Milfoil is a threat because it outcompetes native plants, creating dense mats that block sunlight, reduce biodiversity, and deplete water oxygen when they decompose, harming aquatic ecosystems and native species.
It also impairs recreational activities like fishing and swimming, can damage boat motors, and may cause property values to decrease. Its rapid growth and reproduction through fragmentation make it extremely difficult to control once established.
Ecological Impacts
Suppresses native plants: Milfoil’s rapid growth forms thick mats on the water surface, which prevent sunlight from reaching native aquatic plants.
Reduces biodiversity: By blocking sunlight and outcompeting native plants for space and resources, milfoil reduces the variety of plant and animal life in an ecosystem.
Depletes oxygen: When dense mats of milfoil decompose, the process consumes dissolved oxygen in the water, creating low-oxygen (anoxic) conditions that can kill fish and other aquatic organisms.
Harms native animals: The loss of native plants for food and shelter adversely affects the native animals that depend on them, altering the delicate relationships within the food web.
Human and Economic Impacts
Disrupts recreation: Dense milfoil growth makes boating, fishing, swimming, and other water activities challenging and unpleasant.
Causes property damage: The presence of milfoil can negatively impact shorefront property values.
Degrades water quality: The thick mats can increase murky conditions in the water.
Why it’s so Hard to Control
Rapid reproduction: Milfoil spreads aggressively and reproduces easily from tiny fragments.
Adaptability: It can thrive in a wide variety of water conditions.
Difficulty of eradication: Once established, it is virtually impossible to eradicate, and control methods are costly and often not completely successful.