Ecosystems

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Ecosystems
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What is an ecosystem?
The environment is made of many different types
of ecosystems, e.g. a desert ecosystem.
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Describe some other ecosystems
The environment is made of many different types
of ecosystems, such as oceans, forests and creeks.
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These are all different Australian Ecosystems

• All of these Australian ecosystems are named
  based on the dominant tree or plant.

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Different types of producers are found in
different ecosystems.
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What is a habitat ?
Each ecosystem can be divided into a
habitat the non-living part, i.e. the
physical area in which organisms live. It has all
the things a living thing needs to survive e.g.
oxygen, water, light, shelter..
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Which land habitat?
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Which water habitat?
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What is a community?
Each ecosystem can be divided into a
community the living part, i.e. all the
different organisms living in that particular
habitat producers, consumers, decomposers
(trophic levels)
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The community of an open forest
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The community of a mallee ecosystem
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The community of a rocky coast
Barnacles
Sea star
Strapweed
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What is a population?
Each community is made up of many different
populations. A population is all the members of
a particular species living in one habitat for
example, the population of koalas in bushland.
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Summing Up

• http//videos.howstuffworks.com/discovery/29495-as
  signment-discovery-ecosystem-video.htm

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Natural changes in populations
Lynxes are a type of wild cat that hunt snowshoe
hares in northern parts of North America.
The size of the two populations are very closely
linked. Why do you think this is?
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Predator-prey populations
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Prey population changes
The hare population follows a cyclical pattern,
where it rises and falls in a fairly regular
cycle. Why is this?
The hare population changes due to both the
vegetation growing season and changes in the lynx
population.
Individual hares must compete for food and mates,
and must also avoid being killed by lynxes, their
predators.
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Predator population changes
The lynx population also follows a cyclical
pattern very similar to the hare population. Why
is this?
The lynx is very dependent on hares for food, so
as the hare population changes so does the lynx
population.
This is why the lynx population rises and falls
slightly after the rise and fall of the hare
population.
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Now consider a food web
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What would happen to this forest community if the
mice had a disease and started dying in large
numbers?
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If there are less mice the numbers of owls,
snakes, rabbits and wild cats would drop in
turn the number of kites, lions and jackals would
drop
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Rabbits may eat more vegetation so there is less
for goats so goat numbers and in turn jackal and
lion populations could drop.
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What factors cause damage and changes in
Ecosystems?
Our coral reefs are dying
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What causes changes in ecosystems

• Removal of Predators
• Destruction or alteration of habitats
• Introduction of alien species
• Chemical damage
• Climate change

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Lake Guri (Habitat Destruction)

• A hydroelectric dam in Venezuela flooded an area
  more than 6,000 km2 creating one of South
  America's largest man-made lakes Lake Guri.
• Floodwaters turned hilltops into islands,
  predators such as jaguars, eagles, and
  armadillosdisappeared from the islands. Some
  swam or flew away. Others drowned or starved to
  death.

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Lake Guri

• In the predator's absence, their prey monkeys,
  iguanas, leaf-cutting antsbegan multiplying.
• Soon these plant-eaters had devoured most of the
  forest.

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Loss of Biodiversity
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Deforestation
Humans often destroy forest habitats to make room
for housing or industry.
If a habitat is destroyed some animals may no
longer have resources they need, e.g. food and
shelter.
1950
1985
2005
2000
In Borneo, southeast Asia, forests are slowly
being removed to make way for other crops.
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Save the Orang-utan

• The single biggest threat to the survival of
  orang-utans is the production of palm oil - an
  ingredient found in many packaged supermarket
  products.
• Palm oil is found in about 40 of the products on
  supermarket shelves. Certified Sustainable Palm
  Oil (CSPO) is an alternative ingredient that is
  produced without harming local wildlife and
  communities.

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A decision to be made

• The second largest fishing trawler arrived in
• Australia last year and many Australians did
• not want this ship in Australian waters.
• Suggest why?
• http//www.smh.com.au/opinion/politics/stop-the-ma
  rgiris-and-spare-the-oceans-20120830-253c4.html

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Ecosystems under threat
The cane toad was introduced into Queensland to
control in the 1940s to control the sugarcane
beetle. It quickly spread and is considered a
pest.
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A Bad Decision

• Cane toads spread rapidly and the numbers
• of many native species have declined
• sharply. They poison our native wild life.

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Strange Days on Plant Earth

• http//www.youtube.com/watch?va_HWqlmvX1k
• (19.48) Threat of invasive species

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Australian Pests

• http//www.youtube.com/watch?vTmYld25z-JU

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Biological Magnification

• Humans have created many problems for organisms
  high in the food chain because of chemicals they
  have released into the environment.

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Biological Magnification
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Biological Magnification Interactive
http//www.sciencelearn.org.nz/Contexts/Toxins/Sci
-Media/Animations-and-Interactives/Bioaccumulation
-in-the-sea
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Mercury Poisoning(Minamata Bay Disaster)

• Japanese government officially recognizes over
• 2,000 victims due to dumping mercury wastes.
• Symptoms - muscle spasms,
• - blindness
• - brain damage
• - paralysis
• - babies born with deformed limbs

http//firstterm.acjnewsline.org/upload20for20gr
oup20A/Industrial20disasters20group201/FINAL/m
inamata.htm
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Damage due to DDT Spraying

• Eagle/bird numbers dropped so low they faced
  extinction.

DDT lead to eggs being laid with soft shells
DDT tends to concentrate in the body fat of
animals. DDT can become a problem for many
animals high in a food chain.
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Summing Up

• http//videos.howstuffworks.com/discovery/29495-as
  signment-discovery-ecosystem-video.htm
• Choose discover biodiversity

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Environmental effects of climate change
Human activity may be causing a change in the
worlds climate.
The production of carbon dioxide, and other
heat-trapping gases from the burning of fossil
fuels may be causing the earths climate to
change. This is called the enhanced greenhouse
effect.
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An Inconvenient Truth
http//www.youtube.com/watch?vwnjx6KETmi4
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Evidence for global temperature change
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Environmental effects of climate change
This change in the earths climate could result
in

• higher global temperatures

• sea level rising

• a different geographical distribution of rain
  fall.

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How could change affect ecosystems?
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The effect of change on polar bears
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Effects of environmental change
Animals are adapted to suit their environment,
helping them survive and reproduce. However if
the environment changes they may no longer have
this advantage.
A change in environment can cause extinction.
Extinction is when the last individual of a
species dies.
When a species is at risk of extinction, it is
endangered. Over 1,100 animal species and over
700 plant species are classed as endangered or
threatened.
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Extinction due to climate change
If climate change causes an impact on habitats
and ecosystems this could result in more species
becoming extinct.
It is thought that 2030 of species are likely
to be at risk of extinction if the global average
temperature rises by 1.52.5 C beyond 1990
levels.
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Why is important to conserve species?
Extinction can cause a decrease in biodiversity.
Biodiversity is the number and variety of
organisms found in an area.
If one species becomes extinct this can have a
huge impact on the rest of the community.
Extinction can also decrease the resources
available to humans. Some medicines are made
from plants if a plant species becomes extinct
its unique chemicals are no longer available to
us.
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The Future

• By the year 2100, human activities such as
  pollution, land clearing, and overfishing may
  have driven more than half of the world's marine
  and land species to extinction.

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Work to Complete

• Food chains and webs assignment
• Choose one topic to write a creative newspaper
  article on one Australian pest
• Rabbit
• Cane Toad
• Crown of Thorn Starfish

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Topic One

• Where do rabbits originally come from?
• 2. How and why were rabbits introduced to
• Australia?
• 3. Why did rabbits reach plague proportions?
• 4. What damage did rabbits cause to Australian
• ecosystems?
• 5. How do we try to control rabbit population
• numbers?

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Topic Two

• Where do cane toads originally come from?
• 2. How and why were cane toads introduced to
• Australia?
• 3. Why did cane toads reach plague proportions?
• 4. What damage did cane toads cause to Australian
  
• ecosystems?
• 5. How do we try to control cane toad population
  
• numbers?

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Topic Three

• Where do crown starfish originally come from?
• 2. How and why were crown starfish introduced to
  
• Australia?
• 3. Why did crown star fish reach plague
  proportions?
• 4. What damage did crown starfish cause to
  Australian
• ecosystems?
• 5. How do we try to control crown starfish
  population
• numbers?

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