Coccolithophore populations and their contribution to carbonate export during an annual cycle in the Australian sector of the Antarctic zone

• Published in: Biogeosciences
• Main Authors: Rigual-Hernández, Andrés S., Flores, José Abel, Sierro, Francisco Javier, Fuertes, Miguel A., Cros, Lluïsa, Trull, Thomas W.
• Other Authors: Australian Government, Macquarie University, European Commission
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: European Geosciences Union 2018
• Subjects: Antarctic; Southern Ocean; The Antarctic; Antarc*; Ocean acidification
• Online Access: http://hdl.handle.net/10261/164540; https://doi.org/10.5194/bg-15-1843-2018; https://doi.org/10.13039/501100001230; https://doi.org/10.13039/501100000780

20 pages, 7 figures, 1 table, 1 plate, supplemental material https://doi.org/10.5194/bg-15-1843-2018-supplement, data availability https://data.aad.gov.au/metadata/records/ Coccol-ithophore_Fluxes_SAZ, https://doi.org/10.4225/15/5ab86f35e277e The Southern Ocean is experiencing rapid and relentless change in its physical and biogeochemical properties. The rate of warming of the Antarctic Circumpolar Current exceeds that of the global ocean, and the enhanced uptake of carbon dioxide is causing basin-wide ocean acidification. Observational data suggest that these changes are influencing the distribution and composition of pelagic plankton communities. Long-term and annual field observations on key environmental variables and organisms are a critical basis for predicting changes in Southern Ocean ecosystems. These observations are particularly needed, since high-latitude systems have been projected to experience the most severe impacts of ocean acidification and invasions of allochthonous species. Coccolithophores are the most prolific calcium-carbonate-producing phytoplankton group playing an important role in Southern Ocean biogeochemical cycles. Satellite imagery has revealed elevated particulate inorganic carbon concentrations near the major circumpolar fronts of the Southern Ocean that can be attributed to the coccolithophore Emiliania huxleyi. Recent studies have suggested changes during the last decades in the distribution and abundance of Southern Ocean coccolithophores. However, due to limited field observations, the distribution, diversity and state of coccolithophore populations in the Southern Ocean remain poorly characterised. We report here on seasonal variations in the abundance and composition of coccolithophore assemblages collected by two moored sediment traps deployed at the Antarctic zone south of Australia (2000 and 3700 m of depth) for 1 year in 2001–2002. Additionally, seasonal changes in coccolith weights of E. huxleyi populations were estimated using circularly polarised micrographs ...