322 
PACIFIC SCIENCE, Vol. V, October, 1951 
individuals who assisted actively in the work 
and to members of the staff of the Department 
of Zoology and Entomology, University of 
Hawaii, who have made helpful suggestions. 
PHYSICAL FEATURES OF KANEOHE BAY 
Kaneohe Bay (Fig. 1), on the windward 
(east) shore of Oahu, is about 7 miles in 
length and about 2 miles in width. It lies in 
a general northwest-southeast direction and 
has a total area of about 12 square miles. 
For the most part, a continuous but irregu- 
larly indented coral reef follows the shoreline 
and averages about 400 yards in width. It is 
broken at the mouths of streams by mud 
flats. The main body of the bay is studded 
with coral reefs of various sizes and shapes. 
At low tide these, and also the shoreside reef, 
are either awash or are covered by about a foot 
of water; at high tide they are covered by 3 
or 4 feet of water. In some places, e.g., the 
southern sector of the bay, the reefs have 
been removed by dredging. Deducting the 
area of the coral reefs and flats from the total, 
the navigable water area is about 6 square 
miles. 
The southern sector of the bay, which 
averages about 40 to 45 feet in depth, is pro- 
tected from the open sea by Mokapu Penin- 
sula. The middle sector of the bay is partially 
protected from the open sea by coral reefs 
and by a large sand flat, known as Sand Is- 
land, which is partly exposed at some phases 
of the tide. Within the middle sector, the 
channels between the reefs average about 40 
feet in depth. The northern sector of the bay 
is also partially protected from the outer sea 
by sand shallows and coral reefs, although 
not to the same extent as the southern and 
middle sectors. Its average depth is less than 
that of the other two sectors, about 15 to 20 
feet. 
Thus, apart from a few shallow channels, 
Kaneohe Bay is virtually cut off from direct 
interchange with the outer ocean. Although 
surface water will flow over the shallows and 
enter the bay, propelled by the strong north- 
east trade winds, the bay would be expected 
to have a variety of simple to complex in- 
ternal circulatory systems, each depending on 
the configuration of the shoreline, the pres- 
ence of reefs, the strength of the wind, the 
phase of the tide, and the amount of fresh 
water entering the bay from several small 
streams. 
In the southern and middle sectors, the 
water has a brownish tinge, indicating the 
presence of silt and, perhaps, plankton. It is 
quite cloudy alongshore where a strong j 
turbulence is created by the usual onshore || 
wind. In the northern sector, the water close |[ 
to shore is also somewhat brownish and |i 
cloudy. However, the blue ocean water, en- j 
tering through the main northern channel, :| 
impinges on the bay water and, on occasion, f 
forms a definite line of demarcation. 
I 
I 
STATIONS AND SURVEYS ! 
Twenty-three stations in representative lo- 
cations were selected from a chart of Kane- 
ohe Bay, nine (Stations 1 to 9) in the southern 
^ . . . . 'I 
sector, eight (Stations 10 to 17) in the middle 
sector, and six (Stations 18 to 23) in the 
northern sector (Fig. 1). The stations were i 
not spot locations; rather, they were straight ! 
or sinuous courses followed by the research 
vessel Salpa in towing plankton nets. The 
straight courses were followed in the more 
open parts of the bay; the sinuous courses 
were necessary at stations located among the | 
coral reefs. As nearly as possible, the same 
course was followed at each station during || 
successive surveys. j! 
Four main surveys were undertaken on the !| 
following dates: (1) September 6, 7, and 8, || 
1949 , (2) December 27, 28, and 29, 1949, 1 
(3) March 16, 17, and 18, 1950, and (4) June !: 
21, 22, and 23, 1950. In each survey, the j 
stations of each sector were worked on sue- ’ 
cessive days. In addition, two interim surveys ,| 
were made in the vicinity of Station 4 as j 
follows: (la) November 25, 1949, and (lb) i; 
