Seth Knochel

Invasive Species

What is an invasive species? What makes them invasive?Why do we care?What is the government doing?Invasives in TexasInvasives in the U.S.Invasives in other parts of the world

Invasive Species

An "invasive species" is defined as a species that is non-native (or alien) to the ecosystem under consideration and whose introduction causes or is likely to cause economic or environmental harm or harm to human health. (Executive Order 13112).

Most commonly associated with harm to ecosystem and/or native species

Non-native vs. Invasive

What is an Invasive Species?

Some intentionally introducedEuropean Starling introduced as part of a plan

to have all the species in the works of Shakespeare in the U.S.

Accidental introductionFire ants on a ship from South America

Bred/introduced with good intentionsAfricanized “killer” bees were meant to

produce more honey

How They Spread

Common Traits of Invasive SpeciesAble to reproduce quicklyFast maturation rateAble to disperse quicklyTolerant to wide range on environmentsTend to be generalistsAble to tolerate some human interaction

These traits allow invasive species to outcompete native wildlife

What Makes a species Invasive

One species can have a major impact on an ecosystem

Niches that are already occupied

Preserving native wildlife

Why we care

National Invasive Species Council (NISC) was established by Executive Order 13112February 8th, 1999Manages invasive species at a national, state,

and even ecosystem levelComposed of members 13 federal departments

and agenciesIncludes the EPA, USDA, USFWS, etc.

Drafts the budget for invasive speciesProvide advice for other nations

Governmental Response

Many different methods employedSome invasive species are only “controlled” while

the government attempts to eliminate others

PlantsHerbacidesManual removal

AnimalsTrappingBirth controlPoisoningShooting

Government Management

NutriaSemi-aquatic rodentSexually mature at 4 monthsBreed year round

IntroductionIntroduced for the fur trade (CA, WA, OH, MI, OR,

LA, NM)Spread to other states to control undesirable

vegetationThreat

Destroys millions of dollars of crops each yearDestroys native aquatic vegetation

Texas Invasives

HydrillaAquatic PlantVery hardyCan grow 1 inch a day

IntroductionIntroduced for aquarium tradeReproduces from stem fragments dispersed by

waterfowlThreat

Raises water pH and temperatureLimits number of large fish

Texas Invasives

Fire Ants (Red imported fire ant)Live in large coloniesAble to tolerate wide range on environmentsReproduce very quickly

IntroductionOn a cargo ship from South America that docked

in AlabamaThreat

1.2 billion dollars in Texas annuallyDamage native plants and animalsNegatively impact

red ants/Texas Horned Lizard

Texas invasives

Silver CarpAsian carp speciesWeigh up to 100 lbs.Move up river 50 miles per yearReproduce extremely rapidly

Introduction Introduced to Illinois and Mississippi Rivers to help control

algae and as a food sourceThreat

Damage to boatsOutcompete other native species of filter feeders (other

carp and mussels)Feared to eventually become the dominant species in the

Great Lakes

American Invasives

Zebra MusselSmall mussel at about 3.5-4 cmHigh Rate of filtrationAble to tolerate wide range of temperatures

IntroductionThought to have spread from Eurasia to United

States by ballast water released from sea-going ships

ThreatHigh rate of filtration lowers amount of green algaeFeed on zooplanktonIncrease depth of light penetration

American Invasives

Ring-necked PheasantWell-known game bird in AmericaAble to tolerate fragmented habitatThrives near humans

IntroductionIntroduced from Georgia to Oregon as a game

bird in 1881Threat

Threat to the Lesser Prairie ChickenLekkingCompetition for Resources and Habitat

American Invasives

Brown Tree SnakeNative to Australia, Indonesia, and Papua New Guinea3 – 6 feet in lengthReproduce year round

IntroductionAccidentally introduced in Guam from a cargo ship

from the South PacificThreat

No natural predators on the islandLead to extinction of the majority of vertebrate

species on the island, especially birdsCauses power outages

Invasives of the World

Red Fox5 – 31 lbsWill consume a wide variety of preyListed as one of worlds 100 worst

invasive speciesNative to Europe, Asia,

and North AmericaIntroduction

Intentionally introduced to Australia between 1855 and 1871 to control European rabbits

ThreatThreat to biodiversityMajor predator of various species of Wallabies, as well as

other fauna

Invasives of the World

Giant HogweedNative to AsiaCan grow to over 18 feet tallSpreads very quickly

IntroductionBrought to Ireland as an ornamental plant for

gardens and parksThreat

Health hazardAble to outcompete native plants by growing rapidly

and blocking sunlightDecreases invertebrate biodiversity by limiting plants

that serve as food sources

Invasives of the World

Do you think the Government should control invasive species?

Do you think humans should be considered an invasive species?

Have you ever directly seen the impact of an invasive species?

Food for Thought