Virginia Institute of Marine Science
The Antarctic is a unique environment in which substantial variations in irradiance occur over a number of time scales, and as a result phytoplankton need to acclimate and adapt to these changes. We conducted field and laboratory manipulations in the Ross Sea, Antarctica to examine photophysiological differences between Phaeocystis antarctica and Pseudonitzschia sp. a diatom that commonly occurrs in the Ross Sea, since these are the two functional groups that dominate abundance and productivity. Both exhibited reduced quantum yields due to high irradiances. P. antarctica, a haptophyte, displays a distinct photophysiological response to irradiance when compared to diatoms. P. antarctica showed a rapid recovery from high light exposure, as indicated by the rapid return to initial, high quantum yields, in contrast to diatoms, which responded more slowly. Absorption cross sections were high in both forms, but those in P. antarctica were significantly higher. Both organisms recovered within 24 h to initial quantum yields, suggesting that high irradiance exposure does not have a permanent effect on these organisms. Among all micronutrient additions (iron, cobalt, zinc and vitamin B-12), only iron additions resulted in rapid impacts on quantum yields. Iron limitation also can result in reduced photosynthetic efficiency. Understanding these photophysiologial responses and the impact of oceanographic conditions provides constraints on modeling efforts of photosynthesis and primary productivity in the Antarctic.
PHYTOPLANKTON TAXA; SOUTHERN-OCEAN; FRAGILARIOPSIS-CYLINDRUS; CHLOROPHYLL FLUORESCENCE; LIGHT STRESS; IRON; GROWTH; PRYMNESIOPHYCEAE; PHOTOPHYSIOLOGY; PHOTOPROTECTION
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This research was funded by grants from the US NSF (OPP-0087401 and ANT-1443258). We thank all our CORSACS colleagues, especially M. Saito, P. Sedwick and Z. Kolber. This paper is Contribution No. 3633 of the Virginia Institute of Marine Science, College of William & Mary.
Sasha Tozzi, Walker O. Smith. Contrasting Photo-physiological Responses of the Haptophyte Phaeocystis Antarctica and the Diatom Pseudonitzschia sp. in the Ross Sea (Antarctica). AIMS Geosciences, 2017, 3(2): 142-162. doi: 10.3934/geosci.2017.2.142