Vertical Distributions of Coccolithophores, PIC, POC, Biogenic Silica, and Chlorophyll a Throughout the Global Ocean

• Published in: Global biogeochemical cycles 2018-01, Vol.32 (1), p.2-17
• Main Authors: Balch, William M., Bowler, Bruce C., Drapeau, David T., Lubelczyk, Laura C., Lyczkowski, Emily
• Format: Article
• Language: English
• Subjects: Bacillariophyta; Ballast; Basins; Biogeochemical Cycles, Processes, and Modeling; Biogeochemical Kinetics and Reaction Modeling; Biogeochemistry; Biogeosciences; Biomineralization; Blooms; Calcium; Calcium carbonate; Calcium carbonates; Carbon; Carbon Cycling; Carbon sequestration; Carbonates; Chemical analysis; Chlorophyll; Chlorophyll a; Coccoliths; Critical components; Cryosphere; Deep sea; Deep sea environments; Density stratification; Depth; Desert environments; Detection; Diatoms; Ecological effects; Ecology; Euphotic zone; Fluxes; Global Change; Inorganic carbon; Integrals; Ocean basins; Ocean color; Ocean colour; Oceanography: Biological and Chemical; Oceans; Optical analysis; Optical properties; Organic carbon; Organic matter; Paleoceanography; Particulate organic carbon; Phytoplankton; Plankton; Predictions; Productivity; Radiation; Reflectance; Remote Sensing; Remote sensors; Satellite data; Satellite observation; Satellites; Seawater; Silica; Silicon dioxide; Stratification; Surface boundary layer; Temperature (air-sea); Variance; Vertical distribution; Water analysis
• ISSN: 0886-6236; 1944-9224
• DOI: 10.1002/2016GB005614

Coccolithophores are a critical component of global biogeochemistry, export fluxes, and seawater optical properties. We derive globally significant relationships to estimate integrated coccolithophore and coccolith concentrations as well as integrated concentrations of particulate inorganic carbon (PIC) from their respective surface concentration. We also examine surface versus integral relationships for other biogeochemical variables contributed by all phytoplankton (e.g., chlorophyll a and particulate organic carbon) or diatoms (biogenic silica). Integrals are calculated using both 100 m integrals and euphotic zone integrals (depth of 1% surface photosynthetically available radiation). Surface concentrations are parameterized in either volumetric units (e.g., m−3) or values integrated over the top optical depth. Various relationships between surface concentrations and integrated values demonstrate that when surface concentrations are above a specific threshold, the vertical distribution of the property is biased to the surface layer, and when surface concentrations are below a specific threshold, the vertical distributions of the properties are biased to subsurface maxima. Results also show a highly predictable decrease in explained‐variance as vertical distributions become more vertically heterogeneous. These relationships have fundamental utility for extrapolating surface ocean color remote sensing measurements to 100 m depth or to the base of the euphotic zone, well beyond the depths of detection for passive ocean color remote sensors. Greatest integrated concentrations of PIC, coccoliths, and coccolithophores are found when there is moderate stratification at the base of the euphotic zone. Plain Language Summary We use a global shipboard data set to describe the vertical distributions of coccolithophores (marine phytoplankton that produce microscopic calcium carbonate scales). These plants are responsible for over half of all the suspended calcium carbonate in the ocean, they can cause major increases in water reflectance in blooms spanning entire ocean basins, and they provide ballast to organic matter to the deep sea and thus are strong drivers of the ocean's biological carbon pump (responsible for sequestering carbon in the deep sea). This paper describes global relationships that relate the surface concentrations of coccolithophores and their particulate inorganic carbon (as observed by satellite) to concentrations found over the upper 100 m of t