Chemical and structural defenses of the gorgonian coral Briareum asbestinum vary among different sites in the Caribbean and between depths at a single site. High site.specific variation in types of secondary terpenoid compounds of Briareum asbestinum may be environmentally induced. DR. Harvell will determine whether the observed variation in chemical and structural defenses of Briareum is genetic or environmentally induced and whether it is caused by selection by biotic agents. Briareum is distinguished not only by a diverse complement of briareins (compounds) in adult colonies, but also a high investment in chemical defense of the oocytes, embryos, and larvae, affording the opportunity to investigate the ontogeny of chemical defense in the life cycle. Despite a decade of intense research by chemists on bioactive compounds from gorgonians, no studies have explored quantitative or qualitative of the life cycle. In the first phase of the project the PI will (1) reciprocally transplant clonal replicates of shallow and deep adult colonies to measure genetic and environmental components of defense, (2) determine sources of natural mortality of embryo and larval stages, and (3) quantify the timing of switches in synthesis of major briarein compounds in colony development. In the second phase of the project she will (1) collect and analyze (growth and defenses) the adult transplant, (2) establish juvenile transplants and selection experiments, and (3) investigate the palatability of briareins to predators using bioassays with artificial foods.
