Great Lakes marshes are unique areas where the land and water meet. Marshes are home to diverse plant and animal life and provide valuable services to people. Pollution, development and aquatic invasive plants, such as Phragmites australis (common reed) are threats to marshes. Natural resource managers are working on marsh restoration projects to protect the biodiversity of plants throughout the Great Lakes and provide educational resources about the importance of marshes.
- National Science Education Standards – 5th-8th grade
- Michigan Grade Level Content Expectations – 5th-7th grade
- HS-LS2-2 Ecosystems: Interactions, Energy & Dynamics. Use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems of different scales.
- HS-LS2-6 Ecosystems: Interactions, Energy & Dynamics. Evaluate the claims, evidence and reasoning that the complex interactions in ecosystems maintain relatively consistent numbers and types of organisms in stable conditions, but changing conditions may result in a new ecosystem.
- HS-LS2-7 Ecosystems: Interactions, Energy & Dynamics. Design, evaluate and refine a solution for reducing the impacts of human activities on the environment and biodiversity.
- HS-ESS3-4 Earth & Human Activity. Evaluate or refine a technological solution that reduces impacts of human activities on natural systems.
For alignment, see: NGSS Summary
- Describe Great Lakes marsh habitats and the threat posed by invasive species like Phragmites (pronounced: frag-might-ease).
- Describe the importance of coastal marsh ecosystems to both humans and wildlife.
- Talk about what natural resource managers are doing to restore marshes in Lake St. Clair and why their efforts are important.
- Write testable hypotheses based on preliminary research data, describe how to test these hypotheses, and predict possible graphs of data based on hypotheses.
Meet the Marsh
Marshes are unique areas where water saturates the soil and covers the land for most or all of the year. The marsh, which is a type of wetland, is full of nutrients and is home to many plants and animals that need the marsh habitat to survive. Marshes usually have some open water, shrubs and grass-like plants.
Wetlands, including marshes, are found all over the world. In the Great Lakes, they are mostly found at the edges of rivers and lakes. Lake St. Clair in southeast Michigan is home to marshes typical of coastal wetlands found throughout the Great Lakes basin.
The Marsh and Wildlife
Coastal marshes provide important wildlife habitat. Great Lakes marshes are considered one of the most productive ecosystems on earth. With the constantly shifting water levels and conditions, a wide variety of plants and animals can take advantage of the diverse habitat, such as the marsh wren (pictured).
The Lake St. Clair marshes support several rare species of animals and plants that rely on wetlands for survival, such as the bittern, fox snake, marsh wren, terns and the marsh bellflower.
Marsh By Number:
- Michigan boasts about 2,300 native plant species.
- About 50% of these are wetland species, and more than 25% of these wetland species are threatened or endangered.
- More than 40% of vertebrate species (animals with spines) in Michigan live in or use wetlands at some stage in their lives, including birds, fish, frogs, reptiles and mammals. For example, waterfowl, shorebirds and songbirds use marshes to rest, nest and feed while migrating.
- At least 32 different species of lake fish rely on the coastal marshes and move into these areas to spawn and feed.
Marshes have disappeared at an alarming rate in the Great Lakes region. Nearly 85 percent of the Lake St. Clair marshes have vanished since the mid-1800s. Pollution, runoff and sedimentation (build-up of a solid material like soil in a place where it wasn’t before) have taken their toll. Many have been filled in for development or broken into smaller pieces, reducing their ability to function as a system. Invasive species, like Phragmites, are pushing out native species and changing marsh ecosystems.
How Can a Plant Attack?
Invasive species disrupt environments by reducing habitat or food available for native species or by preying directly upon native species. Invasive Phragmites has moved in and taken over many wetland areas. It is one of the tallest and toughest grasses in the Great Lakes region. It can grow up to 20 feet high and develop up to 30 feet of roots in one year! Phragmites are also thought to produce chemicals that inhibit other plants from growing near it.
Interestingly, Phragmites has had negative effects on marshes in the Great Lakes, but in some parts of the world, it is considered valuable.
Phragmites at a Glance
- Each stalk produces up to 2,000 seeds, dispersed by wind and carried by water to new areas.
- Average height is 8-10 feet tall. The plants grow very quickly.
- New stems are strong and hollow, grow quickly, and send oxygen down to the plant roots, like a snorkel.
- Despite its height, most of the plant (nearly 80%) is found below the ground. Roots spread horizontally and vertically and can extend 6-8 feet deep. This makes them virtually impossible to pull out.
- Thick stands of common reed can contain more than 20 stems per square foot. Can you imagine trying to make your way through that?
- Stands expand through aboveground runners called stolons. Thin runners grow on the ground and produce new shoots and roots. Runners can grow four inches a day and extend longer than 40 feet!
- Rhizomes are thick, woody underground bulb-like roots. Water, oxygen and nutrients can travel through the rhizomes from stem to stem. New shoots and roots grow off of rhizomes every few inches. So, if you try to dig up the rhizome and pieces break off, each piece has the potential to regenerate into a new plant.
- All of these factors mean: Phragmites is extremely difficult to get rid of once it has been established.
Ours to Protect
Why should we protect and preserve marshes? Our coastal marshes are unique to the Great Lakes and are considered rare and in danger. When the wetlands are lost, it’s not just the diverse plant and animal life that we lose. Marshes also provide valuable services, such as:
- They help reduce floods by absorbing and storing water like a sponge. As the climate continues to change, this could prove to be even more valuable.
- They improve our water quality by filtering and cleaning runoff.
- Marsh plants and microorganisms use extra nutrients like phosphorus and nitrogen to grow, removing them from the water. These excess nutrients can cause problems like algal blooms if they remain in the water.
- Plants found in marshes help anchor the soil in place, which stops land from eroding and absorbs waves.
- Coastal marshes have long provided food and recreation for people.
- Marshes provide critical wildlife habitat.
Restoring the Marsh: Controlled Burn
Natural resource managers faced a challenging problem: save the marsh at Lake St. Clair. Since Phragmites is aggressive and very difficult to get rid of once established, the measures to control the invader had to be strong. Resource managers worked with state agencies to develop a plan of attack to remove the invader along the coastal areas. Herbicide, a chemical used to kill plants, was applied by helicopters and “on the ground” with sprayers. Controlled burns, in combination with the herbicide treatments, were used to remove dead plants. Burning the stalks down allowed sunlight to penetrate the ground and native seeds to germinate.
Did it work? See: Great Lakes Echo Article
Standards and Assessments
- Writing Hypotheses: Battle for the Marsh
Summary: Students learn about the coastal marsh ecosystem and characteristics of an invasive plant, Phragmites australis (common reed). They will also review Phragmites vegetation sampling data and observations of bird use to develop a testable hypothesis about their relationship. Students will also predict and sketch a graph of what data that supports their hypotheses might look like.
Time: One or two 50-minute class periods