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Wetlands: nature’s unique aquatic systems

Wetlands: nature’s unique aquatic systems. Allison Parnell Coastal & Wetlands Ecology Lab Texas A&M University at Galveston. WHAT ARE WETLANDS?. A transition zone between land and water bodies; neither “land” nor “water”. Refers to a variety of habitats: Coastal salt marshes

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Wetlands: nature’s unique aquatic systems

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  1. Wetlands: nature’s unique aquatic systems Allison Parnell Coastal & Wetlands Ecology Lab Texas A&M University at Galveston

  2. WHAT ARE WETLANDS? • 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 Photo: A.R. Armitage • 3 distinguishing characteristics define wetlands: • Hydrology-presence of water • Hydric soils-soils that are anoxic • Hydrophytic vegetation

  3. WHAT ARE WETLANDS? • All marshes are wetlands BUT not all wetlands are • marshes. • Wetlands can be divided into two main habitats: • Marshes-dominated by herbaceous (non-woody) vegetation • Example: salt marsh • Swamps-dominated by trees • Example: Cypress -tupelo • swamp Photo: Conservationfund.org Photo: A.R. Armitage

  4. 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).

  5. 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”.

  6. ARE WETLANDS ESTUARIES? Upper Texas Coast River discharge Salt marsh Photo: A.R. Armitage Tidal flooding Photo: www.galvbayinvasives.org

  7. 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.

  8. INHABITANTS OF SALTWATER WETLANDS • Vegetation: • Cordgrass of the Spartina genus most prominent. • Smooth cordgrass-low elevation. • Maritime saltwort-mid elevation. • Indian blanket, Fire wheel-upland elevation. Maritime saltwort Indian Blanket, Fire wheel Smooth cordgrass Photos: A.R. Armitage

  9. INHABITANTS OF SALTWATER WETLANDS • Invertebrates: • Shrimp, fiddler & blue crabs & oysters. • Vertebrates: • Waterfowl, wading & shore birds. • Variety of fish species. • Alligators, bobcats, raccoons, snakes & river otters. Photo: chesapeake-bay.org Photo: flickr.com Photos: A. Parnell Photo: coolcreatureshotplanet.com

  10. INHABITANTS OF FRESHWATER WETLANDS • Vegetation: • Water tupelo & bald cypress-dominant trees. • Water hickory, water locust, black tupelo & many others are common to swamps. Water tupelo Bald cypress Water locust Water hickory Photo: jcho.masgc.org Photo: statesymbolsusa.org Black tupelo Photo: forestryimages.org Photo: aggie-horticulture.tamu.edu Photo: my-photo-gallery.com

  11. 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). Photos: C. Nunnally Photo: permies.com Photo: A. Parnell Photo: ecotravel.ctaudubon.org

  12. 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. • Wetlands support regional biodiversity-threatened & • endangered species. Photo: fws.gov Photo: tpwd.state.tx.us • Wetland plants help improve water quality & may take up CO₂ from the atmosphere and subsequently influence climate change patterns.

  13. THE IMPORTANCE OF WETLANDS • 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. • 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.

  14. THE IMPORTANCE OF WETLANDS • Social: • High biodiversity in wetlands provide fishing, nature tourism (kayaking & boating), hunting & bird watching. Photo: txstate.edu Photo: A. Parnell Photo: bird-watching.purzuit.com

  15. Questions? Photos: A. Parnell

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