ECOLOGY AND TAXONOMY OF Holimeda 



243 



retrieval and cycling work, but we know much less about the parallel 

 systems in a coral atoll. It seems not unreasonable to expect that 

 nutrient retrieval and cycling is sponsored by the primary producers, 

 suggesting that the productivity of the various plant components of 

 the reef ecosystem is a necessary subject for research. 



Figures 79 and 80 are photographs of the section of the Enewetak 

 reef studied by the Odums and the SYMBIOS group. This section was 



Fig. 79. The inter-island study site of Odum and Odum (1955) is 0-4 km north (right) 

 of this islet, Japtan, on Enewetak Atoll, and north of the ship hulk, a relict of the 

 Second World War. The Odum ti-ansect extended from the algal ridge, where the 

 waves are breaking, towards the lagoon for approximately 300 m. The reef in this 

 region is approximately 455 m wide. (Data from Odum and Odum, 1955.) 



chosen for its suitability to the flow-respiratory method of productivity 

 measurement and does not include all parts of the atoll system. In 

 particular, it does not include most of the macrophytes. Plants included 

 in the transect were principally the algae of mats together with the 

 symbiotic and boring algae associated with the corals, as well as some 

 encrusting algae. In a careful search of much of this section of reef in 

 1975 I was unable to find a single Halimeda plant. This observation is 

 perhaps brought into perspective by noting that borings from Enewetak 

 show that Halimeda segments are a principal ingredient of the Enewetak 

 reef matrix, just as they are at Funafuti (Couch et al., 1975). 



