WETLANDS: NATURE’S UNIQUE AQUATIC SYSTEMS

Allison ParnellCoastal & Wetlands Ecology Lab

Texas A&M University at Galveston

•A transition zone between land and water bodies; neither “land” nor “water”.

•Refers to a variety of habitats:•Coastal salt marshes•Forested swamps•Freshwater marshes•Brackish (intermediate salinity) marshes

•3 distinguishing characteristics define wetlands:•Hydrology-presence of water•Hydric soils-soils that are anoxic•Hydrophytic vegetation

WHAT ARE WETLANDS?

Photo: A.R. Armitage

•All marshes are wetlands BUT not all wetlands are marshes.

•Wetlands can be divided into two main habitats:

Swamps-dominated by treesExample: Cypress -tupeloswamp

Photo: A.R. Armitage Photo: Conservationfund.org

Marshes-dominated by herbaceous (non-woody) vegetationExample: salt marsh

WHAT ARE WETLANDS?

SALTWATER VS FRESHWATER WETLANDS

•Salt marshes are regularly tidally inundated.•Some fully marine (salinity ~32‰).•Many are estuarine-where freshwater from rivers or streams mixes with ocean water (Gulf of Mexico water).

•Estuarine marshes result in brackish salinities (~0.5-30‰).

•Brackish conditions may be temporary (only after large rain events) or may be constant if nearby source of freshwater (river output).

ARE WETLANDS ESTUARIES?

•An estuary is defined by Pritchard (1967) as:“a semi-enclosed coastal body of water which has a free connection with the open sea and within which seawater is measurably diluted with freshwater derived from land drainage”.

Upper Texas Coast

River dischargeSalt marsh

Tidal flooding

ARE WETLANDS ESTUARIES?

Photo: www.galvbayinvasives.org

Photo: A.R. Armitage

SALTWATER VS FRESHWATER WETLANDS

•Swamps remain flooded for extensive period of time and may only dry out occasionally.

•Occur in low lying areas of floodplains (depressions).

•Dominant source of water is from overbank flooding or may be runoff from precipitation.

INHABITANTS OF SALTWATER WETLANDS

•Maritime saltwort-mid elevation.

Smooth cordgrass

Maritime saltwortIndian Blanket, Fire wheel

•Vegetation:•Cordgrass of the Spartina genus most prominent.•Smooth cordgrass-low elevation.

•Indian blanket, Fire wheel-upland elevation.

Photos: A.R. Armitage

INHABITANTS OF SALTWATER WETLANDS

•Vertebrates:•Waterfowl, wading & shore birds.•Variety of fish species.•Alligators, bobcats, raccoons, snakes & river otters.

•Invertebrates:•Shrimp, fiddler & blue crabs & oysters.

Photo: coolcreatureshotplanet.comPhotos: A. Parnell

Photo: flickr.com

Photo: chesapeake-bay.org

INHABITANTS OF FRESHWATER WETLANDS

•Vegetation:•Water tupelo & bald cypress-dominant trees.

Photo: jcho.masgc.org Photo: statesymbolsusa.org

Water tupelo Bald cypress

Photo: aggie-horticulture.tamu.edu

Water hickory

Photo: forestryimages.org

Water locust

Photo: my-photo-gallery.com

Black tupelo

•Water hickory, water locust, black tupelo & many others are common to swamps.

INHABITANTS OF FRESHWATER WETLANDS

•Invertebrates:•Variety of insects (flies, beetles, dragonflies & damselflies).•Spiders & scorpions.•Mollusks-slugs & snails & freshwater bivalves.•Vertebrates:•Bald eagles, woodpeckers, ducks & wading birds.•Variety of reptiles & amphibians.•Bats, rabbits, beaver, foxes & deer.•Variety of freshwater fish species (gars, catfish, bass & minnows).

Photo: A. Parnell

Photo: ecotravel.ctaudubon.org

Photo: permies.com

Photos: C. Nunnally

THE IMPORTANCE OF WETLANDS

•Ecological:

•In coastal areas nurseries for estuarine organisms, habitat for migratory birds & spawning & feeding areas for recreational and game fish species.

•Wetland plants help improve water quality & may take up CO₂ from the atmosphere and subsequently influence climate change patterns.

•Wetlands support regional biodiversity-threatened & endangered species.

Photo: fws.govPhoto: tpwd.state.tx.us

THE IMPORTANCE OF WETLANDS

•Salt marshes-oyster production, commercial fisheries (>$400 million/year), employ ~30,000 coastal residents , sport fishing ($2 billion/year industry).

•Swamps-contribute to the timber & crayfish industry.

•Economic:

•Coastal wetlands reduce wave energy subsequently reducing flooding and protecting shorelines from erosion.

•Inland wetlands store floodwaters thus controlling flood damage and erosion and stabilize river flows & groundwater levels.

THE IMPORTANCE OF WETLANDS

•Social:

• High biodiversity in wetlands provide fishing, nature tourism (kayaking & boating), hunting & bird watching.

Photo: A. Parnell Photo: bird-watching.purzuit.com

Photo: txstate.edu

Questions?

Photos: A. Parnell