A feature common to many benthic marine plants and animals is the rele
ase of propagules that serve as the organism's only mechanism of dispe
rsal. Successful dispersal depends to a large extent on the process of
settlement-the transient phase between the pelagic life of the propag
ule and the benthic existence of the adult. The how of water may affec
t settlement on three levels: 1. Flow can act by exerting hydrodynamic
forces on settling propagules. These forces may affect the propagule'
s encounter with the substratum, its behavior following encounter, or
both. 2. Flow may provide a settlement cue that induces active behavio
r of motile propagules. 3. Flow may act to mediate various settlement
cues (e.g. sediment load and the concentration of attractants). We dis
cuss these three levels of flow effects as a means of examining the po
tential importance of flow in the settlement process, and then we expl
ore the ecological consequences of settlement in different flow-regime
s in light of the direct effects of how and flow-derived factors.