Subject: Water Pollution from Organisms
I want to ask you how small animals such as fish contribute to water pollution?
All organsims "pollute", in the sense that they excrete waste materials
from their bodies to the surrounding environment. What is "waste"
for one organism can be essential to another. Think for instance
of the CO2 humans and other respiring organisms produce as waste
from buring carbohydrates with oxygen. This CO2 is essential
for plants, who combine it with energy from the sun to make
carbohydrates, thus producing O2 as waste. In this case, life itself
has evolved into a synergistic system where one group's waste is
another's essential ingredient and vice versa.
Most animals and fish contribute waste to their environments that
are essentially the same as human waste (fecal matter laden with
bacteria and reduced compounds). If the population of an environment
exceeded the capability of the environment to neutralize or at least
tolerate those wastes, certain organisms will begin to die. This
limit is known as the "carrying capacity" of the environment. In
general, nature is wise enough to not naturally reach this limit
in most instances, such that most systems can self regulate themselves
and avoid reaching this limit.
There are examples of indivividual organisms that can excrete
specific polutants or toxins into an environment, usually as a
defense mechanism. There are also plenty of examples of organisms
that can detoxify and store polutants from an environment in
their bodies, making the overall environment "safer" (until the
organism dies, at which point some toxins can be re-released to
the environment).
Dr. Ken Rubin, Assistant Professor
Department of Geology and Geophysics
University of Hawaii, Honolulu HI 96822
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