Community and ecosystem level consequences of chemical cues in the plankton.

Aquatic organisms produce compounds that deter consumers, alter prey behavior, suppress or kill target and nontarget species, and dramatically affect food-web structure, community composition, and the rates and pathways of biogeochemical cycles. Toxins from marine and freshwater phytoplankton create health hazards for both aquatic and terrestrial species and can significantly affect human activities and the economic vitality of local communities. A reasonable case can be made that phytoplankton metabolites such as dimethyl sulfide (DMS) link interaction webs that span hundreds to thousands of kilometers and connect production from oceanic phytoplankton to desert cacti and coyotes via zooplankton, fishes, and sea birds. The possible role of DMS in global heat budgets expands this effect even further. The ecosystem-wide and potentially global consequences of aquatic chemical cues is an underappreciated topic that warrants additional attention.