Methods for Management of Nonindigenous Aquatic Plants

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Methods for Management of Nonindigenous Aquatic
Plants

• Author Jennifer Tsang
• Instructors Dr. Fitzsimmons and Dr. Glenn
• Course Ecol 474
• 12/9/2003

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What are nonindigenous aquatic species?

• Members (i.e. individual, group, or population)
  of a species that enters a body of water or
  aquatic ecosystem outside of its historic or
  native range.
• The importance of studying nonindigenous
  organisms is to learn what effects they may have
  on the native organisms and the physical
  environment.

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Nonindigenous Plants

• Nonindigenous plants can colonize aquatic
  communities where they compete with and often
  displace native species.
• Hydrilla, water-hyacinth, and Eurasian
  watermilfoil are examples well known for their
  ability to alter physical and biological
  functions of aquatic systems.

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Images
Eurasian Watermilfoil
Water-Hyacinth
Hydrilla
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Effects of Nonindigenous plants

• Nonindigenous species create dense canopies
  resulting in
• decreased oxygen exchange
• increased nutrient loadings
• and increased water temperatures.
• Reduces diversity and abundance of indigenous
  plants
• Also may cause physiological stress to fish

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Biological Control

• Biological control has typically targeted either
  insects or pathogens as control agents.
• The best approach to manage nonindigenous plants
  is to find their indigenous pests and introduce
  these naturally associated control agents from
  their native land.

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Chemical Control

• Herbicides (contact or systemic)
• Contact Herbicides immediately on the tissues
  contacted, typically causing extensive cellular
  damage at the point of uptake
• Systemic Herbicides translocated throughout the
  plant. They are slower acting but often result in
  mortality of the entire plant.
• Cause for increased concern for human health, the
  environment, and wildlife resources.

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Mechanical Control

• In mechanical techniques the machines act
  directly upon the plants
• Use of hand cutters, rakes or bare hands to
  remove vegetation
• This is the most common method used worldwide

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Physical Control

• In physical techniques the environment of the
  plants is manipulated
• Physical techniques include
• Dredging
• benthic barriers (plants are covered with a layer
  of growth-inhibiting material)
• shading or light attenuation (planting trees)
• nutrient inactivation (limits the growth of
  algae).

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Conclusion

• Many management techniques are available for
  control of indigenous aquatic plants.
• No one technique is superior to others or
  applicable to all situations
• Each is a valued tool with economic,
  environmental and technical strengths and
  weaknesses.