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.

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 SpeciesSometimes called Non-nativeAlienNon- indigenous

Invasive SpeciesWhen a new species enters an ecosystem that

is not its original homeThe species is considered “invasive” when it

causes harmEconomic or environmental harmHarm to human health

Invasive SpeciesInvasive species can be plants, animals, and

other organisms (e.g., microbes).Introduced to new environments by

globalization

Steps to Becoming InvasiveSpecies must be …1.Introduced 2.Established3.Invasive

How are Species Introduced?They are transported from their home to a

new place

This can be done on purpose- intentionallyOrThis can be done on accident -

unintentionally

Intentional IntroductionStocking 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 IntroductionCanals- 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 pressure2. Natural History of the introduced species3. Susceptibility of environment to new

species

Propagule PressureThe number of organisms released into a new

habitatThe more individuals released over time, the

more likely that a species will become established

Propagule PressureIf too few individuals are released at the

same timethey many not be able to reproduce enough

offspring to become established they will die out

Natural History Origin DietGrowth rateHabitat conditionsReproductive

behaviors

Above: Example of Species’ Natural History Summary

Ecological ImpactsWhat are the consequences of bringing this species

to Lake Michigan?How does the invasive species impact the native

species?

Does it …Compete for resourcesHunt and eat native speciesBring infectious pathogensDecrease water availability

When does it become INVASIVE?When it causes harmKills or hurts native speciesCosts communities money to manageReduces recreation Loss to fishermenLoss of food resources to farmersIntroduces 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)