Heterogeneity in the photoprotective capacity of three Antarctic diatoms during short-term changes in salinity and temperature
The Antarctic marine ecosystem changes seasonally, forming a temporal continuum of specialised niche habitats including open ocean, sea ice and meltwater environments. The ability for phytoplankton to acclimate rapidly to the changed conditions of these environments depends on the species’ physiology and photosynthetic plasticity and may ultimately determine their long-term ecological niche adaptation. This study investigated the photophysiological plasticity and rapid acclimation response of three Antarctic diatoms—Fragilariopsis cylindrus, Pseudo-nitzschia subcurvata and Chaetoceros sp.—to a selected range of temperatures and salinities representative of the sea ice, meltwater and pelagic habitats in the Antarctic. Fragilariopsis cylindrus displayed physiological traits typical of adaptation to the sea ice environment. Equally, this species showed photosynthetic plasticity, acclimating to the range of environmental conditions, explaining the prevalence of this species in all Antarctic habitats. Pseudo-nitzschia subcurvata displayed a preference for the meltwater environment, but unlike F. cylindrus, photoprotective capacity was low and regulated via changes in PSII antenna size. Chaetoceros sp. had high plasticity in non-photochemical quenching, suggesting adaptation to variable light conditions experienced in the wind-mixed pelagic environment. While only capturing short-term responses, this study highlights the diversity in photoprotective capacity that exists amongst three dominant Antarctic diatom species and provides insight into links between ecological niche adaptation and species’ distribution.
KeywordsCyclic Electron Transport Pelagic Environment Photoprotective Pigment Pelagic Condition Photosynthetic Plasticity
Thanks to Olivia Sackett for experimental assistance and Marlene Zbinden and Vinod Kumar for HPLC analyses. This work was supported by the Australian Research Council grant (DP0773558) awarded to Peter J Ralph, with additional support provided by Aquatic Processes Group and the Department of Environmental Sciences, University of Technology, Sydney. Katherina Petrou was supported by an Australian Postgraduate Award and Commonwealth Scientific and Industrial Research Organisation (CSIRO) Flagship top-up scholarship.
- Jeffrey SW, Humphrey GF (1975) New spectrophotometric equations for determining chlorophyll a, b, c1, and c2 in higher plants and natural phytoplankton. Biochem Physiol Pfl 165:191–194Google Scholar
- Lavaud J (2007) Fast regulation of photosynthesis in diatoms: mechanisms, evolution and ecophysiology. Func Plant Sci Biotech 1:267–287Google Scholar
- Lavergne J, Briantais J-M (1996) Photosystem II heterogeneity. In: Ort DRaY CF (ed) Oxygenic photosynthesis: the light reactions. Kluwer, Dordrecht, pp 265–287Google Scholar
- Petrou K, Hill R, Doblin MA, McMinn A, Johnson R, Wright SW, Ralph PJ (2011) Photoprotection of sea ice microalgal communities from the East Antarctic pack ice. J Phycol 47, (in press)Google Scholar
- Schreiber U (2004) Pulse-amplitude-modulated (PAM) fluorometry and saturation pulse method. In: Papagiorgiou GG (ed) Advances in photosynthesis and respiration, vol 19. Springer, Dordrecht, pp 279–319Google Scholar
- Wilhelm C (1990) The biochemistry and physiology of light-harvesting processes in chlorophyll b- and chlorophyll c-containing algae. Plant Physiol Biochem 28:293–306Google Scholar