FEEDING EXPERIMENTS 



The feeding experiments were conducted by transporting large quantities 

 of selected algae (e.g., Avrainvillea nigricans , Caulerpa cuppressoides , 

 Caulerpa prolifera , Halimeda incrassata , Penicillus capitatus , Udotea 

 conglutinata , Dictyota bartayresii , Pocockiella variegata , Gracilaria 

 cylindrica and Wrightiella tumanowiczi ) from transect 2 to the reef near 

 the habitat. In essence, separate piles of different diets were prepared 

 in order to observe the feeding habits and/or specificity of the reef 

 fish. Observations, totaling 12 hours, were made for three consecutive 

 days. It soon became evident that some of the algae were of little 

 interest to the fish (particularly Avrainvillea nigricans ), whereas 

 other species seemed to be actively eaten. The Parrot fish were par- 

 ticularly interested in Halimeda incrassata , and the plants were 

 systematically cut up into small fragments. Many of the other fish did 

 not eat Halimeda incrassata . The Grey Angel fish was most interested in 

 the more succulent portions of Caulerpa spp., Wrightiella t\]manowiczi 

 and Gracilaria cylindrica . After three days the the samples were examin- 

 ed to determine what quantities were still remaining. Halimeda 

 incrassata , Gracilaria cylindrica , Wrightiella tumanowiczi and Caulerpa 

 spp. were reduced to very small quantities. Limited amounts of Udotea 

 conglutinata , Penicillus capitatus , Dictyota bartayresii and Pocockiella 

 variegata were still evident. Very little Avrainvillea nigricans was 

 eaten. 



EPIPHYTIC ALGAE 



A total of 31 species of epiphytic algal flora were recorded, consisting 

 of 19 species of red algae, 9 green and 3 brown. The red algae were 

 found on the widest variety of plants, in part because of their small 

 size. Four green (Blastophysa rhizopus , Caulerpa racemosa , Caulerpa 

 taxifolia and Halimeda incrassata ) and four red algae (Digenia simplex , 

 Dudresnaya sp. , Liagora sp. and Spyridia filamentosa ) were restricted 

 to a single host plant. Each of these species, except Blastophysa 

 rhizopus and Dudresnaya sp., was also found on sand, shells or other 

 solid substrates. Although no quantitative evaluation was made, it was 

 apparent that the epiphytic flora was much higher in silty areas than in 

 sandy portions of the transect. Thus, a high diversity and quantity of 

 epiphytes was found from 42 - 171m, where maximum numbers of Halimeda 

 incrassata and Avrainvillea nigricans were also evident. Twenty-five 

 species of epiphytes were found on Avrainvillea nigricans , 14 of which 

 were red algae. In addition, 17 species of epiphytes were found on 

 Halimeda incrassata and 13 on Udotea conglutinata . Again, most of the 

 epiphytes on the latter species were red algae. Avrainvillea was the 

 largest plant and Udotea the smallest (compare Figure 9). Thus, there 

 is a good correlation between availability of space and diversity of 

 epiphytes . 



VI-126 



