1. Methods for Management of Nonindigenous Aquatic Plants Author: Jennifer Tsang Instructors: Dr. Fitzsimmons and Dr. Glenn Course: Ecol 474 12/9/2003

2. 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.

3. 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.

4. Images Eurasian Watermilfoil Water-Hyacinth Hydrilla

5. 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

6. 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.

7. 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.

8. 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

9. 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).

10. 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.