Invasive Plants NOT Found In Crescent Lake

Invasive aquatic species are introduced exotic flora and fauna that displace native plant and animal communities. Infestations result in habitat disruption, loss of property values, diminished water quality, reduced fishing and water recreation opportunities and significant expense for mitigating these environmental costs. Crescent Lake is invasive free as of 2017. These 11 species are the "most wanted".
Variable Water Milfoil
Impacts:  Variable Milfoil is a highly competitive plant that is capable of rapid growth and spread.  It can displace native species, reduce biodiversity, hamper recreational uses, reduce real estate, diminish aesthetic values and decrease water quality.
  • Once established, it can out-compete native vegetation. Species that depend on that native vegetation to survive are forced to relocate or perish, resulting in a loss of biodiversity.
  • It produces dense large mats of vegetation on the water surface,  thus intercepting sunlight leading to the exclusion of other submerged plants.
  • As they die and sink to the lake bottom, sediment levels increase.
  • Variable Milfoil greatly impedes boaters, fisherman, water skiers and swimmers, and these limitations on water use can negatively impact real estate values.
  • When dense mats of Variable Milfoil decay, the available oxygen in the water is depleted. The resulting low oxygen conditions (anoxia) can lead to fish kills and harm other aquatic organisms.

​Identification Video
Eurasian Water Milfoil
Eurasian water-milfoil is an invasive aquatic plant native to Europe, Asia and northern Africa. Introduced to North American in the 19th century, it is now one of the most widely distributed invasive aquatic plants on the continent. It may have been introduced through the aquarium trade or the ballast water of ships. Eurasian water-milfoil prefers shallow water three to 9 feet deep, but can root in up to 32 feet of water. A fast-growing perennial, it forms dense underwater mats that shade other aquatic plants. When large stands begin to die off in the fall, the decaying plants can reduce oxygen levels in the water. The plant can interbreed with native milfoils, creating a more aggressive form of the invasive species. Because tiny plant pieces can develop into new plants, Eurasian water-milfoil is easily spread when water currents, boat propellers, trailers or fishing gear carry plant fragments to new areas.

​Identification Video 
Curly-leaved Pondweed
Impacts: A highly competitive plant that is capable of rapid growth and spread.
  • Can displace native species, reduce biodiversity, impede recreational activities and alter water quality.
  • Can form dense single species stands that may not provide ideal habitat or food for native wildlife, and these native wildlife populations are often forced to relocate or perish, ultimately resulting in a loss of biodiversity.
  • Can impede boaters, fisherman, water skiers and swimmers, and these limitations on water use can negatively impact real estate values.
  • Dies back in July, and when dense mats decay, the available oxygen in the water may be depleted. The resulting low oxygen conditions (anoxic) can lead to fish kills and harm other aquatic organisms. Nutrients released from the decaying plants may also contribute to algal blooms.
Hydrilla
Impacts: Hydrilla can invade deep, dark waters where most native plants cannot grow. The plant’s aggressive growth (hydrilla’s 20 - 30 foot stems can add up to an inch per day) can spread into shallow water areas and form thick mats that block sunlight to native plants below, effectively displacing the native vegetation of a waterbody. Major colonies of hydrilla can alter the physical and chemical characteristics of lakes:
  • It is one of the world's worst aquatic invasive plants
  • It blocks sunlight and displaces native plants below with its thick, dense surface mats
  • Stratification of the water column and decreased dissolved oxygen levels can lead to fish kills
  • The weight and size of sportfish can be reduced when open water and natural vegetation are lost
  • Waterfowl feeding areas and fish spawning sites are eliminating by dense surface mats
  • Thick mats of vegation can obstruct boating, swimming and fishing
  • The value of shorefront property can be significantly reduced, hurting both homeowners and the communities that rely on taxation of shoreline property
  • In severe infestations, intakes at water treatment, power generation, and industrial facilities can be blocked

​Identification Video
Parrot Feather
Impact: Dense infestations can rapidly overtake small ponds and sloughs, impeding water flow resulting in increased flood duration and intensity. Parrot feather may also out-compete more desirable native macrophytes. Little information exists on the direct impact that parrotfeather has on fish and wildlife. Dense beds of parrot feather have resulted in reductions in dissolved oxygen in the water column, which may be detrimental to fish. Parrot feather growth can inhibit the growth of more desirable plant species such as pondweeds and coontail, which are readily utilized by waterfowl as food items.  A strong correlation was determined between the density of parrot feather growth and the presence of mosquito eggs and larvae, which may lead to increases in mosquito born diseases that could infect wildlife and humans.

​Identification Video
Brazilian Elodea
Native to South America and introduced through aquarium trade their rapid growth leads to dense, monospecific mats on the surface of the water. These mats crowd out native aquatic plant species, provide poor habitat for fish, and impede boat movement and other recreational activities.


​Identification Video
Water Chestnut
Water chestnut has become a significant environmental nuisance throughout much of its range. The plant can form nearly impenetrable floating mats of vegetation. These mats create a hazard for boaters and other water recreators. The density of the mats can severely limit light penetration into the water and reduce or eliminate the growth of native aquatic plants beneath the canopy. The reduced plant growth combined with the decomposition of the water chestnut plants which die back each year can result in reduced levels of dissolved oxygen in the water, impact other aquatic organisms, and potentially lead to fish kills. The rapid and abundant growth of water chestnut can also out-compete both submerged and emergent native aquatic vegetation. Water chestnut has little nutritional or habitat value to fish or waterfowl and can have a significant impact on the use of an infested area by native species.
Yellow Floating heart
Impact: Dense mats of this plant restrict light availability to photosynthetic species underneath, which can exclude native plants Decay of the aging vegetation decreases the oxygen levels in water bodies, causing stagnant areas. This species also limits recreational activities such as swimming, boating, and fishing.  
European Frogbit
 This plant increases in size rapidly by vegetative reproduction and forms dense mats. These mats can limit light penetration into the water, limiting growth of vegetation beneath the mats. In addition, the dense mat of vegetation can also limit the amount of nutrients and dissolved gases reaching native plants beneath the frog-bit mats. In extreme cases in shallow water, the frog-bit may fill the water column, crowding out native vegetation. This change in community diversity may also affect native aquatic fauna. In autumn, as the mats decompose and settle to the bottom of the waterbody, dissolved oxygen levels can be dramatically decreased, resulting in the death of fish and native vegetation. Dense mats of European frog-bit can also inhibit movement of waterfowl, large fish and boats, and limit recreational activities such as swimming.
Fanwort
Impacts and Threats Posed by Fanwort: Fanwort is a highly competitive plant that is capable of rapid growth and spread. Fanwort can displace native species, reduce biodiversity, hamper recreational uses, reduce real estate value, diminish aesthetic values, and decrease water quality.  • Once established, Fanwort can negatively impact and out-compete native vegetation. Fish and animals that were dependent on the native vegetation must relocate or perish, leading to a decline in biodiversity. • Fanwort can greatly impede boaters, fisherman, water skiers and swimmers, and these limitations on water use can negatively impact real estate values. • C. caroliniana produces dense large mats of vegetation on the water surface, thus intercepting sunlight to the exclusion of other submerged plants.  • Sediment levels increase with increasing Fanwort abundance.  • When dense mats of Fanwort decay, the available oxygen in the water may be depleted. The resulting low oxygen conditions (anoxic) can lead to fish kills and harm other aquatic organisms. 

​Identification Video

European naiad
Impacts and Threats Posed by European Naiad: European Naiad grows and reproduces rapidly, and often displaces native species, reduces biodiversity, hampers recreational uses, and reduces real estate and aesthetic values
  • Once established, European Naiad can out-compete native vegetation, especially native naiads, and drive out the animals that depend on the native vegetation for survival. 
  • Can produce dense large mats of vegetation on the water surface, thus intercepting sunlight to the exclusion of other submerged plants.
  • Sediment levels often increase with increasing European Naiad abundance.
  • Dense stands of European Naiad may greatly hamper fishing, boating, swimming and other activities and the loss of recreational and aesthetic value can cause a decline in surrounding lake property value.
  • When dense mats of European Naiad decay, the available oxygen in the water maybe significantly depleted. The resulting low oxygen conditions (anoxia) can lead to fish kills.