Controlled field release of a waterborne chemical signal stimulates planktonic larvae to settle

Settlement rates and distributions of planktonic larvae are critical determ inants of population dynamics in marine and freshwater benthic communities. On the basis of the principles of solute diffusion from a porous material, chemical-releasing collectors (CRCs) were engineered and tested in an estu ary, Significantly move barnacle larvae (Balanus amphitrite) were found to colonize collectors emitting trace amounts of the synthetic peptide analog, g14 glycyl-glycyl-L-arginine (5 X 10(-8) M), than those emitting either se awater or an organic enrichment (glycyl-glycyl-L-histidine) control. The in ductive compound is similar in structure to peptide signal molecules that h ave been shown to elicit settlement under laboratory conditions and are nat urally released by adult barnacles and oysters. The potent effects of subtl e changes in seawater chemistry may thus warrant careful attention as putat ive agents mediating habitat colonization.