Methods for Management of Nonindigenous Aquatic Plants Author: Jennifer Tsang Instructors: Dr. Fitzsimmons and Dr. Glenn Course: Ecol /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. 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. 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. 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. Hydrilla, water-hyacinth, and Eurasian watermilfoil are examples well known for their ability to alter physical and biological functions of aquatic systems.

Images Eurasian WatermilfoilWater-HyacinthHydrilla

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

Biological Control Biological control has typically targeted either insects or pathogens as control agents. 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. 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) Herbicides (contact or systemic) Contact Herbicides: immediately on the tissues contacted, typically causing extensive cellular damage at the point of uptake 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. 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. Cause for increased concern for human health, the environment, and wildlife resources.

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

Physical Control In physical techniques the environment of the plants is manipulated In physical techniques the environment of the plants is manipulated Physical techniques include: 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. Many management techniques are available for control of indigenous aquatic plants. No one technique is superior to others or applicable to all situations 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. Each is a valued tool with economic, environmental and technical strengths and weaknesses.