Beyond the. vegetated plain, a calcareous sand plain extends seaward, 

 gradually increasing in depth. No excursions were made beyond 230 m 

 west of tLe reef, and during the mission, the greatest depth attained 

 was approximately 24 meters. During the training period, however, a 

 dive was made approximately one mile south of Lameshur Bay in 31 m 

 depth. There growing on a calcareous sand Bottom that resembled the 

 sand plain near the TEKTITE habitat, 21 Chlorophyta, 3 Phaeophyta, 

 and 32 Rhodophyta were found. Plant cover was moderate, the conspicuous 

 plants including species of Udotea , Caulerpa , Codium , Halimeda , 

 Avrainvillea , Neomeris , Anadyomene , Lobophora , Dasya , Gracilaria , 

 Scinaia , Lauren cia . Griff ithsia and Janla. 



To assess the influence of grazing activity on the attached vegetation 

 members of Mission 4-50 placed cages at intervals along the two 

 transect lines previously described. On transect 1, cages were placed 

 at 20 m, 100 m and 180 m; on transect 2 at 3 m, 60 m, 120 m, and 180 m. 

 An area .6 m was denuded before the cages were positioned and the 

 plants enumerated and weighed. The cages were then fixed so that 

 half of the denuded area was within the cage. Mathieson, Fralick, 

 Burns and Flahive (this report) found after 19 days that no change 

 in quantity or type of vegetation had occurred for the 3 m and 180 m 

 cages along transect 2, but there was a conspicuous increase in growth 

 under the 60 m cage; seventeen new plants of Udotea conglutinata 

 were evident, as well as newly- recorded Acanthophora spicifera , 

 Cottoniella arcuata , Dasya pedicellata and Dlctyota bartayresii . 

 Under the 120 m cage, four new Udotea conglutinata and conspicuous 

 regeneration of Syringodium filiforme had occurred, and Dasya 

 pedicellata , Wrightiella tumanowiczi and Dictyota bartayresii 

 were obtained for the first time. 



Observations were continued on the growth within the cages and grazers 

 present in the vicinity throughout Mission 6-50, beginning on July 6 

 and ending July 19 to 20, seven weeks after the cages were put in place. 



On transect 1, cage 1, 20 m from the reef, the amount of plant 

 material inside appeared equivalent to that outside, including 

 abundant Gelidium corneaum , but several small plants of Padina sanctae- 

 crucis were within the cage and none were found nearby outside. Several 

 small dusky damself ishes ( Eupomocentrus fuscus) moved in and out of the 

 cages at will, and small surgeonf ishes (Acanthrus chirurgus) and puffers 

 (Canthigaster rostrata) nibbled diatoms and filamentous algae from the 

 cage surface. In the vicinity were numerous grazing surgeonf ishes , 

 parrotf ishes , and others. 



VI-141 



