Background and objectives Most macroscopic marine organisms, from algae to fish, are sessile or sedentary organisms reproducing through propagules (spores, vegetative fragments, larvae) that spend minutes to months 2 in the plankton. The existence of a planktonic propagule in the life cycle of these organisms has two major consequences to the dynamics of the populations: i) many marine species form metapopulations and ii) small variations in the mortality factors during the dispersal phase originate large changes in supply to the adult habitat.