Biotic Communities of Marsh Systems

Fresh/Saltwater Systems

Freshwater marsh0.5-5.0 ppt (between oligohaline zone and non-tidal freshwater) Saltwater marsh5.0-35.0 ppt or greater depending upon conditions

Comparison

Saltwater-lg. Tidal influence-sandy, lower OM-marine and

estuarine macrophytes

-low species diversity-moderate to high

algal production

Freshwater-riverine influence-silt and clay, high OM-freshwater

macrophytes-high species diversity-very low algal

production (<1%pp)

Salt Marsh Ecology

Complex systemsShaped by water,sediments, and vegetationFound on low energy coastlines and protected back barriers

United States Salt Marshes

Basic Characteristics

Found in inter-tidal zonesFewer species present, occupying broader niches (recent geologic origin)Stressful environment Large gradients present for temperature, salinity, and pH

Development

Tidal sequence provides major source of sediment loadTerrestrial runoff provides secondary sourceSalt tolerant plant species invade and thrive following deposition of sediments

Atchafalaya Delta Region

Recent studies prove importance of riverine inputDelta receives 1/3 of Miss. River flowWetland area actually increasingSurrounding areas are in rapid decline due to subsidence and sea level rise

Global Variations

North AmericaGulf CoastWest CoastEast Coast

EuropeanArctic (North and South)

European Salt Marshes

Found above low neap tide linePeriodic inundationDifferent physiology due to tidal influenceSalicornia, Suaeda maritima, Juncus maritimus

Primary Production -Classical View

Spartina alterniflora responsible for majority of production3300 g/m/yr productionProduction influenced by tides

Primary Production-Modern Approach

Isotopic analysisC13/c12 ratio point towards other sourcesAlgae, diatomsOminvores complicate data

Primary Consumers

Trophic relationships begin with algae or Spartina detritusRich benthic communities developBacteria rich detritus more valuable when compared to plant tissueSpecies of Uca, Callinectes, and Penaeus common in systems

Primary Consumers cont.

Deposit Feeders-take in bottom

sediments-filter organic

particles-oligochaetes,etc.

Suspension Feeders-filter organic

material and other nutrients out of water column

-use siphons, internal filters

-American oysters, mussels

Value to Marsh System

Macro-consumers provide an essential link in salt marsh energeticsTake potentially harmful nutrients out of water column (phosphorus, etc.)Bioturbation aerates the soil, increasing algal productivityFeces provide new food source for microbial communities

Secondary Consumers

Birds, fish, and crabs compose a majority of the species for this trophic levelPrimary consumers provide valuable food source for juvenile populationsMay feed on organisms in sediments and water column

Aerobic Zones

Occur in top 2-3mm of soilHigh content of oxidized ions (Fe+++,Mn+4,NO3-, SO4--)Vital source of energy for systemMetals later reduced in anaerobic environment

Anaerobic Zone

Nitrate 2 pathwaysAssimilatory nitrate reduction (plant uptake)Dissimilatory nitrate reduction (denitrification)Significant loss of N in salt marsh

Nitrogen Cycling

Complex interactions in both aerobic and anaerobic zonesMineralization production of ammonium ion from organic NPulled upward (gradient change)oxidized by chemoautotrophsNitrification (nitrosomonas, nitrobacter)

Mg and Fe reduction

Follows dentrificationCause of grey/green coloration in soilForms ferrous oxides which can inhibit nutrient uptake around plant roots

Sulfur reduction

Assimilatory S reduction DesulfovibrioOM producedCombines with Fe to reduce H2S concentrations in sediments (limits toxicity)PS bacteria (purple sulfur)create OM on surface of the salt marsh

Methanogenesis

Occurs in extremely reduced conditionsAfter oxygen, nitrate, sulfate are used upCan be recycled by bacteria during droughts

Conclusions

Complex interactions regarding salt marsh energeticsAlgal growth and diatom formation provide basic primary productionNutrient cycling in anaerobic zones, rich bacterial communitiesLow species richness due to emphimeral nature and harsh environment

Food Web Interactions

Tidal freshwater Marshes

Definition

Tidal freshwater wetlands are a distinctive type of ecosystem located upstream from tidal saline wetlands (salt marshes) and downstream from non-tidal freshwater wetlands

Characteristics

Near freshwater conditions 0.5 ppt average annual salinity (more concen. during periods of drought )Plant and animal communities dominated by freshwater speciesA daily lunar tidal fluctuation

Tidal Freshwater Wetlandslies between the oliogohaline zone and non-tidal freshwater

Tidal Freshwater Marshes

Are characterized by a large diverse group of broad-leafed plants, grasses, rushes, shrubs and herbacious plants.

Grasses, rushes, shrubs

Simplifying terminology

Odum, et al (1984) identifies similar terminology in literature such as palustrine emergent wetland, freshwater tidal, transition marsh combined with arrow-arum and pickerelweed marsh…simplified to tidal freshwater marsh for convenience and term is more widely used.

Tidal Freshwater Marshes classified as either:

System: palustrineClass: emergent wetlandSubclass: persistent and non-persistent

System : riverineClass: emergent wetlandSubclass: non-persistent

Water regimes for either classification:

Permanently flooded – tidal

Regularly flooded

Seasonally flooded – tidal

The system selected depends on the position of the marsh with respect to the river channel

High back marshes with persistent vegetation classified as palustrine

Fringing low marshes along river edges classified as riverine

Along United States East Coast

Most extensive development of freshwater tidal marshes between Southern New England and Georgia

Best developed in locations…

Major influx of freshwaterDaily tidal amplitude of at least 0.5m (1.6ft.)A geomorphological structure which constricts & magnifies the tidal wave in the upstream portion of the estuary

In North Carolina estuaries lie behind Outer Banks

reduced tidal amplitude Almost all coastal river systems have tidal and freshwater systems Slight tidal change Irregular tides and greatly affected by the wind

North Carolina is unique…

Tidal plant communities present typically restricted in size

Tidal swamps present Cape Fear River system, one exception

One meter tide Extensive areas of typical tidal freshwater marshes

Characteristics of freshwater wetlands by region

Florida, tidal freshwater marshes are very restricted in size or very seasonal

Gulf, Louisiana – extensive tidal freshwater marshes

• Irregular• Low amplitude• Wind driven

Continued

Pacific Coast - relatively rareAlaska – extensiveCalifornia – associated with large river systems, ex. Sacramento Washington and Oregon – associated with Columbia River

Geological History – relatively recent

Freshwater coastal marshes expanded rapidly as drowned river systems were inundated and filled with sediment

Northern Gulf of Mexico coast, marshes are probably still expanding due to increased runoff associated with land clearing and human activities

Soil and Water Chemistry Coastal Marsh sediments generally organic Sediments are anaerobic except for a thin surface layer Ammonium is present in the winter but reduced to lower levels in the summer due to plant uptake Nitrogen present in organic form Phosphorus levels vary High cation exchange capacity (CEC) Soil pH generally close to neutral (6.3 to 7.0)

Decomposition – 3 Factors

Temperature, major factor in decayAs temperatures increase, decay increases

Oxygen and water availabilityPlants in anaerobic or dry environments decompose slowly

Plant tissue: broadleaf perennials (high concentrations of nitrogen, leaf tissue readily decays) high marsh grasses (low nitrogen concentrations and structural tissue resistant to decay)

• Litter tends to accumulate around persistent grasses• Low erosion rates ( and low tidal energy)

Organic ExportLosses of organic carbon from marshes occur through respiration

Peat forms below root zoneCan convert to methane that escapes as a gasExported in bodies of consumers that feed on the marsh

In anaerobic freshwater, little sulfur available, carbon dioxide can be reduced to methane (which is lost to the atmosphere)

General Model of N & P Cycling

Nutrient budgets

Appears to be similar to salt water marshes

Open systems Long-term sinks, sources or transformers of nutrients Most inputs are inorganic transformed chemically or biologically to organic forms Recycle most nutrients used within the system; imports and exports are a small percentage of the total material cycled

Tidal Wetland Ecosystem

Marsh Vegetation – Brackish to Fresh

Marsh cord grass (Spartina cynosuroides)Narrow leaved cat-tail (Typha angustifolia)Coastal cat-tail (Typha domingensis)Marsh fleabane (Pluchea purpurascens)Arrow-arum (Peltandra virginica)Wild rice (Zizania aquaticaSwamp rose (Rosa palustris)Mallows (Hibiscus spp.)

Plants indicating FreshwaterWax myrtle (Myrica cerifera)Sedges (Carex spp.)Jewelweed (Impatiens capensis)Blue flag (Iris versicolor)Broadleaf cat-tail (Typha latifolia)Wild celery (Vallisneria spiralis)Red maple (Acer rubrum)Water tupelo (Nyssa aquatica)

Algae & Microscopic Organisms

AlgaeGreen (Chlorophytes)Blue-green (Cyanophytes)

Plankton (non to poor swimmers)

Protozoans (animal like w/flagella)

• dinoflagellatesDiatoms (type of phytoplankton; phyto = green)

• Building block of food chain

Forams (animal like, eat diatoms)

Bacteria

Larger Lower Animals WormsSmall snailsJellyfishShrimp (various spp.)Crab (various spp.) SpongesMollusksBivalve (oyster, bent mussel)BarnaclesSea squirt

Fish and Shellfish ClassificationAnadromous (spawns in freshwater, lives in saltwater); Semiandromous (spawns in freshwater adults remain in lower estuaries) ex. Striped bass, Herring. Shad, Sturgeon; Catadromous (spawns in saltwater, lives in freshwater) ex. ex. American eel

Estuarine-Marine (a few species move into freshwater marshes to spawn) ex. Spot, Croaker, Brown Shrimp, Summer Flounder

Estuarine (complete entire lifecycle in estuary, extend range into freshwater marshes) ex. Killifish, Bay Anchovy, Hogchoker

Freshwater (spawn and complete lives in freshwater areas) ex. Bluegill, Sunfish, Largemouth Bass

Amphibians and Reptiles

Frogs, ToadsDiamondback Terrapins American alligator Water snakes ex. Cottonmouth moccasins

Birds – 280 species reported

Waterfowl (44 spp.) Wading birds (15 spp.) Rails and shorebirds (35 spp.)Birds of prey (23 spp.)Gulls, terns, kingfishers and crows (20 spp.)Arboreal birds (90 spp.)Ground and shrub birds (53 spp.)

MammalsMuskratNutriaMeadow mouse, white footed mouseCottontailFoxRaccoonOtterOpossumSkunkWhitetail deerManateeBeaver

Freshwater Food Web

Floating Marshes

Usually associated with non-tidal systems Marsh substrate composed of a thick organic mat, entwined with living roots that rises and falls with the surrounding water levels Coastal Louisiana tidal marshes has the largest area of floating marshes in US

The flora is diverse but dominated by ferns in spring and Panicum hemitomon in summer and fall

ResourcesAlongi,D.M. 1998. Coastal Ecosystem Processes. Univ. of

Minnesota, Minneapolis. pp. 419.Bertness, Mark D. 1999. The Ecology of Atlantic Shorelines,

Sinauer Associates, Inc. Pbulishers Sunderland, Massachusetts, pp. 417.

McLusky, D.S. 1981. The Estuarine Ecosystem. John Wiley &Sons, New York. pp. 150.

Mitsch, William J. and James G. Gosselink. 1993. Wetlands, 2d ed., Van Nostrand Reinhold, New York, pp. 722.

Odum, W. E., T. J. Smith III, J.K. Hoover, C.C. McIvor. 1984. The Ecology of Tidal Freshwater Marshes of the United States East Coast: A Community Profile, U.S. Fish and Wildlife Service, FWS/OBS-83/17,Washington, D.C., pp. 177.

Pomeroy, L.R. and Weigert,R.G. 1981. The Ecology of a Salt Marsh. Springer-Verlag, New York. pp. 271

Roberts, Mervin F. 1979. The Tidemarsh Guide, E.P. Dutton, a Division of Sequoia-Elsevier, New York, pp. 240.

ResourcesShabreck,R.H. 1988. Coastal Marsh Ecosystem and Wildlife

Management. Univ. of Minnesota Press. pp.138Statler, Richard. 1993. Barrier Island Botany The Southern United

States, Wm. C. Brown Dubuque, Iowa, pp. 164.Tiner, Ralph W. Jr.. 1987. A Field Guide to Coastal Wetland

Plants of the Northeastern United States,The University of Massachusetts Press, pp. 285.

Wharton, Charles H.. 1978. The Natural Environments of Georgia, Geological and Water resources Division and Resource Planning Section, Office of Planning and Research Georgia Department of Natural Resources Atlanta, Georgia, pp. 227.

www.epa.gov/owow/wetlandswww.excite.com (photo gallery)www.uf.edu ( plant photo gallery)www.h20.denr.nc.state.gov

Resourceshttp://agen521.www.ecn.purdue.edu/AGEN521/epadir/wetlands/freshwtr_marsh.htmlhttp://www.mobilebaynep.com/habitats/fresh.htmhttp://www.uncwil.edu/people/hosier