Shedding light on marine phytoplankton and phosphorus

04-25-2014

Bigelow scientists Mike Lomas and Nicole Poulton teamed with Woods Hole Oceanographic Institution colleagues Patrick Martin, Sonya Dyhrman, and Benjamin A.S. Van Mooy to investigate how phytoplankton respond to potentially growth-limiting concentrations of phosphorus. Their findings were published in The Proceedings of the National Academy of Sciences on April 21, 2014.

Phytoplankton alter their biochemical composition according to the nutrients that are available and their composition can vary across oceanic provinces. In subtropical ocean regions where phosphorus is scarce, for example, phytoplankton adjust their biochemical composition so they require less phosphorus.

The authors studied phytoplankton from the Sargasso Sea, which is ultra-low in phosphorus, and found phytoplankton there were unexpectedly enriched with a phosphorus molecule (polyphosphate or polyP), as compared to nutrient rich temperate waters also in the North Atlantic Ocean. This contradicted the long-held view of PolyP as a luxury phosphorus storage molecule, rather than serving as a primary nutrient in marine phytoplankton.

The authors further found that polyP appears to be more readily recycled in the surface ocean than other forms of phosphorus-containing biochemicals. "The high relative levels of polyP and its fast cycling may increase the availability of phosphorus for primary production in marine phytoplankton, explains Lomas, " and this potentially reduces the likelihood that phytoplankton growth would be limited by the availability of phosphorus."