Phytoplankton Diversity and the Composition of Marine Dissolved Organic Matter


Thursday, April 19, 2012
Redfield Auditorium - 12:00 Noon
Mr. Jamie Becker
Ph.D. Candidate, Joint Program in Biological Oceanography

Through the production and release of dissolved organic matter (DOM), marine phytoplankton provide the majority of organic carbon substrates consumed by heterotrophic microbes in the sea.  If the chemical composition of marine DOM is related to its biological origin, then DOM may impact microbial diversity by acting as a link between autotrophic and heterotrophic community structure.  To investigate this potential link, organic material released by eight pure strains of marine phytoplankton was characterized and compared using high-performance liquid chromatography coupled to mass spectrometry.  We identified connections between DOM composition (both quantity and quality) and phylogeny on multiple diversity levels, indicating that marine phytoplankton produce different DOM signatures that mirror their genetic similarities.  Phytoplankton-derived DOM suites are also being given to natural seawater communities as well as axenic cultures of heterotrophic bacterioplankton to assess lability.  Potentially labile and diagnostic compounds can be identified in this manner and will be targets for additional characterization.  Our results suggest a relationship between phytoplankton diversity and DOM composition and implicate marine DOM as a potential driver of microbial diversity in the sea.