278 L. HILLIS-COLINVAUX 



of inter-island reefs in which Halimeda is entirely absent or a minor 

 component. And yet Halimeda is one of the principal contributors to 

 reef structure, sometimes perhaps the most important one (Section, IX). 

 Two reef systems have been examined with Halimeda principally in 

 mind. They are a section of the fringing reef on the north shore of 

 Jamaica where a Halimeda census was made (Hillis-Colinvaux, 1972), 

 and Enewetak Atoll where two Halimeda investigators have dived. 



A. The Glory Be reef, Ocho Rios, Jamaica 



"Glory Be" is the name of a house near the village of Ocho Rios, 

 sited roughly in the centre of the north shore of Jamaica. The patch of 

 reef approached from the house was chosen for this study because two 

 headlands marked off a convenient length of reef (Fig. 89), and because 

 the high cliff of fossil limestone gave a vantage point which greatly 

 aided mapping of the various regions of the reef. The approximate 

 coordinates of the reef section are 77°0' W, 18°24' N. 



The reef at Ocho Rios is part of the Jamaican fringing reef which has 

 been extensively studied and described by Goreau and members of his 

 laboratory working from the nearby Discovery Bay (Goreau, 1959; 

 Goreau and Goreau, 1973), and I first became interested in the north- 

 shore reef system when conducted overit byT.F. Goreau in 1962. 1 made 

 a preliminary survey of the Glory Be reef in September 1968 (when the 

 water was somewhat disturbed from the passage of a hurricane), and 

 carried out the main part of the census in three weeks in June 1969. The 

 census extends out only to the beginning of the outer channel or moat 

 zone (7 in Fig. 89), being extended beyond this down to a depth of 20 m 

 (moat, buttress and fore-reef) only by qualitative observation, supple- 

 mented by observations at our other work site of Runaway Bay. 

 Qualitative descriptions of Halimeda populations down to about 70 m 

 are given in Goreau and Goreau (1973). Seasonal assays of Halimeda 

 populations at these greater depths are urgently needed. 



A profile through the Glory Be reef is given in Fig. 90, the numbered 

 parts of which are included on Fig. 89 and in Table XXXIII. These 

 reef zones need to be understood in the context of the reef nomenclature 

 established by Goreau and his laboratory, the usages of which have 

 changed slightly over the years. In Table XXXIII the Goreau equiva- 

 lents are given as they appear in Goreau and Goreau (1973). The 

 comparison of the Glory Be nomenclature with Goreau's reveals not 

 only a finer classification of the near-shore zones at Glory Be, but also 

 some added features of the Glory Be reef system not present in Goreau's 

 generalized model. 



