2011 to 2013, the model identified a critical phase of the gyre that resulted in an extreme ocean acidification event in the Gulf of Alaska’s core. This occurred before to the 2014-2016 “blob” of unusually warm water in the same region.
“The blob appeared right after a powerful ocean acidification event,” explained Hauri. “Initially, some organisms may have been stressed due to ocean acidification, and then they were hit with heat.”
More research is needed, according to Hauri, to understand the effects of numerous concurrent stress factors on marine ecosystems and to discover how ocean acidification and climate change combine.
Another conclusion of this study is that numerous decades of empirical data are required to distinguish the long-term trend of ocean acidification from natural fluctuation caused by the strength of the subpolar vortex. There is presently no such dataset for the Gulf of Alaska.
Hauri and her colleagues hope that this work and the efforts it inspires will provide important information for those who participated in subsistence and commercial fishing as they prepare and adjust for the coming years.
Originally published on Sciencedaily.com. Read the original article.
Reference: Claudine Hauri, Rémi Pagès, Andrew M. P. McDonnell, Malte F. Stuecker, Seth L. Danielson, Katherine Hedstrom, Brita Irving, Cristina Schultz, Scott C. Doney. Modulation of ocean acidification by decadal climate variability in the Gulf of Alaska. Communications Earth & Environment, 2021; 2 (1) DOI: 10.1038/s43247-021-00254-z
