Eavesdropping algae: Chemical signaling, growth, and herbivory in Ulva lactuca
Giovanna Tomat-Kelly and Kathryn Van Alstyne
Shannon Point Marine Center, Western Washington University
BackgroundMany green algae contain an organic compound called dimethylsulfoniopropionate (DMSP). DMSP is thought to serve many functions, including acting as an osmolyte and as a cyroprotectent in algae (Karsten et al. 1996). Apart from its immediate functions, DMSP cleavage is believed to function as an activated chemical defense system against herbivores (Van Alstyne et al 2001). When algae are grazed, the DMSP in the algal cells is cleaved into acrylic acid and dimethyl sulfate (DMS)( Gage et al 1997).
Both of these compounds function as herbivore deterrents, meaning herbivores will avoid algae that produce either compound (Van Alstyne and Houser 2003). Dimethy sulfate (DMS) is also believed to function as an airborne chemical signal in marine systems. Neighboring algae “eavesdrop” on the airborne DMS produced by herbivore-damaged algae and respond to the signal by elevating cellular concentrations of DMSP(Smith and Van Alstyne 2007). There is ample evidence that eavesdropping between terrestrial plants through airborne chemical signaling can increase the production of herbivore deterrents in eavesdropping plants, but no such observations exist in marine systems.
PurposeThe purpose of our study was to better understand the role of DMS as an airborne signal in marine ecosystems. To do this, we tested how eavesdropping between algae affects algal growth and herbivory on algae by consumers. We hypothesized that exposure of the green macroalgae Ulva lactuca to DMS would decrease herbivory by one of its native predators, the snail Lacuna vincta and that DMS exposed algae would grow more than control algae.
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