Abstract: Chemical cues mediatemany critical life processes, such as feeding, reproduction, andbenthic settling, for aquatic organisms. Depending on the fluidvelocity and flow regime, released chemicals are transported viadiffusion, laminar advection, or turbulent advection prior toorganism reception. Here, we review transport mechanisms andecological consequences in each regime.We discuss cue structuresin terms of concentration gradients, concentration fluctuations,and spatial patterns and draw conclusions about strategies thatanimals use to acquire information. In some cases, chemicaltransport occurs through a combination of mechanisms, whichrequires a multiscale analysis. Regime and scaling are majorthemes that emerge from recent research. In particular,nondimensional parameters that combine biological and physicalvariables reveal general principles under which organisms respondto chemical cues and facilitate defining regimes of behavior.