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 dangeradapted to climate changes such as drought, flood, and winter icesurvived the ice ageamphibians 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 inthey can signal changes in bothaquatic and terrestrial environmentsexposed 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 ForestGrassland

PondLake

Type of consumer

Carnivore Herbivore

Prey Small insects Small fish

AlgaeDetritus

Predators Large fishBirdsReptilesSmall 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 CategoriesCategory 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 Change A 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 disastrousit 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 the 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 FactorsThe effect of living things on the ecosystems such as:

predatorspreycompetitors 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. 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 Assignment

Nature 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 ConsumerEat secondary and primary consumers. (Heterotroph)

Bear, lion

Third Trophic Level Secondary ConsumerEat primary consumers and producers. (Heterotroph)

Eagles, wolves

Second Trophic Level

Primary ConsumerEat producers for food. (Heterotroph)

Deer, mice, bugs

First Trophic Level ProducerMake 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

trophic level for reproduction, living, growing and waste (feces &heat loss).

Calculating energy efficiencyThis 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 = 100kJEnergy Accounted for = 63kJ + 4kJ = 67kJEnergy 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 = 4kJTotal Energy Input for the cow = 100kJEnergy 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