OLI Funded Grant: Population limitation at the land-sea interface: do jungle derived secondary metabolites structure marine sessile communities?


Grant Funded: 2004

Most coastal species living on the sea bottom have a two phase life cycle. Adults are large and live associated to the sea floor whereas juveniles are small and drift at the mercy of ocean currents. Larvae born near the shore disperse offshore and, typically after a few weeks, return to the adult habitat to settle, grow and reproduce. These species form communities structured by two types of processes that depend on larval supply.

(1) When larval supply is abundant, factors such as biological interactions, physical stress and disturbances that occur after larvae have settled structure communities. (2) When larval supply is limited, community structure is determined by processes influencing the drifting larvae. In the latter case, researchers have focused on larval transport and small scale hydrodynamics. Here we address a different process, the limitation of supply due to larval mortality by natural stressors. In Bahia Honda, Panama, sessile communities on mangrove roots (epibionts) are conspicuously scarce or lacking. This contrasts strikingly with mangrove communities in other regions of the Pacific and the Caribbean, where sessile mollusks and crustaceans are abundant. We hypothesize that secondary metabolites that prevent herbivory in the flora of tropical rain forests accumulate in near-shore waters and cause larval mortality of potential epibionts. Population density of epibionts is thus limited and the effects of the metabolites are greater in mangrove systems where terrestrial material is abundant and accumulates more than in non mangrove near-shore habitats. We propose to test this hypothesis with transplant experiments, bioassays on larvae, and observations on circulation.