Abstract

Sulfur Signal Dinner Phytoplankton produces large amounts of the compound dimethylsulfoniopropionate (DMSP), which can be transformed into the gas dimethylsulfide and emitted into the atmosphere in sufficient quantities to affect cloud formation. The functional role of DMSP is somewhat unclear, but it is degraded by marine bacteria as a source of reduced carbon and sulfur. It also acts as a foraging cue for a variety of aquatic animals ranging from copepods to marine mammals. Now, Seymour et al. (p. 342 ) have developed a microfluidic device to observe the behavior of motile microorganisms in response to pulses of DMSP. Contrary to accepted thought, these compounds appear primarily to play a defensive role—for most motile organisms, they are strongly attractive and act as an important infochemical throughout the marine food web.