Aquatic Sciences Meeting, Albuquerque 2001

SS22 Strategies To Reduce Mortality in Marine and Freshwater Phytoplankton

Date: Wednesday, February 14, 2001, Time: 10:45:00 AM

Location: Acoma/Zuni/Tesuque

Strom, S, L, Shannon Point Marine Center, Western Washington University, Anacortes, USA, stroms@cc.wwu.edu

Wolfe, G, V, California State University Chico, Deparatment of Biological Sciences, Chico, USA,

Slajer, A, , Shannon Point Marine Center, Western Washington University, Anacortes, USA,

PHYTOPLANKTON DMSP RELEASE: A POSSIBLE CHEMICAL DEFENSE AGAINST PROTIST GRAZERS?

We examined grazing by heterotrophic protists on the coccolithophorid Emiliania huxleyi to determine whether algal cleavage of DMSP (dimethylsulfoniopropionate) was associated with reductions in grazing rate. E. huxleyi clones exhibiting contrasting (high vs. low) DMSP lyase activity were employed in laboratory experiments with ciliates and heterotrophic dinoflagellates. Four out of five grazer species fed at higher rates on low lyase E. huxleyi clones. In further experiments, the preferred E. huxleyi clone was offered in combination with nM - uM dissolved DMSP or its cleavage products, DMS or acrylate. Surprisingly, grazing rates were reduced only upon addition of DMSP, and the magnitude of the feeding reduction was proportional to DMSP concentration, suggesting it can act as a grazing deterrent. The signal sense of DMSP, a chemoattractant for some protists, appears highly grazer-specific. While both low and high lyase clones have similar intracellular DMSP concentrations, preliminary evidence indicates that high lyase clones might release DMSP more readily. This behavior might help E. huxleyi and other DMSP-rich phytoplankton taxa form persistent blooms.

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Aquatic Sciences Meeting, Albuquerque 2001

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