Dependence of sustainability on the configuration of marine reserves and larval dispersal distance

Marine reserves hold promise for maintaining biodiversity and sustainable f ishery management, but studies supporting them have not addressed a crucial aspect of sustainability: the reduction in viability of populations with p lanktonic larvae dispersing along a coastal habitat with noncontiguous mari ne reserves. We show how sustainability depends on the fraction of natural larval settlement (FNLS) remaining after reserves are implemented, which in turn depends on reserve configuration and larval dispersal distance. Susta inability requires FNLS to be greater than an empirically determined minimu m, Maintaining an adequate value for all species requires either a large, u nlikely fraction (> 35%) of coastline in reserves, or reserves that are lar ger than the mean larval dispersal distance of the target species. FNLS is greater for species dispersing shorter distances, which implies reserves ca n lead to: (1) changes in community composition and (2) genetic selection f ur shorter dispersal distance. Dependence of sustainability on dispersal di stance is a new source of uncertainty.