Antarctic diatom silicification diminishes under ocean acidification

Brief description

This data set was collected during an ocean acidification mesocosm experiment performed at Davis Station, Antarctica during the 2014/15 summer season. It includes:
- description of methods for all data collection and analyses.
- diatom cell volume
- bulk silicification
- species specific silicification via fluorescence microscopy
- bulk community Fv/Fm on day 12
- single-cell PAM fluorometry data (maximum quantum yield of PSII: Fv/Fm)

A natural community of Antarctic marine microbes from Prydz Bay, East Antarctica were exposed to a range of CO2 concentrations in 650 L minicosms to simulate possible future ocean conditions up to the year ~2200. Diatom silica precipitation rates were examined at CO2 concentrations between 343 to 1641 micro atm, measuring both the total diatom community response and that of individual species, to determine whether ocean acidification may influence future diatom ballast and therefore alter carbon and silica fluxes in the Southern Ocean.

Described and analysed in:
Antarctic diatom silicification diminishes under ocean acidification (submitted for review)

Methods described in:
Antarctic diatom silicification diminishes under ocean acidification (submitted for review)

Location: Prydz bay, Davis Station, Antarctica (68 degrees 35'S, 77 degrees 58' E)
Date: Summer 2014/2015

Worksheet descriptions:

Bulk silicification - raw data
Measured total and incorporated biogenic silica using spectrophotometer for all tanks on day 12 after 24 h incubation with PDMPO - raw data

Bulk Fv/Fm - dark-adapted maximum quantum efficiency of PSII (Fv/Fm) on whole community - raw data
Measured Fv/Fm of individual cells from 3 mesocosm tanks.

Single-cell silicificiation, Fluorescence microscopy - raw data
Measured autofluorescence and PDMPO fluorescence of individual diatoms from 6 mesocosm tanks

Single-cell PAM, dark-adapted maximum quantum efficiency of PSII (Fv/Fm) - raw data
Measured Fv/Fm of individual cells from 3 mesocosm tanks.

Cell volume
Calculated cell volume (um3) of 7 species from minicosm tanks 1 and 6 - raw data


Abbreviations:
Fv/Fm Maximum quantum yield of PSII
PDMPO 2-(4-pyridyl)-5-((4-(2-dimethylaminoethylaminocarbamoyl)methoxy)phenyl)oxazole
Tant Thalassiosira antarctica
DiscLg Large Discoid centric diatoms
Stella Stellarima microtrias
Chaeto Chaetoceros spp.
Prob Proboscia truncata
Pseu Pseudonitzschia turgiduloides
FragLg Fragilariopsis cylindrus / curta
Centric Large Discoid centric diatoms
LargeThalassiosira Large Discoid centric diatoms

Lineage

Progress Code: completed

Statement: No problems were encountered with data collection. The six level fCO2 gradient approach meant that our data could be analysed using a regression model, allowing us to identify functional relationships between our fCO2 treatment and our response variables. Gradient designs are more effective at uncovering underlying responses patterns to environmental drivers, improving interpolation potential and generally deliver more useful quantitative information for models.

Notes

Purpose
Based on the results of a previous study, a natural community of Antarctic marine microbes from Prydz Bay, East Antarctica were exposed to a range of CO2 concentrations in 650 L mesocosms to simulate possible future ocean conditions up to the year ∼2200. Diatom silica precipitation rates were examined at CO2 concentrations between 343 to 1641 micro atm, measuring both the total diatom community response and that of individual species, to determine whether ocean acidification may influence future diatom ballast and therefore alter carbon and silica fluxes in the Southern Ocean.