Meeting Abstract

93.5  Thursday, Jan. 7  Chemical Communication, Keystone Molecules, and Forces Structuring Natural Communities FERRIER, G.A.*; ZIMMER, C.A.; ZIMMER, R.K.; Univ. of California, Los Angeles; Univ. of California, Los Angeles; Univ. of California, Los Angeles

Sensory systems provide critical filters that enable organisms to detect and recognize valuable resources. Trophic cascades, structuring populations and communities, are largely determined by trait-mediated interactions that rely on sensory inputs. Certain molecules, serving as chemical signals, can establish the course of community dynamics at multiple trophic levels. Here, we investigated the roles of surface-adsorbed proteins in mediating predator-prey dynamics on wave-swept shores. For cuticle/shell formation, barnacles (Balanus glandula) are required to produce a high molecular weight, insoluble, glycoprotein complex. A primary subunit (~98 kDa) of this protein complex was isolated, purified, and, in field tests, evoked settlement by conspecific larvae. The subunit thereby operates as a seminal recruitment cue. Moreover, the same compound triggered a predatory response in numerically dominant whelk species distributed throughout the eastern Pacific (Acanthinucella spirata, Nucella emarginata, N. ostrina, N. canaliculatta, N. lamellosa). Such proteins, therefore, simultaneously influence demographic processes that enhance or diminish barnacle populations. As dominant competitors for space, the relative balance between barnacle recruitment and predation mortality has strong direct and indirect effects which influence community dynamics. Furthermore, the ability of all whelks to detect and respond to these signals suggests that the biogeography of barnacles, and their population stability, is affected in comparable ways. The conserved response of many species to the same signal, and the resultant cascading effects across multiple trophic levels, signify barnacle glycoproteins as keystone molecules that structure communities on wave-swept shores.