194 
PACIFIC SCIENCE, Vol. 1, October, 1947 
HABITAT 
The fishponds already mentioned are dis¬ 
cussed by Hiatt (ined.) from the standpoint 
of construction and as a habitat for fish and 
invertebrates. These ponds are usually en¬ 
closures along the seacoast but may at times 
be exposed directly to the sea. They are en¬ 
closed by a stone or mud wall oceanward. 
Into some ponds fresh-water streams enter 
on the land side. The ponds were handed 
down among the natives for generations, and 
were used mainly for the purpose of raising 
fish for the kings and chieftains of the vari¬ 
ous islands until 50 years ago, when they be¬ 
came somewhat commercialized. Several of 
the ponds under study, however, are still 
held within the original families who were 
given the ponds by chieftains. 
The continued utilization of these fish¬ 
ponds no doubt has been encouraged by the 
desire of various racial groups in the Ha¬ 
waiian Islands for certain kinds of table fish 
which live in brackish water, at least dur¬ 
ing part of their life history. It was found 
by the zoologists in the 1946 biological sur¬ 
vey that the two most desirable fish, mullet 
(Mugil cep halos) and milkfish or awa 
(Chanos chanos ), fed largely on micro¬ 
benthos, and the milkfish fed also on larger 
algae if they were available (Hiatt, loc. cit .). 
Identification of the dominant algae was 
made in order to help "farm” the fishponds 
intelligently, as it was found that the food 
chain ultimately rested with some of these 
forms. 
These ponds furnish a type of habitat the 
study of which may give additional ecolog¬ 
ical information. They are not usually more 
than 6 feet in depth, and thus would allow 
the penetration of light sufficient for the 
growth of algae. However, the water is 
usually turbid and stirred by the wind. The 
bottom, consisting of mud, or more rarely 
mud and sand, is frequently moved by the 
ebb and flow of the tide through the gates 
from the adjoining ocean. In most ponds, 
therefore, the algae must of necessity be at¬ 
tached to the walls or on halophytic phanero¬ 
gams [Batis maritima, Halophila ovalis (R. 
Br.) Hooker; see Fig. 1]. 
Fig. 1 . Halophila ovalis (R. Br.) Hooker. 
Habit of a portion of a plant from Molii Pond. 
Natural size. 
Most of the algae show an affinity for the 
more marine (sea wall) portions of the 
ponds. They are found abundantly in such 
localities, and but sparingly in other regions 
of the ponds. The fresh-water species are 
restricted to the mouths of streams where 
there is little contact with the ocean, or to 
fresh-water ponds which are apparently fed 
by artesian wells. Diatoms are abundant 
epiphytically, and in some ponds form a 
thick mat on the floor of the pond, mixed 
with other small algae and the larvae of cer¬ 
tain animals. 
No seasonal variation in the appearance 
and disappearance of various forms was 
noted. 
