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

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