1. An Introduction to Ecology
Silence of the Frogs
Please help us!
An Introduction to Ecology

2. What is an Ecosystem?
Ecosystem
A term used to describe the relationships between the many species living in a particular environment and between the living (biotic) and non-living (abiotic) components of this environment.

3. Frogs (as tadpoles and adults) occupy two different ECOSYSTEMS
Eggs and Tadpoles
Live in ponds (aquatic ecosystems)
Adult Frogs
Live in forests and grasslands (terrestrial ecosystems)

4. Model of an Ecosystem ECOSYSTEM ABIOTIC FACTORS BIOTIC FACTORS
Non-living agents in an
ecosystem
e.g. water temperature,
amount of light reaching
pond floor, etc.
BIOTIC FACTORS
A factor in an ecosystem
created by the presence
and roles of other living
things
e.g. number of frogs,
amount of algae, etc.
Each part of the ecosystem is affected by other parts!

5. What is a Food Chain? Food Chain:
Consumer
Food Chain:
A step by step linear sequence linking organisms that feed on each other.
Starts with a food source such as plants (producers) and continues with animals and other living things that feed on plants and on each other (consumers).
Consumer
Consumer
Consumer
Producer

6. Producers can make their own food by taking energy from the Sun.
Consumers are unable to create their own food, therefore they get energy by eating producers (plants) and/or other consumers (animals).

7. Frogs (as tadpoles and adults) occupy two different FOOD CHAINS
Adult frogs are carnivores (feed on other animals)
e.g. they eat insects
Predatory birds (herons) prey on them
(1) ADULT FROG – FOOD CHAIN
Grass Insects Adult Frog Heron

8. Larger insects eat tadpoles
Tadpoles are herbivores (feed on plants). They eat living algae and dead algae (an example of detritus – waste from dead plants and animals)
Larger insects eat tadpoles
(2) TADPOLE – FOOD CHAIN
Algae (living) Tadpole Insects Fish
or Dead Algae

9. Why should we care that frogs are dying?
Because frogs and tadpoles are part of two different ecosystems and two different food chains, their decline affects many species, including us!
A decline in the frogs results in an increase in the number of insects (e.g. mosquitoes). The more mosquitoes, the more malaria and hence, human death. This has already occurred in Bangladesh.
A decline in the reproductive ability of frogs (e.g. from pesticides) leads to a decrease in number of tadpoles in the next generation. This increases the amount of algae (dead and living), thus increasing detritus above normal levels.
A decline in the frogs results in a decrease in the number of species that eat frogs (e.g. snakes and herons)

10. Why are Frogs Dying? Loss of habitat (home) Poor Air and water quality
Increasing ultraviolet radiation
Climate change
Increased stress on frogs’ immune systems
Decreased resistance to disease
Chytrid Fungus

11. 1. Loss of Habitat
We are destroying the water with pollution (e.g. pesticides, prescription drugs etc.)
We are cutting down forests
We are building highways and cities between the two ecosystems, increasing exposure to predators

12. 2. Poor Air and Water Quality
Frogs have thin, sensitive skin.
Frogs breathe through their skin and by their lungs.
Acid rain and pesticides can therefore go through their skin easily.
This affects their ability to reproduce

13. 3. Ultraviolet Radiation
Their thin skin is also susceptible to UV radiation.
The damage to the ozone layer (protective layer of atmosphere surrounding the Earth) caused by pollution increases the amount of UV waves that reach the surface of the Earth.
This causes cell damage in both frogs and humans.

14. 4. Climate Change Human activities are causing changes in the climate.
Increase use of fossil fuels (coal, oil, gas)
Increased global temperatures means less water available.

15. To Do
Fill in missing definitions and examples from Sections 1.1 and 1.5 from your text.
Complete “You and Food Chains” Activity.

16. Pictures from: http://picture-book.com/node/7029