Event Title

The combined effects of acidification and hypoxia in Washington coastal waters

Presentation Abstract

The continental shelf waters off the Washington and British Columbia coasts are exposed to water with increasing concentrations of anthropogenic CO2 (Canthro) from exchanges with the atmosphere. We used the 2nd order polynomial approach described in Feely et al (2016) to determine the spatial variations of Canthro in the California Current Ecosystem based on cruise data sets from 2007, 2011, 2012, 2013 and 2016. Our results show large vertical gradients in Canthro in subsurface waters, in which Canthro increases at a rate of ~1 µmol kg-1 yr-1 in surface waters, and decreases to values of ~0.3 µmol kg-1 yr-1 at depths near 400 m. Carbon chemistry data from the surface and subsurface waters of the West Coast of North America have also been compared with similar data from the northern Gulf of Mexico to demonstrate how future changes in CO2 emissions will impact coastal waters affected by respiration-induced hypoxia (<62 µmol kg-1 O2). In surface waters, the percentage change in the carbon parameters due to increasing CO2 emissions are very similar for both regions even though the absolute decrease in aragonite saturation is much higher in the warmer waters of the Gulf of Mexico. However, in subsurface waters the changes are enhanced due to the differences in the initial oxygen concentration and the changes in the buffer capacity (i.e., increasing Revelle Factor) with decreasing oxygen concentration, with the largest impacts on pH and CO2 partial pressure (pCO2) occurring in the colder waters. As anthropogenic CO2 concentrations increase in subsurface waters, the increased atmospheric CO2 will expose organisms to hypercapnia conditions (>1000 µatm pCO2) within subsurface depths. The extent of exposure will occur sooner and more widespread in colder surface and subsurface waters. This phenomenon is a result of the changing initial carbonate and oxygen chemistry and increasing Revelle Factor.

Session Title

Ocean Acidification: Observations and Monitoring in Salish Sea Waters

Conference Track

SSE5: Climate Change: Impacts, Adaptation, and Research

Conference Name

Salish Sea Ecosystem Conference (Seattle, WA : 2018)

Document Type

Event

SSEC Identifier

SSE5-244

Start Date

5-4-2018 10:00 AM

End Date

5-4-2018 10:15 AM

Type of Presentation

Oral

Contributing Repository

Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.

Geographic Coverage

Salish Sea (B.C. and Wash.)

Rights

This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.

Type

text

Language

English

Format

application/pdf

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Apr 5th, 10:00 AM Apr 5th, 10:15 AM

The combined effects of acidification and hypoxia in Washington coastal waters

The continental shelf waters off the Washington and British Columbia coasts are exposed to water with increasing concentrations of anthropogenic CO2 (Canthro) from exchanges with the atmosphere. We used the 2nd order polynomial approach described in Feely et al (2016) to determine the spatial variations of Canthro in the California Current Ecosystem based on cruise data sets from 2007, 2011, 2012, 2013 and 2016. Our results show large vertical gradients in Canthro in subsurface waters, in which Canthro increases at a rate of ~1 µmol kg-1 yr-1 in surface waters, and decreases to values of ~0.3 µmol kg-1 yr-1 at depths near 400 m. Carbon chemistry data from the surface and subsurface waters of the West Coast of North America have also been compared with similar data from the northern Gulf of Mexico to demonstrate how future changes in CO2 emissions will impact coastal waters affected by respiration-induced hypoxia (<62 >µmol kg-1 O2). In surface waters, the percentage change in the carbon parameters due to increasing CO2 emissions are very similar for both regions even though the absolute decrease in aragonite saturation is much higher in the warmer waters of the Gulf of Mexico. However, in subsurface waters the changes are enhanced due to the differences in the initial oxygen concentration and the changes in the buffer capacity (i.e., increasing Revelle Factor) with decreasing oxygen concentration, with the largest impacts on pH and CO2 partial pressure (pCO2) occurring in the colder waters. As anthropogenic CO2 concentrations increase in subsurface waters, the increased atmospheric CO2 will expose organisms to hypercapnia conditions (>1000 µatm pCO2) within subsurface depths. The extent of exposure will occur sooner and more widespread in colder surface and subsurface waters. This phenomenon is a result of the changing initial carbonate and oxygen chemistry and increasing Revelle Factor.