Transcript Methods for Management of Nonindigenous Aquatic Plants

Methods for Management of
Nonindigenous Aquatic Plants
Author: Jennifer Tsang
Instructors: Dr. Fitzsimmons and Dr. Glenn
Course: Ecol 474
12/9/2003
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.
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.
Images
Eurasian Watermilfoil
Water-Hyacinth
Hydrilla
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
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.
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.
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
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).
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.