Grazing and behavioral response of Gyrodinium spirale to diatom-associated oxylipins

Heterotrophic dinoflagellates are major grazers of marine diatoms, and as part of the microzooplankton contribute to the removal of >50% of their daily production. Among naked heterotrophic dinoflagellates, Gyrodinium spirale is known to be key diatom predator and is globally distributed in productive neritic ecosystems. Here we analyzed the grazing and growth response of G. spirale to diatom cultures under nutrient replete and silicon limitation, which is known to induce dramatic changes in diatom oxylipin chemistry. In addition, we also tested the response of this heterotrophic dinoflagellate on different species of diatoms that are known to have major differences in their oxylipin profiles. Increases in the production of certain oxylipin compounds decreased grazing rates of G. spirale and had subtle, but significant effects on its motility and behavior. We propose that as aging diatom blooms become nutrient limited, they alter their interactions with their major grazers through changes in oxylipin chemistry, resulting in increased survival and greater potential for diatom biomass sedimentation.  

Presentation Preference: Oral

Primary Presenter: Matthew Johnson, Woods Hole Oceanographic Institution (mattjohnson@whoi.edu)

Authors:

Matthew Johnson, Woods Hole Oceanographic Institution  (mattjohnson@whoi.edu)

Houshuo Jiang, Woods Hole Oceanographic Institution  (hsjiang@whoi.edu)

Bethanie Edwards, University of California, Berkeley  (bethanie_edwards@berkeley.edu)