Keller, M. D.. Bigelow Laboratory for Ocean Sciences, mkeller@bigelow.org
Matrai, P. D.. Bigelow Laboratory for Ocean Sciences, pmatrai@bigelow.org
Kiene, R. P.. Department of Marine Sciences, rkiene@jaguar1.usouthal.edu

 
DYNAMICS OF DMSP AND GLYCINE BETAINE (GBT) IN COASTAL PHYTOPLANKTON POPULATIONS IN RESPONSE TO NITROGEN ADDITIONS
 
DMSP and its nitrogen analog, glycine betaine (GBT), are organic osmolytes that are produced by many marine phytoplankton. Levels of GBT are directly related to nitrogen availability, and for some species that produce both GBT and DMSP, DMSP is produced selectively when cells are nitrogen-limited. In addition, phytoplankton appear to be capable of actively releasing and assimilating these compounds under changing nitrogen conditions. Production of GBT over DMSP, or the selection of species that produce GBT, may be favored in high nitrogen environments, or with nitrogen addition. We tested this hypothesis in the Gulf of Maine in areas where surface waters are nitrogen- deplete in the summer, conducting short-term (12 h) and long-term (48 h) nitrogen enrichment experiments. Variations in DMSP and GBT, in relation to phytoplankton population dynamics, were examined. DMSP was released in some incubations when nitrate was added, but there was not an equivalent increase in GBT. In other incubations, the nitrogen additions had no effect on DMSP dynamics. These findings may be the result of the species composition and physiological state of the populations. There does not appear to be a strict reciprocal relationship between these two functionally and structurally analogous compounds.
 
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
 
Code: SS37TH0437S