Amplified bottom water acidification rates on the Bering Sea shelf from 1970–2022
<p>The Bering Sea shelf supports a highly productive marine ecosystem that is vulnerable to ocean acidification (OA) due to the cold, carbon-rich waters. Previous observational evidence suggests that bottom waters on the shelf are already seasonally undersaturated with respect to aragonite (i....
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-07-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/22/3103/2025/bg-22-3103-2025.pdf |
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| Summary: | <p>The Bering Sea shelf supports a highly productive marine ecosystem that is vulnerable to ocean acidification (OA) due to the cold, carbon-rich waters. Previous observational evidence suggests that bottom waters on the shelf are already seasonally undersaturated with respect to aragonite (i.e. <span class="inline-formula">Ω<sub>arag</sub><1</span>) and that OA will continue to increase the spatial extent, duration, and intensity of these conditions. Here, we use a regional ocean biogeochemical model to simulate changes in ocean carbon chemistry for the Bering Sea shelf from 1970–2022. Over this timeframe, model results suggest that surface <span class="inline-formula">Ω<sub>arag</sub></span> decreases by <span class="inline-formula">−0.043</span> per decade and surface pH by <span class="inline-formula">−0.014</span> per decade, comparable to observed global rates of OA. However, bottom water pH decreases at twice the rate of surface pH, while bottom [H<span class="inline-formula"><sup>+</sup></span>] decreases at nearly 3 times the rate of surface [H<span class="inline-formula"><sup>+</sup></span>]. This amplified bottom water acidification has emerged over the past 25 years and is likely driven by a combination of anthropogenic carbon accumulation and increasing primary productivity and subsurface respiration and remineralization. Due to this enhanced bottom water acidification, the spatial extent of bottom waters with <span class="inline-formula">Ω<sub>arag</sub><1</span> has greatly expanded over the past 2 decades, along with pH conditions harmful to red king crab. Interannual variability in surface and bottom <span class="inline-formula">Ω<sub>arag</sub></span>, pH, and [H<span class="inline-formula"><sup>+</sup></span>] has also increased over the past 2 decades, resulting in part from the increased physical climate variability. We also find that the Bering Sea shelf is a net annual carbon sink of 1.1–7.9 Tg C yr<span class="inline-formula"><sup>−1</sup></span>, with the range resulting from the difference in the two different atmospheric forcing reanalysis products used. Seasonally, the shelf is a significant carbon sink from April–October but a somewhat weaker carbon source from November–March.</p> |
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| ISSN: | 1726-4170 1726-4189 |