Download Ecosystem - WordPress.com

Life Sciences: Sustainability of Ecosystems
Science 10
Define the following words:
ecosystem
amphibian
food chain
producer
consumer
herbivore
carnivore
omnivore
detritus
decomposer
habitat
Section 1.1
The Silence of the Frogs
about
30% of North America’s frogs and toads are in
danger
adapted to climate changes such as drought, flood,
and winter ice
survived the ice age
amphibians have been around for more than 400
million years
Why are Scientists Concerned?
the
health of the amphibians
indicates the health of the
ecosystems they live in
they
can signal changes in both
aquatic and terrestrial
environments
exposed
to hazards in two
ecosystems (water as eggs and
tadpoles and forest & grassland
as adults)
a
change in either of their
ecosystems can result in a loss of
population.
Frogs
are good
environmental indicators
 if
they start to die off it is a sign
that the ecosystem is in trouble.
Frogs
skin
breathe through their
 they
may be more sensitive to
pollution and provide early
warning of serious problems
part
of two different food
chains
see
11
Figures 2 and 3 on page
Frogs in Their Ecosystems
Stage
Adult Frog
Tadpole
Ecosystem
Forest
Grassland
Pond
Lake
Type of consumer Carnivore
Herbivore
Prey
Small insects
Small fish
Algae
Detritus
Predators
Large fish
Birds
Reptiles
Small mammals
Insects
Fish
If frogs
disappeared,
what would
happen
to their
ecosystems?
Why Are Frogs Disappearing?
Some Factors Affecting Frog Populations
1. Loss of Habitat
 Frogs
need clean water, a forest
or field, and a safe path between
them to survive
 Roads are being built and forests
are being cut down
 Ponds are drained to create farm
land
2. Air and Water Quality


Frogs breathe through their thin skin
and pollutants are also able to pass
through it
Acid rain and chemicals in the water
cause the frogs to become sick. It
also affects their ability to reproduce
3. Ultraviolet Radiation

Frog skin can be damaged by the sun
just as ours can
4. Climate Change

Global warming increases
temperatures and reduces wetland
Video Clip: Feeling the Heat with Frogs
Assignment:
Read
pages 10-13 and answer questions 1-6.
Read the article “Last Chance “ and answer the questions below. Please copy the questions and
answer them in complete sentences as your work will be marked.
(12 points)
1. What lead to the rapid decline of the Kihansi spray toads? (1)
2. How is the Kihansi spray toad unique from other amphibians? (1)
3. Why should we be concerned about protecting the frogs?
(give at least 2 reasons) (1)
4. Why are frogs so sensitive to pollution? (1)
5. The chytrid fungus has been linked to the declining frog
populations. Explain what is believed to be the origin of this
fungus. (1)
6. How do scientists believe they can help treat the chytrid fungus
once the frogs are in captivity? (1)
7. List the 6 threats, from the article, that frogs are facing and briefly
explain how each one has played a role in the decline of the frog
populations. (6)
Section 1.2
Canada’s Endangered Species
As of 2011, 602 species are classified by the
Committee on the Status of Endangered Wildlife in
Canada (COSEWIC) as being at risk,
including 262 Endangered,
151 Threatened,
166 Special Concern (Vulnerable),
23 Extirpated Species
•
In addition, 13 species are Extinct.
Link to various endangered species
PEI Piping Plover Video
Species at Risk Categories
Category
Description
Example
Vulnerable
At risk due to declining numbers in
some areas.
Grey Fox – Ontario
Threatened
Likely to become endangered if factors Wood Bison
are not reversed.
Extirpated
No longer exists in specific areas, but
can be found in others.
Grizzly Bear - No
longer in SK or MB but
still found in AB and
BC.
Endangered
Close to extinction in all parts of
Canada.
Eastern Cougar
Extinct
A species that does not exist
anywhere.
Blue Walleye
Video Clip: Species At Risk
Assignment
Read
pages 14-15 and complete questions
1, 2 and 4 on page 15.
Section 1.3
Extinction in the Modern World
Humans
have sped up or caused the extinction of
many species in the past 25 years.
It
is thought that over 500 million different
species have existed on Earth and that over 90%
have either become extinct or evolved into new
species.
Mass Extinction
Causes of Extinctions
Asteroids
large asteroids hit the Earth & caused a large
cloud of dust that blocked the light from the sun
and set off many volcanoes
The extinction of dinosaurs (65 million years ago)
is thought to have been caused by an asteroid.
There is a crater in Mexico that is 10 km deep and
300 km wide and dates back to that time.
Climate Change
A change in a species environment forces them to
adapt or die.
Competition
If a new species arrives it may cause competition for
the same food sources and/or habitat. One wins, the
other adapts or dies.
Human Factors
Logging, oil exploration, expanding cities, expansion
of agriculture, introduction of new species
Effects of Extinction
Biodiversity is the number of different species in
an ecosystem.
 all
species in an ecosystem are linked, and a change
in one species causes a domino effect.
Restoring
Balance
allowing or forcing
just one species to
become extinct could
be disastrous
it would take many
years to figure out all
of the consequences.
Biodiversity Video
Assignment
Read
pages 16-19 and complete questions 1 - 3
on page 19.
Species
at Risk Research
(see project outline)
Section 1.5
Ecology
Ecology
the study of how organisms interact with each
other
Ecology focuses on the following:
a) examining organisms within their natural setting
b) how organisms interact with their environment
c) how factors in the environment affect an
organism’s growth, feeding habits and reproduction
Abiotic Factors
Nonliving factors that can affect an organism
such as:
Amount of sunlight
Temperature changes
Strength and direction of wind
Biotic Factors
The effect of living things on the ecosystems
such as:
predators
prey
competitors for food and
reproduction
Organisms do not live in isolation
 group themselves with others of their own kind forming a
POPULATION
 populations of different organisms will interact and form a
COMMUNITY
 communities of different organisms will also interact with all
the biotic and abiotic factors in an area creating an
ECOSYSTEM
This pond ecosystem consists of a pond
habitat with populations of aquatic plants,
waterside plants, micro-organisms (in the
mud at the bottom of the pond), minnows
and herons. The organisms together make
up a community of living things.
Ecotone
transition area between two different ecosystems
where species from each can interact. There is
often greater biodiversity in the ecotone than in
either of the two ecosystems bordering it.
any
area with greater biodiversity is less fragile.
( gives consumers more choices for food sources,
so if one disappears, they have others)
An
ecotone helps guard against extinction.
Example of an Ecotone
Questions to ponder:
1.
2.
How are weeds different from plants?
How do abiotic factors affect the distribution of
weeds?
Section 1.8
Comparing Ecosystems
Artificial ecosystems are ones that humans made
or maintained.
 fish
tank, farms, parks
Natural ecosystems are made by nature.
 Species
are able to interact with their surroundings
freely. Humans will still have an impact on the
ecosystem but they do not control it.
Assignment
Read
pages 22-23 and complete questions 1 – 5
on page 23.
Complete
 Nature
the Comparing Ecosystems Assignment
Walk
 Handout explaining Mini-poster and Marking Rubric
Section 1.11
Following Energy Movement in Ecosystems
Energy is constantly moving within ecosystems. To
understand how living things gain their energy we must
look at trophic levels.
Most ecosystems only contain about three trophic levels.
All organisms are either:
1.
Autotrophs -make their own food (producers)
2.
Heterotrophs -can’t make their own food (consumers)
Energy is passed through the TROPHIC levels of
an ecosystem. Trophic means “feeder”.
Trophic Level
Role
Examples
Fourth Trophic Level
Tertiary Consumer
Eat secondary and primary consumers.
(Heterotroph)
Bear, lion
Third Trophic Level
Secondary Consumer
Eat primary consumers and producers.
(Heterotroph)
Eagles, wolves
Second Trophic Level
Primary Consumer
Eat producers for food.
(Heterotroph)
Deer, mice, bugs
First Trophic Level
Producer
Make their own food from basic
nutrients and sunlight.
(Autotroph)
Grass, berries,
trees
Every organism in an ecosystem provides energy for
other organisms. Food Chains provide a step by
step sequence of who eats whom in an ecosystem.
Ex. Plants  Rabbits  Wolves
When several food chains are connected a
Food Web is created.
 graphical
representation of the feeding relationships
between organisms in an ecosystem.
 A single organism can be a part of many food chains.
 The most stable ecosystems (greatest biodiversity)
have such complex food webs that the removal of one
producer or consumer does not have a great negative
affect on the other food chains in the web.
Video Clip: Food Web
Limits on Energy Transfer
Energy is constantly changing forms and moving
within ecosystems.
Thermodynamics is the study of energy changes.
The sun’s energy must obey the laws of
thermodynamics:
1) First Law – energy can be changed from one
form to another, it cannot be created or destroyed
2) Second Law – during energy changes some of
the energy is lost in the form of heat and therefore
cannot be passed on
Limits on Energy Transfers and the
Number of Trophic Levels
There is a limit on the energy transfer within a
food chain. Only about 10% of the available
energy in a lower trophic level is transferred to the
next trophic level.
10%
10%
Plants  Rabbits  Wolves
The other 90% is used
within the original trophic
level for reproduction,
living, growing and waste
(feces &heat loss).
Calculating energy efficiency
This cow has eaten 100 kJ of
energy in the form of grass, and
excreted 63 kJ in the form of
feces, urine and gas. The energy
stored in its body tissues is 4 kJ.
So how much has been used up
in respiration?
Energy can’t just disappear (Law of Thermodynamics).
The total amount of energy used up by the cow must equal
the total taken in as food.
Total Energy = 100kJ
Energy Accounted for = 63kJ + 4kJ
= 67kJ
Energy for Respiration = 100kJ - 67 kJ
= 33kJ.
We can also work out the energy efficiency at each trophic
level by dividing the useful energy output by the total
energy input. Multiplying this fraction by 100 gives you the
percentage efficiency.
Useful Energy for the next trophic level
= 4kJ
Total Energy Input for the cow
= 100kJ
Energy Efficiency for the cow = 4/100 x 100 = 4%
Assignment:
Complete Questions 1-10 on page 39.
Food Chain Song
Ecological Pyramids
Energy transfers in ecosystems can be graphed.
1) PYRAMID OF ENERGY- represent energy flow through
the food chain or web. Measured in kilojoules or calories
2) PYRAMID OF NUMBERS –represent the number of
organisms at each trophic level of a food chain
3) PYRAMID OF BIOMASS – the dry mass (water
removed) of all the organisms at each trophic level.
Measured in kilograms
Assignment
Read
pages 34-39and complete questions 11 and
14 on page 39.
Chapter 1 Review Questions: page 46 #1,2,3,4,6,9
Complete
Chapter 1 Review Sheets for the test