Connectivity of marine populations: Open or closed?

Most marine populations are thought to be well connected via long-distance dispersal of larval stages. Eulerian and Lagrangian flow models, coupled wi th Linear mortality estimates, were used to examine this assumption. The fi ndings show that when simple advection models are used, Larval exchange rat es may be overestimated; such simplistic models fail to account for a decre ase of up to nine orders of magnitude in larval concentrations resulting fr om diffusion and mortality. The alternative process of larval retention nea r local populations is shown to exist and may be of great importance in the maintenance of marine population structure and management of coastal marin e resources.