How Foreign Species Affect Ecosystems Section 3.3 – BC Science 10, pg. 138 - 144

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)

The affects of foreign species on ecosystems

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?

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?......

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?

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

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.

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

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.

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

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

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.

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)