Ecological Studies of Black Coral in Hawaii 1 
Richard W. Grigg 2 
The black corals (Order Antipatharia) are 
found in all oceans. However, the great majority 
of the 150 species have been collected with 
dredges below the limits of human observation 
{see Table 1). It is therefore not surprising that 
very little ecological work has been done within 
this group. The anatomy and taxonomy have 
been reviewed by Brook, 1889, Cooper, 1907— 
1909, and Van Pesch, 1914. 
In 1958 off Lahaina, Maui, Jack Ackerman 
and Larry Windley, using SCUBA equipment, ac- 
cidentally discovered a vast "bed” of black coral 
in 50 m of water. Previous to this find, the 
black coral Antipathes grandis Verrill had rarely 
been observed in Hawaii. Only occasionally had 
divers found stunted colonies in shallow caves 
where surge was not excessive. 
At least three species of black coral are rep- 
resented in the Hawaiian Islands, all limited to 
deeper water generally beyond 30 m. Only 
one species has been recorded in the literature, 
A. grandis, and since it is the most common 
form, it was selected for this study (Fig. 1). 
The purpose of this research was to study and 
delineate the ecological factors which limit the 
distribution of this animal to deeper water. 
METHODS AND MATERIALS 
Plan of Work 
A series of stations was selected, some with 
and some without colonies of actively growing 
A. grandis (Fig. 2). Over a period of six months, 
hydrographic data were collected: light penetra- 
tion, current, turbidity, surge, oxygen concentra- 
tion, salinity, temperature, and depth. In addi- 
tion, the texture and type of substrate were- 
analyzed and population counts were made. By 
so doing, a comparison between stations could 
1 Portion of a Master’s Thesis, University of Hawaii, 
completed in July, 1963. Manuscript received Decem- 
ber 8, 1963. 
2 Scripps Institute of Oceanography, La Jolla, Cali- 
fornia. 
readily be made and the factors limiting distri- 
bution could be outlined. 
Branches of the living colonies were trans- 
planted to various habitats, where regular ob- 
servations could be made to determine if the 
animal was alive, dying, or dead. These trans- 
plants were put in places where it was hoped the 
effects of environmental extremes could be dis- 
covered. For example, the headland off Moku 
Manu Islands, Oahu, was selected because here 
wave action and surge reach a maximum, while 
turbidity, oxygen concentration, salinity, and 
temperature are relatively constant. On the other 
hand, the muddy bottom of Kaneohe Bay, Oahu, 
was also used, for it is extremely turbid, with no 
excessive fluctuations in salinity, oxygen con- 
centration, temperature, and surge. Thus, it was 
attempted to measure one factor while keeping I 
the other factors relatively stable, thereby using 
the environment as a natural laboratory. Experi- 
ments in the laboratory were impractical be- 
cause of the problem involved with handling the 
animal. 
Collection of Data 
LIGHT: Light measurements were carried out 
with a flat plate irradiance meter which was 
calibrated with a footcandle meter. Two photo- 
electric cells were first connected to a galva- 
nometer which was adjusted to a zero reading 
TABLE 1 
The Bathymetric Distribution of 66 Species of j 
Antipatharia Collected by the Challenger 
Expedition During the Years 1872-1876 
(Brook, 1889 ) 
ZONE 
METERS 
NUMBER OF SPECIES 
1 ... 
0-18 
6 
2 
18-183 
25 
3 
183-914 
26 
4 
914 - 1,829 
2 
5 
1 , 829 - 3,658 
3 
6 
3 , 658 - 5,486 
4 
244 
