Depth, salinity, temperature, pH, total alkalinity, and dissolved inorganic carbon collected from CTD profiler equipped with a pH sensor and Niskin bottles, using a spectrophotometer, open-cell potentiometric titration, and a Licor-700 CO2 detector at the University of Washington’s Friday Harbor Laboratory or a CO2 coulometer at the University of Washington’s School of Oceanography from 2012-04-09 to 2012-06-16 (NCEI Accession 0259305)

We characterized the pH environment currently experienced by Euphausia pacifica eggs and larvae at 2 stations in the northern end of Hood Canal in Puget Sound, Washington, USA (47.61, -122.94 and 47.66, -122.86; Puget Sound Regional Synthesis Model [PRISM] stations P14 and P15). The southwest station, P14, is deeper (180 m) than the northeastern station, P15 (130 m). Samples were collected during the day and night on 9−10 April and 15−16 June 2012. This design was chosen to sample during the spawning season of E. pacifica (approximately February to July) in an area where low pH waters occur. We collected physical and chemical data using a CTD profiler equipped with a pH sensor and Niskin bottles, which were used to collect water at 6 depths for spectrophotometric pH, total dissolved inorganic carbon (DIC), and total alkalinity (TA) analyses. The CTD pH sensor was not accurate, so it was only used to determine the shape of the pH profile relative to discrete measurements. Spectrophotometric pH was measured shipboard immediately after water sampling. Total alkalinity was measured by open-cell potentiometric titration, and DIC was measured by acidification and quantification either using a Licor-700 CO2 detector, or a CO2 coulometer.