CHAPTER I: INTRODUCTION 



Marjorie L. Reaka 

 Department of Zoology 

 The University of Maryland 

 College Park, Maryland 20742 



This volume presents the results of a workshop on the ecology of coral 

 reefs that was held at the American Society of Zoologists meetings in Philadel- 

 phia, December 1983. The workshop, which included four symposium presentations, 

 four discussion sections, and presentations of undersea research facilities by 

 NOAA's Office of Undersea Research, was sponsored by the Division of Ecology of 

 the ASZ. The four symposium talks and discussion sections addressed the topics 

 of growth and life history patterns, recruitment, community organization, and 

 community metabolism in coral reef systems. The workshop was unusually well 

 attended (attendance in the Ecology Division of the ASZ was 30% higher than in 

 previous years and two additional contributed paper sessions in the Division 

 of Ecology were devoted specifically to coral reef ecology), and vigorous group 

 discussions continued well into the night. The objective of the workshop was 

 to focus attention on what we do and do not know about the ecology of coral 

 reefs, particularly along depth gradients, and to assess the most important 

 directions for future research on coral reefs. 



A previous volume in this series (Reaka, 1983), containing symposium 

 presentations and contributed papers in each of the four topical areas, was 

 made available at the Coral Reef Workshop. The present volume presents the 

 main conclusions derived from the discussion sections (Chapter II) and additional 

 contributed papers on the ecology of coral reefs (Chapter III). 



In Chapter II, the discussion leaders summarize the topics discussed and 

 the conclusions reached in each discussion section. William McFarland points 

 out that astonishingly little is known about recruitment in coral reef species. 

 He identifies some of the reasons for our lack of knowledge in this area, not 

 the least of which is the prevalence of planktonic larvae in reef organisms. 

 The production of hundreds to millions of tiny dispersing planktotrophic larvae 

 distinguishes marine animals from those in every other major environment. 

 Furthermore, the incidence of species with long-lived planktotrophic larvae is 

 inversely related to latitude (Thorson, 1950; Mileikovsky, 1971), so that, in 

 contrast to marine communities from high latitudes, the vast majority of coral 

 reef species produce planktonic dispersing young. This phenomenon has profound 

 implications for the population dynamics, community organization, and even 

 evolutionary patterns of marine species compared to those in terrestrial or 

 fresh water environments. In marine species thousands of recruits may occur in 

 local areas in some years but not in others; planktonic larvae may settle in 

 their parent population, may be carried to distant habitable sites, or even may 

 be swept out to sea without any favorable substrate having been encountered. 

 McFarland discusses several mechanisms that enhance the predictability of local 

 recruitment on coral reefs, including the timing and dynamics of reproduction, 

 currents or eddies that may return larvae to their parent populations, and 

 behavioral patterns of the larvae and settling juveniles themselves. These 



