Newswise – New research from the University of Alaska Fairbanks has shown that ocean circulation and wind fluctuations can temporarily speed up or reverse ocean acidification in the Gulf of Alaska.
” We often think of ocean acidification in terms of a slow pressure on the environment that slowly changes the carbon chemistry within the ocean,” said Claudine Hauri, an Arctic Research Center researcher at UAF International Arctic Research Center.
Hauri stated that marine organisms’ chemical conditions can shift on a daily or seasonal basis. This fluctuation is despite the long-term trend towards ocean acidification due to an increase in atmospheric carbon dioxide levels. New research also shows that there are massive cycles every five to 10 year.
“Chemical situations will deteriorate in offshore areas for many years before stabilizing or improving slightly again,” stated Andrew McDonnell, co-author from the UAF College of Fisheries and Ocean Sciences. “We don’t know exactly how organisms respond to that, but in general some organisms are sensitive to these types of changes in environmental conditions.”
Hauri and her team examined ocean acidification through a model that combines physical, biogeochemical and hydrological ocean models to reproduce past Gulf of Alaska conditions from 1980-2013.
The study revealed natural decadal fluctuations within chemical conditions that are driven primarily by the strength and influence of the North Pacific subpolar Gyre.
This gyre, which is large and driven by wind, affects the Gulf of Alaska with its circulating ocean currents. The ocean’s surface is flooded with more carbon dioxide-rich deep water when the gyre is strong. This can lead to ocean acidification and extreme events that can cause stress for sensitive organisms. The gyre’s strength can reduce carbon delivery to the surface. This can either dampen or reverse the ocean acidification effect.
The model revealed that the strong phase of gyre caused extreme ocean acidification in the middle of the Gulf of Alaska. This event preceded the 2014-2016 “blob” of exceptionally warm water in the same region.
” The blob occurred right after the very strong ocean acidification events,” Hauri explained. “First, some organisms were likely stressed by ocean acidification, then they were hit with heat,” Hauri explained.
Hauri highlighted that more research is required to better understand the effects of multiple stressors on marine ecosystems and how climate change and ocean acidification interact.
Another consequence of this work is the need for multiple decades of observational evidence to distinguish the long-term trend in ocean acidification from natural variability caused by the strength and subpolar gyre. For the Gulf of Alaska, this type of data is not yet available.
Hauri hopes that her work and the effort it inspires will provide the information needed for those involved in subsistence and commercial fishing as they plan for the future.
Co-authors include Remi Pages, Malte Stuecker, Seth Danielson, Katherine Hedstrom, Brita Irving, Cristina Schultz and Scott Doney.
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