Biodiversity Case Study THE SILENCE OF THE FROGS

Biodiversity Case Study THE SILENCE OF THE FROGS PAGES 10 -13 IN TEXT

Biodiversity Case Study THROUGH THIS CASE STUDY ON FROGS WE WILL LEARN ABOUT: - BIODIVERSITY LOSS FOOD CHAINS FOOD WEBS

Disappearing Frogs Problem �Frogs have survived multiple extinctions over the last 250 million years of Earth’s history. �They can be found in most ecosystems that contain water

Disappearing Frogs Problem �Scientists are noticing a decline in frog populations and the # of species of frogs. �Over 30% of North American frog species are in trouble! Question Why are scientists concerned about frogs?

Disappearing Frogs Answer Scientists believe that frogs are a good indicator species. Indicator Species: a species with a population that varies with the health of an ecosystem.

Why are Frogs an Indicator Species? Frogs are considered top be indicator species because they live two different lives!

Why are Frogs an Indicator Species? Life #1: In aquatic ecosystems as eggs and tadpoles. Life #2: In terrestrial/aquatic ecosystems as adult frogs. Tadpoles Frogs

Why are Frogs an Indicator Species? By studying frogs we can find evidence for problems in both aquatic and terrestrial ecosystems. Ponds Forests and Grasslands

African Bullfrog �Video 1 �Bullfrog battle

Frogs and the Food Chain �Because they exist in two ecosystems, frogs are a part of two very different food chains Food Chain: a step-by-step sequence showing a feeding relationship in an ecosystem. Mr. T must be at the top of the food chain

Frogs and the Food Chain As an Herbivore (Pond Ecosystem) Algae Producer Tadpole Consumer (Herbivore) Water Boatman Consumer (Carnivore) Trout Consumer (Carnivore)

Frogs and the Food Chain As a Carnivore (Forest Ecosystem) Grass Producer Grasshopper Adult Frog Consumer (Herbivore) Consumer (Carnivore) Heron Consumer (Carnivore)

Disappearing Frogs �What effect would the loss of frogs have on an ecosystem? Consider the food chain / web! No Frogs = More Insects! =

�More insects like Mosquitos means problems for humans �Mosquitos carry malaria, a life threatening parasitic disease. �Cases of malaria have increased in areas where frog populations have declined.

Disappearing Frogs �How does this affect OTHER species in the same ecosystem? ? =

Disappearing Frogs Ecosystems do not only operate in simple food chains! Food webs represent more complicated feeding relationships in ecosystems There are other things that feed off the same insects as frogs. They would have more food once frogs are gone.

So Why are Frogs Disappearing? �Scientists have identified four main reasons: 1) Habitat Destruction 2) Pollution of Air and Water 3) Ultraviolet Radiation 4) Climate Change All of these factors are enhanced or directly caused by human activity.

Why are Frogs Disappearing? ? 1) Loss of Habitat (place to live) �Frogs need ponds and wetlands, to lay eggs and keep their skin moist. �As adults they need forests and grasslands to catch insects.

Why are Frogs Disappearing? ? 1) Habitat Destruction �Forestry �Farming �road construction �growth of towns and cities These all destroy frog habitat! Habitat: where an organism lives

Why are Frogs Disappearing? ? 2) Pollution of air and water �Water pollution Frogs have lungs but also breathe through their skin!! Their skin is THIN and pollutants can pass through! Close up of frog skin!

Why are Frogs Disappearing? ? 2) Air and water quality �Acid Rain Water becomes more acidic This causes reproductive and growth problems �Fewer Eggs fertilized �Embryos develop more slowly �Deformed tadpole limbs!

Why are Frogs Disappearing? ? 3) Ultraviolet Radiation �Frogs thin skin is sensitive to UV radiation from the sun �Depleted ozone layer means more radiation gets to earth �Damages frogs skin Harms humans too! More skin cancer!

Why are Frogs Disappearing? ? 4) Climate Change �People burn fossil fuels that contribute to global warming. If it gets drier = less habitat for frogs

Why are Frogs Disappearing? ? 4) Climate Change If it gets wetter = faster rivers and less insects so less food

Habitat Destruction