Near-surface seawater from the northeastern subarctic Pacific was incubated on deck for 8 d, supplemented with (1) control, no additions (2) ϩZn (3) ϩFe (4) ϩZnϩFe. Concentrations of total Zn and Fe at time zero (t 0 ) and in the control remained at ϳ0.1-0.2 nmol L Ϫ1. In the control, chlorophyll (Ͻ0.3 mg m Ϫ3 ), 14 C uptake into POC and PIC, and inorganic nutrients all remained relatively constant. Addition of Zn slightly but significantly increased chlorophyll (p Ͻ 0.05), decreased phosphate (p Ͻ 0.01) and nitrate (p Ͻ 0.05), and in P versus E experiments, increased P m Ͼ10-fold and P 2-3-fold. The abundance of small diatoms and coccolithophores was higher in the chl m ϩZn treatment compared to the control. The ϩFe and ϩZnϩFe treatments, compared to the control, both showed Ͼ10-fold increases in chlorophyll and 14 C uptake into POC and PIC and complete removal of nitrate (Յ0.2 mmol m Ϫ3 ). However, differences were observed in size-fractionated data; the ϩZnϩFe treatment had significantly lower percent chlorophyll in the Ͼ20-m fraction (p Ͻ 0.01) and a higher percentage in the 0.2-5-m fraction (p Ͻ 0.01) than the ϩFe treatment. In P versus E experiments, both ϩFe treatments increased P m and ␣ around 100-fold and P and ␣ chl by 5-10-fold compared to the control. The ϩFe treatment showed a slightly higher ␣ chl and slightly chl m lower P than the ϩZnϩFe treatment. Abundance of large diatoms, small diatoms, small flagellates, and coccolchl m ithophores all increased substantially (ϳ7-1,000-fold) in response to Fe addition, whereas dinoflagellate abundance only doubled. The ϩZnϩFe treatment had higher abundances of small diatoms and small flagellates than the ϩFe treatment. We conclude that Zn additions had limited influence on conventional indices of phytoplankton growth compared to Fe, but that there might be subtle influences of Zn that require further attention.

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Abstract. The biological production of calcium carbonate (CaCO3), a process termed calcification, is a key term in the marine carbon cycle. A major planktonic group responsible for such pelagic CaCO3 production (CP) are the coccolithophores, single-celled haptophytes that inhabit the euphotic zone of the ocean. Satellite-based estimates of areal CP are limited to open-ocean waters, with current algorithms utilising the unique optical properties of the cosmopolitan bloom-forming species Emiliania huxleyi, whereas little understanding of the optical properties and environmental responses by species other than E. huxleyi are currently available to parameterise algorithms or models. To aid future areal estimations and validate future modelling efforts we have constructed a database of 2765 CP measurements, the majority of which were measured using 12 to 24 h incorporation of radioactive carbon (14C) into acid-labile inorganic carbon (CaCO3). We present data collated from over 30 studies covering the period from 1991 to 2015, sampling the Atlantic, Pacific, Indian, Arctic and Southern oceans. Globally, CP in surface waters (

Abstract. The biological production of calcium carbonate (CaCO3), a process termed calcification, is a key term in the marine carbon cycle. A major planktonic group responsible for such pelagic CaCO3 production (CP) is the coccolithophores, single-celled haptophytes that inhabit the euphotic zone of the ocean. Satellite-based estimates of areal CP are limited to surface waters and open-ocean areas, with current algorithms utilising the unique optical properties of the cosmopolitan bloom-forming species Emiliania huxleyi, whereas little understanding of deep-water ecology, optical properties or environmental responses by species other than E. huxleyi is currently available to parameterise algorithms or models. To aid future areal estimations and validate future modelling efforts we have constructed a database of 2765 CP measurements, the majority of which were measured using 12 to 24 h incorporation of radioactive carbon (14C) into acid-labile inorganic carbon (CaCO3). We present data collated from over 30 studies covering the period from 1991 to 2015, sampling the Atlantic, Pacific, Indian, Arctic and Southern oceans. Globally, CP in surface waters ( < 20 m) ranged from 0.01 to 8398 µmol C m−3 d−1 (with a geometric mean of 16.1 µmol C m−3 d−1). An integral value for the upper euphotic zone (herein surface to the depth of 1 % surface irradiance) ranged from  < 0.1 to 6 mmol C m−2 d−1 (geometric mean 1.19 mmol C m−2 d−1). The full database is available for download from PANGAEA at https://doi.org/10.1594/PANGAEA.888182.

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