title: Phenotypic plasticity of southern ocean diatoms: key to success in the sea ice habitat?
abstract: Diatoms are the primary source of nutrition and energy for the Southern Ocean ecosystem. Microalgae, including diatoms, synthesise biological macromolecules such as lipids, proteins and carbohydrates for growth, reproduction and acclimation to prevailing environmental conditions. Here we show that three key species of Southern Ocean diatom (Fragilariopsis cylindrus, Chaetoceros simplex and Pseudo-nitzschia subcurvata) exhibited phenotypic plasticity in response to salinity and temperature regimes experienced during the seasonal formation and decay of sea ice. The degree of phenotypic plasticity, in terms of changes in macromolecular composition, was highly species-specific and consistent with each species' known distribution and abundance throughout sea ice, meltwater and pelagic habitats, suggesting that phenotypic plasticity may have been selected for by the extreme variability of the polar marine environment. We argue that changes in diatom macromolecular composition and shifts in species dominance in response to a changing climate have the potential to alter nutrient and energy fluxes throughout the Southern Ocean ecosystem.
authors.affiliation: School of the Environment and the Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, New South Wales, Australia ; School of Biological Sciences, Monash University, Victoria, Australia.
authors.forename: Olivia
authors.initials: O
authors.lastname: Sackett
authors.affiliation: School of the Environment and the Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, New South Wales, Australia.
authors.forename: Katherina
authors.initials: K
authors.lastname: Petrou
authors.affiliation: School of Chemistry and Forensic Science, University of Technology, Sydney, New South Wales, Australia.
authors.forename: Brian
authors.initials: B
authors.lastname: Reedy
authors.affiliation: School of Chemistry and Forensic Science, University of Technology, Sydney, New South Wales, Australia.
authors.forename: Adrian
authors.initials: A
authors.lastname: De Grazia
authors.affiliation: Centre for Marine Bio-Innovation and Sydney Institute of Marine Science, School of Biological, Earth and Environmental Sciences, The University of New South Wales, New South Wales, Australia.
authors.forename: Ross
authors.initials: R
authors.lastname: Hill
authors.affiliation: School of the Environment and the Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, New South Wales, Australia.
authors.forename: Martina
authors.initials: M
authors.lastname: Doblin
authors.affiliation: Centre for Biospectroscopy and School of Biological Sciences, Monash University, Victoria, Australia.
authors.forename: John
authors.initials: J
authors.lastname: Beardall
authors.affiliation: School of the Environment and the Plant Functional Biology and Climate Change Cluster, University of Technology, Sydney, New South Wales, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Ralph
authors.affiliation: Centre for Biospectroscopy and School of Biological Sciences, Monash University, Victoria, Australia.
authors.forename: Philip
authors.initials: P
authors.lastname: Heraud
mesh_terms: D017377:Diatoms / Q000502:physiology*; D017753:Ecosystem; D010641:Phenotype; D012621:Seasons