Aquatic Sciences Meeting, Albuquerque 2001

PC01 Harmful Algal Blooms

Date: Tuesday, February 13, 2001

Location: Southwest Hall

Miller, C, A, Gallaudet University, Washington D.C., USA, Caroline.Miller@gallaudet.edu

Lessard, E, J, University of Washington, Seattle, USA, elessard@u.washington.edu

Keil, R, G, University of Washington, Seattle, USA, rickkeil@ocean.washington.edu

Foy, M, S, University of Washington, Seattle, USA, mfoy@ocean.washington.edu

Measurements of the carbon and nitrogen composition of polymer gels of the alga, Phaeocystis sp., under different nutrient conditions

The colonial-forming prymnesiophyte, Phaeocystis sp., produces extracellular polymers that may contribute significantly to the dissolved organic matter pool. Two species, Phaeocystis globosa (CCMP 629, isolated from the N. Atlantic) and Phaeocystis antarctica (isolated from the Ross Sea, Antarctica) were grown under two different N:P conditions to examine the effect of nitrogen sufficiency on the C:N ratio, an potential indicator of the biodegradability of the polymers. Polymers were first separated from cells, then isolated by ultrafiltration (1,000D spiral wound membrane cartridge), and freeze-dried for analysis by a Lehman CHN analyzer and a MALDI-TOF mass spectrometer. The C:N ratio of the polymer gels of Phaeocystis sp. under these growth conditions was lower than previously published ratios (<8), suggesting nitrogen-rich polymers. Furthermore, Phaeocystis antartica polymers had lower C:N ratios than Phaeocystis globosa. Additional information from MALDI-TOF data shows that the nitrogen is not protein, but smaller organic nitrogen-containing compounds such as fragmented amino sugars or amide groups. The low C:N ratios and nitrogen composition of the extracellular polymers has important implications for our understanding of freshly-produced organic matter from phytoplankton.

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Aquatic Sciences Meeting, Albuquerque 2001

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