Invasive Species

Lecture Objectives:

1. Be introduced to biological invasions

2. Know several examples of invasive species

3. Learn what you can do to stop the spread of invasive species

Introduced (non-native, exotic) - species introduced deliberately or accidentally from somewhere else

Definitions:

Domestic/Feral (released pets, livestock and game animals) - can spread disease, compete with native species

Human commensal or subsidized (out of control natives) - native species that benefit from our land use (disturbance)

Invasive species - species that spread subsequent to establishment usually at some cost.

Invasive Species

Some introduced deliberately:

•naturalization societies

•Shakespeare fans

•game animals

•domestic animals

Some accidental:

•ballasts of ships

•unprocessed wood

•fruit shipments

•by-pass natural barriers

Intentional Release of Target Species into Containment:

Escapes from Zoos and Botanical GardensFarmed Species

- Aquaculture- Research

Vectors of invasion into ecosystems

Intentional Release of Target Species into the Environment:

- Plants for Agriculture- Plants for Forestry- Plants for Soil Improvements

- fire suppression, erosion control- Ornamental Plants- Birds and Mammals for Hunting- Biological Control- Released Pets and Pet Trade

Vectors of invasion into ecosystems

Release of Non-Target Species (AKA “Accidental” Releases):

Contaminants or Hitchhikers with ProduceContaminants or Hitchhikers with Ornamental PlantsContaminants or Hitchhikers with AquacultureTimberContaminants of Seed StockCarsPlanesHitchhikers with Packing Material, CargoBallast in shipsHull FoulingTourists, LuggageCanals

Vectors of invasion into ecosystems

Ballast Tanks

Movement of/ increased exposure to exotic species includes pathogens!!

• Emerging Infectious Disease – never known before or absent for 20 years • Schistosomiasis, AIDS, SARS, etc.

“Forecast and control of epidemics in a globalized world.” Hufnagel et al. PNAS 2004

• In 1999, there were more than 50,000 exotic species in the USA

Why study biological invasions?

Unique opportunities for basic researchcommunity ecology

animal behaviorevolution

Consequencesthreaten biodiversity

costlywidespread

Estimated annual costs associated with non-native species:

Group costs (in millions)Plants (purple loosestrife, weeds) 34,000Mammals (feral pigs, rats) 37,000Birds (pigeons, starlings) 2,000Fishes 1,000Arthropods (ants, termites, other pests) 19,000Mollusks (zebra mussel, asian clam) 1,200Microbes (plant pathogens, animal disease) 41,000

All organisms over $136 billion per year

Source: Pimentel et al. 2000 BioScience

Percentage of threatened or endangered species imperiled by:

Habitat degradation and loss - 85%

Invasive species - 49%

Pollution - 24%

Overexploitation - 17%

Disease - 3%

Source: Wilcove et al.1998 BioScience

Hypotheses for the success of introduced species:

Pre-adapted to disturbed environments

Increased competitive ability outcompete native species

Escape from natural enemies predators, parasites, disease

Characteristics of invasive species

general diet and habitat requirementshigh abundancesmall body size

high reproductive potential (r-strategy)good competitorssocial / gregarious

Generalities would be nice!Make invasion biology a more predictive science.

Stages of invasion

(different characteristics may be important at different stages)

3. Spread

2. Establishment

1. Opportunity (transport)

What makes certain ecosystems more vulnerable?

Islands: little history with competitors, predators, parasites, or diseases

Human residential areas: many European species that are commensal with humans

Disturbed habitats: full of invaders

Diverse, undisturbed communities have few invaders

European starling

Monk Parakeet

Birds

Mute swan

•First successful introduction was 60 European starlings released in Central Park, NY. in 1890, by fans of Shakespeare

European Starling

•slippery sidewalks

–competes with bluebirds, woodpeckers

•The House Sparrow was introduced into Brooklyn, New York,

in 1851.

House Sparrow

•Competition from the House Sparrow for cavity nests can cause decline of some native species.

InsectsAfricanized Bees

• In 1956, African Honey Bees were imported into Brazil

•In 1957, 26 African queens escaped

•Reached US in 1990

•More aggressive than European Honey Bees, have killed 1,000 people

•Impact honey and pollination industries

Insects

• Crop pests– boll weevil, corn

borer

• Culex mosquitos– carry avian malaria

and pox– driven 20 Hawaiian

bird species extinct

Adult boll weevil

Insects

• Asian Long-horned Beetle– attacks and kills

many native trees

Found in Chicago in 1998

• Gypsy moth

•Introduced in 1860s

•Originally brought to the US for silk production

•now defoliates entire forests

Insects

Reptiles and Amphibians

Cane toad – native to Central and South America

•milky secretions are highly toxic. Kill dogs, cats and small native animals

•Introduced world-wide to control insects

Brown Tree Snake

Reptiles and Amphibians

•Introduced to Guam via cargo transported by U.S. military ships during World War II

•On Guam wiped out 9 of 13 indigenous bird species

Mammals• Goats and pigs

– in Hawaii wiped out native plants

• Horses in Grand Canyon– causing erosion

• Game animals– “Texotics”

“Texotics” Oryx Photo: Dr Mike Hill

PlantsKudzu

•kills other plants by smothering them under a solid blanket of leaves

•Introduced into the U.S. in 1876 at the Philadelphia Centennial Exposition

•promoted as a forage crop and an ornamental plant until 1953

PlantsGarlic mustard

Buckthorn•garlic mustard outcompetes native plants by monopolizing light, moisture, nutrients, soil and space.

•Not as good food for herbivores as many native species

•poses a severe threat to native plants and animals

Northern Snakehead(Channa argus)Found in Maryland in 2002

Giant snakehead (Channa micropeltes) found in Wisconsin in 2003

Fish

Laurentian Great Lakeswww1.ncdc.noaa.gov/pub/data/images/ great-lakes-ice-avhrr.gi

Superior

Mic

higa

n

Huron

Erie

Ontario

Mills et al. 1993

Over 140 exotic species

Many fish species were (and continue to be) released intentionally

Many other exotics have entered the lake accidentally:

Escape from captivity

Canals

Bait buckets, live wells and gear

Ballast water

19 locks, filled and emptied by gravity

Welland Canal

Begun in 1829

Niagara Falls was the major obstacle to an uninterrupted waterway

Sea Lamprey (Petromyzon marinus)

Invaded the Great Lakes after the opening of the Welland Canal

Devastated native fish stocks, especially lake trout

Other fish (>25 species)

Alewife (1873)(Alosa pseudoharengus)Canals

Coho salmon (1933)(Oncorhynchus kisutch)Deliberate release

Round goby (1990)(Neogobius melanostomus)Ballast water

Chinook salmon (1873)(Oncorhynchuys tshawytscha)Deliberate release

Exotic Crustaceans (>6 species)

Bythotrephes cederstromi (1984)Ballast water

Cercopagis pengoi (1998)Ballast water

Exotic mollusks (> 14 species)

Asiatic clam (1980)(Corbicula fluminea)Aquarium release

Quagga mussel (1990s)(Dreissena bugensis)Ballast water

ZEBRA MUSSEL — Dreissena polymorpha

Found in 1988 in Lake St. Clair (Lake between Huron and Erie, just off of Detroit, MI).

Likely came to North America in ballast water

Up to 70,000 individuals per m2

Also attaches to boat hulls, docks, locks, breakwaters and navigation aids, increasing maintenance costs and impeding waterborne transport.

One of the most expensive exotic species

Will biofoul and restrict the flow of water through intake pipes (drinking, cooling, processing and irrigating water)

They have a free-living planktonic larval stage— veliger

Characteristics of zebra mussels:Can attach to hard surfaces

Females can produce 40,000 veligers

These are typical characteristic of marine species

Veligers are easily transported in bait buckets and livewells and anywhere else water collects

Adults can attach to hulls and survive outside of water for several days.

Cover most hard surfaces

Negative effects on native clams

Zebra mussels cover them and prevent them from feeding and moving

Plants (> 59 species)

Eurasian Watermilfoil (1881)Myriophyllum spicatum

Purple Loosestrife (early 1800s)Lythrum salicaria

How to prevent the spread of aquatic nuisance species?

Empty all water before leaving site

Never dump bait buckets!!

Before leaving site, inspect gear, boats and trailers for exotics

Let equipment dry for several days (does not work for species with resting eggs)

Rinse your boat and equipment with high pressure hot water, especially if moored for more than a day