Science of Water : Concepts and Applications

156 The Science of Water: Concepts and Applications
Ecology is important because the environmental challenges we face today include all the same
ones that we faced more than 30 years ago at the fi rst Earth Day celebration in 1970. In spite of
unfl agging efforts of environmental professionals (and others), environmental problems remain.
Many large metropolitan areas continue to be plagued by smog, our beaches are periodically
polluted by oil spills, and many of our running and standing waters (streams and lakes) still suffer
the effects of poorly treated sewage and industrial discharges. However, considerable progress has
been made. For example, many of our rivers and lakes that were once unpleasant and unhealthy are
now fi shable and swimmable.
This is not to say that we are out of the woods yet. The problem with making progress in
one area is that new problems are discovered that prove to be even more intractable than those we
have already encountered. In restoring our running and standing waters to their original pristine
state, this has been found to be the case.
Those interested in the science of freshwater ecology (e.g., water practitioners and students) must
understand the effects of environmental stressors, such as toxics, on the microbiological ecosystem
in running and standing waters. Moreover, changes in these ecosystems must be measured and
monitored.
The science of freshwater ecology is a dynamic discipline; new scientifi c discoveries are made
daily and new regulatory requirements are almost as frequent. Today’s emphasis is placed on
other aspects of freshwater ecology [e.g., nonpoint source pollution and total maximum daily load
(TMDL)]. Finally, in the study of freshwater ecology it is important to remember the axiom: left to
her, Mother Nature can perform wonders, but overload her and there might be hell to pay.
SETTING THE STAGE
We poison the caddis fl ies in a stream and the salmon runs dwindle and die. We poison the gnats in a
lake and the poison travels from link to link of the food chain and soon the birds of the lake margins
become victims. We spray our elms and the following springs are silent of robin song, not because we
sprayed the robins directly but because the poison traveled, step by step, through the now familiar elm
leaf-earthworm-robin cycle. These are matters of record, observable, part of the visible world around
us. They refl ect the web of life—or death—that scientists know as ecology.
—R. Carson (1962)
As Rachel Carson points out, what we do to any part of our environment has an impact upon
other parts. There is the interrelationship between the parts that make up our environment. Probably
the best way to state this interrelationship is to defi ne ecology. Ecology is the science that deals with
the specifi c interactions that exist between organisms and their living and nonliving environment. The
word “ecology” is derived from the Greek word oikos, meaning home. Therefore, ecology is the
study of the relation of an organism or a group of organisms to their environment (their “home”).
Charles Darwin explained ecology in a famous passage in The Origin of Species—a passage
that helped establish the science of ecology. A “web of complex relations” binds all living things
in any region, Darwin writes. Adding or subtracting even a single species causes waves of change
that race through the web, “onwards in ever-increasing circles of complexity.” The simple act of
adding cats to an English village would reduce the number of fi eld mice. Killing mice would benefi t
the bumblebees, whose nest and honeycombs the mice often devour. Increasing the number of
bumblebees would benefi t the heartsease and red clover, which are fertilized almost exclusively by
bumblebees. So adding cats to the village could end by adding fl owers. For Darwin, the whole of
the Galapagos archipelago argues this fundamental lesson. The volcanoes are much more diverse
in their ecology than their biology. The contrast suggests that in the struggle for existence, species
are shaped at least as much by the local fl ora and fauna as by the local soil and climate. “Why else
would the plants and animals differ radically among islands that have the same geological nature,
the same height, and climate?” (Darwin, 1998).