Ecology of cryptic coral reef communities. IV. Community development and life histories of encrusting cheilostome bryozoa

Abstract

Life histories of encrusting cheilostome species from the cryptic reef community at Rio Bueno, Jamaica, were studied on fouling panels over 3 yr. Recruitment and growth were generally slow compared with those reported for temperate cheilostomes. Most species that became abundant and persisted throughout the study did so through relatively rapid growth to a large size by a few successful colonies, rather than by accumulating great numbers of small colonies. This pattern, which reflects a striking increase in maximum survival with increasing colony size, is the basis for the extremely patchy distributions of bryozoans under corals. Reproduction in these species is delayed, and only a few long-lived, large colonies ever reproduce. Only one species, Drepanophora tuberculatum (Osburn), approached the characteristic opportunistic pattern of high recruitment, small colony size, and early reproduction. Grazing and nesting activities of one yellowtail damselfish greatly affected distributions of major taxa and cheilostome species on one set of panels. Species more abundant on grazed panels are more heavily calcified and showed other protective features, compared with species more abundant elsewhere. Despite intensive grazing by the fish, overgrowth interactions occurred frequently on both sets of panels. The fish affected what organisms were present, but did not obviously reduce the amount of overgrowth.