Ecology of intertidal and sublittoral cryptic epifaunal assemblages. II. Nonlethal overgrowth of encrusting bryozoans by colonial ascidians

Total overgrowth of encrusting cheilostome bryozoans by sheet-like colonial ascidians is commonly observed in epifaunal sessile assemblages on marine hard substrata. Although death of the overgrown colony is the usual outcome, we show here that such interactions need not necessarily lead to the demise of the bryozoans, despite continuous total covering for perhaps several months. Because colonial ascidians were essentially "early" colonists of the experimental panels, most of our data pertain to small bryozoans. Colonies of several bryozoan species spanning a wide range of sizes did, nonetheless, survive overgrowth in both the intertidal and sublittoral. The importance of repeated, as opposed to single, overgrowth observations is discussed in relation to the analysis of competitive relationships among epifaunal organisms.