Assessment of ocean acidification and biological response in Washington state coastal and estuarine waters

Chair: Victoria Cole

Jan Newton (1), Richard Feely (2), Simone Alin (2), Nina Bednarsek (1), Terrie Klinger (1)

1 University of Washington, Seattle, WA, 98105, USA; 2 NOAA Pacific Marine Environmental Lab, Seattle, WA USA

Background
Established by the Washington legislature in 2011, the Washington Ocean Acidification Center is charged to establish an expanded and sustained ocean acidification monitoring network to measure trends in local acidification conditions and related biological responses. This monitoring will allow detection of local acidification conditions and increase our scientific understanding of local species responses.

Methods
The Washington Ocean Acidification Center is using a mix of moored sensors and ship-board cruises to assess pH and aragonite saturation state in the coastal waters of Washington and within Puget Sound. Additionally, we are measuring shell dissolution of planktonic calcifiers, pteropods, at key stations.

Findings
Corrosive waters are evident seasonally at depth and at the surface. Because the stratification and dynamics of Washington’s waters vary dramatically, so too do water properties and the nature of exposure to corrosive conditions. Off the coast, upwelling dominates the signal with more corrosive conditions during summer. In Puget Sound, stratified areas have strong gradients in corrosivity, with summer surface conditions less corrosive than deep waters. While pteropod shells show minor dissolution off the coast, this becomes more severe in Puget Sound, correlating with intensity and duration of seawater corrosivity. Some shells in productive (and corrosive) areas of Puget Sound even have holes.

Conclusions
Monitoring over space and time are essential to understanding spatial and temporal patterns of ocean acidification in coastal waters, where inherent variability is higher. Corrosive waters and impacts on native species are occurring now.