Download The Human Impact on the Environment

Invasive Species
Invasive Species
• Apparently harmless animals and
plants that are transported around
the world.
• In their new habitats invasive
species reproduce rapidly
because they lack predators that
keep their population in check.
Purple Loosestrife
• Brought to America from Europe in the
1800’s as an ornamental plant.
• Destroys native wetland ecosystems
Purple Loosestrife
• No herbivores eat
this flower so it
grows very rapidly
and displaces
native plant
species.
Native cattails are endangered
because Purple Loosestrife
is taking up its space!
Zebra Mussels
• Brought over on cargo ships during the
1980’s and are destroying the Great Lakes
ecosystems
Zebra Mussels
Gypsy Moths
• A native of
Europe they were
brought
accidentally to the
US in the 1880’s
• They defoliate
native trees like
aspens
Sea Lamprey
• Brought over from Europe on cargo ships
the Sea Lamprey has killed many native
fish in the Great Lakes
Sea Lamprey attach to other fish
and “suck” out their guts!
Control of Invasive Species
• Biological Control – using a predator from
its homeland THAT WILL ONLY EAT THE
TARGET SPECIES to kill native species
or at least control it.
Leaf Eating Beetles and Purple
Loosestrife
1 Year After Beetles Introduced
Before Beetles Introduced
Pesticide Use and
Fertilizer Use
Pesticide & Fertilizer Use
• Pesticides are used to kill insects and
protect crops/plants
• Fertilizers are used to increase the growth
rate of crops/plants
Ecological Problems with
Pesticides
• Pesticides are dangerous chemicals that
trickle down into ground water aquifers.
Biological Magnification
• Chemicals
accumulate or build
up as it goes up the
food chain often
becoming lethal
• As a general rule,
every step up on
the food chain these
toxins are found,
they are magnified
about 10 times.
Biological Magnification
• Pregnant women
are told not to eat
seafood due to
biological
magnification of
chemicals, like
mercury that can
be harmful to the
fetus
Where Does Mercury Come
From?
• Mercury is the most toxic non-radioactive
element in the world and it is released when coal
is burned.
• Mercury falls to the ground and is distributed to
streams, rivers and lakes and to the oceans
where it is consumed by bacteria and becomes
methyl-mercury, an organic form that is then
easily absorbed by plankton and zooplankton.
• Mercury is an immortal element; there is no way
to get rid of it once it is released in the
environment.
DDT Biomagnification and the Bald
Eagle
• DDT a pesticide to
kill mosquitoes
• Harmed the shells of
Bald Eagles bringing
them close to
extinction
DDT Pesticide
• Wide scale use of DDT
banned in 1972
Stockholm Convention
• Toxic to humans &
animals when
absorbed or
swallowed.
• Limited use today as
disease vector control
• The Bald Eagles are
BACK!
Ecological Problems with Fertilizers
• Fertilizers contain high levels of nitrogen
and phosphorus that runs off into streams
and marine ecosystems causing algae
blooms.
Algae Bloom
• When nitrogen levels in rivers and streams
increase, they aid in algae overgrowth. As algae
dies and decomposes, organic matter in the water
increases. This process uses up oxygen, causing
levels to drop. Without the oxygen, fish, crabs and
other aquatic life die.
Solutions - Organic
•
•
•
•
Organic pesticides to kill pests
Limit use of fertilizers
Hand pull weeds
Crop rotation – alternating the crop grown
each year.
• Using pests to fight pests - Integrating
predatory insects into a farm, such as
ladybugs or predatory mites, can help kill
off pests.