Download What is Biodiversity? - WARE-RET Curriculum Development Collab

What is Biodiversity?
http://www.nwf.org/Wildlife/Wildlife-Conservation/Biodiversity.aspx
Biodiversity is the variety of life. It can be studied on many levels. At the highest level, you can look at all the different species on the entire
Earth. On a much smaller scale, you can study biodiversity within a pond ecosystem or a neighborhood park. Identifying and understanding the
relationships between all the life on Earth are some of the greatest challenges in science.
Most people recognize biodiversity by species. A species is a group of living organisms that can interbreed. Examples of species include, blue
whales, white-tailed deer, white pine trees, sunflowers and microscopic bacteria that you cannot even see with your eye. Biodiversity includes the full
range of species that live in an area.
Biodiversity at a Glance
Let’s look at the species biodiversity within a local pond. At first glance, we can identify different plants, including cattails and water lilies. If we wait a
while, we might be able to spot a garter snake, a bullfrog or maybe a red-winged blackbird. With a closer look, you can see invertebrates and worms
under leaves, on grasses and in the pond water.
Think you’re done? - You have not even scratched the surface of the biodiversity within the pond! Using a microscope, you would be able to see
hundreds or even thousands of different bacteria that inhabit the pond water. They are all part of the species biodiversity of this small ecosystem!
Biodiversity is More than Just Species
Species diversity is only one part of biodiversity. To properly catalogue all the life on Earth, we also have to recognize the genetic diversity that exists
within species as well as the diversity of entire habitats and ecosystems.
Genetic Biodiversity is the variation in genes that exists within a species. A helpful way to understand genetic diversity is to think about dogs. All
dogs are part of the same species, but their genes can dictate whether they are Chihuahua or a Great Dane. There can be a lot of variation in genes –
just think about all the colors, sizes, and shapes that make up the genetic diversity of dogs.
Ecological Biodiversity is the diversity of ecosystems, natural communities and habitats. In essence, it’s the variety of ways that species interact
with each other and their environment. The forests of Maine differ from the forests of Colorado by the types of species found in both ecosystems, as
well as the temperature and rainfall. These two seemingly similar ecosystems have a lot of differences that make them both special.
Some Biodiversity Facts
Researchers have estimated that there are between 3 - 30 million species on Earth, with a few studies predicting that there may be over 100 million
species on Earth! Currently, we have identified only 1.7 million species, so we have a long way to go before we can come close to figuring out how
many species are on Earth!
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There is more biodiversity within tropical ecosystems than temperate or boreal ecosystems. Tropical rainforests have the most diversity.
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The most diverse group of animals are invertebrates. Invertebrates are animals without backbones, including insects, crustaceans, sponges, scorpions
and many other kinds of organisms. Over half of all the animals already identified are invertebrates. Beetles are some of the most numerous species.
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Science has so much more to learn about the biodiversity of microscopic organisms like bacteria and protozoa.
The Importance of Biodiversity
Biodiversity is extremely important to people and the health of ecosystems. A few of the reasons are:
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Biodiversity allows us to live healthy and happy lives. It provides us with an array of foods and materials and it contributes to the economy. Without a
diversity of pollinators, plants, and soils, our supermarkets would have a lot less produce.
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Most medical discoveries to cure diseases and lengthen life spans were made because of research into plant and animal biology and genetics. Every
time a species goes extinct or genetic diversity is lost, we will never know whether research would have given us a new vaccine or drug.
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Biodiversity is an important part of ecological services that make life livable on Earth. They include everything from cleaning water and absorbing
chemicals, which wetlands do, to providing oxygen for us to breathe—one of the many things that plants do for people.
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Biodiversity allows for ecosystems to adjust to disturbances like extreme fires and floods. If a reptile species goes extinct, a forest with 20 other
reptiles is likely to adapt better than another forest with only one reptile.
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Genetic diversity prevents diseases and helps species adjust to changes in their environment.
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Simply for the wonder of it all. There are few things as beautiful and inspiring as the diversity of life that exists on Earth.
Threats to Biodiversity
Extinction is a natural part of life on Earth. Over the history of the planet most of the species that ever existed, evolved and then gradually went
extinct. Species go extinct because of natural shifts in the environment that take place over long periods of time, such as ice ages.
Today, species are going extinct at an accelerated and dangerous rate, because of non-natural environmental changes caused by human
activities. Some of the activities have direct effects on species and ecosystems, such as:
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Habitat loss/ degradation
Over exploitation (such as overfishing)
Spread of Non-native Species/ Diseases
Some human activities have indirect but wide-reaching effects on biodiversity, including:
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Climate change
Pollution
All of these threats have put a serious strain on the diversity of species on Earth. According to the International Union for Conservation of Nature
(IUCN), globally about one third of all known species are threatened with extinction. That includes 29% of all amphibians, 21% of all mammals and
12% of all birds. If we do not stop the threats to biodiversity, we could be facing another mass extinction with dire consequences to the environment
and human health and livelihood.
Helping Biodiversity in your Own Backyard
You can play a part in protecting the biodiversity of your local community by creating a Certified Wildlife Habitat®. One of the greatest threats to
biodiversity is habitat loss. A Certified Wildlife Habitat ® provides food, shelter, water and a place to raise young for native wildlife—the essential
elements of habitat that wildlife need to survive. A Certified Wildlife Habitat ® can provide food and homes for a range of local species that need your
help.
Reading Questions:
Article: What is Biodiversity?
1. What is a species?
2. What are some examples of species?
3. What is Biodiversity?
4. Explain Genetic Biodiversity (3 sentences).
5. Describe Ecological Biodiversity (4 sentences).
6. Describe the most diverse group of animals (5 sentences).
7. Explain and describe why biodiversity is important, give some reasons, gives some examples (8 sentences).
8. List some ways biodiversity is being lost. Explain how this is affecting the ecosystem (give statistics from the article) (8 sentences).
9. Create four ways that biodiversity can be protected. One of those ways can come from the article, but you must come up with three more ways by doing some research. (12 sentences
and diagrams/pictures).
Habitat loss
Due to destruction, fragmentation or degradation of habitat—is the primary threat to the survival of wildlife in the United States.
When an ecosystem has been dramatically changed by human activities—such as agriculture, oil and gas exploration,
commercial development or water diversion—it may no longer be able to provide the food, water, cover, and places to raise
young. Every day there are fewer places left that wildlife can call home.
There are three major kinds of habitat loss:
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Habitat destruction: A bulldozer pushing down trees is the iconic image of habitat destruction. Other ways that people are
directly destroying habitat, include filling in wetlands, dredging rivers, mowing fields, and cutting down trees.
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Habitat fragmentation: Much of the remaining terrestrial wildlife habitat in the U.S. has been cut up into fragments by roads
and development. Aquatic species’ habitat has been fragmented by dams and water diversions. These fragments of habitat may
not be large or connected enough to support species that need a large territory in which to find mates and food. The loss and
fragmentation of habitat make it difficult for migratory species to find places to rest and feed along their migration routes.
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Habitat degradation: Pollution, invasive species and disruption of ecosystem processes (such as changing the intensity of fires
in an ecosystem) are some of the ways habitats can become so degraded that they no longer support native wildlife.
What are the main drivers of habitat loss in the U.S.?
Agriculture: Much of the habitat loss from agriculture was done long ago when settlers converted forests and prairies to
cropland. Today, there is increasing pressure to redevelop conservation lands for high-priced food and biofuel crops.
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Land conversion for development: The conversion of lands that once provided wildlife habitat to housing developments,
roads, office parks, strip malls, parking lots and industrial sites continues, even during the current economic crisis.
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Water development: Dams and other water diversions siphon off and disconnect waters, changing hydrology and water
chemistry (when nutrients are not able to flow downstream). During the dry season, the Colorado River has little to no water in
it by the time it reaches the Sea of Cortez.
Pollution: Freshwater wildlife are most impacted by pollution. Pollutants such as untreated sewage, mining waste, acid rain,
fertilizers and pesticides concentrate in rivers, lakes and wetlands and eventually end up in estuaries and the food web.
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Global warming: Global warming is the emerging driver of habitat loss. Wildlife that need the cool temperatures of high
elevations, such as the American pika, may soon run out of habitat. Coastal wildlife may find their habitat underwater as sea
levels rise.
Overexploitation
People have always depended on wildlife and plants for food, clothing, medicine, shelter and many other needs. But today we are taking more than the
natural world can supply. The danger is that if we take too many individuals of a species from their natural environment, the species may no longer be
able to survive. The loss of one species can affect many other species in an ecosystem.
Overexploitation is the over use of wildlife and plant species by people for food, clothing, pets, medicine, sport and many other purposes.
The hunting, trapping, collecting and fishing of wildlife at unsustainable levels is not something new. The passenger pigeon was hunted to extinction early
in the last century, and overhunting nearly caused the extinction of the American bison and several species of whales.
Today, the Endangered Species Act protects some U.S. species that were in danger from overexploitation, and the Convention on International Trade in
Endangered Species of Fauna and Flora (CITES) works to prevent the global trade of wildlife. But there are many species that are not protected from
being illegally traded or overharvested.
What Wildlife are Being Overexploited?
Fish and other aquatic species
As fishing gear and boats have improved, the fishing industry has become very efficient at harvesting fish and shellfish. The industrialization of the fishing
industry and the increasing world demand for seafood have people taking more fish from oceans, lakes and rivers than is sustainable. Prized fish, such as
swordfish, cod and tuna, have undergone dramatic declines. In the Great Lakes overfishing has caused whitefish, walleye, and sturgeon populations to
decline. Beyond their role in the food supply, freshwater and marine fish are also trapped for the aquarium trade and fished for sport.
Birds
Birds are collected or hunted for sport, food and the cage-bird pet trade (parrots and songbirds are prized as pets). Millions of birds are traded
internationally each year. Close to 30% of globally threatened birds are threatened by overexploitation, particularly parrots, pigeons and pheasants. The
Carolina parakeet was once the only species of parrot in the U.S., but it was hunted to extinction early in the last century for food, to protect crops and
for its feathers (which adorned ladies’ hats).
Mammals
People have always hunted mammal species—for fur, food, sport, and for their horns or antlers. Mammals are also trapped for the pet trade, zoos and
biomedical research. Today, illegal hunting still threatens many species, especially large mammals such as tigers, rhinoceros, bears and even primates,
whose body parts are highly valued in some parts of the world for traditional medicine.
Amphibians
Amphibians are collected and shipped all over the world for the pet trade, medicine, education (frogs are dissected in many biology classes), scientific
research and for food (frog legs are a delicacy in many parts of the world). The California red-legged frog, now a federally protected endangered species,
was over hunted for food and its numbers seriously depleted during the Gold Rush in the area around San Francisco.
Reptiles
Reptiles are harvested and traded around the world for their skins or shells, their eggs, meat, and for the pet trade. Overharvesting of the Kemp’s ridley
sea turtle’s eggs nearly led to its extinction, and today it is still an endangered species. In the U.S., box turtles are being collected at unsustainable levels
for the overseas pet trade. Some reptile skins—such as crocodile, python and monitor lizard—are highly prized as exotic leathers.
Invertebrates
Invertebrates make up at least 75% of all known animal species. Insects, oysters, octopus, crayfish, sea stars, scorpions, crabs and sponges are all kinds
of invertebrates. Today, many invertebrates—particularly marine invertebrates—are at risk from overharvesting. Chesapeake Bay oysters, once an
important part of the Bay economy, are now in decline. Horseshoe crabs, whose eggs provide food for migratory birds, fish and other organisms, are
being harvested as bait for eel and whelk fishing. Octopus are suffering declines world-wide due to heavy fishing pressure. Shells and corals are collected
for ornaments and jewelry.
Plants
Plants are vital to our survival and are the foundation of most of the Earth’s ecosystems. People harvest plants for food, medicine, building materials,
and as raw materials for making other products. But we are taking too many plants from the wild. Some plants, such as orchids, are so prized by
collectors that they are now endangered and legally protected from poaching by international law. Some medicinal plants, such as American ginseng,
have also been so enthusiastically collected that it is now very hard to find them in the wild. A number of tree species that are prized for their wood, such
as mahogany, are under threat because of overharvesting.
Invasive Species
"Invasive species" — it doesn’t sound very threatening, does it? But these invaders, large and small, have devastating effects on U.S. wildlife. Invasive species are
one of the leading threats to native wildlife. Approximately 42% of Threatened or Endangered species are at risk primarily due to invasive species.
Human health and economies are also at risk from invasive species. The impacts of invasive species on our natural ecosystems and economy cost billions of dollars
each year. Many of our commercial, agricultural, and recreational activities depend on healthy native ecosystems.
What makes a species invasive?
An invasive species can be any kind of living organism—an amphibian (like the cane toad pictured left), plant, insect, fish, fungus, bacteria, or even an organism’s
seeds or eggs—that is not native to an ecosystem and which causes harm. They can harm the environment, the economy or even, human health. Species that grow
and reproduce quickly, and spread aggressively, with potential to cause harm, are given the label of “invasive”.
An invasive species does not have to come from another country. For example, lake trout are native to the Great Lakes, but are considered to be an invasive species
in Yellowstone Lake in Wyoming because they compete with native cutthroat trout for habitat.
How do invasive species spread?
Invasive species are primarily spread by human activities, often unintentionally. People, and the goods we use, travel around the world very quickly, and they often
carry uninvited species with them.
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Ships: Ships can carry aquatic organisms in their ballast water.
Wood products: Insects can get into wood, shipping palettes and crates that are shipped around the world.
Ornamental plants: Some ornamental plants can escape into the wild and become invasive.
Pet trade: Some invasive species are intentionally or accidentally released pets. Burmese pythons are becoming a big problem in the Everglades.
Why do invasive species pose such a threat?
Invasive species cause harm to wildlife in many ways. When a new and aggressive species is introduced into an ecosystem, it might not have any natural predators
or controls. It can breed and spread quickly, taking over an area. Native wildlife may not have evolved defenses against the invader or they cannot compete with a
species that has no predators.
The direct threats of invasive species:
preying on native species
out-competing native species for food or other resources
causing or carrying disease
preventing native species from reproducing or killing their young
The indirect threats of invasive species:
Changing food webs: Invasive species can change the food web in an ecosystem by destroying or replacing native food sources. The invasive species may provide
little to no food value for wildlife.
Decreasing biodiversity: Invasive species can alter the abundance or diversity of species that are important habitat for native wildlife. Aggressive plant species like
kudzu can quickly replace a diverse ecosystem with a monoculture of just kudzu.
Altering ecosystem conditions: Some invasive species are capable of changing the conditions in an ecosystem, such as changing soil chemistry or the intensity of
wildfires.
Examples of invasive species
There are unfortunately many examples of invasive species invasions across the United States. Here are just a few:
Asian carp —a catchall title for species of silver, bighead and
black carp from Asia—are a fastgrowing fish that out-compete
native fish for food and habitat.
Brown marmorated stink bugs have become an increasing nuisance in homes and to the agriculture industry. Away from
their natural predators, stink
bug populations are expanding
rapidly.
West Nile virus, spread by mosquitoes infected with the virus, is an invasive pathogen that has caused direct harm to humans (sometimes resulting in death) as
well as to wildlife (especially birds). It has been detected throughout most of the continental United States.
Cogongrass is an Asian plant that arrived in the U.S. as seeds in packing material. It is now spreading through the Southeast, displacing native plants. It provides
no food value for native wildlife, and increases the threat of wildfire as it burns hotter and faster than native grasses.
Feral pigs will eat almost anything, including native birds. They compete with native wildlife for food sources such as acorns. Feral pigs spread diseases, such as
brucellosis, to people and livestock. E. coli from their feces was implicated in the E. coli contamination of baby spinach in 2006.
Zebra mussels first came to the U.S. from Eurasia in ship ballast water released into the Great Lakes. Since 1988, they have spread dramatically, out-competing
native species for food and habitat. Zebra mussels can attach to almost any hard surface - they clog water intake and discharge pipes, attach themselves to boat
hulls and docks, and they even attach to native mussels and crayfish.
European green crabs found their way into the San Francisco Bay area in 1989. They out-compete native species for food and habitat and eat huge quantities of
native shellfish, threatening commercial fisheries.
Dutch elm disease (caused by the fungus Ophiostoma ulmi) is transmitted to trees by elm bark beetles. Since 1930, the disease has spread from Ohio through most
of the country, killing over half of the elm trees in the northern U.S.
Water hyacinth is a beautiful aquatic plant, introduced to the U.S. from South America as an ornamental. In the wild, it forms dense mats, reducing sunlight for
submerged plants and aquatic organisms, crowding out native aquatic plants and clogging waterways and intake pipes.
Invasive species and global warming
Higher average temperatures and changes in rain and snow patterns caused by global warming will enable some invasive plant species—such as garlic mustard,
kudzu and purple loosestrife—to move into new areas. Insect pest infestations will be more severe as pests such as mountain pine beetle are able to take advantage
of drought-weakened plants.
What you can do to help curb the spread of invasive species
Plant native plants and remove any invasive plants in your garden. There are many good native plant alternatives to common exotic ornamental plants.
Learn to identify invasive species in your area. Report any sightings to your county extension agent or local land manager. Learn more about invasive species in
your state.
Regularly clean your boots, gear, boat, tires and any other equipment you use outdoors to remove insects and plant parts that may spread invasive species to new
places.
When camping, buy firewood near your campsite (within 30 miles) instead of bringing your own from home, and leave any extra for the next campers.
Invertebrates and plants can easily hitch a ride on firewood you haul to or from a campsite -- you could inadvertently introduce an invasive to a new area.
Disease
Disease is a normal part of the natural world. Most ecosystems include organisms such as viruses, bacteria, fungi and parasites
that cause disease. Healthy wildlife and ecosystems have evolved defenses to fend off most diseases before they have devastating
impacts. An ecosystem with lots of variation (genetic diversity and diversity of species) is more resilient to the impacts of disease
because there are greater possibilities that some species have evolved resistance, or if a species is lost, there will likely be
another species to fill the niche of an extinct species.
Where ecosystems are not healthy, due to a loss in biodiversity and threats such ashabitat loss, global
warming, pollutants or invasive species, wildlife and ecosystems are more vulnerable to emerging diseases. Diseases caused by or
carried by invasive species are particularly threatening, as native wildlife may have no natural immunity to them.
Diseases Threatening U.S. Wildlife
The following are a few of the many diseases threatening U.S. wildlife:
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Chytrid Fungus: Batrachochytrium dendrobatidis (or “chytrid” for short), is a fungus that grows on the skin of amphibians,
interfering with their ability to breathe or take up water through their skin. It has spread across the globe, infecting and
decimating frog populations. It is a global killer of amphibians.
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Fibropapillomatosis: Sea turtles worldwide are becoming infected with this disease, possibly caused by viruses, which causes
tumors to appear on the skin or internally. These tumors can make it difficult for a turtle to swim, eat or see, and they weaken
immune systems.
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White-nose Syndrome: Hundreds of thousands of bats in the Northeast and Mid-Atlantic states have been infected or have died
from the white-nose fungus. The disease affects hibernating bats, making them appear to have a white substance on their faces
and wings.
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Chronic wasting disease: This disease is a highly contagious, fatal neurological disease (spongiform encephalopathy) that
infects primarily deer and elk. The disease is believed to be caused by a modified protein called a prion.
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Whirling disease: Trout, salmon and whitefish in 25 states have been infected by the parasite Myxobolus cerebralis that causes
whirling disease. It damages nerves and cartilage, causing young fish to die and older fish to swim in a tail-chasing or whirling
motion, making it hard for them to find food and increasing their vulnerability to predators.
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Sylvatic plague: Prairie dogs are highly susceptible to this bacterial disease, which is transmitted by fleas. The endangered
black-footed ferret is at even greater risk from the effects of the disease, because not only can it be infected by the disease, but
prairie dogs are also its primary food source.
Human Health and Wildlife Health
Wildlife and human health are closely intertwined, as illustrate
Climate Change
Global warming is quickly becoming the biggest threat to the long-term survival of America’s wildlife. Average temperatures in the
U.S. over the last century have already increased by more than one degree fahrenheit. Seven of the top 10 warmest years on
record for the contiguous 48 states have occurred since 1998, and 2012 was the warmest year on record.
Observed Changes in Wildlife and Ecosystems
Changes in range: Wildlife and plants that are able to adjust are shifting their ranges northward or to higher altitudes to adjust
to warming temperatures. Wildlife that already live at high altitudes or latitudes, such as the American pikaor polar bears in the
Arctic, may find themselves with nowhere to go.
Changes in timing of natural events: Many species take their cues about when to migrate, flower, nest or mate from seasonal
changes in temperature, precipitation and daylight (phenology). Global warming is confusing those signals. The changes in the
climate force wildlife to alter life cycle and seasonal events. Sometimes they might get out of synch with other species in their
ecosystem or with other natural events. For example, some animals are laying eggs, migrating, or emerging from hibernation
much earlier than they used to, only to find that the plants or the insects they need for food have not yet emerged.
Widespread forest loss: In the western U.S., warming and drought stress are causing trees to die and making them more
vulnerable to pine beetle and other insect infestations. Higher temperatures and increased fuel from dead trees have led to more
wildfires.
Coral bleaching: Coral bleaching occurs when colorful algae that live in corals die or are expelled from corals under stress. The
algae live symbiotically with coral polyps, providing them with nutrients and oxygen. If the algae die and are not replaced, the
corals will also die. Scientists believe that the biggest cause of coral bleaching is warm sea surface temperatures caused by global
warming. If coral reef bleaching continues, many other marine organisms that depend on coral reefs will also be in jeopardy.
Melting of Arctic sea ice: Arctic ice is melting at a faster pace than was predicted even a few years ago. Some scientists are
now saying that the Arcticcould be ice free in the late summer as early as 2012. Many Arctic mammals, such as polar bears,
walrus, and seals depend on sea ice for their survival.
Additional Threats to Wildlife from Global Warming
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Loss of wetlands: Higher temperatures will lead to drier conditions in the Midwest’s Prairie Potholeregion, one of the most
important breeding areas for North American waterfowl.
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Sea-level rise: Sea-level rise will inundate beaches and marshes and cause erosion on both coasts, diminishing habitat for birds,
invertebrates, fish, and other coastal wildlife.
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Invasive species and disease: Higher average temperatures and changes in rain and snow patterns will enable some invasive
plant species to move into new areas. Insect pest infestations will be more severe as pests such as mountain pine beetle are able
to take advantage of drought-weakened plants. Pathogens and their hosts that thrive in higher temperatures will spread to new
areas.
Pollutants
Every day the byproducts of our daily lives—sewage, exhaust, trash, agricultural and lawn chemicals, industrial and powerplant
emissions and more—make their way via the air and water into the natural environment and become pollutants. As big as our
planet is, it is not big enough to dilute or absorb all the waste, chemicals and nutrients that billions of people are continuously
producing.
Since the 1960s, the United States has made great progress in reducing air and water pollution. We have succeeded at controlling
many point source pollutants —pollutants that can be traced back to a specific source such as a sewage treatment or industrial
plant.
However, there are many nonpoint source pollutants—pollutants that come from many diffuse sources—that are still regularly
released into the environment. These chemicals and nutrients continue to wreak havoc on wildlife and ecosystems.
Excess Nutrients
Phosphorus and nitrogen are limiting factors for plants. Water and soils with little nitrogen and phosphorus have very little plant
growth. For this reason, these two nutrients are the key elements of fertilizers.
After fertilizers are used on farms, many of the excess nutrients not absorbed by plants runoff into nearby streams, lakes and
rivers. The chemicals in fertilizers also combine with excess nutrient runoff from lawns, septic systems and livestock farms. All
those nutrients can wreak havoc in our waterways.
Normally, algae do not have enough nitrogen and phosphorus to grow in excess. With the overflow of nutrient runoff, there is
nothing to keep algae growth in check. Algae can grow into giant blooms that block sunlight underwater plants need to
survive. Algae blooms can create underwater “dead zones”, because they take oxygen from the water that fish and invertebrates
need to survive. Every summer, a big dead zone caused by algal blooms forms in the Gulf of Mexico near where the Mississippi
River enters the Gulf.
Global Warming Pollution
Science shows a direct relationship between the amount of global warming pollution being released into the atmosphere and the
increase in surface temperatures around the globe. Carbon dioxide, one of the biggest global warming pollutants, is the product of
human activities such as burning fossil fuels (primarily oil, natural gas and coal) for our vehicles, heat and power generation. Even
if we stopped burning all fossil fuels right now, the carbon dioxide that is already in the atmosphere will continue to contribute to
global warming for hundreds of years into the future.
Persistent Organic Pollutants
Persistent organic pollutants are synthetic toxic chemicals—such as PCBs, DDT and dioxins—that are easily carried by wind or
water and can persist in the environment for a long time. They can accumulate in the tissues of plants, animals and people, and
pass from one species to another through the food chain. As the chemical move up the food chain, they become more
concentrated (a process known as "biomagnification"). Populations of raptors, such as the bald eagle, declined dramatically in the
50's and 60's because of DDT, which thinned the shells of their eggs so they were not able to produce young. DDT is now banned
in the U.S.
These are only some of the many pollutants that threaten wildlife. The Environmental Protection Agency and the USGS have
additional information on threats to wildlife and people from pollutants.
Guiding Question: Which of the Following Do You Think Leads to the Largest Loss of Biodiversity?
Our Claim:
Our Evidence:
Our Justification: