Aquatic Sciences Meeting, Albuquerque 2001

SS13 Mixotrophic Plankton - Combining Phototrophic and Heterotrophic Nutrition

Date: Friday, February 16, 2001, Time: 8:45:00 AM

Location: Acoma/Zuni/Tesuque

Leising, A, W, University of Washington, Seattle, USA, aleising@ocean.washington.edu

THE ROLE OF MIXOTROPHIC NANOFLAGELLATES IN THE HIGH-NITRATE LOW-CHLOROPHYLL EQUATORIAL PACIFIC

Mixotrophic nanoflagellate abundance in iron-limited high-nitrate low-chlorophyll regions may be higher than previously thought, although it is unclear how much they contribute to primary production as compared to prokaryotic algae. Some mixotrophic nanoflagellates have the advantage that they can ingest bacteria to obtain iron, thus escaping the problems of iron limitation somewhat. To compare the relative importance of mixotrophic versus autotrophic production in the equatorial Pacific, a food web model containing heterotrophic bacteria, autotrophic bacteria, mixotrophic nanoflagellates, heterotrophic nanoflagellates, and a larger protozoan predator was constructed. Dissolved organic matter, nitrate, and iron were also modeled. The model was run as a "chemostat" with steady addition of nutrients representing upwelling, balanced by advective and mixing losses. Depending on the iron uptake ability of the bacteria and available DOM, mixotrophy can be a critical component affecting total primary production, indicating the heterotrophic bacteria form an important link in the recycling of iron from higher in the trophic web. More information about DOM and the forms of recycled iron are needed.

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Aquatic Sciences Meeting, Albuquerque 2001

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