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Ryan O'Connor
Natural Heritage Inventory Ecologist

Submergent Marsh

State Rank: S4     Global Rank: G5   what are these ranks?


Detailed Community Description from Ecological Landscapes of Wisconsin

General natural community overview

Counties shaded blue have documented occurrences for Submergent Marsh in the Wisconsin Natural Heritage Inventory database.

This herbaceous community of aquatic macrophytes occurs in lakes, ponds, and rivers. Submergent macrophytes often occur in deeper water than beds of floating-leaved or emergent species, but there is considerable overlap. Submergent marshes can also be found in deep water wetlands and flowages that have little moving water present. Water depth, water chemistry, water movement, and type of bottom material are among the key ecological factors that determine the nature of the submergent beds. The chemical nature of the water can greatly affect the types and abundance of aquatic plants present. Common or characteristic species and genera include various species of pondweeds (Potamogeton spp.), waterweed (Elodea spp.), coon-tail (Ceratophyllum spp.), slender naiad (Najas flexilis), eel-grass (Vallisneria americana), and several species of water-milfoil (Myriophyllum spp.) and bladderwort (Utricularia spp.).

Aquatic plants, including both emergent and submergent, form the foundation of healthy and flourishing aquatic ecosystems - both within lakes and rivers and on the shores and wetlands around them. They not only protect water quality, but they also produce life-giving oxygen. Aquatic plants are a lake's own filtering system, helping to clarify the water by absorbing nutrients like phosphorus and nitrogen that could stimulate algal blooms. Plant beds stabilize soft lake and river bottoms and reduce shoreline erosion by reducing the effect of waves and current.

Aquatic plants serve as spawning habitat for fish and amphibians, as shelter for various life stages of a variety of animal species, and as nesting habitat for birds. Plant beds support populations of aquatic insects that serve as a food base for other species. Healthy native aquatic plant communities also help prevent the establishment of invasive exotic plants like Eurasian water-milfoil (Myriophyllum spicatum).

Defining Characteristics and Similar Communities

Submergent marshes may contain similar species as floating-leaved marshes but have less than 50% relative cover of floating-leaved aquatic plants. While they often occur adjacent to or intergrade with emergent marshes and wild rice marshes, they are dominated by submersed species rather than emergent plants like cattails, bulrushes, and wild rice. Submergent marshes are also closely related to oligotrophic marshes but lack the abundance of rosette-forming aquatic macrophytes that characterizes that community.

Rare animals

Species of Greatest Conservation Need

Wisconsin Wildlife Action Plan graphic

The following Species of Greatest Conservation Need are listed according to their level of association with the Submergent Marsh natural community type, based on the findings in Wisconsin's 2015 Wildlife Action Plan.

Scores: 3 = high association, 2 = moderate association, and 1 = low association. See the key to association scores for complete definitions.

Blanchard's Cricket FrogAcris blanchardi3
Mink FrogLithobates septentrionalis3
Pickerel FrogLithobates palustris3

A Predaceous Diving BeetleAgabus aeruginosus2

Whooping CraneGrus americana3
American Black DuckAnas rubripes2
Black TernChlidonias niger2
Black-crowned Night-HeronNycticorax nycticorax2
Forster's TernSterna forsteri2
Great EgretArdea alba2
Red-necked GrebePodiceps grisegena2
Yellow-crowned Night-HeronNyctanassa violacea2
Caspian TernHydroprogne caspia1
Common GoldeneyeBucephala clangula1
Common TernSterna hirundo1
Least BitternIxobrychus exilis1

Dragonflies and damselfliesScore
Spatterdock DarnerRhionaeschna mutata3
Sphagnum SpriteNehalennia gracilis3
Mottled DarnerAeshna clepsydra2
Painted SkimmerLibellula semifasciata2
Slaty SkimmerLibellula incesta2
Spangled SkimmerLibellula cyanea2
Lilypad ForktailIschnura kellicotti1

Grasshoppers and alliesScore
Delicate Meadow KatydidOrchelimum delicatum1

Big Brown BatEptesicus fuscus2
Little Brown BatMyotis lucifugus2
Northern Long-eared BatMyotis septentrionalis2
Silver-haired BatLasionycteris noctivagans2

Blanding's TurtleEmydoidea blandingii3
QueensnakeRegina septemvittata3
Wood TurtleGlyptemys insculpta2
Eastern MassasaugaSistrurus catenatus1

Please see Section 2. Approach and Methods of the Wildlife Action Plan to learn how this information was developed.

Rare plants

The Natural Heritage Inventory has developed scores indicating the degree to which each of Wisconsin's rare plant species is associated with a particular natural community or ecological landscape. This information is similar to that found in the Wildlife Action Plan for animals. As this is a work in progress, we welcome your suggestions and feedback.

Scores: 3 = "significantly associated," 2 = "moderately associated," and 1 = "minimally associated."
Scientific Name Common Name Score
Armoracia lacustris Lake Cress 3
Callitriche hermaphroditica Autumnal Water-starwort 3
Callitriche heterophylla Large Water-starwort 3
Didiplis diandra Water-purslane 2
Eleocharis robbinsii Robbins' Spike-rush 2
Littorella uniflora American Shoreweed 3
Najas gracillima Thread-like Naiad 3
Potamogeton bicupulatus Snail-seed Pondweed 3
Potamogeton confervoides Algae-leaved Pondweed 3
Potamogeton diversifolius Water-thread Pondweed 3
Potamogeton hillii Hill's Pondweed 3
Potamogeton oakesianus Oakes' Pondweed 3
Potamogeton perfoliatus Clasping-leaf Pondweed 3
Potamogeton pulcher Spotted Pondweed 3
Potamogeton vaseyi Vasey's Pondweed 3
Schoenoplectus torreyi Torrey's Bulrush 2
Stuckenia filiformis ssp. alpina Northern Slender Pondweed 3
Stuckenia filiformis ssp. occidentalis Slender Pondweed 3
Stuckenia vaginata Sheathed Pondweed 3
Utricularia resupinata Northeastern Bladderwort 2


The following Ecological Landscapes have the best opportunities to manage for Submergent Marsh, based on the Ecological Landscapes of Wisconsin Handbook.

Map of the Ecological Landscapes of Wisconsin.

Major (3 on map)
A major opportunity for sustaining the natural community in the Ecological Landscape exists, either because many significant occurrences of the natural community have been recorded in the landscape or major restoration activities are likely to be successful maintaining the community's composition, structure, and ecological function over a longer period of time.

Important (2 on map)
Although the natural community does not occur extensively or commonly in the Ecological Landscape, one to several occurrences do occur and are important in sustaining the community in the state. In some cases, important opportunities may exist because the natural community may be restricted to just one or a few Ecological Landscapes within the state and there may be a lack of opportunities elsewhere.

Present (1 on map)
The natural community occurs in the Ecological Landscape, but better management opportunities appear to exist in other parts of the state.


Wisconsin Wildlife Action Plan graphic

What are conservation actions?

Conservation actions respond to issues or threats, which adversely affect species of greatest conservation need (SGCN) or their habitats. Besides actions such as restoring wetlands or planting resilient tree species in northern communities, research, surveys and monitoring are also among conservation actions described in the WWAP because lack of information can threaten our ability to successfully preserve and care for natural resources.

Threats/issues and conservations actions for natural communities


The following are additional considerations for Submergent Marsh in Ecological Landscapes with opportunities for protection, restoration, and/or management. For more information, see the Wildlife Action Plan.

Central Lake Michigan Coastal

This Ecological Landscape is heavily developed for agricultural, industrial, and residential purposes. There are continuing effects from past management decisions (e.g., filling of marshes, loss of wild rice). Sedimentation, weed removal, and the use of pesticides can damage marsh habitat and encourage the growth and spread of invasives.

Central Sand Hills

Runoff from agricultural activities adjacent to streambanks and stormwater from urban areas tops the list of non-point source pollution sources in the Central Sand Hills. These sources of pollutants degrade or otherwise threaten many streams, lakes, wetlands and/or groundwater. Additional considerations for submergent aquatic communities in the Central Sand Hills Ecological Landscape are listed below.

  • Assist farmers with nutrient and pesticide management planning to help control non-point discharges within the watershed.
  • Encourage riparian residents and others to participate in self-help volunteer lake monitoring programs.
  • Lakeshore and other waterway developments continue to threaten nearshore terrestrial and aquatic habitat that is critical to species diversity. Through lake associations, lake districts, and others promote a strong riparian owner education effort to help illustrate the importance of proper land and shoreline management.
  • Exotic invasive species such as purple loosestrife, zebra mussel, Eurasian water-milfoil, and curly pondweed continue to expand in this Ecological Landscape, in part due to disturbances.
  • Recreational use of lakes and other waterways is extremely high here. This presents public safety and shoreline erosion concerns, and destroys aquatic vegetation. Regulation, through lake patrols or via other means, should be sought.

    Central Sand Plains

    The hydrology throughout much of the Central Sand Plains has been altered by a maze of dikes, drainage ditches, canals, and constructed impoundments. High acidity and low fertility makes the waters of this Ecological Landscape generally inhospitable to aquatic vegetation. Among the exceptions, though, are several plant species that are adapted to such conditions, such as Farwell's milfoil and twin-stemmed bladderwort, which are locally common in several of the impoundments in the western part of the Ecological Landscape. Most of the impoundments on public lands were originally constructed to benefit waterfowl, something they're not always well-suited for because of the chemical nature of the waters. Others were developed to provide a constant source of water for the cranberry industry, which is a major economic concern in this region. Backwaters of the Wisconsin and Yellow Rivers contain more familiar assemblages of pondweeds, coontail, waterweed, water lilies, watershield, and common bladderwort. Runoff from agricultural activities adjacent to streambanks and impoundments and stormwater runoff from urban areas are non-point pollution sources in the Central Sand Plains. These sources can degrade or otherwise threaten streams, impoundments, wetlands or groundwater. Assistance should be provided to farmers and cranberry growers for development of nutrient and pesticide management plans that help control non-point discharges within the watershed. Riparian residents and others should be encouraged to participate in self-help volunteer lake monitoring programs.

    Forest Transition

    The more intact (i.e., forested) watersheds in this Ecological Landscape occur on the eastern and extreme northern margins. In other portions of this Ecological Landscape, agriculture is a major land use and associated practices can result in soil erosion and water quality problems. Invasive plants may replace native plants and affect the composition of aquatic communities. Submergent marsh occurs in quiet bays of some of the Ecological Landscapes lakes, and in the backwaters of larger rivers such as the Wisconsin and its tributaries. Impoundments are common in the Wisconsin River system, and some of them do provide suitable conditions for the development of submergent marsh.

    North Central Forest

    This community type is present in the deeper, quiet bays of many lakes, in some of the region's low gradient streams, and also in impoundments, such as the Gile Flowage (Iron County), the Chippewa Flowage (Sawyer County) and the Mondeaux Flowage (Taylor County). Invasives such as Eurasian water-milfoil and curly pondweed are problems in parts of this Ecological Landscape.

    Northeast Sands

    Good examples of submergent marsh occur in lakes and stretches of low-gradient streams, especially within some of the public lands in the Ecological Landscape.

    Northern Highland

    This community type is present in many lakes and low gradient streams, as well as in impoundments such as Thunder Marsh (Oneida County), Turtle-Flambeau Flowage (Iron County), Rainbow Flowage and nearby stretches of the Upper Wisconsin River (Oneida County), and Willow Flowage (Oneida County). Development pressures are very high in this Ecological Landscape and there is a need to protect undeveloped shorelines in the near future. Rusty crayfish have significantly impacted lakes in this Ecological Landscape.

    Northern Lake Michigan Coastal

    The Lower Wolf River Bottomlands (Shawano and Outagamie Counties), Oconto River Marsh (Oconto County), Peshtigo Harbor Marsh (Marinette County) and Green Bay West Shore Wetlands (Oconto County) contain examples of this community. Uplands should be buffered and shorelines should be managed to prevent erosion and sedimentation, and limit input of pollutants (including through pathways associated with the underground aquifers and fractured dolomite bedrock that underlies the Door Peninsula). Disturbance of polluted sediments buried in the bottoms of Green Bay and the larger rivers should be avoided.

    Northwest Lowlands

    The Trade River Wetlands (Polk and Burnett Counties) are an example of this community type. Most problems are associated with the larger developed lakes, where invasive plants (e.g., purple loosestrife) have replaced natives and shoreline habitat has been developed. This type is less common in this Ecological Landscape than elsewhere. Peatlands are the major wetland community types here.

    Northwest Sands

    This community type is present in quiet bays of many lakes in this Ecological Landscape, along certain stretches of low gradient streams, and in impoundments such as Gordon Flowage (Douglas County), Phantom Flowage on Crex Meadows State Wildlife Area (Burnett County), Amsterdam Sloughs State Wildlife Area (Burnett County), and the Clam River Flowage (Burnett County). Development pressures on shorelines are very high here and there is a need to protect more undeveloped lakes.

    Southeast Glacial Plains

    There are continuing impacts from past management decisions (e.g., draining and filling marshes and loss of wild rice). Additional considerations for submergent aquatic communities in the Southeast Glacial Plains Ecological Landscape are listed below.

  • Weed removal and use of pesticides can damage habitat and encourage invasives.
  • Land use planning needs to be comprehensive and emphasize conservation considerations to improve conditions for aquatic communities.
  • Sedimentation and pollution from agricultural and urban areas negatively affects water quality and substrate conditions. Manage watersheds to control runoff from surrounding agricultural and urban areas that contributes pollutants, nutrients, and sediments.
  • Invasive plants and animals are an extreme problem in this heavily developed landscape. Carp management can also have impacts on submergent marsh.
  • Restore wild rice to appropriate locations, if possible (most aquatic systems in this Ecological Landscape are too hydrologically altered, sediment-filled, and nutrient-enriched to support wild rice at this time).

    Superior Coastal Plain

    Submergent aquatic communities are primarily associated with coastal embayments and estuaries on Lake Superior. Inland lakes are scarce in this Ecological Landscape. Additional considerations for submergent aquatic communities in the Superior Coastal Plain Ecological Landscape are listed below.

  • Disturbance from recreational powerboats coming into the larger rivers from Lake Superior can suspend sediments and physically damage beds of aquatic plants.
  • Use of herbicides can damage habitat.
  • Eutrophication (e.g., in the St. Louis River estuary (Douglas County), Port Wing (Bayfield County), or in the Fish Creek Sloughs (Ashland County)) can cause detrimental changes to community composition and structure.
  • Invasive plants such as curly pondweed, purple loosestrife, and giant reed have replaced sensitive natives. Problematic invasive animals include spiny water flea, round goby, ruffe, and white perch.
  • Soil erosion and sedimentation from uplands into water bodies is a particular threat in this Ecological Landscape due to the erodible soils, agricultural activities, and impermeable surfaces.
  • The lack of conifers in the forests of the region contributes to increased peakflow episodes during spring snowmelt that can exacerbate erosion.
  • Unsustainable forest management and other land use practices can result in soil erosion and diminished water quality. Use Best Management Practices and other sustainable forest management practices to limit activities detrimental to soil and water.
  • Protect more of this community type by working with conservation managers and interest groups.
  • Restore wild rice where possible; protect and maintain rice beds in the Kakagon Sloughs.
  • Reforest uplands within the watershed, restoring conifers where appropriate.
  • Use adaptive management techniques to restore structure and composition to damaged streams and degraded wetlands.
  • Gather more information on land use in the watershed and research its effects on peakflows.

    Western Coulee and Ridges

    The Mississippi River corridor, including its associated marshes and floodplain, is of continental importance to migratory waterfowl. The series of dams constructed on the Mississippi in the early part of the Twentieth Century severely disrupted the natural periodicity and magnitude of floods. While marsh habitat has been created in some areas, much of the sediment load that was formerly carried downstream is now deposited in the backwaters, filling them in and shortening the natural life of the aquatic beds. The submergent marsh community is now well-developed in some backwaters of the large rivers (e.g., Mississippi, Wisconsin, Chippewa, and Black Rivers). It provides an important fish nursery. Significant examples due to their size and importance to migratory waterfowl, other birds, turtles, and fish exist at several locations on the Mississippi River. Restoration efforts are taking place in areas such as Lake Onalaska, which is being replanted with wild celery. Wild celery is a favorite food plant of the canvasback duck, which stops here in vast numbers along with many other waterfowl species during migration periods. Good examples of marshes dominated by American lotus occur at Trempealeau National Wildlife Refuge (Trempealeau County) and Bertom Lake (Grant County). Additional considerations for submergent aquatic communities in the Western Coulees and Ridges Ecological Landscape are listed below.

  • Manage submergent marsh as part of a complex, with other marsh and wet meadow communities, floodplain forest, shrub-carr, and adjoining uplands.
  • Development on ridges above rivers can alter shoreline habitat and increase erosion. Rip-rapping, levees, seawalls, and dikes have been constructed and have impacted habitat (in some locations these have had some positive effects by protecting marshes from sedimentation and pollutants behind dikes).
  • Use of pesticides can damage habitat and encourage invasives.
  • Agricultural practices can result in soil erosion and water quality problems.
  • Sedimentation is damaging wild celery beds and detrimentally impacting migratory waterfowl.
  • Invasive plants, such as curly pondweed, can replace native plants and degrade aquatic communities. Invasive animals (e.g., zebra mussels and carp) are also a significant problem in this Ecological Landscape.
  • Barge traffic on the Mississippi River requires dredging and subsequent disposal of dredge spoils, which stirs up bottom sediments. Wave action from barges and other boat traffic can damage aquatic beds.
  • Past filling for roads, railroads, and industrial sites has affected this community. Competing economic interests limit opportunities for this type in the Ecological Landscape.

    Western Prairie

    This community is found in backwaters of the St. Croix River, and in some prairie pothole lakes and ponds. Past agricultural practices have detrimentally impacted this community, and soil and water quality are still being affected in negative ways. Sedimentation is damaging aquatic beds and detrimentally impacting migratory waterfowl. Additional considerations for submergent aquatic communities in the Western Prairie Ecological Landscape are listed below.

  • Invasive plants and animals are problems here.
  • The raising of baitfish in prairie pothole lakes and ponds is a threat to native invertebrate and herptiles populations and should be controlled. Nesting birds can also be disrupted when the baitfish are harvested.
  • Protect more of this community type by working with conservation managers and private interest groups.
  • Manage the marshes as integral components of the prairie pothole landscape, including extensive open grasslands, or as part of the St. Croix River floodplain mosaic.

  • Photos

    Submergent Marsh Photos

    Submergent Marsh Photo

    St. Louis River Marshes above Oliver. Submergent marsh with Potamogeton nutans.

    Photo by Eric Epstein.

    Submergent Marsh Photo

    White water-lily (Nymphaea odorata) and "island" with beaked bladderwort (Utricularia cornuta) and round-leaved sundew (Drosera rotundifolia). Julian Bay Lagoon.

    Photo by Emmet Judziewicz.

    Submergent Marsh Photo

    Stretches of this free-flowing warmwater stream support lush, diverse beds of submergent aquatic vegetation. Rice Creek, Northern Highland Ecological Landscape.

    Photo by Eric Epstein.

    Submergent Marsh Photo

    Rich beds of aquatic plants including Potamogeton spp. and Elodea sp. Rice Creek, Vilas County.

    Photo by Eric Epstein.

    Submergent Marsh Photo

    Submergent marsh countaining various plants in Bayfield, Wisconsin.

    Photo by Brenton Butterfield.

    Note: photos are provided to illustrate various examples of natural community types. A single photograph cannot represent the range of variability inherent in a given community type. Some of these photos explicitly illustrate unusual and distinctive community variants. The community photo galleries are a work in progress that we will expand and improve in the future.

    Last revised: Tuesday, August 30, 2022