9.8 - Invasive Species

Question 1

Invasive Species Basics

Answer 1

• Species not native to an area, introduced often by human transport
• No natural predators to control pop.
• Highly competitive (aggressive feeders or fast growers) for resources
• Can thrive in their non-native habitats
• R-selected and generalist species are more likely to be invasive
• High biotic potential & low parental care
• Highly adaptable
• Diverse habitat & food needs

Question 2

Invasive Species to Know

Answer 2

Zebra Mussel:
- Transported by ship ballast water
- Aggressive filter feeders, eating algae many other species rely on
- 1 mil. eggs/yr
- Clog intake pipes

Kudzu Vine:
- Planted to limit soil erosion in southern US
- Grows very rapidly
- Outcompetes natives for sunlight; growing over them
- No herbivore control in US

Asian Carp:
- Brought in to control algae growth in aquatic farms
- Escaped to Mississippi river; outcompete native fish for food and space
- Decreases fishery production & value

Emerald Ash Borer:
- Spread by wood packing materials of ships/planes & fire wood
- Larvae laid in bark, eat their way into phloem
- Disrupts tree nutrient transport, killing them
- Expanding range due to global warming

Cane Toad:
- Introduced to eat cane beetles causing sugarcane crop loss in Australia
- Became invasive due to huge appetite
- Drove declines in other amphibians and small reptiles

Pythons:
- Brought to Florida as pets, released into wild by owners
- Decimated mammal populations in Everglades ~90-95%
- Aggressive hunters with no natural predators

Question 3

Controlling Invasives

Answer 3

• Invasives estimated to cost US $120 billion/year (2005 est.)
• Lost ag. productivity, tourism, property value decline, fishery decline, control and removal costs

Question 4

Control/Removal Methods

Answer 4

• Laws preventing transport of invasives (firewood for emerald ash borer)
• Removal of hosts (dead ash trees for EAB) to reduce spread
• Careful boat cleaning & inspection (zebra mussels)
• Introduction of natural predator (biological control)
  ( Chinese wasps to kill emerald ash bore)
• Physical removal (hunting pythons, detaching z. mussels, pulling plants out, cutting trees down)