Environmental Engineering Reference
In-Depth Information
tablished scientifically. This principle is based on the
commonsense idea behind many adages such as “Bet-
ter safe than sorry,” “Look before you leap,” “First, do
no harm,” and “Slow down for speed bumps.”
As an analogy, we know that eating too much of
certain types of foods and not getting enough exercise
can greatly increase our chances of a heart attack, dia-
betes, and other disorders. The exact connections be-
tween these health problems, chemicals in various
foods, exercise, and genetics are still under study and
often debated. People with such conditions could use
this uncertainty and unpredictability as an excuse to
continue overeating and not exercising. In reality, the
wise course is to eat better and exercise more to help
prevent
potentially serious health problems.
Recently, the precautionary principle has served
as the basis of several international environmental
treaties. For example, a global treaty developed by 122
countries in 2000 seeks to ban or phase out 12
persistent
organic pollutants (POPs).
Some analysts point out that we should be selective
in applying the precautionary principle. Although we
need to project possible unintended effects carefully,
we can never predict all of the unintended effects of our
actions and technologies. We must always be willing to
take some risks. Otherwise, we would stifle creativity
and innovation and severely limit the development of
new technologies and products.
In Chapter 7, we will apply the principles of popu-
lation dynamics and sustainability discussed in this
chapter to the growth of the human population. In
Chapters 8 and 9, we apply those principles to under-
stand the earth's terrestrial and aquatic biodiversity
and to consider how to help sustain them.
4.
Many conservationists consider the practice of catch-
ing sharks, removing their fins, and then throwing the
live shark back into the water to die cruel and unethical.
Others support this practice because they say sharks do
not experience pain, have no inherent right to exist as a
species, and bite or kill a few people each year. Do you
believe we have an ethical obligation to treat sharks hu-
manely? Explain.
5.
How would you reply to someone who argues that
(a)
we should not worry about our effects on natural sys-
tems because succession will heal the wounds of human
activities and restore the balance of nature,
(b)
efforts to
preserve natural systems are not worthwhile because na-
ture is largely unpredictable, and
(c)
because there is no
balance in nature and no stability in species diversity we
should cut down diverse old-growth forests and replace
them with tree farms?
6.
Why are pest species likely to be extreme r-selected
species? Why are many endangered species likely to be
extreme K-selected species?
7.
A bumper sticker reads, “Nature always bats last and
owns the stadium.” What does this mean in ecological
terms? What is its lesson for the human species?
8.
Identify aspects of your lifestyle that follow or violate
each of the four sustainability principles shown in Fig-
ures 6-18 and 6-19 (p. 126). Would you be willing to
change aspects of your lifestyle that violate these sustain-
ability principles? List the three most important ways
you could do so.
LEARNING ONLINE
The website for this topic includes review questions for
the entire chapter, flash cards for key terms and concepts,
a multiple-choice practice quiz, interesting Internet sites,
references, and a guide for accessing thousands of
InfoTrac
®
College Edition articles.
Visit
We cannot command nature except by obeying her.
S
IR
F
RANCIS
B
ACON
http://biology.brookscole.com/miller11
Then choose Chapter 6, and select a learning resource. For
access to animations, additional quizzes, chapter outlines
and summaries, register and log in to
CRITICAL THINKING
1.
Some homeowners in Florida believe they should have
the right to kill any alligator found on their property.
Others argue against this policy, noting that alligators are
a threatened species, and that housing developments
have invaded the habitats of alligators, not the other way
around. Others go further and believe the American alli-
gator species has an inherent right to exist. What is your
opinion on this issue? Explain.
2.
How would you respond to someone who claims it is
not important to protect areas of temperate and polar
biomes because most of the world's biodiversity is found
in the tropics?
at
esnow.brookscole.com/miller11
using the access code
card in the front of your topic.
Active Graphing
Visit
http://esnow.brookscole.com/miller11
to
explore the graphing exercise for this chapter.
3.
How would you determine whether a particular
species found in a given area is a keystone species?
