PHOSPHORUS COMPETITION AMONG DIATOMS FROM CONTRASTING NUTRIENT REGIMES

Diatoms are significant contributors to global carbon cycling, yet genera isolated from oligotrophic regions like the Sargasso Sea remain understudied relative to those from coastal environments. Oligotrophic regions are expected to expand in the future, requiring predictions of how different phytoplankton groups will respond to low nutrient conditions. We compared the physiological responses of a diatom isolated from low P Sargasso Sea (Chaetoceros sp.; P8E6) with a diatom isolated from a high P coastal environment (Thalassiosira pseudonana; CCMP1335). A series of biovolume-normalized competition studies were performed for this comparison in low P media. Cell abundance and growth rate data suggest that Chaetoceros sp. is not able to out-compete a coastal isolate at low P. A survey of transcriptomic data from these, and other, diatom isolates grown under low P identified a suite of commonly P-regulated transcripts, including transcripts for alkaline phosphatase and 5’ nucleotidase. These data indicate that Chaetoceros sp. and T. pseudonana exhibit similar responses to low P, challenging the hypothesis that diatoms from oligotrophic regions have distinct mechanisms to cope with P scarcity that might confer a competitive advantage. These findings highlight the need for additional experimental efforts to resolve underpinning adaptive responses and forecast the ecological implications for diatom communities in expanding oligotrophic regions.

Presentation Preference: Poster

Primary Presenter: Maxfield Palmer, Lamont-Doherty Earth Observatory (max.palmer54@gmail.com)

Authors:

Maxfield Palmer, Lamont-Doherty Earth Observatory  (mp4316@columbia.edu)

Sheean Haley, Lamont-Doherty Earth Observatory  (shaley@ldeo.columbia.edu)

Sonya Dyhrman, Columbia University  (sdyhrman@ldeo.columbia.edu)