Taxon-specific responses of Southern Ocean diatoms to Fe enrichment revealed by synchrotron radiation FTIR microspectroscopy
|Author(s)||Sackett O.1, 2, 3, Armand L.4, Beardall J.2, Hill R.5, Doblin M.1, Connelly C.6, Howes J.1, Stuart B.7, Ralph P.1, Heraud P.2, 3|
|Affiliation(s)||1 : Univ Technol Sydney, Plant Funct Biol & Climate Change Cluster C3, Sydney, NSW 2007, Australia.
2 : Monash Univ, Sch Biol Sci, Clayton, Vic 3800, Australia.
3 : Monash Univ, Ctr Biospect, Sch Chem, Clayton, Vic 3800, Australia.
4 : Macquarie Univ, Dept Biol Sci & Climate Futures, N Ryde, NSW 2109, Australia.
5 : Univ New S Wales, Ctr Marine Bioinnovat, Sydney, NSW 2052, Australia.
6 : Deakin Univ, Sch Life & Environm Sci, Geelong, Vic 3217, Australia.
7 : Univ Technol Sydney, Sch Chem, Sydney, NSW 2007, Australia.
|Source||Biogeosciences (1726-4170) (Copernicus Gesellschaft Mbh), 2014-10-20 , Vol. 11 , N. 20 , P. 5795-5808|
|WOS© Times Cited||18|
|Note||Special issue KEOPS2: Kerguelen Ocean and Plateau Study 2|
|Abstract||Photosynthesis by marine diatoms contributes substantially to global biogeochemical cycling and ecosystem productivity. It is widely accepted that diatoms are extremely sensitive to changes in Fe availability, with numerous in situ experiments demonstrating rapid growth and increased export of elements (e. g. C, Si and Fe) from surface waters as a result of Fe addition. Less is known about the effects of Fe enrichment on the phenotypes of diatoms, such as associated changes in nutritional value - furthermore, data on taxon-specific responses are almost non-existent. Enhanced supply of nutrient-rich waters along the coast of the sub-antarctic Kerguelen Island provide a valuable opportunity to examine the responses of phytoplankton to natural Fe enrichment. Here we demonstrate the use of synchrotron radiation Fourier Transform Infrared (SR-FTIR) microspectroscopy to analyse changes in the macromolecular composition of diatoms collected along the coast and plateau of Kerguelen Island, Southern Ocean. SR-FTIR microspectroscopy enabled the analysis of individual diatom cells from mixed communities of field-collected samples, thereby providing insight into in situ taxon-specific responses in relation to changes in Fe availability. Phenotypic responses were taxon-specific in terms of intraspecific variability and changes in proteins, amino acids, phosphorylated molecules, silicate/silicic acid and carbohydrates. In contrast to some previous studies, silicate/silicic acid levels increased under Fe enrichment, in conjunction with increases in carbohydrate stores. The highly abundant taxon Fragilariopsis kerguelensis displayed a higher level of phenotypic plasticity than Pseudo-nitzschia spp., while analysis of the data pooled across all measured taxa showed different patterns in macromolecular composition compared to those for individual taxon. This study demonstrates that taxon-specific responses to Fe enrichment may not always be accurately reflected by bulk community measurements, highlighting the need for further research into taxon-specific phenotypic responses of phytoplankton to environmental change.|