Non-native species

“The two great destroyers of biodiversity are, first habitat destruction and, second, invasion by exotic species.” –E.O. Wilson

The spread of invasive species is recognized as a major factor contributing to ecosystem change and instability leading to biodiversity reduction. Preventing non-native invasives from becoming established has a much better rate of success than eliminating the species once it is established. At the Apostle Islands, both aquatic and terrestrial species continually threaten the park. From microscopic organisms to large trees, the potential is always there for non-native species to invade and overtake the fragile ecosystems that make the lakeshore a popular destination for hikers, boaters, and sightseers alike.

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Park Ranger Japanese Knotweed
Park Ranger is attacked by Japanese Knotweed

Damon Panek


Non-native invasive species
Invasive species are non-native species which cause harm to the economy, environment, or human health. Their common characteristics are:
• Cause more harm than good to the invaded ecosystem
• High growth/reproduction rate
• Free from established predators, competitors parasites or diseases in the invaded ecosystem
• Easily dispersed/moved from place to place

Many of these species can be transported via boats such as on hulls and in bilges, on our clothing or gear that has come in contact with them, and even our firewood. For example, the zebra mussel can be transported from water body to water body through just a few drops of water. Spotted knapweed, a plant which has the potential to invade every beach on the Apostle Islands, can be transported and established through seeds carried in the soles of a shoe. The gypsy moth can be easily transported on firewood.


What can be done?
“This is one environmental problem that we can do something about. I have seen the tremendous difference that even a few individuals can make in the battle to regain the land for native species.” -E. Czarapata

The best way to solve a problem is to prevent it from happening. Actions all visitors can take are preventative measures to keep non-native invasive species out of The Apostle Islands National Lakeshore. Whether kayaking, sailing, hiking, camping, fishing, or enjoying a picnic, attention can be given to keeping invasives out.
• Burn only dead and down firewood from the islands
• Clean, drain, and dry watercraft of all sizes
• Dispose of all fishing bait properly
• Clean all camping, boating, hiking, and other equipment after use
• Get involved in conservation efforts
• Educate yourself and others about invasive species

Kayaker cleaning his boat of invasives
Kayaker cleaning his boat of invasives

Neil Howk


Spreading non-native invasive species
“Give a weed and inch and it will take a yard” –Anonymous

The rapid natural spread of a non-native invasive species is usually due its general lack of predators, competitors, parasites, and disease in the invaded ecosystem. Essentially, there are inadequate factors to bar the movement and establishment of an invasive species in an ecosystem which it is not native to. The interdependent balance which preserves an ecosystem’s biodiversity is disrupted by the addition of an invasive non-native plant, animal, insect, or pathogen.

Human actions are the most pivotal factors in the spreading of non-native invasive species. Check this list of the most common ways humans have spread invasives to see how many you pay attention to during your park visits.
• Gypsy Moth or Emerald Ash borer in firewood
• Zebra mussels or Eurasian Water Milfoil on boat hulls/bilges/boat trailers
• Spotted Knapweed seeds on clothing or footwear
• Camping equipment carrying soil infected with the sudden oak death pathogen
• Pet’s fur carrying Purple Loosestrife seeds
• Bait buckets being dumped with minnows infected with VHS pathogen
• Transplanting non-native plants from other areas
• Tire treads containing buckthorn berries
• Non-native landscaping close to native ecosystems
• Ship ballasts bringing the next aquatic invasive from oversees

Strive to be invasive free…
Your actions make a difference


Apostle Islands National Lakeshore non-native species reports

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Bayfield, WI 54814


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