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example, mercury was thought to be relatively immobile as a metal, 
but, under natural conditions, it can become incorporated into organic 
compounds such as methyl mercury. This compound is very active 
and biologically hazardous in concentrating mercury in the food web. 
Physical baselines.—Physical baselines are also necessary. Among 
these are temperature, salinity, dissolved gases, depth, currents, etc. 
These physical parameters have a direct effect on the ecology of the 
estuaries and oceans. In cases where an electric power-generating 
facility is proposed, temperature changes created by the facility may 
have severe effects on the biota im the vicinity. Pollution-related 
changes in thermal and density gradients and ocean-atmosphere 
equilibria may affect weather and climate. Comprehensive physical 
baseline data are necessary to assess environmental changes. 
Biological baselines—Baseline data of biological populations are 
another requirement. These most directly affect man since a major 
element of food supply is derived from the oceans. Pollutants which 
themselves weaken or destroy a link in the food chain will also affect 
all the links further along. Sometimes the effect of a pollutant is not 
readily apparent or known. An oil spill may cause the death of a few 
high order organisms such as birds and fish but unnoticed millions of 
micro-organisms may also perish. Millions of others may become 
contaminated. The effect of this loss on the ecology of an area may 
not be immediately evident. Baseline data on populations of micro- 
organisms, in addition to higher order life forms, may help assess 
damage to the marine environment. 
Distribution and Dispersal Mechanisms 
Accurate knowledge of distribution and dispersal mechanisms 
such as currents, tides, waves, estuarine circulation, and wind patterns 
over the oceans, etc. is important in pollution control. The oceans can 
be utilized as repositories for many materials. In some cases this 
will be unavoidable since materials deposited on Jand or in the atmos- 
phere will not tend to remain there. In other cases intentional releases 
into the oceans may be the most suitable means of diluting or disposing 
of a substance. The latter, however, cannot be accomplished in a re- 
sponsible and controlled fashion without prior knowledge of the 
distribution of the material within the marine environment. Informa- 
tion on speed, direction, and fluctuations of currents must be available 
to assure proper dilution and dispersion and guarantee that there will 
be no harmful concentration. In other cases knowledge of. dispersal 
mechanisms may be used to assure that a material will not be dispersed, 
Monitor Changes 
Monitoring systems established to determine changes in the marine 
environment induced by man’s activities are of central importance. 
A number of technological developments are now available to facilitate 
this type of program. Satellite sensors can monitor temperatures ‘and 
atmospheric conditions. Surface measurements can be made from 
bouys, ships, and floating platforms. Seabed sensors are also being 
developed. Key parameters need to be selected to yield the information 
necessary to assess the implications and future effects of any deviations 
from baseline data. 
