Biological InvadersBiological Invaders• How can foreign organisms successfully

compete with naturally-occurring ones?• How are biological invaders introduced?• What can be done?

ExamplesExamples

Round Goby fish Purple Loostrife

Asian longhorn beetleSea lamprey

Biological InvadersBiological Invaders• Any foreign species that is introduced to an

ecosystem. • Can have devastating effects on the naturally-

occurring plant and animal life.

Why are some Invaders so Why are some Invaders so Successful?Successful?

• 1) NO Predators - they have evolved elsewhere; no predators

are present• 2) NO Competition – similar species, with similar niches, have

not evolved to compete with invaders

How are Biological Invaders How are Biological Invaders Introduced?Introduced?

• -sometimes, through natural migration

• MOSTLY carried by humans (not always intentionally!)

How are Biological Invaders How are Biological Invaders Introduced?Introduced?

• Ballast water from ocean going ships– Water is picked up in ship’s home port and

then dumped when it reaches the Great Lakes• Human transport

– Boat picks up species in one lake; boat is then trailered to a neighbouring lake (zebra mussels)

Who cares?Who cares?

• Native species dying out (negatively impacts ecological balance)

• Huge costs (Ontario sportfishing – lamprey; water intake – zebra mussels)

• Pain in the butt (feet) – zebra mussels cut up your feet when you swim

How can they be Stopped?How can they be Stopped?

• Natural competition of the ecosystem (eg. exotic fish)

• By physical or chemical means (eg. lamprey eel, weeds)

• Tighter controls in the shipping industry

• BIOLOGICAL CONTROLS (other foreign species) are also introduced to prey on invader (purple loosestrife)