Accumulation and enhanced cycling of polyphosphate by Sargasso Sea plankton in response to low phosphorus
Dyhrman, Sonya T.
Lomas, Michael W.
Poulton, Nicole J.
Van Mooy, Benjamin A. S.
Date of Issue2014
Phytoplankton alter their biochemical composition according to nutrient availability, such that their bulk elemental composition varies across oceanic provinces. However, the links between plankton biochemical composition and variation in biogeochemical cycling of nutrients remain largely unknown. In a survey of phytoplankton phosphorus stress in the western North Atlantic, we found that phytoplankton in the phosphorus-depleted subtropical Sargasso Sea were enriched in the biochemical polyphosphate (polyP) compared with nutrient-rich temperate waters, contradicting the canonical oceanographic view of polyP as a luxury phosphorus storage molecule. The enrichment in polyP coincided with enhanced alkaline phosphatase activity and substitution of sulfolipids for phospholipids, which are both indicators of phosphorus stress. Further, polyP appeared to be liberated preferentially over bulk phosphorus from sinking particles in the Sargasso Sea, thereby retaining phosphorus in shallow waters. Thus, polyP cycling may form a feedback loop that attenuates the export of phosphorus when it becomes scarce, contributes bioavailable P for primary production, and supports the export of carbon and nitrogen via sinking particles.
Proceedings of the National Academy of Sciences
© 2014 The Author(s). This paper was published in Proceedings of the National Academy of Sciences and is made available as an electronic reprint (preprint) with permission of the Author(s). The paper can be found at the following official DOI: http://dx.doi.org/10.1073/pnas.1321719111. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.