Database for time-series stations K2 and S1

These data are primary production rates measured by the ¹³C method at stations K2 and S1. The measurements were conducted at eight depths which determined optically, including the surface (0 m). The data are arranged in one MS Excel file for each cruise.

Primary production (PP) was measured on board ship by using the ¹³C method developed by Hama et al. (1983) instead of the ¹⁴C method (Steeman-Nielsen, 1952; Marra and Barber, 2004). Incubations for PP measurements were conducted by the in situ incubation method by using a drifting mooring and/or the simulated in situ incubation method with light-controlled water baths on the deck of the ship. In both methods, water samples were collected at eight depths including the surface and seven depths pre-determined by an optical profiler. Samples were collected with a bucket (for surface water) or CTD/Carousel Water Sampling System (CTD: Sea-Bird 9plus, and 12-L Niskin-X bottles). The Niskin-X bottles and their Viton rubber O-rings were thoroughly acid-washed before sampling to prevent inhibition of primary production (Matsumoto et al., 2012). The PP incubation bottles were Nalgene polycarbonate bottles (about 1-L) with screw caps. All samples were spiked with 0.2 µmoles/mL of NaH¹³CO₃ solution. After being spiked, the bottles to be incubated in situ were positioned on the drifter at the depths from which the water had been collected. For simulated in situ incubations, natural sunlight was adjusted to the light level at each depth with clear blue acrylic plates on the onboard water baths. Incubations were begun before dawn and continued for 24 h. Glass fiber filters (Whatman GF/F, 25-mm diameter), pre-combusted at 450^oC for at least 2 h, were used to separate the phytoplankton from the water after the incubations. Before analysis, the filters were dried in an oven (45 ^oC) for at least 20 h and inorganic carbon was removed by acid treatment in an HCl vapor bath for 30 minutes. The ¹³C content of the particulate material was measured with an automatic nitrogen and carbon analyzer (ANCA-SL) mass spectrometer (SerCon).

The following is an explanation of the indicated columns of data.

• Hama, T., Miyazaki, T., Ogawa, Y., Iwakuma, T., Takahashi, M., Otsuki, A., Ichimura, S., 1983. Measurement of photosynthetic production of a marine phytoplankton population using a stable 13C isotope. Marine Biology 73, 31-36.
  
• Marra, J., Barber, R.T., 2004. Phytoplankton and heterotrophic respiration in the surface layer of the ocean. Geophysical Research Letters, 31, L09314, doi:10.1029/2004GL019664.
  
• Matsumoto, K., Fujiki, T., Honda, M.C., Wakita, M., Kawakami, H., Kitamura, M., Saino, T., 2012. Inhibition of primary production by nitrile rubber O-rings in Niskin sampler. JAMSTEC Report of Research and Development 14, 17-25. (in Japanese)
  
• Steemann-Nielsen E., 1952. The use of radio-active carbon (14C) for measuring organic production in the sea. Journal du Conseil International pour Exploration de la Mer 18, 117-140.