Habitats of Aquatic Plants: Wetlands

Wetlands are transitional areas between terrestrial and aquatic systems where the water table is usually at or near the surface or the land is covered by shallow water. A wetland is characterized by the three components: presence of water/water table level, water-logged soil conditions, and presence of hydrophytes/absence of flooding- intolerant vegetation.

Depending on hydrologic and physicochemical characteristics, geographical location and landscape, and dominant plant type, aquatic plant habitats can be classified as the following:
Wetland Indicator Categories of Aquatic Plants (U.S. Fish and Wildlife Service)

"+" indicates the wetter side of the category (e.g. FACW+)
"-" indicates the drier side of the category (e.g. FAC-)

Major Aquatic Plants Habitats

Estuarine Seagrass/SAV beds

Halodule grass bed

Thalassia grass bed. This plant was not found in Mississippi during the latest survey

The dominant vascular plants in the subtidal estuarine ecosystems are submerged aquatic vegetation (SAV) and seagrass species such as Ruppia maritima and Halodule wrightii.

SAV’s are important plants as they protect shorelines from erosion, improve water quality by trapping sediments, provide habitat, and are highly productive. The productivity of these habitats is largely due to an abundance of algae and diatom phytoplankton, which feed a diverse foodweb. Seagrasses may contain up to 1000 times more animals than a comparable area of bare sediment. Juveniles of numerous shellfish and fish can be found in seagrass habitats. Many SAV species require lots of light, and are restricted to shallow waters, which makes them prone to damage from boaters. Trimming engines up and slowing down in shallow waters can help to protect delicate and fragile SAV. Ensuring good quality water is also critical to plant success, so reducing turbidity and nutrients in storm water runoff will aid in the survival of SAV.

Salt Marshes

Spartina alterniflora growing in a salt marsh

Spartina alterniflora salt marsh

Tidal salt marshes occur in the intertidal zone that is between low and high tides on low-energy coasts such as estuaries. Common salt marsh plants in the Mississippi coast include Spartina alterniflora and Juncus romerianus.

Tidal Oligohaline Marshes

Sagittaria lancifolia along a tidal marsh

Phragmites australis, common reed

Tidal oligohaline marshes are grass-dominated wetlands of low salinity brackish (0.5-5ppt) zones along tidal rivers and streams and bayous. Cladium jamaicense, Spartina cynosuroides, Spartina patens, Sagittaria lancifolia are the characteristic and abundant species that often form extensive stands along edges of the tidal channels.

Freshwater Marshes

Cattail (Typha) and waterhyacinth (Eichhornia) in a freshwater marsh

Pickerelweed (Pontederia cordata)

Freshwater marshes are often found in open areas near rivers , streams, bayous as well as ponds and lakes. They can be categorized into tidal- and non-tidal marshes. The water in freshwater marshes is usually is rich in minerals. Species diversity is generally higher in freshwater marshes than in salt marshes. Non-woody plants such as grasses and sedges are common. Bulrushes and cattails are often found at the edges of a marsh.

Freshwater Swamps

Short, conical "knees" are characteristic features of bald cypress swamps

Tupelo swamp

Swamps are wetlands dominated by woody vegetation and trees. Cypress-tupelo swamps are common in Mississippi. Common tree species include bald cypress (Taxodium distichum), pond cypress (Taxodium ascendens), and water tupelo (Nyssa aquatica). Swamps are seasonally or permanently flooded by shallow water that is typically slightly acidic and low in nutrients.