DISPERSAL OF INTERTIDAL INVERTEBRATES - A STRATEGY TO REACT TO DISTURBANCES OF DIFFERENT SCALES

Investigations on settlement and recruitment of intertidal macrofauna and recolonization experiments shed light on the ability of postlarval stages to disperse, significantly prolonging the dispersal phase of the planktonic stages of macrofauna. Unfortunately, the ecological importance of postlarval dispersal as well as the mobility of adults has been disregarded in the past. Three types of dispersal are compared in this report: planktonic larvae, postlarvae (temporary meiofauna) and adults of the macrofauna. Data on the permanent meiofauna are.also included. Scales of dispersal vary with size and age of the animals involved: (i) large-scale: planktonic larvae, (ii) mesoscale: postlarvae and permanent meiofauna, and (iii) small-scale: adult macrofauna. Different disturbance scales also exist: large areas (e.g. disturbed by pollutants), zones and patches (e.g. disturbed by feeding of epibenthic predators). It is suggested that all modes of dispersal contribute to the recovery of these areas. Settlement of planktonic larvae predominates if the disturbed areas are large. In smaller affected plots, postlarval transport as well as immigration of adults begin to play a more significant role. It is concluded that the ability of the macrofauna to disperse during their benthic life stage contributes to the elasticity of coastal and intertidal benthic communities.