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December 2011, Volume 34, Issue 12, pp 1915–1928 | Cite as

Spatial and temporal variation of photosynthetic parameters in natural phytoplankton assemblages in the Beaufort Sea, Canadian Arctic



During summer 2008, as part of the Circumpolar Flaw Lead system study, we measured phytoplankton photosynthetic parameters to understand regional patterns in primary productivity, including the degree and timescale of photoacclimation and how variability in environmental conditions influences this response. Photosynthesis–irradiance measurements were taken at 15 sites primarily from the depth of the subsurface chlorophyll a (Chl a) maximum (SCM) within the Beaufort Sea flaw lead polynya. The physiological response of phytoplankton to a range of light levels was used to assess maximum rates of carbon (C) fixation (P m * ), photosynthetic efficiency (α *), photoacclimation (E k), and photoinhibition (β *). SCM samples taken along a transect from under ice into open water exhibited a >3-fold increase in α * and P m * , showing these parameters can vary substantially over relatively small spatial scales, primarily in response to changes in the ambient light field. Algae were able to maintain relatively high rates of C fixation despite low light at the SCM, particularly in the large (>5 μm) size fraction at open water sites. This may substantially impact biogenic C drawdown if species composition shifts in response to future climate change. Our results suggest that phytoplankton in this region are well acclimated to existing environmental conditions, including sea ice cover, low light, and nutrient pulses. Furthermore, this photoacclimatory response can be rapid and keep pace with a developing SCM, as phytoplankton maintain photosynthetic rates and efficiencies in a narrow “shade-acclimated” range.


Phytoplankton Photosynthesis–irradiance measurements Subsurface chlorophyll maximum Beaufort Sea Polynya



This work is a contribution to the International Polar Year Circumpolar Flaw Lead system study (IPY-CFL), supported through grants from the Canadian IPY Federal program office, the Natural Sciences and Engineering Research Council in Canada, and many international collaborators. Support was also provided by the National Science Foundation (grant ANT07325535 to K.R. Arrigo) and NASA (grant NNX09AO48H to K.R. Arrigo and M.A. Palmer). We would like to thank all our international collaborators as well as SCUBA divers J. Stewart and H. Hop; E. Shadwick and H. Thomas for dissolved inorganic carbon data; C. Bourgault-Brunelle for helping process the absorption spectra; Y. Gratton and his team for processing and distributing the CTD data; A. Rossnagel, B. Philippe, A. Sallon, and M. Ardyna for laboratory and field assistance; D. Leitch and the officers and crew of the CCGS Amundsen for logistical support; and the Arrigo laboratory and three anonymous reviewers for comments.






Palmer, M.A., Arrigo, K.R., Mundy, C.J. et al. Polar Biol (2011) 34: 1915. https://doi.org/10.1007/s00300-011-1050-x



