Understanding Ecosystems
Grade 9 Science
Sustainable ecosystems
Big Ideas:
• Ecosystems are dynamic and have the ability
to respond to change, within limits, while
maintaining their ecological balance.
• People have the responsibility to regulate
their impact on the sustainability of
ecosystems in order to preserve them for
future generations.
Looking Ahead
Unit Task Preview:
Ontario’s Species of Concern
• You will select TWO contrasting species that
are of concern in Ontario. You will choose one
NATIVE species that is at risk and one species
that is non-native and INVASIVE.
• For each species you will investigate
• The factors that have led to their current
status.
• How these factors are influencing species and
the health of the ecosystem they live in.
• Implications related to human interests.
• Actions that could change the species status.
Key Question: How are organisms influenced by their living and
non-living environment?
Unit B
Sustainable
Ecosystems
Chapter 2
Understanding
Ecosystems
Chapter 3
Natural
Ecosystems and
stewardship
Chapter 4
Ecosystems by
Design
Key Concepts
Life on Earth exists in
the atmosphere,
lithosphere and
hydrosphere
Human activities
influence
biogeochemical cycles
such as the water and
carbon cycles
Photosynthesis and
cellular respiration are
complimentary
processes in an
ecosystem
Energy passes through
ecosystems, whereas
matter cycles within
ecosystems
Ecosystems are
composed of biotic and
abiotic components
Terrestrial biomes and
aquatic ecosystems are
largely determined by
their abiotic
characteristics.
It’s All Greek to me....
•
•
•
•
•
Lithos - means stone
Atmos – means vapour
Hydro - means water
Bio – means life
Sphere - means ball
Life on Planet Earth
•
•
•
•
• Terms to Know:
Atmosphere – layer of gases surrounding the
Earth.
Lithosphere – Earth’s solid outer layer
Hydrosphere – all of Earth’s water in solid,
liquid or gas form
Biosphere – the zone around Earth where life
can exist.
The Atmosphere
What is it?
A layer of gases
surrounding the Earth
What is it made of?
What does it hold in?
Nitrogen, carbon dioxide,
oxygen, water vapour,
other gases.
Thermal energy (heat)
What does it block out?
U-V light.
Lithosphere, Biosphere, Atmosphere, Hydrosphere
• Plants (biosphere) require minerals
(lithosphere), water (hydrosphere) and carbon
dioxide (atmosphere) to grow.
• Think of another example related to the movie
red crabs crazy yellow ants.
The Gaia Hypothesis
• In 1960 James Lovelock advanced the Gaia
hypothesis. He proposed that Earth through
the interactions among the biosphere,
lithosphere, atmosphere and hydrosphere
behaving like a living organism. He proposed
that the Earth is capable of responding to
changes in its environment and maintaining
relatively consistent internal conditions over a
long period of time – just like a living cell.
Scale Model of Planet Earth.
11.8mm
108.66
0.13
1.57
Wrong = 11.8mm
Ecosystem
Composed of populations of plant and animal
species, abiotic and biotic environments
Word Associations
Abiotic & Biotic Factors
• Abiotic – means non living such as
–Air
–Temperature
–Rock
–Water
–Minerals
• Biotic all living organisms their remains and
their waste.
• Plants
• Animals
• Bacteria
Symbiosis: the interaction between members of two different
species that live in close association.
Fungi receive shade and nutrition from the trees, mushrooms
help the trees absorb water.
Predation: when one organism consumes another organism for
food. The organism that is consumed is called prey. The one that
eats the prey is called a predator. The relationship between
predator and prey can influence the population of both the
predator and the prey and affect the whole ecosystem in which
they live .
Competition occurs when two or more
organisms compete for the same resource
such as food, space, light.
Energy Flow in Ecosystems
• All energy on Earth comes from the Sun
• Plants use solar energy to turn carbon dioxide
and water into sugar. They need the green
chlorophyll in their leaves to help them do
this. This process is called PHOTOSYNTHESIS.
• It means making food (synthesis) from light
(photo).
Photosynthesis vs. Respiration
• Photosynthesis: Green plants
• Uses light energy from the sun, Carbon
Dioxide and water
• Makes sugar and oxygen.
• Respiration: All living things
• Uses food (sugar) and Oxygen
• Makes Carbon dioxide and water, releases
energy
CO2 = Carbon dioxide, H2O = water, O2 = oxygen
2009 Carbon dioxide concentration in the troposphere.
"Present day" (1990s) sea surface dissolved inorganic carbon
concentration (from the GLODAP climatology
Producers
• Because plants can use the energy from the
Sun to make food they are called Producers.
• Producers form the first link in all the food
chains.
254.3
25..43
2.543
Consumers
• Animals eat plants or eat animals that eat plants.
They are called Consumers.
• Herbivores are consumers that eat plants
• Carnivores: are consumers that eat herbivores.
• Omnivores: Eat both plant and animal materials
• Scavengers: are consumers that eat dead remains
• Parasites: are consumers that feed on living
organisms.
Each step in the food chain is known as a TROPHIC level.
Plants are called Autotrophs – they make their own food.
Animals are called Heterotrophs – they consume food
made by plants.
Fisher-man
0.1%
Trout 1%
Australian Blackfish
10%
Algae 100%
Sun energy
Sun
First trophic
level
Second
trophic level
Third trophic
level
Fourth trophic
level
Primary
Producers
plants
Primary
Consumers
herbivores
Secondary
Consumers
carnivores
Tertiary
Consumers
Top carnivores
Decomposers
Bear, Red tailed Hawk
Butterfly, Marmot , Deer, Grouse,
Chipmunk
Berries, flowers, grasses & seeds
Decomposers
Food Web Great Lakes
Eutrophication
• Eutrophication (also known as nutrient
enrichment) is a result of large amounts of
nutrients being released into a nutrient deficient
water body which leads to excessive amounts of
aquatic plant growth.
• Eutrophication can be accelerated by the release
of nutrients from human activities such as from
fertilizers used in agriculture and at our homes.
This rapid transition is not beneficial for the fish
and other organisms which live in lakes who have
to cope with depleted oxygen levels because of
the decomposition of plants,
Eutrophication in the Sea of Azov.
(Source: NASA).
What can Eutrophication Do?
Deformed frogs
have been linked
to an increase in
phosphates and
Nitrates
Ramshorn Snail
Bioaccumulation
• Bioaccumulation refers
to how pollutants
enter a food chain
• increase in
concentration of a
pollutant from the
environment to the
first organism in a food
chain
Biomagnification
• biomagnification refers to the tendency of
pollutants to concentrate as they move from
one trophic level to the next.
• increase in concentration of a pollutant from
one link in a food chain to another
Why is this important?
• Means that even small concentrations of
chemicals in the environment can find their
way into organisms in high enough dosages to
cause problems. In order for biomagnification
to occur, the pollutant must be:
• long-lived
• mobile
• soluble in fats
• biologically active
• If a pollutant is short-lived, it will be broken
down before it can become dangerous.
• If it is not mobile, it will stay in one place and
is unlikely to be taken up by organisms.
• If the pollutant is soluble in water it will be
excreted by the organism.
• Pollutants that dissolve in fats, however, may
be retained for a long time.
What did DDT do?
•Caused the top
predatory birds such as
Eagles, Hawks, Falcons,
Gulls to lay eggs with
thin shells.
•Led to loss of
successful breeding.
•Numbers of these
species declined.
What does PCB’s do?
• Polychlorinated biphenyls
(PCBs) are a group of
manmade chemicals.
They are oily liquids or
solids, clear to yellow in
color, with no smell or
taste.
How do PCBs get into the
environment?
• PCBs have been released into the environment through
spills, leaks from electrical and other equipment, and
improper disposal and storage. It is estimated that
more than half of the PCBs produced have been
released into the environment.
• Once in the environment, PCBs can be transported long
distances and they bind strongly to soil and sediment
so they tend to be persistent in the environment. They
have been found in air, water, soil, and sediments
throughout the world. Because PCBs have not been
made since 1977, the levels in the environment and in
the food chain have been declining.
• Most people are exposed to PCBs by eating
contaminated fish, meat, and dairy products.
Catfish, buffalo fish, and carp usually have the
highest PCB levels.
• Plants take up only small amounts of PCBs from
the soil, so amounts in grazing animals and dairy
products are generally lower than in fish.
• Dust contaminated with very small levels of PCBs
may be found on the outer surfaces of fruits and
vegetables
• Birth defects have been linked to mothers who have
been exposed to PCBs.
• Developing fetuses and young children are the most
vulnerable to PCBs, therefore, children and women
who may become pregnant, are pregnant, or nursing
should limit their exposure to PCBs.
• A pregnant woman can pass these chemicals to her
unborn child.
• Mothers who eat highly contaminated fish before
giving birth may have children who have slower mental
development.
• PCBs also can be passed to a baby through breast milk.
However, the significant benefits of breastfeeding far
outweigh the risks. Young children also may experience
developmental health effects.
Mercury
• Mercury compounds can be toxic at low levels in
the environment. The characteristics of mercury
that make it a health and environmental problem
are its toxicity and persistence in the
environment, and its ability to accumulate and
bioconcentrate as methyl mercury in fish and
fish-eating predators such as large fish or loons.
• Mercury also moves over long distances on air
currents and can be deposited on land and in
rivers, lakes and oceans far from the source of
release, therefore spreading the potential
exposure to many more people.
Minamata