In pelagic ecosystems, phytoplankton contain high concentrations of DMSP (dimethylsulfoniopropionate), an osmolyte that helps marine algae regulate their internal osmotic environment and may also serve as a cryoprotectant. When phytoplankton are eaten by zooplankton such as crustaceans, DMSP is released into the water, where it is converted into DMS (dimethyl sulfide) and acrylic acid. DMS then travels to the surface of the water and is released into the atmosphere, where it gives off a distinct smell that attracts several procellariiform seabirds, including albatrosses, petrels, and shearwaters, which feed on crustaceans. This establishes a mutually beneficial relationship where phytoplankton release DMS, which seabirds use as a cue to find and eat prey, thereby reducing the grazing pressure on the phytoplankton. This relationship suggests that DMS serves as a “keystone” infochemical in marine trophic interactions.Edit Summary
Dimethylsulfide (DMS) Iis ubiquitous in the surface waters of the ocean and appears always to be present in concentrations far in excess of the concentrations expected at atmospheric equilibrium. This large concentration gradient between the oceans and the atmosphere drives almost half the biogenic sulfur flux to the earth’s atmosphere. DMS constitutes about 90% of the flux of biogenic sulfur from the ocean to the atmosphere. As a result, considerable attention has been focused on the distribution and dynamics of DMS in ocean water in an effort to understand mechanisms controlling its flux to the atmosphere. The DMS in seawater appears to originate from algae, most likely produced by the decomposition of dimethylsulfoniopropionate (DMSP), a tertiary sulfonium compound analogous to the quaternary ammonium compounds (for example, glycinebetaine and proline) that are widespread in marine organisms. As with these ammonium compounds, DMSP may be involved in regulating cellular osmotic pressure in algae. Decomposition of DMSP appears to occur mainly by an enzymatically catalyzed elimination reaction, yielding DMS and acrylic acid” (Dacey et al. 1986:1314).
Oceanic Dimethylsulfide: Production During Zooplankton Grazing on PhytoplanktonScience 19 Sep 1986: Vol. 233, Issue 4770, pp. 1314-131September 19, 1986
“Petrels, albatrosses and other procellariiform seabirds have an excellent sense of smell, and routinely navigate over the world’s oceans by mechanisms that are not well understood. These birds travel thousands of kilometres to forage on ephemeral prey patches at variable locations, yet they can quickly and efficiently find their way back to their nests on remote islands to provision chicks, even with magnetic senses experimentally disrupted. Over the seemingly featureless ocean environment, local emissions of scents released by phytoplankton reflect bathymetric features such as shelf breaks and seamounts. These features suggest an odour landscape that may provide birds with orientation cues. We have previously shown that concentrated experimental deployments of one such compound, dimethyl sulphide (DMS), attracts procellariiforms at sea, suggesting that some species can use it as a foraging cue. Here we present the first physiological demonstration that an Antarctic seabird can detect DMS at biogenic levels. We further show that birds can use DMS as an orientation cue in a non-foraging context within a concentration range that they might naturally encounter over the ocean” (Nevitt et al. 2005:303)