DOI: 10.5061/dryad.5x69p8ddx
title: Data from: Light-dependent methane production by a coccolithophorid may counteract its photosynthetic contribution to carbon dioxide sequestration

description: Many phytoplankton produce methane (CH4), a potent greenhouse gas.
 However, little is known about the relationship between their CH4
 production and photosynthesis, the biggest biological reaction driving
 carbon  sequestration in the oceans. Here, by ruling out the
 possibility of classical methanogenesis in the cultures, we show that the
 bloom-forming marine microalga Emiliania huxleyi released CH4 during
 photosynthesis (did not generate CH4 in darkness) while grown under
 different light levels, the amount of CH4 released correlated positively
 with photosynthetic electron transfer and carbon fixation. Under
 growth-saturating light, E. huxleyi produces CH4 at a maximal rate of
 about 6.6 ×10−11 μg CH4 cell−1 d−1 or 3.9 μg CH4 g−1 particulate organic
 carbon d−1.  We estimated that the microalga released 7 moles CH4
 while fixing about 105 moles of CO2. Considering the higher global warming
 potential of CH4 than that of CO2 and complicated processes involved in
 CH4 fluxes from the surface oceans, the warming potential of phytoplankton
 CH4 production should be broadly evaluated.
description: We used Counter Particle counter and size analyzer (Z2 Coulter,
 Beckman, U.S.A.), Picarro G2308 (Picarro Inc., U.S.A.), Multi-color PAM
 (Walz, Germany), liquid scintillation counter (Beckman, LS6500, Germany)
 and a CHNS elemental analyzer (Vario EL cube Elementar, Germany) to
 measure the samples and collect our data. CO2SYS
 software (V.2.3) was used to calculate parameters of the seawater
 carbonate system, and SPSS statistics (V.21) was used to analyzed the
 data.
description: # Data from: Light-dependent methane production by a coccolithophorid may
 counteract its photosynthetic contribution to carbon dioxide sequestration
 [https://doi.org/10.5061/dryad.5x69p8ddx](https://doi.org/10.5061/dryad.5x69p8ddx) ## Description of the data and file structure We used Counter Particle counter and size analyzer (Z2 Coulter, Beckman, U.S.A.) to analyze cell density and cell size, Picarro G2308 (Picarro Inc., U.S.A.) to measure CH4 concentration, Multi-color PAM (Walz, Germany) to analyze the photosynthesis parameters, liquid scintillation counter (Beckman, LS6500, Germany) to measure the carbon fixation and a CHNS elemental analyzer (Vario EL cube Elementar, Germany) to measure the particulate organic carbon in Emiliania huxleyi culture. CO2SYS software (V.2.3) was used to calculate parameters of the seawater carbonate system, which is necessary in the subsequent calculation of carbon fixation rate. All data and significance between treatments were analyzed using SPSS Statistics (V. 21) ### Files and variables #### File: Original\_Data.xlsx **Description:** Our dataset includes all original data of parameters measured (Photosynthesis parameters, cell growth, methane production, carbon fixation, particulate carbon content) in our control experiment on marine microalga Emiliania huxleyi PMLB 92-11. ##### Variables * Cell density: cell density per mL in the culture system * μ: specific growth rate of microalga cells * Fv/Fm: Maximum quantum yield of photosystem Ⅱ of microalga cells * Fv'/Fm': effective quantum yield of photosystem Ⅱ of microalga cells - NPQ: non-photochemical quenching  - rETRmax: the maximum of relative electron transport rate - rETRgrowth: the relative electron transport rate at growth light intensities - CH4: changes in CH4 concentration in the culture system. - CH4 production rate: the mass of CH4 produced by Emiliania huxleyi per cell per day. - Carbon fixation rate: the mass of carbon fixed by photosynthesis per cell per day. - Diameter: the average diameter of Emiliania huxleyi cells. - CH4 production quotient: the ratio of CH4 production to carbon fixaion. - POC content: particulate organic carbon content per cell. - POC-normalized CH4 production rate: the CH4 produced per gram POC per day - rETR: relative electron transport rate - TPC content: total particulate organic content per cell. ## Code/software Our data is provided in Excel.  CO2SYS software (V.2.3) was used to calculate parameters of the seawater carbonate system, which is necessary in the subsequent calculation of carbon fixation rate.  All data and significance between treatments were analyzed using SPSS Statistics (V. 21) ## Access information Other publicly accessible locations of the data: * There's no publicly locations. Data was derived from the following sources: * There's no data derived from other sources.