Salt Marshes -biotic perspectives

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Salt Marshes-biotic perspectives
http//dcm2.enr.state.nc.us/wetlands/Coastal_Explo
rers/cpfmodule/bhi/bhi_marsh2.htm
http//www.texaswetlands.org/estuarine.htm

• Modified from
• Maia McGuire, PhD
• Florida Sea Grant Extension Agent

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What is a salt marsh?

• A community of emerged halophytic vegetation in
  areas alternately inundated and drained by tidal
  action.
• Expansive inter- or supratidal areas occupied by
  rooted emergent vascular macrophytes and a
  variety of epiphytes and epifauna.

Emerged sticking out of the water Halophytic
salt-loving Inundated flooded macrophyte
plant thats large enough to see epiphyte plant
growing on another organism but not a parasite
epifauna animal version of epiphyte
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Where are salt marshes found?

• Along intertidal shore of estuaries
• Flat, protected waters
• Extensive from Maine-Florida, along Gulf coast
  from Florida-Texas
• Roughly 163,228 acres in Galveston Bay alone in
  2005
• (NOAA 2006 Lester and Gonzalez 2008).

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Salt vs. Brackish vs. Freshwater marsh

• Whats the difference?
• Proximity to salt water
• Changes daily
• Still exhibit zonation in salt and brackish
  marshes
• Due to tidal influence
• Main difference is the plant species found at
  brackish vs. salt marsh
• Often the term Salt and Brackish marshes are
  used interchangeably

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Salt and Brackish marsh grasses

• Salt Marsh
• Spartina alterniflora
• Smooth cord grass
• Juncus roemerianus
• Black needle rush
• Cladium mariscoides
• Swamp sawgrass
• Spartina patens
• Salt meadow cord grass

Brackish Marsh Spartina alterniflora Smooth cord
grass Juncus roemerianus, -black
needlerush Phragmites australis - common reed
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Associated plants
Salicornia sp.

• Many are succulent
• Exceptions include saltgrass
• Many are edible (saltwort, glasswort, sea
  purslane)
• Form transitional zone between salt marsh and
  maritime forest

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Zonation at the salt marsh

• Zonation in general is caused by differences in
  climate or soil conditions.

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• Zonation depends on several factors two
  important ones are salinity and nutrient
  availability. Salinity changes depending on these
  conditions
• a. frequency of tidal inundation b.
  rainfall c. tidal creeks and drainage d.
  soil texture e. vegetation f. depth of
  water table g. freshwater inflow
• Nutrient availability also varies based on oxygen
  abundance

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Salt/Brackish marsh zonation

• Subtidal channel- channels which are permanently
  filled with water
• Mudflat- muddy, rocky, or sandy bottom. Only
  exposed at low tides. Algae prevalent
• Low marsh- underwater during high tides dry at
  high tide. Spartina, Juncus, Phragmites
• High marsh (above mean high water)Distichlis
  spicata, Batis maritima, Salicornia spp.,
  Borrichia sp., Sueda linearis, Limonium
  carolinanum

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The flooding and ebbing of the tides is one of
the most important forces shaping and influencing
the estuary.
Tidal waters flood the estuary twice each day
bringing nutrients, sediment, and oxygen rich
waters from the ocean. Tidal currents also
transport flora such as algae and fauna such as
fish, crabs, and shrimp into the estuary. The
tides shape the shoreline as they flood and ebb,
moving tons of sediment and water each day.
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High tides and low tides can make the same place
look very different.
Where rooted, flowering plants cannot withstand
the strong currents and salty, murky tidewater,
the mudflats are found. These areas are more
properly called tide flats since they may be
muddy, sandy, or even rocky. At the lowest
tides, the only visible water is contained in the
open water channel.
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Marsh Zones lower estuary (i.e. by the ocean,
need some salt water here)
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Estuary zones lower estuary
Subtidal channel
Support oyster, flounder, and other invertebrates
at low tide and serve as spawning and nursery
areas for aquatic animals.
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Estuary zones lower estuary
Subtidal channel
Mud flat
Mud flats are coastal wetlands that form when mud
is deposited By tides or rivers. They support
large populations of migratory Shorebirds,
crabs, mollusks and fish.
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Estuary zones lower estuary
Subtidal channel
Mud flat
low marsh
Low Marsh is flooded daily. Is shallow, silt
laden and salty. Home to many halophytes like
Spartina.
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The salt marsh community

• Plants
• Marsh grasses (various species described
  previously)
• Associated halophytic (salt-tolerant) plants
• Animals
• Permanent residents
• Visitors

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Resident animals

• Littorina irrorata
• Marsh periwinkle (snail)
• Crabs
• Fiddler crabs (Uca spp.)
• Marsh crabs (Sesarma spp.)
• Geukensia demissa
• Ribbed mussel

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Tidal Marsh Visitors

• Birds
• Crabs
• Shrimp
• Fish
• Diamondback terrapin

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• The majority of commercially-important marine
  species rely on estuaries/salt marsh at some
  stage of life
• Examples include blue crab, oysters, hard clams,
  shrimp, red drum, seatrout, sheepshead, bluefish,
  mullet

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Succession

• The progressive replacement of one dominant type
  of species or community by another in an
  ecosystem until a stable climax community is
  established

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Wrack

• Wrack, a mat of dead marsh grass gets washed up
  on the marsh, smothering all the plants below it
• The wrack is broken down or removed by flooding,
  leaving a bar patch of mud, or a salt pan.

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Succession

• 1) Water evaporates from the mud flat, leaving
  behind extra salt.
• 2) Salt loving plants (like Salicornia) move in
  to the area
• 3) As they grow the provide shade, which lowers
  water loss due to evaporation
• 4) Soil salinity decreases, and other salt
  tolerant plants move in now that the soil isnt
  as salty

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Succession

• This process constantly repeats itself
• Leads to a definite zonation of the marsh
  (subtidal channel, mud flat, low marsh, high
  marsh)