Type of Presentation

Oral

Session Title

Ocean Acidification in the Salish Sea

Description

Ecology conducted a pilot study to add key acidification variables to the long-term marine monitoring network. Funding covered monthly samples collected over a year from six sites that span the range of ocean influence from Admiralty Inlet inland to the finger inlets of South Puget Sound. The focus was on the logistics of collecting sufficient sample volume from within the space-constrained sea plane as well as the logistics of partnering with NOAA on sample analysis and reporting. The subsequent data provide a valuable overview of the seasonal variability of acidification variables, including aragonite saturation state.

We focused on surface waters to capture high near-surface variability across sampling dates, as other programs are not able to sample as frequently. The surface layer also serves a critical role in many species life stages. Samples were analyzed for alkalinity and dissolved inorganic carbon by NOAA’s Pacific Marine Environmental Laboratory. We calculated aragonite saturation state, pH, and pCO2 under in situ conditions using CO2SYS.

Aragonite saturation state was lowest in the winter months (October through March), when both primary productivity and stratification reach their seasonal lows. Aragonite saturation values below 1.0 indicate corrosive conditions. Between April and September, the aragonite saturation state was often between 1 and 2, at values where some non-lethal species effects have been shown in laboratory studies. The surface pH followed similar seasonal patterns, with higher and more variable pH in the summer and lower in the winter.

Surface water pCO2 was greater than atmospheric pCO2 in the winter months, indicating that CO2 was outgassing to the atmosphere from the water. During the summer months, surface water pCO2 varied above and below atmospheric pCO2, indicating that CO2 was moving both directions depending on the location.

Results will inform the acidification source attribution model of the Salish Sea currently under development.

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Seasonal variation in aragonite saturation state in surface waters of Puget Sound – A pilot study

2016SSEC

Ecology conducted a pilot study to add key acidification variables to the long-term marine monitoring network. Funding covered monthly samples collected over a year from six sites that span the range of ocean influence from Admiralty Inlet inland to the finger inlets of South Puget Sound. The focus was on the logistics of collecting sufficient sample volume from within the space-constrained sea plane as well as the logistics of partnering with NOAA on sample analysis and reporting. The subsequent data provide a valuable overview of the seasonal variability of acidification variables, including aragonite saturation state.

We focused on surface waters to capture high near-surface variability across sampling dates, as other programs are not able to sample as frequently. The surface layer also serves a critical role in many species life stages. Samples were analyzed for alkalinity and dissolved inorganic carbon by NOAA’s Pacific Marine Environmental Laboratory. We calculated aragonite saturation state, pH, and pCO2 under in situ conditions using CO2SYS.

Aragonite saturation state was lowest in the winter months (October through March), when both primary productivity and stratification reach their seasonal lows. Aragonite saturation values below 1.0 indicate corrosive conditions. Between April and September, the aragonite saturation state was often between 1 and 2, at values where some non-lethal species effects have been shown in laboratory studies. The surface pH followed similar seasonal patterns, with higher and more variable pH in the summer and lower in the winter.

Surface water pCO2 was greater than atmospheric pCO2 in the winter months, indicating that CO2 was outgassing to the atmosphere from the water. During the summer months, surface water pCO2 varied above and below atmospheric pCO2, indicating that CO2 was moving both directions depending on the location.

Results will inform the acidification source attribution model of the Salish Sea currently under development.