DISPERSAL BY MACROALGAE

Seaweed dispersal is discussed in relation to the properties of the propagules, the parent plant and the water motion. The magnitude of water flow velocities is overwhelmingly important. Even motile propagules have little control over their destiny. The fate of both liberated propagules and drifting plants is discussed in relation to dispersal distance and the likelihood of successful colonization at journey’s end. Analogies are drawn between the dispersion and drift of algal propagules and that of smoke particles and fungal spores. The fecundity of the parent plant, the point and mode of propagule release are also influential. Many larger plants have release mechanisms that limit rather than enhance dissemination. Moreover, contrary to accepted dogma, invertebrates that consume or transport spores also tend to limit rather than extend dispersal range. The relative merits of local consolidation vs. widespread dispersal are discussed. © 1992 The British Phycological Society.