ECOLOGY AND TAXONOMY OF Holimeda 



303 



possessed the same high Halimeda species richness that was encountered 

 in the fast-flowing lagoonward end of the inter-island channel between 

 Lojwa and Alembel. Species of section Opuntia other than opuntia, the 

 taxa copiosa, distorta and to a lesser extent minima, achieved promi- 

 nence on these knolls. 



The flattish top of Pole pinnacle lies approximately 4 m below the 

 surface of the water at low tide ; its base is reached at about — 40 m. 

 Halimeda distorta and macrophysa filled crevices between colonies of 



Fig. 101. Cluster of H. copiosa on Pole pinnacle near Rex Islet at a depth of 12—15 m, 

 in December. The thalli are relatively small, with the width of broadest segments 

 shown being 10-14 mm. 



living coral on the brightly lighted, essentially horizontal upper surface 

 of this pinnacle, with sizeable, dense clumps of macrophysa in places 

 providing almost closed cover. The species copiosa, although present 

 near the top with the other taxa mentioned, was more prominent under 

 overhangs lower down (Fig. 101), often growing from under protuber- 

 ances of the pinnacle. The thalli tended to be small, but this may be a 

 seasonal phenomenon. Halimeda minima occurred under such over- 

 hangs too, but was not as abundant as copiosa, and other Halimeda 



