Life Sciences: Sustainability of EcosystemsScience 10

Define the following words:

ecosystem carnivoreamphibian omnivorefood chain detritusproducer decomposerconsumer habitatherbivore

Section 1.1

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

The Silence of the Frogs

Why are Scientists Concerned?

the health of the amphibians indicates the health of theecosystems they live in

they can signal changes in bothaquatic and terrestrial environments

exposed to hazards in two ecosystems (water as eggs andtadpoles and forest & grasslandas adults)

a change in either of their ecosystems can result in a loss ofpopulation.

Frogs are good environmental indicators

if they start to die off it is a sign

that the ecosystem is in trouble.

Frogs breathe through their skin

they may be more sensitive to

pollution and provide early

warning of serious problems

part of two different food chains

see Figures 2 and 3 on page 11

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?

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

Some Factors Affecting Frog Populations

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

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)

Assignment:

Section 1.2

• 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.

Canada’s Endangered Species

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

are not reversed.

Wood Bison

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

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

Extinction in the Modern World

Causes of Extinctions

Asteroidslarge asteroids hit the Earth & caused a large cloud of dust that blocked the light from the sun and set off many volcanoesThe 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 ChangeA change in a species environment forces them to adapt or die.

CompetitionIf 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

Balanceallowing 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

Ecologythe study of how organisms interact with each other

Ecology focuses on the following:a) examining organisms within their natural settingb) how organisms interact with their environmentc) how factors in the environment affect an organism’s growth, feeding habits and reproduction

Ecology

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.

Ecotonetransition 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. How are weeds different from plants?

2. How do abiotic factors affect the distribution of

weeds?

Section 1.8

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.

Comparing Ecosystems

Assignment

Read pages 22-23 and complete questions 1 – 5 on page 23.

Complete the Comparing Ecosystems AssignmentNature Walk

Handout explaining Mini-poster and Marking Rubric

Section 1.11

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)

Following Energy Movement in Ecosystems

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 TransferEnergy 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 destroyed2) 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 trophiclevel 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 trophiclevel 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 PyramidsEnergy 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