Environmental Encyclopedia

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Environmental Encyclopedia 3

Exotic species

dinarily effective colonists, spreading quickly and eliminating

competition

as they become established.

The list of species introduced to the Americas from

Europe, Asia, and Africa is immense, as is the list of species

that have made the reverse trip from the Americas to Europe,

Asia, and Africa. Some notable examples are

kudzu

(Puer-

aria lobata), the

zebra mussel

(Dreissena polymorpha), Afri-

canized bees Apis mellifera scutellata), and

Eurasian milfoil

(Myriophyllum spicatum).

Kudzu is a cultivated legume in Japan. It was intention-

ally brought to the southern United States for ground cover

and

erosion

control. Fast growing and tenacious, kudzu

quickly overwhelms houses, tangles in electric lines, and

chokes out native vegetation.

Africanized “killer” bees were accidentally released in

Brazil by a beekeeper in 1957. These aggressive insects have

no more venom than standard honey bees (also an Old

World import), but they attack more quickly and in great

numbers. Breeding with resident bees and sometimes travel-

ing with cargo shipments, Africanized bees have spread

north from Brazil at a rate of up to 200 miles (322 km) each

year and now threaten to invade commercially valuable fruit

orchards and domestic bee hives in Texas and California.

The zebra mussel, accidentally introduced to the

Great

Lakes

around 1985 presumably in ballast water dumped

by ships arriving from Europe, colonizes any hard surface,

including docks, industrial water intake pipes, and the shells

of native bivalves. Each female zebra mussel can produce

50,000 eggs a year. Growing in masses with up to 70,000

individuals per square foot, these mussels clog pipes, suffo-

cate native clams, and destroy breeding grounds for other

aquatic animals. They are also voracious feeders, competing

with fish and native mollusks for

plankton

and microscopic

plants. The economy and environment of the Great Lakes

now pay the price of zebra mussel infestations. Area indus-

tries spend hundreds of millions of dollars annually unclog-

ging pipes and equipment, and commercial fishermen com-

plain of decreased catches.

Eurasian milfoil is a common aquarium plant that can

propagate from seeds or cuttings. A tiny section of stem and

leaves accidentally introduced into a lake by a boat or boat

trailer can grow into a huge mat covering an entire lake.

When these mats have consumed all available nutrients in

the lake, they die and rot. The rotting process robs fish and

other aquatic animals of oxygen, causing them to die.

Exotic species have brought ecological disasters to ev-

ery continent, but some of the most extreme cases have

occurred on isolated islands where resident species have lost

their defensive strategies. For example, rats, cats, dogs, and

mongooses introduced by eighteenth century sailors have

devastated populations of ground-breeding birds on Pacific

islands. Rare flowers in Hawaii suffer from grazing goats

537

and rooting pigs, both of which were brought to the island

for food, but have escaped and established wild populations.

Grazing sheep threaten delicate plants on ecologically fragile

North Atlantic islands, while rats, cats, and dogs endanger

northern seabird breeding colonies. Rabbits introduced into

Australia

overran parts of the island and wiped out hundreds

of acres of grassland.

Humans have always carried plants and animals as

they migrated from one region to another with little regard

to the effects of these introductions might have on their new

habitat. Many introduced species seem benign, useful, or

pleasing to have around, making it difficult to predict which

imports will become nuisance species. When an exotic plant

or animal threatens human livelihoods or economic activity,

as do kudzu, zebra mussels, and “killer” bees, people begin

to seek ways to control these invaders.

Control efforts include using pesticides and herbicides,

and introducing natural predators and parasites from the

home range of the exotic plant or animal. For example,

beetles that naturally prey on purple loosestrife have been

experimentally introduced in American loosestrife popula-

tions. This deliberate introduction requires a great deal of

care, research, and monitoring, however, to ensure that an

even worse problem does not result, as happened with the

house sparrow. Such solutions, and the time and money to

develop them, are usually elusive and politically controversial,

so in many cases effective control methods remain un-

available.

In 1999, President Bill Clinton signed the Executive

Order on Invasive Species. This order established the Inva-

sive Species Council to coordinate the activities of federal

agencies, such as the Aquatic Nuisance Species Task Force,

the Federal Interagency Committee for the Management of

Noxious and Exotic Weeds, and the Committee on Environ-

ment and

Natural Resources

. The Invasive Species Council

is responsible for the development of a National Invasive

Species Management Plan. This plan is intended to be up-

dated very two years to provide guidance and recommenda-

tions about the identification of pathways by which invasive

species are introduced, and measures that can be taken for

their control.

Non-profit environmental organizations across the

globe are leading the effort for control of exotic species. For

example,

The Nature Conservancy

has established Land-

scape Conservation Networks to address issues of land con-

servation that include invasive species management. These

networks bring in outside experts and land conservation

partners to develop innovative and cost effective means of

controlling exotic species. The Great Lakes information

Network, managed by the Great Lakes Commission based

in Ann Arbor, Michigan, provides online access about envi-

ronmental issues, including exotics species, in the Great

Environmental Encyclopedia 3

Experimental Lakes Area

Lakes region. The Florida Exotic

Pest

Plant Council,

founded in 1984, provides funding to organizations that

educate the public about the impacts of exotic invasive plants

in the State of Florida.

[Mary Ann Cunningham and Marie H. Bundy]

ESOURCES

OOKS

Cunningham, W. Understanding Our Environment: An Introduction. Du-

buque, IA: William C. Brown, 1993.

ERIODICALS

Barrett, S. C. H. “Waterweed Invasions.” Scientific American 261 (October

1989): 90–7.

Rendall, Jay. “ Invasive Species". Imprint 7, no. 4 (1990): 1–8, 1990.

Walker, T. “Dreissena Disaster—Scientists Battle an Invasion of Zebra

Mussels.” Science News 139 (May 4, 1991): 282–84.

Experimental Lakes Area

The Experimental Lakes Area (ELA) in northwestern On-

tario is in a remote landscape characterized by Precambrian

bedrock, northern mixed-species forests, and

oligotrophic

lakes, bodies of water deficient in plant nutrients. The Cana-

dian Department of Fisheries and Oceans began developing

a field-research facility at ELA in the 1960s, and the area

has become the focus of a large number of investigations by

D. W. Schindler and others into chemical and biological

conditions in these lakes.

Of the limnological investigations conducted at ELA,

the best known is a series of whole-lake experiments designed

to investigate the ecological effects of perturbation by a

variety of

environmental stress

factors, including eutrophi-

cation,

acidification

, metals,

radionuclides

, and

flooding

during the development of reservoirs.

The integrated, whole-lake projects at ELA were ini-

tially designed to study the causes and ecological conse-

quences of eutrophication. In one long-term experiment,

Lake 227 was fertilized with phosphate and nitrate. This

experiment was designed to test whether

carbon

could limit

algal growth during eutrophication, so none was added. Lake

227 responded with a large increase in

primary productivity

by drawing on the

atmosphere

for carbon, but it was not

possible to determine which of the two added nutrients,

phosphate or nitrate, had acted as the primary limiting factor.

Observations from experiments at other lakes in ELA,

however, clearly indicated that phosphate is the primary

limiting

nutrient

in these oligotrophic water bodies. Lake

304 was fertilized for two years with

phosphorus

nitrogen

and carbon, and it became eutrophic. It recovered its oligo-

trophic condition again when the phosphorus fertilization

was stopped, even though nitrogen and carbon fertilization

538

were continued. Lake 226, an hourglass-shaped lake, was

partitioned with a vinyl curtain into two basins, one of which

was fertilized with carbon and nitrogen, and the other with

phosphorus, carbon, and nitrogen. Only the latter treatment

caused an

algal bloom

. Lake 302 received an injection of

all three nutrients directly into its hypolimnion during the

summer. Because the lake was thermally stratified at that

time, the hypolimnetic nutrients were not available to fertil-

ize plant growth in the epilimnetic euphotic zone, and no

algal bloom resulted. Nitrogen additions to Lake 227 were

reduced in 1975 and eliminated in 1990. The lake continued

with high levels of productivity by fixing nitrogen from the

atmosphere.

Research of this sort was instrumental in confirming

conclusively the identification of phosphorus as the most

generally limiting nutrient to eutrophication of freshwaters.

This knowledge allowed the development of

waste man-

agement

systems which reduced eutrophication as an envi-

ronmental problem by reducing the phosphorus concentra-

tion in

detergents

, removing phosphorus from sewage, and

diverting sewage from lakes.

Another well known ELA project was important in

gaining a deeper understanding of the ecological conse-

quences of the acidification of lakes. Sulfuric

acid

was added

to Lake 223, and its acidity was increased progressively, from

an initial

near 6.5 to pH 5.0–5.1 after six years. Sulfate

and

hydrogen

ions were also added to the lake in increasing

concentrations during this time. Other chemical changes

were caused indirectly by acidification: manganese increased

by 980%, zinc by 550%, and

aluminum

by 155%.

As the acidity of Lake 223 increased, the

phytoplank-

ton

shifted from a community dominated by golden-brown

algae to one dominated by chlorophytes and dinoflagellates.

Species

diversity declined somewhat, but productivity was

not adversely affected. A mat of the green alga Mougeotia

sp. developed near the shore after the pH dropped below

5.6. Because of reduced predation, the density of cladoceran

zooplankton

was larger by 66% at pH 5.4 than at pH

6.6, and copepods were 93% more abundant. The nocturnal

zooplankton predator Mysis relicta, however, was an impor-

tant

extinction

. The crayfish Orconectes virilis declined be-

cause of reproductive failure, inhibition of carapace harden-

ing, and effects of a parasite. The most acid-sensitive fish was

the fathead minnow (Pimephales promelas), which declined

precipitously when the lake pH reached 5.6.

The first of many year-class failures of lake trout

(Salvelinus namaycush) occurred at pH 5.4, and failure of

white sucker (Catastomus commersoni) occurred at pH 5.1.

One minnow, the pearl dace (Semotilus margarita), increased

markedly in abundance but then declined when pH reached

5.1. Adult lake trout and white sucker were still abundant,

though emaciated, at pH 5.0–5.5, but in the absence of

Environmental Encyclopedia 3

Exponential growth

successful reproduction they would have become extinct.

Overall, the Lake 223 experiment indicated a general sensi-

tivity of many organisms to the acidification of lake water.

However, within the limits of physiological tolerance, the

tests showed that there can be a replacement of acid-sensitive

species by relatively tolerant ones.

In a similarly designed experiment in Lake 302, nitric

acid was shown to be nearly as effective as sulfuric acid in

acidifying lakes, thereby alerting the international commu-

nity to the need to control atmospheric emissions of gaseous

nitrogen compounds. See also Acid rain; Algicide; Aquatic

chemistry; C:N ratio; Cultural eutrophication; Water pol-

lution

[Bill Freedman Ph.D.]

ESOURCES

OOKS

Freedman, B. Environmental Ecology. San Diego: Academic Press, 1995.

Schindler, D. W. “The Coupling of Elemental Cycles by Organisms: Evi-

dence from Whole-Lake Chemical Perturbations.” In Chemical Processes in

Lakes, edited by W. Stumm. New York: Wiley, 1985.

ERIODICALS

Schindler, D. W., et al. “Long-Term Ecosystem Stress: The Effects of

Years of Experimental Acidification of a Small Lake.” Science 228 (June

21, 1985): 1395–1401.

Exponential growth

The distinction between arithmetic and exponential growth

is crucial to an understanding of the nature of growth. Arith-

metic growth takes place when a constant amount is being

added, as when a child puts a dollar a week in a piggy-bank.

Although the total amount increases, the amount being

added remains the same. Exponential growth, on the other

hand, is characterized by a constant or even accelerating rate

of growth.

At a constant rate of increase, measured in percentages,

the amounts added grow themselves. Growth is then usually

measured in doubling times because these remain constant

while the amounts added increase. When the annual rate of

increase is 1%, the doubling time will be 70 years. From

this fact, a simple formula to calculate doubling times given

a rate of increase can be derived: dividing 70 by the percent-

age rate will yield the number of years it takes to double the

original amount.

A savings account with, say, a fixed annual interest

rate of 5% furnishes a convenient example. If the original

deposit is $1,000, then the growth over the first year is $50.

Over the second year, growth will be $52.50. In 14 years,

there will be $2,000 in the account (70 divided by 5 equals

14). In the first period of 14 years, then, total growth will

539

be $1,000, but in the second period of 14 years total growth

will be $2,000, and so on. During the tenth 14-year period,

$512,000 is added, and at the end of that period the total

amount in the account will be $1,024,000. As this example

illustrates, growth will be relatively slow initially, but it will

start speeding up dramatically over time. When growth takes

place at an accelerating rate of increase, doubling times of

course will become shorter and shorter.

The notion of exponential growth is of particular inter-

est in

population biology

because all populations of organ-

isms have the capacity to undergo exponential growth. The

biotic potential or maximum rate of reproduction for all

living organisms is very high, that is to say that all

species

theoretically have the capacity to reproduce themselves

many, many times over during their lifetimes. In actuality,

only a few of the offspring of most species survive, due to

reproductive failure, limited availability of space and food,

diseases, predation, and other mishaps. A few species, such as

the lemming, go through cycles of exponential

population

growth

resulting in severe overpopulation. A catastrophic

dieback

follows, during which the population is reduced

enormously, readying it for the next cycle of growth and

dieback. Interacting species will experience related fluctua-

tions in population levels. By and large, however, populations

are held stable by environmental

resistance

, unless an envi-

ronmental disturbance takes place.

Climatological changes and other natural phenomena

may cause such

habitat

disturbances, but more usually they

result from human activity.

Pollution

predator control

and the introduction of foreign species into habitats that

lack competitor or predator species are a few examples among

many of human activities that may cause declines in some

populations and exponential growth in others.

An altogether different case of exponential population

growth is that of humans themselves. The human population

has grown at an accelerating rate, starting at a low average

rate of 0.002% per year early in its history and reaching a

record level of 2.06% in 1970. Since then the rate of increase

has dropped below 2%, but human population growth is still

alarming and many scientists predict that humans are headed

for a catastrophic dieback.

[Marijke Rijsberman]

ESOURCES

OOKS

Cunningham, W., and B. W. Saigo. “Dynamics of Population Growth.”

In Environmental Science: A Global Concern. Dubuque, IA: Wm. C. Brown

Publishers, 1990.

Miller, G. T. “Human Population Growth.” In Living in the Environment.

Belmont, CA: Wadsworth Publishing, 1990.

Environmental Encyclopedia 3

Externality

External costs

see

Internalizing costs

Externality

Most economists argue that markets ordinarily are the supe-

rior means for fulfilling human wants. In a market, deals

are ideally struck between consenting adults only when the

parties feel they are likely to benefit. Society as a whole is

thought to gain from the aggregation of individual deals

that take place. The wealth of a society grows by means of

what is called the hidden hand of free market mechanisms,

which offers spontaneous coordination with a minimum of

coercion and explicit central direction. However, the market

system is complicated by so-called externalities, which are

effects of private market activity not captured in the price

system.

Economics distinguishes between positive and nega-

tive externalities. A positive externality exists when producers

cannot appropriate all the benefits of their activities. An

example would be research and development, which yields

benefits to society that the producer cannot capture, such

as employment in subsidiary industries.

Environmental

degradation

, on the other hand, is a negative externality,

or an imposition on society as a whole of costs arising from

specific market activities. Historically, the United States have

encouraged individuals and corporate entities to make use

natural resources

on public lands, such as water, timber,

and even the land itself, in order to speed development of

the country. Many undesirable by-products of the manufac-

turing process, in the form of exhaust gases or toxic waste,

for instance, were simply released into the

environment

no cost to the manufacturer. The

agricultural revolution

brought new farming techniques that relied heavily on fertil-

izers, pesticides, and

irrigation

, all of which affect the envi-

ronment.

Automobile

owners did not pay for the

air pollu-

tion

caused by their cars. Virtually all human activity has

associated externalities in the environmental arena, which

do not necessarily present themselves as costs to participants

in these activities. Over time, however, the consequences

have become unmistakable in the form of a serious depletion

of renewable resources and in

pollution

of the air, water,

and

soil

. All citizens suffer from such environmental degra-

dation, though not all have benefited to the same degree

from the activities that caused them.

In economic analysis, externalities are closely associ-

ated with common property and the notion of

free riders

Many natural resources have no discrete owner and are there-

fore particularly vulnerable to abuse. The phenomenon of

degradation of common property is known as the

Tragedy

of the Commons

. The costs to society are understood as

540

costs to nonconsenting third parties, whose interests in the

environment have been violated by a particular market activ-

ity. The consenting parties inflict damage without compen-

sating third parties because without clear property rights

there is no entity that stands up for the rights of a violated

environment and its collective owners.

Nature’s owners are a collectivity which is hard to

organize. They are a large and diverse group that cannot

easily pursue remedies in the legal system. In attempting to

gain compensation for damage and force polluters to pay

for their actions in the future the collectivity suffers from

the free rider problem. Although everyone has a stake in

ensuring, for example, good

air quality

, individuals will

tend to leave it to others to incur the cost of pursuing legal

redress. It is not sufficiently in the interest of most members

of the group to sue because each has only a small amount

to gain. Thus, government intervention is called for to pro-

tect the interests of the collectivity, which otherwise would

be harmed.

The government has several options in dealing with

externalities such as pollution. It may opt for regulation and

set standards of what are considered acceptable levels of

pollution. It may require reduced

lead

levels in

gasoline

and require automakers to manufacture cars with greater

fuel economy and reduced emissions, for instance. If manu-

facturers or social entities such as cities exceed the standards

set for them, they will be penalized. With this approach,

many polluters have a direct incentive to limit their most

harmful activities and develop less environmentally costly

technologies. So far, this system has not proved to be very

effective. In practice, it has been difficult (or not politically

expedient) to enforce the standards and to collect the fines.

Supreme Court decisions since the early 1980s have reinter-

preted some of the laws to make standards much less strin-

gent. Many companies have found it cheaper to pay the

fines than to invest in reducing pollution. Or they evade

fines by declaring bankruptcy and reorganizing as a new

company.

Economists tend to favor pollution taxes and

dis-

charge

fees. Since external costs do not enter the calculations

a producer makes, the producer manufactures more of the

good than is socially beneficial. When polluters have to

absorb the costs themselves, to internalize them, they have

an incentive to reduce production to acceptable levels or to

develop alternative technologies. A relatively new idea has

been to give out marketable pollution permits. Under this

system, the government sets the maximum levels of pollution

it will tolerate and leaves it to the market system to decide

who will use the permits. The costs of past pollution (in the

form of permanent environmental damage or costly clean-

ups) will still be borne disproportionately by society as a

whole. The government generally tries to make responsible

Environmental Encyclopedia 3

Extinction

parties pay for clean-ups, but in many cases it is impossible

to determine who the culprit was and in others the parties

responsible for the pollution no longer exist.

A special case is posed by externalities that make them-

selves felt across national boundaries, as is the case with

acid

rain

ozone layer depletion

, and the pollution of rivers

that run through more than one country. Countries that

suffer from environmental degradation caused in other coun-

tries receive none of the benefits and often do not have

the leverage to modify the polluting behavior. International

conservation

efforts must rely on agreements specific coun-

tries may or may not follow and on the mediation of the

United Nations. See also Internalizing cost; Trade in pollu-

tion permits

[Alfred A. Marcus and Marijke Rijsberman]

ESOURCES

OOKS

Mann, D., and H. Ingram. “Policy Issues in the Natural Environment.”

In Public Policy and the Natural Environment, edited by H. Ingram and R.

K. Goodwin. Greenwich, CT: JAI Press, 1985.

Marcus, A. A. Business and Society: Ethics, Government, and the World

Economy. Homewood, IL:. Irwin Press, 1993.

Extinction

Extinction is the complete disappearance of a

species

, when

all of its members have died or been killed. As a part of

natural selection, the extinction of species has been on-

going throughout the earth’s history. However, with modern

human strains on the

environment

, plants, animals, and

invertebrates are becoming extinct at an unprecedented rate

of thousands of species per year, especially in tropical rain

forests. Many thousands more are threatened and endan-

gered.

Scientists have determined that mass extinctions have

occurred periodically in prehistory, coming about every 50

million years or so. The greatest of these came at the end

of the Permian period, some 250 million years ago, when

up to 96% of all species on the earth may have died off.

Dinosaurs and many ocean species disappeared during a

well-documented

mass extinction

at the end of the Creta-

ceous period (about 65 million years ago). It is estimated

that of the billions of species that have lived on the earth

during the last 3.5 billion years, 99.9% are now extinct.

It is thought that most prehistoric extinctions occurred

because of climatological changes, loss of food sources, de-

struction of

habitat

, massive volcanic eruptions, or asteroids

or meteors striking the earth. Extinctions, however, have

never been as rapid and massive as they have been in the

modern era. During the last two centuries, more than 75

541

species of mammals and over 50 species of birds have been

lost, along with countless other species that had not yet

been identified. James Fisher has estimated that since 1600,

including species and subspecies, the world has lost at least

100 types of mammals and 258 kinds of birds.

The first extinction in recorded history was the Euro-

pean lion, which disappeared around

A.D.

80. In 1534, sea-

men first began slaughtering the great auk, a large, flightless

bird once found on rocky North Atlantic islands, for food

and oil. The last two known auks were killed in 1844 by an

Icelandic fisherman motivated by rewards offered by scien-

tists and museum collectors for specimens. Humans have also

caused the extinction of many species of marine mammals.

Steller’s sea cow, once found on the Aleutian Islands off

Alaska, disappeared by 1768. The sea mink, once abundant

along the coast and islands of Maine, was hunted for its fur

until about 1880, when none could be found. The Caribbean

monk seal, hunted by sailors and fishermen, has not been

found since 1962.

The early European settlers of America succeeded in

wiping out several species, including the Carolina parakeet

and the

passenger pigeon

. The pigeon was one of most

plentiful birds in the world’s history, and accounts from the

early 1800s describe flocks of the birds blackening the sky

for days at a time as they passed overhead. By the 1860s

and 1870s tens of millions of them were being killed every

year. As a result of this

overhunting

, the last passenger

pigeon, Martha, died in the Cincinnati Zoo in 1914. The

pioneers who settled the West were equally destructive, caus-

ing the disappearance of 16 separate types of

grizzly bear

six of

wolves

, one type of fox, and one cougar. Since the

Pilgrims arrived in North America in 1620, over 500 types

of native American animals and plants have disappeared.

In the last decade of the twentieth century, the rate

of species loss was unprecedented and accelerating. Up to

50 million species could be extinct by 2050, with a rate of

three per day. Most of these species extinctions will occur—

and are occurring—in tropical rain forests, the richest biolog-

ical areas on the earth. Rain forests are being cut down at

a rate of one to two acres per second.

In 1988, Harvard professor and biologist

Edward O.

Wilson

estimated the current annual rate of extinction at

up to 17,500 species, including many unknown

rain forest

plants and animals that have never been studied or even seen,

by humans. Botanist Peter Raven, director of the Missouri

Botanical Garden

, calculated that a total of one-quarter

the world’s species could be gone by 2010. A study by the

World Resources Institute

pointed out that humans have

accelerated the extinction rate to 100 to 1,000 times its

natural level.

While it is impossible to predict the magnitude of

these losses or the impact they will have on the earth and

Environmental Encyclopedia 3

Exxon Valdez

its

future generations

, it is clear that the results will be

profound, possibly catastrophic. In his book, Disappearing

Species: The Social Challenge, Eric Eckholm of the

Worldwatch Institute

observed that humans, in their igno-

rance, have changed the natural course of

evolution

with

current mass-extinction rates. “Should this biological massa-

cre take place, evolution will no doubt continue, but in a

grossly distorted manner. Such a multitude of species losses

would constitute a basic and irreversible alteration in the

nature of the

biosphere

even before we understand its

workings...”

Eckholm further notes that when a plant species is

wiped out, some 10 to 30 dependent species, such as insects

and even other plants, can also be jeopardized. An example

of the complex relationship that has evolved between many

tropical species is the 40 different kinds of fig trees native

to Central America, each of which has a specific insect

pollinator. Other insects, including pollinators of other

plants, depend on these trees for food. Thus, the extinction

of one species can set off a

chain reaction

, the ultimate

effects of which cannot be foreseen.

Although scientists know that human life will be

harmed by these losses, the weight of the impact is unclear.

As the

Council on Environmental Quality

states in its book

The Global Environment and Basic Human Needs, over the

next decade or two, “unique ecosystems populated by thou-

sands of unrecorded plant and animal species face rapid

destruction—irreversible genetic losses that will profoundly

alter the course of evolution.” This report also cautions that

species extinction entails the loss of many useful products.

Perhaps the greatest industrial, agricultural and medical costs

of species reduction will stem from future opportunities un-

knowingly lost. Only about 5% of the world’s plant species

have yet been screened for pharmacologically active ingredi-

ents. Ninety percent of the food that humans eat comes

from just 12 crops, but scores of thousands of plants are

edible, and some will undoubtedly prove useful in meeting

human food needs. See also Biodiversity; Climate; Dodo;

Endangered species

[Lewis G. Regenstein]

ESOURCES

OOKS

Etheredge, N. The Miner’s Canary: A Paleontologist Unravels the Mysteries

of Extinction. Englewood Cliffs, NJ: Prentice-Hall, 1991.

Raup, D. M. Extinction: Bad Genes or Bad Luck? New York: Norton, 1991.

Tudge, C. Last Animals at the Zoo: How Mass Extinction Can Be Stopped.

Washington, DC: Island Press, 1992.

542

Exxon Valdez

On March 24, 1989, the 987-foot super tanker Exxon Valdez

outbound from Port Valdez, Alaska, with a full load of oil

from Alaska’s Prudhoe Bay passed on the wrong side of a

lighted channel marker guarding a shallow stretch of

Prince

William Sound

. The momentum of the large ship carried

it onto Bligh Reef and opened a 6 x 20 ft hole in the ship’s

hull. Through this hole poured 257,000 barrels (11 million

gallons) of crude oil, approximately 21% of the ship’s 1.26

million barrel (53 million gallon) cargo, making it the largest

oil spill in the history of the United States.

The oil spill resulting from the Exxon Valdez accident

spread 38,0000 metric tonnes of oil along 1,500 miles of

pristine shoreline on Prince William Sound and the Kenai

Peninsula, covering an area of 460 miles. Oil would eventu-

ally reach shores southwest of the spill up to 600 miles away.

The Exxon Valdez Oil Spill Trustee Council estimates

that 250,000 seabirds, 2,800 sea otters, 300 harbor

seals

250 bald eagles, and 22 killer

whales

, were killed. These

figures may be an underestimate of the animals killed by

the oil because many of the carcasses likely sank or washed

out to sea before they could be collected. Most of the birds

died from hypothermia due to the loss of insulation caused

by oil-soaked feathers. Many predatory birds, such as bald

eagles, died as a result of ingesting contaminated fish and

birds. Hypothermia affected sea otters as well, and many of

the dead mammals suffered lung damage due to oil fumes.

Billions of

salmon

eggs were also lost to the spill. While a

record 43 million pink salmon were caught in Prince William

Sound in 1990, by 1993 the harvest had declined to a record

low of three million.

Response to the oil spill was slow and generally ineffec-

tive. The Alyeska Oil Spill Team responsible for cleaning

oil spills

in the region took more than 24 hours to

respond, despite previous assurances that they could mount

a response in three hours. Much of the oil containment

equipment was missing, broken, or barely operable. By the

time oil containment and recovery equipment were in place,

42 million liters of oil had already spread over a large area.

Ultimately, less than 10% of this oil was recovered, the

remainder dispersing into the air, water, and

sediment

Prince William Sound and adjacent sounds and fjords. Ex-

xon reports spending a total of $2.2 billion to clean up the

oil. Much of this money employed 10,000 people to clean

up oil-fouled beaches; yet after the first year, only 3% of the

soiled beaches had been cleaned.

In response to public concern about the poor response

time and uncoordinated initial cleanup efforts following the

Valdez spill, the Oil

Pollution

Act (OPA; part of the

Clean

Water Act

) was signed into law in August 1990. The Act

Environmental Encyclopedia 3

Exxon Valdez

After hitting Bligh Reef on March 24, 1989, the

Exxon Valdez

sits near Naked Island, Alaska, swirls of crude

oil surrounding the ship. Containment booms can be seen attached to the ship. (AP/Wide World Photos. Reproduced

by permission.)

543

Environmental Encyclopedia 3

Exxon Valdez

established a Federal trust fund to finance clean-up efforts

for up to $1 billion per spill incident.

Ultimately,

nature

was the most effective surface

cleaner of beaches; winter storms removed the majority of

oil and by the winter of 1990, less than 6 miles (10 km) of

shoreline was considered seriously fouled. Cleanup efforts

were declared complete by the U.S. Coast Guard and the

State of Alaska in 1992.

On October 9, 1991, a settlement between Exxon and

the State of Alaska and the United States government was

approved by the U.S. District Court. Under the terms of

the agreement, Exxon agreed to pay $900 million in civil

penalties over a 10-year period. The civil settlement also

provides for a window of time for new claims to be made

should unforeseen environmental issues arise. That window

is from September 1, 2002 to September 1, 2006.

Exxon was also fined $150 million in a criminal plea

agreement, of which $125 million was forgiven in return for

the company’s cooperation in cleanup and various private

settlements. Exxon also paid $100 million in criminal restitu-

tion for the environmental damage caused by the spill.

A flood of private suits against Exxon have also del-

uged the courts in the years since the spill. In 1994, a district

court ordered Exxon to pay $287 million in compensatory

damages to a group of commercial fishermen and other

Alaskan natives who were negatively impacted by the spill.

The jury who heard the case also awarded the plaintiffs $5

billion in punitive damages. However, in November 2001 a

federal appeals judge overturned the $5 billion punitive

award, deeming it excessive and ordering the district court

to reevaluate the settlement. As of May 2002, the final

punitive settlement had not been determined.

The Captain of the Exxon Valdez, Joseph Hazelwood,

had admitted to drinking alcohol the night the accident

occurred, and had a known history of alcohol abuse. Never-

theless, he was found not guilty of charges that he operated

a shipping vessel under the influence of alcohol. He was

found guilty of negligent

discharge

of oil, fined $50,000,

and sentenced to 1,000 hours of community service work.

Despite official cleanup efforts by Exxon having ended,

the environmental legacy of the Valdez spill lives on. The

544

Auke Bay Laboratory of the Alaskan Fisheries Science Cen-

ter conducted a beach study of Prince William Sound in the

summer of 2001. Researchers found that approximately 20

acres of Sound shoreline is still contaminated with oil, the

majority of which has collected below the surface of the

beaches where it continues to pose a danger to

wildlife

.Of

the 30

species

of wildlife affected by the spill, only two—the

American

bald eagle

and the river otter— were considered

recovered in 1999. Preliminary 2002 reports from the Exxon

Valdez Oil Spill Trustee Council reflect progress is being

made in the area of wildlife recovery, however, black

oystercatchers, common murres, killer whales, subtidal com-

munities, sockeye salmon, and pink salmon are all classified

as recovered in the April draft of the organization’s “Update

on Injured Resources and Services,” bringing the total recov-

ered species to eight.

[William G Ambrose and Paul E Renaud and Paula A

Ford-Martin]

ESOURCES

OOKS

Keeble, J. Out of the Channel: The Exxon Valdez Oil Spill in Prince William

Sound, 10th Anniversary Edition. Spokane, WA: Eastern Washington Uni-

versity Press, 1999.

Picou, J. S., et al. The Exxon Valdez Disaster: Readings on a Modern Social

Problem, 2nd ed. Dubuque, IA: Kendall/Hunt Publishing, 1999.

ERIODICALS

Berg, Catherine. “The Exxon Valdez Spill: 10 Years Later.” Endangered

Species Bulletin 26, no.2 (March/April 1999): 18–9.

THER

Alaska Fisheries Science Center, National Marine Fisheries Service,

NOAA. “The Exxon Valdez Oil Spill: How Much Oil Remains?” AFSC

Quarterly(July-September 2001). http://www.afsc.noaa.gov/Quarterly/

jas2001/feature_jas01.htm. Accessed May 28, 2002.

U.S. Environmental Protection Agency Oil Spill Program. [cited May 28,

2002]. <http://www.epa.gov/oilspill/index.htm>.

RGANIZATIONS

The Exxon Valdez Oil Spill Trustee Council, 441 West Fifth Avenue,

Suite 500, Anchorage, AL USA 99501 (907) 278-8012 , Fax: (907) 276-

7178 , Toll Free: (800) 478-7745 (within Alaska), Toll Free: (800) 283-

7745 (outside Alaska), Email: restoration@oilspill.state.ak.us, http://

www.oilspill.state.ak.us/

Falco peregrinus

see

Peregrine falcon

Falcon

see

Peregrine falcon

Fallout

see

Radioactive fallout

Family planning

The exaxt population of the world is unknown but believed

at about 6.2 billion; it continues in its unrelenting growth

especially in developing countries. Worldwide

famine

has

been postponed thanks to modern agricultural procedures,

known as the Green Revolution, which have greatly in-

creased grain production. Nevertheless, with limited land

and resources that can be devoted to food production—and

increasing numbers of humans who need both space and

food—there appears to be a significant risk of catastrophe

by overpopulation. Because of this, there is increased interest

in family planning. Family planning in this context means

birth control to limit family size.

The subject of “family planning” is not limited to

birth control but includes procedures designed to overcome

difficulties in becoming pregnant. About 15% of couples are

unable to conceive children after a year of sexual activity

without using birth control. Many couples feel an intense

desire and need to conceive children. Aid to these couples

is thus a reasonable part of family planning. However, for

most discussions of family planning, the emphasis is on

limitation of family size, not augmentation.

Birth control procedures have evolved rapidly in this

century. Further, utilization of existing procedures is chang-

545

ing with different age groups and different populations. Thus

any account of birth control is likely to become rapidly

obsolete. An example of the changing technology includes

oral contraception with pills containing hormones. Birth

control pills have been marketed in the United States since

the 1960s. Since that time there have been many formula-

tions with significant reductions in dosage. There was much

greater acceptance of pills by American women under the

age of 30. The intrauterine device (IUD) was much more

popular in Sweden than in the United States whereas steril-

ization was more common in the United States than in

Sweden.

A very common form of birth control is the condom,

which is a thin

rubber

sheath worn by men during sexual

intercourse. They are generally readily accessible, cheap, and

convenient for those individuals who may not have sexual

relations regularly. Sperm cannot penetrate the thin (0.3—

0.8 mm thick) latex. Neither the human immunodeficiency

virus

(HIV) associated with

AIDS

nor the other pathogenic

agents of sexually transmitted diseases (STDs) are able to

penetrate the latex barrier. Some individuals are opposed

to treating healthy bodies with drugs (hormones) for birth

control, and for these individuals, condoms have a special

appeal. Natural “skin” (lamb’s intestine) condoms are still

available for individuals who may be allergic to latex, but this

product provides less protection to HIV and other STDs.

The reported failure rate of condoms is high and is

most likely due to improper use. Yet during the Great De-

pression in the 1930s—when pills and other contemporary

birth control procedures were not available—it is thought

that the proper use of condoms caused the birth rate in the

United States to plummet.

Spermicides—surface active agents which inactivate

sperm and STD pathogens—can be placed in the vagina in

jellies, foam, and suppositories. Condoms used in conjunc-

tion with spermicides have a failure rate lower than either

method used alone and may provide added protection against

some infectious agents.

Environmental Encyclopedia 3

Family planning

Types of Contraceptives

Predicted Actual

Effectiveness (%) (%)

Birth control pills 99.9 97

Condoms 98 88

Depo Provera 99.7 99.7

Diaphragm 94 82

IUDS 99.2 97

Norplant 99.7 99.7

Tubal sterilization 99.8 99.6

Spermicides 97 79

Vasectomy 99.9 99.9

The vaginal diaphragm, like the condom, is another

form of barrier. The diaphragm was in use in World War

I and was still used by about one third of couples by the

time of World War II. However, because of the efficacy

and ease of use of oral contraceptives, and perhaps because

of the protection against disease by condoms, the use of

vaginal diaphragms is down. The diaphragm, which must

be fitted by a physician, is designed to prevent sperm access

to the cervix and upper reproductive tract. It is used in

conjunction with spermicides. Other similar barriers include

the cervical cap and the contraceptive sponge. The cervical

cap is smaller than the diaphragm and fits only around that

portion of the uterus that protrudes into the vagina. The

contraceptive sponge, which contains a spermicide, is in-

serted into the vagina prior to sexual intercourse and retained

for several hours afterwards to insure that no living sperm

remain.

Intrauterine devices (IUDs) were popular during the

1960s and 1970s in the United States, but their use today

has dwindled. However in China, a nation which is rapidly

attending to its population problems, about 60 million

women use IUDs. The failure rate of IUDs in

less devel-

oped countries

is reported to be less than that with the

pill. The devices may be plastic,

copper

, or stainless steel.

The plastic versions may be impregnated with barium sulfate

to permit visualization by x ray and also may slowly release

hormones such as progesterone. Ovulation continues with

IUD use. Efficacy probably results from a changed uterine

environment

which kills sperm.

Oral contraception is by means of the “pill.” Pills con-

tain an estrogen and a progestational agent, and current

dosage is very low compared with several decades ago. The

combination of these two agents is taken daily for three

weeks followed by one week with neither hormone. Fre-

546

quently a drug-free pill is taken for the last week to maintain

the pill-taking habit and thus enhance the efficacy of the

regimen. The estrogenic component prevents follicle matu-

ration, and the progestational component prevents ovulation.

Pill-taking women who have multiple sexual partners may

wish to consider the addition of a barrier method to minimize

risk for STDs. The reliability of the pill reduces the need

for abortion or surgical sterilization. There may be other

salutary health effects which include less endometrial and

ovarian

cancer

as well as fewer uterine fibroids. Use of oral

contraceptives in women over the age of 35 who also

smoke

is thought to increase the risk of heart and vascular disease.

Contraceptive hormones can be administered by routes

other than oral. Subdermal implants of progestin-containing

tubules have been available since 1990 in the United States.

In this device familiarly known as Norplant, six tubules are

surgically placed on the inside of the upper arm, and the

hormone diffuses through the wall of the tubules to provide

long term contraceptive activity. Another form of progestin-

only contraception is by intramuscular injection which must

be repeated every three months.

Fears engendered by IUD litigation are thought to

have increased the reliance of many American women on

surgical sterilization (tubal occlusion). Whatever the reason,

more American women rely on the procedure than do their

European counterparts. Tubal occlusion involves the me-

chanical disruption of the oviduct, the tube that leads from

the ovary to the uterus, and prevents sperm from reaching

the egg. Inasmuch as the fatality rate for the procedure is

lower than that of childbirth, surgical sterilization is now

the safest method of birth control. Tubal occlusion is far

more common now that it was in the 1960s because of the

lower cost and reduced surgical stress. Use of the laparoscope

and very small incisions into the abdomen have allowed the

procedure to be completed during an office visit.

Male sterilization, another method, involves severing

the vas deferens, the tube that carries sperm from the testes

to the penis. Sperm comprise only a small portion of the

ejaculate volume, and thus ejaculation is little changed after

vasectomy. The male hormone is produced by the testes and

production of that hormone continues as does erection and

orgasm.

Most abortions would be unnecessary if proper birth

control measures were followed. That of course is not always

the case. Legal abortion has become one of the leading

surgical procedures in the United States. Morbidity and

mortality

associated with pregnancy have been reduced

more with legal abortion than with any other event since

the introduction of antibiotics to fight puerperal fever.

Other methods of birth control are used by individuals

who do not wish to use mechanical barriers, devices, or

drugs (hormones). One of the oldest of these methods is