I. What are invasive species?
A. Species introduced into habitats where they are not native
B. Weeds, ornamental, game, crops, pests, diseases, Ö
C. Also called exotics, aliens, non-indigenous species
D. Species that have escaped control
II. How did species invade?
A. Natural pathways (wind, currents, transport by animals)
colonization isnít easy
B. Human created pathways
1. Intentional (for profit, recreation, conservation)
2. Accidental (movement of people, soil from plant nurseries, ballast water)
C. Itís not easy for an invader to get
1. Low establishment success rate
2. problems of small
-extinction from chance events
-individuals may not find mate
D. What are characteristics of successful invaders?
E. Examples from NC:
1. Fire ants
- Imported from Japan for erosion control and as an ornamental
- Grows as much as a foot a day
III. What are the consequences of invasion?
A. What makes ecosystems prone to invasion?
1. Early successional
4. Absence of predators, pathogens
5. Simple (= low diversity)?
B. Consequences of invasions
1. 50,000 invasive species in the US
2. Cause environmental damage and loss of ~$137 billion/yr (Pimentel et al. 1999)
3. Damage caused as pests, weeds, and disease
4. Threaten rare species
examples: brown tree snake, cichlids, zebra mussels
IV. How do we turn back invasive species?
1. Examples: witchweed and Brook trout in N.C.
1. Ban traffic in exotic species
2. Exchange ballast water at sea