Present addresses: Université Paris VI and CNRS, UMR 7144, Station Biologique, BP74 Place George Teissier, 29680 Roscoff, France; ‡Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 1X5.
Cell size trade-offs govern light exploitation strategies in marine phytoplankton
Article first published online: 4 SEP 2009
© 2009 Society for Applied Microbiology and Blackwell Publishing Ltd
Volume 12, Issue 1, pages 95–104, January 2010
How to Cite
Key, T., McCarthy, A., Campbell, D. A., Six, C., Roy, S. and Finkel, Z. V. (2010), Cell size trade-offs govern light exploitation strategies in marine phytoplankton. Environmental Microbiology, 12: 95–104. doi: 10.1111/j.1462-2920.2009.02046.x
- Issue published online: 29 DEC 2009
- Article first published online: 4 SEP 2009
- Received 11 May, 2009; accepted 26 July, 2009.
Marine phytoplankton show complex community structures and biogeographic distributions, the net results of physiological and ecological trade-offs of species responses to fluctuating, heterogeneous environments. We analysed photosynthesis, responses to variable light and macromolecular allocations across a size panel of marine centric diatoms. The diatoms have strong capacities to withstand and exploit fluctuating light, when compared with picophytoplankton. Within marine diatoms, small species show larger effective cross-sections for photochemistry, and fast metabolic repair of photosystem II after photoinactivation. In contrast, large diatoms show lower susceptibility to photoinactivation, and therefore incur lower costs to endure short-term exposures to high light, especially under conditions that limit metabolic rates. This size scaling of key photophysiological parameters thus helps explain the relative competitive advantages of larger versus smaller species under different environmental regimes, with implications for the function of the biogenic carbon pump. These results provide a mechanistic framework to explain and predict shifts in marine phytoplankton community size structure with changes in surface irradiance and mixed layer depth.