Ecosystem Threats II Ecosystems Unit, May 23 rd 2007.

Ecosystem Threats II

Ecosystems Unit, May 23rd 2007

**Major (man-made) Threats to our Ecosystems:

1. Habitat Loss2. Chemical Pollution

3. Introduced Species

4. Acid Rain5. Climate Change

3. Introduced Species

Humans have both intentionally and unintentionally brought new plants and animals to new habitats.

Usually the new species has no

natural predators or diseases to limit their populations in this new habitat so their population numbers increase rapidly!

Examples of Introduced Species

1. Starlings from Eurasia to North America2. Rabbits from England to Australia3. Purple Loosestrife from Europe to North

America4. Cane Toads from South America to Australia

STARLINGS

In 1890 100 starlings were introduced to Central Park, New York

Today there are over 200 million starlings!

Starlings take over the nesting habitats of our native birds. Their large flocks also cause lots of waste, noise and eat farmer’s grain.

Rabbits to Australia

In 1859, 24 rabbits were brought from England to Australia for sport hunting.

Australia had no natural predators that ate rabbits.

Despite lots of shooting, by 1950 there were 600 million rabbits!

Rabbits have caused the extinction of many native plants and animals in Australia.

Invasive Rabbits in Australia Video Clip

PURPLE LOOSESTRIFE

In early 1800s Purple loosestrife was accidentally brought to North America from Europe.

Seeds of the plants were in the sand that was put in the ballast of ships sailing from Europe.

This plant had no natural predators in North America. Each plant could produce 3 million seeds/yr!

Purple Loosestrife taking over a wetland

Leaf Eating Beetles

Effects of Beetles on Purple Loosestrife in a wetland in Ontario

Video of Water Hyacinth

Cane Toads

http://www3.nationalgeographic.com/animals/video/toad_cane.html

Solutions…

Never release unwanted pets into the wild!

If possible, eliminate the new species from the introduced habitat.

Control the population of invasive species to prevent further damage.