Table 3. Chemoautotrophic growth rate, uptake, and chemosynthate release fluxes of C (Tg year⁻¹) and P (Gg year⁻¹) in the global ocean.

Estimates are based on measured ratios of N. maritimus NAOA6 fluxes of C and P relative to nitrite production during radiotracer experiments (Table 1 and fig. S5) and respiration rates of organic C in the euphotic or dark oceans [after (2, 31); see text S1]. In the euphotic zone, the fluxes correspond to the proportion of reduced N from respiration that is assumed to be available for nitrification [43%, after (2, 12)]. The range of total C or P fluxes in the dark ocean corresponds to the low and high estimates of total N mineralization flux (92 or 330 Tmol N year⁻¹; see text). Relatively lower C and P uptake fluxes observed in response to P limitation are accounted for by assuming 13% of the open ocean euphotic zone is P limited [i.e., the N. Atlantic Equatorial and Subtropical Gyre; 15°S to 45°N; (13)]. Thaumarchaeal growth rates (day⁻¹) are estimated on the basis of population densities reported by (11), ocean surface areas (31) and depths of hypsometric regions (43), C content of 12.9 fg cell⁻¹ (22), and the C fixation fluxes reported here for each region.

Zone	Flux	Near-shore	Shelf	Slope	Open	Total
Euphotic	Growth rate (day−1)	0.413	0.209	0.081	0.049	–
	C fixation (Tg year−1)	48	39	60	676	824
	P uptake (Gg year−1)	1.2	1.0	1.4	16.9	20
	DOC release (Tg year−1)	2.1	1.7	2.6	30.4	37
	DOP release (Gg year−1)	0.008	0.006	0.010	0.106	0.13
Dark	Growth rate (day−1)	nd	0.099	0.006	0.002	–
	C fixation (Tg year−1)	1.8	15	29	284	330–1190
	P uptake (Gg year−1)	0.04	0.37	0.70	6.7	8–29
	DOC release (Tg year−1)	0.08	0.66	1.24	12.1	14–51
	DOP release (Gg year−1)	0.0003	0.003	0.005	0.046	0.05–0.19