BCWF Watershed Team

Shallow Open Water Wetlands

Shallow open water wetlands are open bodies of water less than two meters deep, where sunlight can reach the bottom and support the growth of aquatic vegetation. What defines this wetland type is the presence of permanent or seasonally standing water, minimal emergent vegetation, and an abundance of submerged or floating aquatic plants like pondweed or water lilies. These wetlands are typically found along the edges of lakes, rivers, or coastal zones and often connect with other wetland types such as fens, marshes, and swamps.

They are rich in aquatic life and provide vital breeding, feeding, and nursery habitat for fish, amphibians, waterfowl, and aquatic invertebrates. The calm, sunlit waters support plankton and plant growth, forming the base of complex food webs that sustain everything from dragonflies to ducks to trout. For humans, shallow open water wetlands are also popular places for fishing, canoeing, and swimming.

Marshes

Marshes are wetlands characterized by shallow, standing or slow-moving water and dominated by soft-stemmed, herbaceous plants like grasses, sedges, rushes, and cattails. Unlike swamps, which are dominated by woody vegetation, marshes thrive on mineral-rich soils and are typically found beside streams, lakes, and rivers. Saltwater marshes are also often found alongside ocean shorelines. These conditions create ideal habitat for a wide range of species.

Marshes support abundant plant life that offers food, shelter, and breeding grounds for waterfowl, juvenile fish, amphibians, and countless insects. Their nutrient-rich, sunlit waters create ideal nursery habitat and attract a wide range of birds and mammals that rely on these vibrant ecosystems and their diverse food chains. These are critical ecosystems for amphibians like frogs, toads, and salamanders that need emergent vegetation to attach their eggs to in the water.

Beyond supporting biodiversity, marshes play a critical role in filtering pollutants, improving water quality, and capturing large volumes of floodwater—making them vital to both ecological and human communities. Their connection to other water sources such as streams, lakes, and groundwater (along with precipitation) also creates high nutrient availability, which leads to high levels of biodiversity and makes marshes one of the most species-rich wetland types in many landscapes.

Bogs

Bogs are one of the most unique wetland types, formed in cool, wet climates where water is sourced solely from rain or snow. With no connection to groundwater or streams, they develop slowly as plant material accumulates and decomposes very gradually in waterlogged, oxygen-poor conditions—creating layers of peat. This buildup of organic matter traps significant amounts of carbon, making bogs valuable natural allies in climate change mitigation.

Because bogs are highly acidic and low in nutrients (due to precipitation inputs), they support specialized plant life such as sphagnum moss, which can hold up to 20x it’s weight in water, and carnivorous sundews that have evolved to capture and digest insects for nutrients. Wildlife species that thrive in these conditions are equally specialized. Bog-roaming mammals like the bog lemming (Synaptomys) find refuge among the mosses, while birds such as the Wilson snipe (Gallinago delicata) and greater yellowlegs (Tringa melanoleuca) nest and forage in these quiet, open landscapes. Amphibians like wood frogs (Lithobates sylvaticus) are often found near bog pools, where the cool, undisturbed water provides ideal breeding habitat. Despite their seemingly sparse appearance, bogs are teeming with life adapted to thrive in harsh and ancient ecosystems.

Fens

Fens are peat-forming wetlands like bogs, but unlike bogs, they are connected to groundwater or surface water sources. This connection brings in minerals and nutrients, resulting in lower acidity and supporting a much greater diversity of plant life. You’ll often find sedges, grasses, wildflowers, and even shrubs growing in fens, creating a mosaic of habitats that can support a wide array of species. Fens can often be mistaken for marshes, so it’s important to look at the type of soils in these wetlands. Fens will have peat or organic soils greater than 40cm deep, whereas marshes will have mineral or highly decomposed organic soils.

Because of their constant groundwater flow, fens play a critical role in water filtration—trapping sediments and absorbing excess nutrients before they reach downstream waterbodies. This natural filtering function improves water quality and benefits surrounding aquatic ecosystems.

Fens are also rich in wildlife. Birds such as sandhill cranes (Grus canadensis) and bitterns (Botaurinae) rely on fens for nesting and foraging. Insects like dragonflies and butterflies thrive among the flowering plants, while amphibians such as boreal chorus frogs (Pseudacris maculata) find breeding grounds in shallow fen pools. The diverse vegetation also provides habitat for mammals like muskrats (Ondatra zibethicus) and voles (Microtus spp.), which build their homes in the dense plant cover.

Swamps

Swamps can often be mistaken for forests due to the dominance of trees and shrubs, but what makes a swamp a swamp is its saturated soils and standing or slow-moving water that support woody vegetation. Unlike marshes, which are dominated by grasses and sedges, swamps are defined by water-tolerant trees like cedar, spruce, alder, or cottonwood. These wetlands often form in low-lying areas, floodplains, or around slow streams and lake edges, where water collects and drains slowly.

Swamps are essential for stabilizing soil and reducing erosion, protecting the surrounding landscape from being washed away during heavy rain or high water flow. Their thick vegetation and slow-draining soils also help store carbon and filter water, making them vital for both biodiversity and climate resilience.

While animated ogres may have made swamps famous in pop culture, real-life swamps are just as fascinating. Species like the barred owl (Strix varia) thrive in these shadowy, damp environments, using the dense canopy and quiet waters to hunt amphibians and small mammals. Ungulates such as moose (Alces alces) are especially drawn to swamps, feeding on significant amounts of willow and finding refuge in the thick cover. With their mix of trees, standing water, and rich organic soils, swamps are some of the most dynamic and ecologically important habitats in the wetland world.