Abstract
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.
Highlights
The formation, export and burial of CaCO3 is an important component of the oceanic carbon cycle, with the combination of the first two providing a positive feedback on atmospheric CO2 (Archer, 1996; Sarmiento et al, 2002; Berelson et al, 2007)
Around half of oceanic CaCO3 production occurs in shallow neritic environments, with the remainder occurring in the upper waters of the open ocean (Milliman, 1993)
We suggest that a more physiologically sound approach is to normalise CaCO3 production (CP) to coccolithophore cell abundance (Poulton et al, 2010; Fig. 8), which provides a measure of calcification per unit biomass comparable to chlorophyll-normalised photosynthetic rates
Summary
The formation, export and burial of CaCO3 is an important component of the oceanic carbon cycle, with the combination of the first two providing a positive feedback on atmospheric CO2 (Archer, 1996; Sarmiento et al, 2002; Berelson et al, 2007). The scale of biological formation of CaCO3 in the upper ocean, is poorly constrained, in terms of both its magnitude and biogeography (Berelson et al, 2007), due to knowledge gaps existing in the ecological and physiological understanding which is fundamental to allow accurate or reliable parameterisation at a global scale (Balch et al, 2007; Monteiro et al, 2016; Krumhardt et al, 2017; Hopkins and Balch, 2018). Despite recent advances in understanding the biomass distribution of coccolithophores and foraminifera (O’Brien et al, 2013, 2016; Schiebel and Movellan, 2012), and how these may relate to carbonate chemistry (e.g. Bach et al, 2015; Evans et al, 2016; Krumhardt et al, 2017), we still have very little idea of the relative magnitude (or biogeography) of their respective rates in terms of production or export (e.g. Schiebel, 2002; Berelson et al, 2007)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
