1. How Foreign Species Affect Ecosystems
Section 3.3 – BC Science 10, pg

2. Today’s Objectives
Give examples of how foreign species can affect an ecosystem such as: Eurasian milfoil, purple loosestrife, scotch broom, American bullfrog, European starling in BC)

3. The affects of foreign species on ecosystems

4. Native Species vs. Foreign Species
What do you think the difference is?
Native species are plants and animals that naturally inhabit (live in) an area
Introduced or foreign species are plants or animals that are intentionally or accidentally transported into regions where they did not exist before
Also called non-native, exotic, or alien species
Is Mr. Heard a foreign species????
Most foreign species are harmless or even beneficial to their new ecosystem, but some, called invasive species, can be very harmful…..how?

5. Purple loosestrife Plant native to Europe
Early 1800’s was accidentally introduced to North America
Seeds of the plant were carried across the ocean in large boats
Purple loosestrife had no natural predators in North America and produces over 300,000 seeds per plant!
Rapidly spread in North American wetlands, out-competing native species
How can it be stopped?......

6. Introduce another species!!
In Europe, purple loosestrife is eaten by a beetle called the European leaf- eating beetle, helping keep it under control
Scientists tested to see if beetle was safe to introduce to North America
The beetles now provide effective biological control of purple loosestrife
What other methods of control are there?
What are the advantages of biological control?
What are the disadvantages of biological control?

7. Impact of Introduced Species
Foreign species (animals or plants) can often out- compete native species for several reasons:
Often have high reproductive rates
Aggressive competitors
Lack natural predators
Can often drastically change the ecosystem through:
Competition – uses up valuable food and water
Predation – eats native species
Disease
Parasitism
Habitat alteration – alter abiotic factors of an ecosystem

8. Competition
Carpet Burweed is an invasive species found in BC’s Saltspring Island, originally from South America. It competes with four rare native species of plants for habitat, and water. It is also very sharp, and can cut animal and human skin.

9. Predation
Introduced predators have an advantage over native predators because the prey has no adaptations to escape or fight them.
These Yellow Crazy Ants escaped from cargo from Africa, onto Christmas Island of Australia. The ants devour all plants and prey on the young of many animals.
They attack in swarms, and squirt acid on to their prey
Estimated to have killed 20 million land crabs, a keystone species on the island

10. Disease and Parasitism
Disease and parasites can weaken the immune response of an ecosystem, allowing less dominant species to outcompete other species, severely changing the ecosystem
Sea lampreys entered the Great Lakes through man-made canals in the 1880’s, and are now affecting freshwater fish
In forests, Whitebark pine is a keystone species. Now at risk due to disease called blister rust, introduced in the early 1900’s.

11. Habitat alteration
Wild boars can spread weeds that outcompete native species during natural succession, and they also eat native birds, reptiles, frogs, soil organisms, fruit, seeds, and bulbs

12. Some introduced species in BC
Eurasian milfoil
First discovered 1970 in Okanagan Lake
Often spread by boats, makes a thick carpet on the lake bottom and cuts off sunlight to other plants
Norway rat
Escaped from explorer ships
Adapted to all environments, and eat anything!
European starling
Late 1800’s brought on purpose to North America
Since then have caused decline in several native bird species, outcompeting for nesting sites and because they are fast growing
American bullfrog
1930’s brought to BC as source of food in restaurants
Breed rapidly, and eat many other types of frogs

13. An ecosystem under attack
The Garry Oak ecosystem (bottom right) is an endangered ecosystem in BC
Less than 5% of the original ecosystem remains due to land development, and now what’s left is under attack from introduced invasive species
Scotch broom, grey squirrel, and gypsy moth are examples, and all have negatively affected the ecosystem in some way
An organization called the Garry Oak Ecosystem Recovery Team (GOERT) has been established to try to save this rare ecosystem
Scotch broom (left) outcompetes native plants
Grey squirrel is bigger than native red squirrel, can outcompete for available food
Gypsy moth larvae eat all the tree leaves which can kill them
What methods can they use to help the ecosystem?
vs.

14. Review Quiz What is a foreign species? What is an invasive species?
A species that has been introduced to a new ecosystem
What is an invasive species?
An introduced species that negatively affects its new ecosystem by outcompeting native species
What is a native species?
A species that naturally occurs in an ecosystem
How does the American bullfrog affect ecosystems in BC?
Breeds rapidly, eat many other native frog species (reduces biodiversity)
How does Purple loosestrife affect ecosystems in BC?
Outcompetes native plants, using up resources and habitat (reduces biodiversity)