Larval Dispersal: A Biophysical Process Strongly Influenced By Larval [and Adult] Behavior

Dispersal of larval marine fishes was once thought to be a primarily physical process whereby passive larvae were dispersed by currents, leading to genetically and demographically open populations connected over large spatial scales.  Research on the behavioral capabilities of larval marine perciform and beryciform fishes reveals them to be active, very capable swimmers with good orientation and sensory abilities that give them the capacity to strongly influence their dispersal.  Direct measures of dispersal show that self-recruitment is more common than previously thought, but that dispersal over larger distances also takes place.  These advances clearly show that dispersal is a biophysical process involving both behavioral inputs from the larvae and hydrodynamics.  Limited behavioral data on larvae of other fish Orders is an obstacle to understanding whether their larvae have similar abilities.  Adult behavior is also an important input to dispersal. The timing (seasonal, lunar, diel), and location of spawning determine the important starting conditions for dispersal.  Buoyancy of pelagic eggs, and whether eggs are demersal, brooded or pelagic, are also critical determents of dispersal outcomes.  These issues are briefly reviewed, with examples, primarily from tropical systems.  The extent to which larval dispersal differs between high-latitude and low-latitude systems remains unclear.