Table 1.

Single-cell SUP05 CO₂ assimilation rates, contribution to dark CO₂-fixation, and bulk nitrate reduction rates

	Station U1	Station L1	Station L2
SUP05 cell abundance (cells per L)
Range	1.1–9.1 × 109	0.18–4.4 × 108	0.29–2.9 × 107
Mean	1.7 × 109	1.3 × 108	1.2 × 107
Single-cell carbon fixation rates a
Number of SUP05 cells analyzed	107	67	23
Cell volume (µm3)
Mean	0.18 ± 0.01	0.39 ± 0.04	0.31 ± 0.06
Cell carbon content (fmol C per cell)
Mean	5.0 ± 0.3	6.9 ± 0.7	6.1 ± 1.2
C turnover (per day)
Mean	0.038 ± 0.03	0.025 ± .03	0.010 ± 0.02
Per-cell fixation rate (fmol C per cell per day)
Mean	0.19 ± 0.02	0.17 ± 0.02	0.06 ± 0.01
SUP05 contribution to CO 2 fixation b,c
Volumetric SUP05 CO2 fixation rates (nmol C L−1 d−1)
Range	171–592	1.3–77	0–5.1
Mean	324	22	0.7
Depth-integrated SUP05 CO2 fixation rate (mmol C m−2 d−1)	13.4 ± 1.0	8.4 ± 1.0	0.32 ± 0.07
Bulk depth-integrated dark CO2 fixation (mmol C m−2 d−1)	26.2 ± 2.0	8.0 ± 1.0	4.5 ± 0.6
% Dark CO2 fixation by SUP05	51	100	7
Measured bulk nitrate reduction rates
Dentrification to N2 (nmol N L−1 d−1)
Range	0–2044	0–15.9	0–4.3
Mean	1078	7.9	0.7
NO3− to NO2− reduction (nmol N L−1 d−1)
Range	NA	10.3–24.8	0–16.2
Mean		17.9	7.7

See Methods for details regarding single-cell calculations

^a Rates and abundances are from stations and depths, where nanoSIMS measurements were performed: station U1 (30 and 60 m); station L1 (50 and 200 m); and station L2 (200 m)

^b Calculations were made using the per-cell SUP05 CO₂ fixation rate multiplied through the range of measured SUP05 cell abundances determined in the OMZ waters

^c Dark CO₂ fixation rates integrated for station U1 over 30–65 m, L1 over 100–300 m, and L2 over 125–320 m