174 
RESEARCH NEEDS 
Physical processes.—Flushing, circulation, mixing, diffusion, light absorption, 
sedimentation rates. 
Chemical processes.—Fate of terrigenous compounds, fate of man-made 
chemicals. 
Biological processes.—Reactions of various species to pollutants such as oil, 
heavy metals. Nutrition, genetics, general physiology, growth of wetland species— 
including those not directly useful to man. Interrelationships between species 
energy flow. 
Figure V. A list of basic research that must be accomplished before intelli- 
gent decisions concerning multiple use of the wetlands can be made. 
A few examples from this list should show how many of our actions, 
including those not directly related to wetlands, often have very 
serious effects on them. Marshland can be destroyed directly by dredg- 
ing it for harbor and marina construction or it can be reclaimed to make 
space for houses, highways, industry, golf courses, etc. Many of man’s 
activities produce more subtle effects and nearby highway construc- 
tion, erosion of agricultural lands, or sand and gravel operations may 
increase silting to the point where it smothers the marsh and the marsh 
grasses are replaced by less productive species. Drainage of the marsh 
for mosquito control often has mixed effects. It usually results in im- 
proved flushing action which makes more area available for food and 
habitat but vegetation changes also can result in less productive 
grasses being introduced. This is especially true when salt pans are 
drained and the wigeon grass they contain dies, making the marsh 
much less suitable to migratory waterfowl. The introduction of pesti- 
cides or industrial wastes such as heavy metals and petrochemicals 
has been well publicized, along with the resulting destruction or clos- 
ing of shellfish beds. Pollution by such chemicals drastically alters the 
salt marsh system and estroys its function by damaging flora and/or 
fauna species that are critical in the food web. In Connecticut, the 
average annual value of the shellfish crop between 1900 and 1920 was 
$20 million. As a result of the direct destruction of marshland and the 
destruction of its functioning by pollution, the average annual value 
of shellfish since 1955 has been $1.5 million. 
The decision that usually must be made is whether to maintain 
the wetland area in its natural productive state or to alter it to make 
it more directly useful to man. Cost-benefit ratios that are used in 
making this decision are usually computed on a short-range, purely 
economic basis. We must reverse this policy and begin to include all 
of the costs, including the concealed social and long-term costs, when 
making decisions that may cause alterations of the wet lands. Usually 
“development” of wet lands yields substantially imcreased profits 
for the developer, but if all the costs of the resulting damage are 
totaled, the net loss to other users would greatly offset these private 
gains. This does not imply that we cannot utilize wet lands to a greater 
extent than we do now, but any increased utilization must be based 
on ecologically sound principles. For example, usable ‘‘crops’’ such 
as oysters, crabs, and clams can probably be more intensively produced 
but to do this we must first learn more about the energy-flows within 
the system. The diversity of the salt marsh reduces the usable 
production because organisms other than man remove energy from 
the system. However, it is this diversity that gives stability to the 
