bay, but they are not undertaken as ongoing routine monitoring. These 
measurements are being made before diversion and, to the extent necessary, 
will be repeated after the diversion. The sampling design is modified to answer 
specific questions. For example: What are the relationships among variables 
obviously related to water clarity? While an answer can, to some extent, be 
extracted from routine sampling, it is more satisfactorily addressed by sampling 
along strong water clarity gradients which may or may not coincide with the 
routine sampling stations. 
3. Laboratory experiments, also designed to answer specific questions 
about the ecosystem. Particular responses of communities within Kaneohe Bay 
are best addressed by controlled laboratory experiments. These experiments 
vary in volumetric scale from batch phytoplankton cultures in 500 ml flasks, to 
flow-through microcosm tanks which are 500 liters or larger in volume. The 
questions addressed in these simplified, but controlled laboratory experiments, 
cannot be easily answered under natural, and largely uncontrolled field 
conditions. Of course, the largest of the controlled experiments is the bay 
itself, a “reaction vessel” with a water volume in excess of 200 million m^. The 
time scales of these experiments vary from a few days in the flasks, to months 
in the microcosms, and several years in the field. 
In this presentation, I do not explicitly separate these various research 
components. Rather, I synthesize the components into our present view of 
total ecosystem characteristics and predicted responses to sewage diversion. 
This exercise is, of necessity, a preliminary analysis of our ongoing study. 
MAJOR ECOSYSTEM CHANGES IN THE 
PAST TWO DECADES 
The impact of runoff on Kaneohe Bay is largely in the form of short-term 
“catastrophic events.” In the past 17 years, there have been three years with 
monthly rainfall in excess of 75 centimeters within the Kaneohe watershed 
(Figure 23-2). In terms of water delivery to the bay, May 1965 represented an 
extreme: most of the rain fell in a 2-day period and was followed by rapid 
runoff. A freshwater lens from that storm killed corals and other reef 
organisms on the fringing reef and nearshore patch reefs to a depth of up to 1.5 
meters (1). The reef flats are less than 1 meter deep, so such a destructive 
“freshwater kill” virtually decimated the stenohaline marine organisms of the 
reef flats and upper portion of the reef slopes. Below about 2 meters the 
organisms were relatively unaffected. 
Sediment loading associated with runoff has two general effects on the 
ecosystem, one as the material is deposited, the other as the material is in the 
water column. Deposition smothers reef organisms and lowers the availability 
347 
