Strom, S. L.. Shannon Point Marine Center, stroms@cc.wwu.edu
Wolfe, G. L.. Shannon Point Marine Center, wolfeg@oce.orst.edu

 
ARE PROTOZOAN GRAZERS DETERRED BY PHYTOPLANKTON-PRODUCED CHEMICALS?
 
Strom, S. L., Shannon Point Marine Center, Western Washington University, 1900 Shannon Point Rd., Anacortes WA 98221 USA, stroms@cc.wwu.edu Wolfe, G. V., Shannon Point Marine Center, Western Washington University, 1900 Shannon Point Rd., Anacortes WA 98221 USA, wolfeg@oce.orst.edu Although chemical interactions between plants and herbivores are known to be important structuring forces in terrestrial communities, such interactions have received much less attention in the realm of marine plankton ecology. We are testing the hypothesis that phytoplankton production of dimethyl sulfide and acrylate during enzymatic cleavage of dimethylsulfoniopropionate (DMSP) may be a chemical defense against protozoan grazers. The growth and grazing responses of ciliates and heterotrophic dinoflagellates are being assayed in the presence of four clones of the coccolithophorid Emiliania huxleyi. Two of the E. huxleyi clones exhibit high activities of the enzyme DMSP lyase and tend to produce large amounts of DMS in the presence of grazers, while the other two clones have low levels of DMSP lyase activity. Preliminary results indicate that protozoan grazers have a range of responses to the E. huxleyi clones. For at least one heterotrophic dinoflagellate, consumption of all four algal clones was substantial, high rates of growth were observed on the clones with low enzyme activities, and growth was completely suppressed in the presence of the high activity clones. The implications of these grazer responses for plankton community dynamics and the establishment of algal blooms will be discussed.
 
Day: Wednesday, Feb. 3
Time: 09:45 - 10:00am
Location: Hilton of Santa Fe
 
Code: CS60WE0945H