ANTIFOULING EFFECTS OF EPITHALLIAL SHEDDING IN 3 CRUSTOSE CORALLINE ALGAE (RHODOPHYTA, CORALINALES) ON A CORAL-REEF

Crustose coralline algae cover a substantial fraction of surfaces on t he shallow parts of coral reefs. The shedding of surface layers of cel ls by three common species was studied using light and electron micros copy. All three species examined shed epithallial cells in one of two ways: synchronous epithallial shedding involving the simultaneous shed ding of a sheet of cells across a large area of the thallus surface (S porolithon ptychoides and Neogoniolithon fosliei), or nonsynchronous e pithallial shedding which occurs when epithiallial cells degenerate in dividually (Hydrolithon onkodes). Experiments were done to determine w hether these types of epithallial shedding could produce an anti-fouli ng effect. Recruitment onto the surfaces of live and bleach-killed cor alline fragments was compared for two synchronous and one non-synchron ous shedding species. In all cases, the killed corallines became overg rown within a few weeks. Live corallines remained largely free of othe r organisms for the duration of the experiment. The results thus demon strate that both types of epithallial shedding can influence recruitme nt in the reef ecosystem. (C) 1997 Elsevier Science B.V.