Variable recruitment and its effects on the population and community structure of shallow-water gorgonians

Yoshioka, Paul

Recruitment may play a critical role in the structure and dynamics of coral reef populations and communities. In this study recruitment of shallow-water gorgonians was monitored semiannually at two sites on the southwest coast of Puerto Rico for 8 y (1984-1992). Recruitment usually varied between 5 and 10 colonies·m-2 for most of the study period but reached episodic proportions (up to 45 colonies·m-2) from autumn, 1984 throughout 1985. This period of high recruitment has had a major impact on age-frequency distributions and is largely responsible for a 6-fold increase in colony densities (from 9.8 to 62.3 colonies·m-2) during the study period at one of the sites. Gorgonian populations can be termed "recruitment-limited" from this perspective. An examination of "stock-recruitment" relationships indicated that the species composition of recruit colonies largely follows the relative abundances of adult (large) colonies. The episode of high recruitment may have resulted from the mass mortality of a major benthic grazer. Diadema antillarum in 1984. The possibility that high colony densities limited recruitment during the latter stages of this study in the continued absence of Diadema was falsified by field experiments in which higher recruitment occurred in control quadrats compared to quadrats cleared of gorgonians.

Variable recruitment and its effects on the population and community structure of shallow-water gorgonians

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