APES 9.8 Invasive Species

Invasive Species: Overview

• An invasive species is a non-native species introduced to an ecosystem, often due to human activities.

• Example: Zebra mussel, transported via boats between lakes and rivers.

• Invasive species thrive due to lack of natural predators in new ecosystems.

• These species often dominate because:

  • No predators to control their population.

  • Highly competitive for resources (food, space).

  • Adaptable to new environments (temperature, food sources).

Key Examples of Invasive Species

Zebra Mussel

• Native to the Black and Caspian Seas.

• Introduced to the U.S. via ballast water of ships in the St. Lawrence Seaway.

• Highly aggressive filter feeders:

  • Competes with native organisms for food (zooplankton, algae).

  • Can lay up to a million eggs per year; rapid reproduction leads to population explosions.

• Clogs water intake pipes, leading to high economic damages.

Burmese Python

• Introduced to Florida from the exotic animal trade.

• Adaptability allows them to survive by eating various mammals, including pets and deer.

• Lacks natural predators in Florida, leading to population spikes.

Kudzu Vine

• Introduced in the 1930s to combat soil erosion during the Dust Bowl.

• Known for rapid growth (potentially up to a foot per day).

• Outcompetes native plants for sunlight and water, suffocating them due to dense growth.

Asian Carp

• Initially introduced to control algae in aquatic farms; escaped into the Mississippi River.

• Aggressive feeding habits lead to:

  • Displacement of native fish due to competition for food and habitat.

  • Negative impact on recreational and commercial fisheries.

  • Physical injuries and damage due to jumping out of water near boats.

Emerald Ash Borer

• Discovered in Michigan in 2002; likely introduced via wood packaging materials.

• Larvae feed on the phloem of ash trees, leading to tree death.

• Climate change expands the range of the emerald ash borer, potentially increasing its impact.

Economic and Environmental Impacts

• Economic Costs: Estimated at $120 billion annually in the U.S.

  • Losses in agriculture, tourism, fishery productivity.

  • Decrease in property values due to infestations.

• Invasive species disrupt native ecosystems:

  • Impact biodiversity by outcompeting native species.

Control Methods for Invasive Species

Legislation

• Laws to prevent transport of invasive species.

• Example: Minnesota prohibits firewood transport to control the spread of emerald ash borer.

Host Removal

• Thinning ash tree populations to control increasingly spreadable emerald ash borer.

• Reduces available hosts, limiting spread.

Inspection and Cleaning

• Careful inspection of boats to remove aquatic hitchhikers (e.g., zebra mussels).

• Preventive measures before entering new waters.

Biological Control

• Introduction of natural predators to reduce invasive populations.

• Example: Chinese wasps introduced to prey on emerald ash borer larvae.

Physical Removal

• Manual removal of invasive plants (e.g., garlic mustard pulls).

• Hunting campaigns for species like Burmese pythons.

• Cleaning and scraping off zebra mussels from boats and infrastructure.