HOT-288 SKQ201615S 14C NPP

These Simons Collaboration on Ocean Processes and Ecology (SCOPE) data products were produced by the University of Hawaiʻi at Mānoa with support from the Simons Foundation. The HOT288 cruise on the R/V Sikuliaq was performed from November 25th to 29th, 2016 at Station ALOHA (22.75, -158) north of Oahu, Hawaii. Standard HOT protocols were used to measure in vitro primary productivity (PP) via the 14C radiotracer method [Karl et al., 1996]. Water samples were collected from ~5m before dawn and incubated on deck in incubators screened to ~50% of surface irradiance and plumbed with flow through surface seawater for temperature regulation. Duplicate 500-ml bottles were incubated in the incubator for ~12hr and 24hr, light bottles were paired with dark bottles. A time zero sample was taken at each station to ensure acidification was complete. Following dawn to dawn incubations, each sample was filtered onto a 25mm glass fiber filter. Filters were acidified with 1 ml of 2N hydrochloric acid in a fume hood for 12 hr to remove inorganic 14C after which 10 ml of Ultima Gold scintillation fluid was added to each sample. Radioactivity was determined using a Perkins Elmer 2600 liquid scintillation counter. The rate of PP was calculated by multiplying the percent of carbon labeled by the total carbon available for photosynthesis (e.g. dissolved inorganic carbon, DIC, calculated from SST and salinity measured at each station as per Lee et al. [2006]) and dividing by incubation time (t = 1 day). Rate measurements in light bottles were corrected to remove the rate measured in parallel dark bottles. All rates are in units mg C m-3; ‘stdev’ refers to the standard deviation of duplicates for each incubation type. Samples from 11/27 should be used with caution as the incubators were heavily shaded at times. The timestamp is in UTC.