3.3 Threats to Biodiversity (Pages100-109)

Homework: Page 109 # 1, 2, 4

Key Concepts: (Page 109)

• Threats to biodiversity include habitat loss, the introduction of alien species, overexploitation, and breaking the connectivity among ecosystems.

• Deforestation and draining wetlands can result in habitat loss.

• Zebra Mussels

• Extinction is a natural event that has occurred throughout Earth’s history.

• Current extinction rates maybe accelerated due to human activities.

Habitat Loss:

1.What is habitat loss?

Habitat loss is the destruction of habitats, which

usually results from human activities.

2. Suggest ways to remedy deforestation.- Replanting the same or similar species of

trees.

- Limit human activities like farming and building dams in forested areas.

3. List two reasons why wetlands are drained.

Wetlands are drained for farming and for building

homes.

Alien Species:

4. What are alien and invasive species?

Alien species are species that are accidentally or

deliberately introduced into a new location.

Invasive species are species that can take over

the habitat of native species or invade their

bodies.

Aliens Have Landed

5. Give three reasons why alien species often do

well when they are released in a new part of the

world.

a) Conducive environment (climate and weather)

b) Availability of nutrients

c) Out-compete native species where they are introduced

6. What is the negative impact of the introduction of zebra mussels in Great Lakes?

Zebra mussels were eating most of the shrimp-

like crustaceans which are a food source for

many fish, including whitefish and smelt. As the

number of these crustaceans has declined, so

have the numbers of these fish.

7. Describe why round gobies might function effectively as predators and competitors in the Great Lakes.

As predators- Round gobies are known to eat the eggs of native fish.

As competitors- Round gobies compete with

native species for spawning.

Overexploitation:

8. How does overexploitation affect biodiversity of

an ecosystem?

Overexploitation (the use or extraction of a resource until it is depleted) can lead to dangerously low population numbers, if not the complete disappearance of a species.

Disrupting Connectivity Across Ecosystems:

9. Copy down figure 3.17

Life Cycle of a Salmon and Feeding Habits of

Bears:

a) Salmon hatch in freshwater in the temperate rainforest.

b) Salmon spend their adult life in the Pacific Ocean for nutrients.

c) Salmon return to their birthplace to spawn.

d) Bears move Salmon into the forest. Nutrients released from salmon’s decaying bodies are absorbed by plants in the forest.

Extinction Reduces Biodiversity:

10. What are possible reasons why extinction occurs?

**EXTINCTION is the death of all the individuals of a species**

a) Significant changes in the biotic and abiotic features of the species’ ecosystem

b) Introduction of alien species

c) Overhunting

11. What do scientists hypothesize as possible cause of mass extinctions?

a) Sudden change to Earth’s ecosystem-unsustainable and unsustaining

b) An asteroid hit Earth 5 million years ago causing huge changes to the Earth’s climate and thus eliminating the dinosaurs.

c) Massive volcanic activity in Asia caused significant climate change around the world.

12. What is the biodiversity crisis?

Biodiversity crisis- the current accelerated rate of extinction.