Transcript Freshwater Invasive Species

Notes adapted from the Encyclopedia of Inland Waters
“Invasive Species” by R P Keller and D M Lodge, University of Notre Dame, Notre Dame, IN, USA
Invasive Species
Sometimes called
 Non-native
 Alien
 Non- indigenous
Invasive Species
 When a new species enters an ecosystem that is not its
original home
 The species is considered “invasive” when it causes
harm
 Economic or environmental harm
 Harm to human health
Invasive Species
 Invasive species can be plants, animals, and other
organisms (e.g., microbes).
 Introduced to new environments by globalization
Steps to Becoming Invasive
Species must be …
1. Introduced
2. Established
3. Invasive
How are Species Introduced?
 They are transported from their home to a new place
 This can be done on purpose- intentionally
Or
 This can be done on accident - unintentionally
Intentional Introduction
 Stocking waters to establish new food
resources or opportunities for sport
fishing
 Aquaculture – farming of water
organisms for food
 Aquarium trade – sale of aquatic
animals (pet store)
 Water garden trade – sale of aquatic
animals and plants for ponds and
water gardens
Unintentional Introduction
 Canals- species can move
through these waters way which
were made by man
 Fouling Organisms - organisms
hitch a ride on a trade ship in the
ballast tank or on the ships hull
 Contaminants – small
organisms can be transported on
larger organisms through
aquarium trade or water garden
trade
How Do Species Become Established?
Depends on the interactions among these factors:
1. Propagule pressure
2. Natural History of the introduced species
3. Susceptibility of environment to new species
Propagule Pressure
 The number of organisms released into a new habitat
 The more individuals released over time, the more
likely that a species will become established
Propagule Pressure
 If too few individuals are released at the same time
 they many not be able to reproduce enough offspring
to become established
 they will die out
Natural History
 Origin
 Diet
 Growth rate
 Habitat conditions
 Reproductive
behaviors
Above: Example of Species’ Natural History Summary
Ecological Impacts
What are the consequences of bringing this species to Lake
Michigan?
How does the invasive species impact the native species?
Does it …
 Compete for resources
 Hunt and eat native species
 Bring infectious pathogens
 Decrease water availability
When does it become INVASIVE?
 When it causes harm
 Kills or hurts native species
 Costs communities money to manage
 Reduces recreation
 Loss to fishermen
 Loss of food resources to farmers
 Introduces parasites and disease to humans
Asian Tiger Mosquito
• Native to South-East Asia;
• Currently in 28 countries
• Aquatic Larval Stage – spread in water
• Large, aggressive, spreads many diseases
• Spread and transmission of West Nile Virus
• Spread by recycling old tires (globalization)