Ecology of Black Coral — G rigg 
251 
The fact remains, however, that branches did 
survive in calm water as shallow as 1.2 meters. 
Hence, surge appears to be the prime factor 
limiting the viability of adult colonies. 
The fact that the tissue was denuded from 
the skeleton illustrated the abrasive effects of 
surge. The author believes that suspended par- 
ticulate material was largely the cause of this 
abrasion, rather than the frictional drag of the 
water itself. This view is supported by the fact 
that A. grandis is able to withstand currents as 
high as 3 knots in the Auau Channel between 
Maui and Lanai, where the water is remarkably 
free of suspended material. 
Figures 8 and 9 picture two branches of A. 
grandis, at 12 and 24 meters respectively, which 
had been secured above the bottom on a buoyed 
line (Fig. 4), 200 yards off Moku Manu Islands 
for a period of 90 days. After two weeks about 
50% of the branch at 12 meters was alive, while 
FIG. 6. This schematic photograph simulates the in situ orientation to light of a young colony of A. grandis, 
originally collected in 25 meters of water off Kawailoa, Oahu. Notice the positive photo-tropism (toward 
arrow), whereas the site of implantation indicates tha t the larva is negatively phototaxic. p 3 X* 
