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Chapter 10
Wetlands
I. What determines a Wetland?
A. The nature and properties of wetlands
varies widely in Texas and worldwide,
wetlands are typically defined by:
1. Wetland hydrology-water that is
present for part or all of the year, at or
above the surface, or within the root
zone.
2. Wetland soils - soil characteristics
that differ from surrounding uplands.
3. Wetland vegetation - wetlands will
contain plants that are adapted to the
presence of water, and generally lack
plants that are intolerant of wet
conditions.
B. Formation-from geological or ecological
factors such as: tidal flows, flooding
rivers, connections with groundwater, or
because they are above aquifers or
potholes.
C. Characteristics
1. Found all over the world in lowland
areas or along rivers, lakes and streams
2. Most are temporary and seasonal;
usually occurring for a few weeks at a
time.
3. Some wetlands are always under water.
D. Approximately 90% of Texas’ saltwater and
freshwater fish species depend on
wetlands for food, spawning, and nursery
grounds.
Texas coastal wetlands, an image in Texas
Aquatic Science by author Rudolph Rosen
E. Within an acre of wetland you can find
more kinds of animals and plants species
than in most any other kind of ecosystem,
making it one of the most biologically
diverse on the planet.
F. Examples of Organisms
1. Plants- cattails, rushes and
other tall grass-like plants,
bald cypress trees.
2. Animals- turtles, otters,
alligators, herons
and many migratory
species.
II. Role of Wetlands in an Ecosystem
A. Prevent flooding by holding water much
like a sponge.
B. Helps keep river levels normal by
accepting and releasing water.
C. Wetlands purify water by filtering out
sedimentation, decomposing vegetative
matter and converting chemicals into
useable form.
D. The ability of wetlands to recycle nutrients
makes them critical in the earth’s
functioning.
E. No other ecosystem type is as productive
or unique in the conversion process.
F. The natural process of purification:
III. Texas Wetlands are divided into two
broad categories: Freshwater and Coastal.
A. Freshwater wetlands form wherever
shallow water collects on the land.
1. The types are river floodplains,
bottomland, hardwoods, marshes,
seeps, springs, ponds, playa lakes,
sloughs, oxbows, swamps, along many
stream banks and lake areas, and
places where the water table reaches
the surface.
2. Freshwater wetlands plant species have
adapted to life where water levels may
fluctuate. Many of these species can
withstand periods
when wetlands
may become dry.
3. Cattail leaves
have spaces
that transport
air to the roots.
Credit: Missouri Department of Conservation
B. Coastal wetlands form where
saltwater and freshwater mix.
1. The types are coastal shorelines,
shallow bays and inlets, and swamps,
marshes, mud flats, and deltas of our
coastal lowlands and estuaries.
2. Coastal wetland plant species must be
able to survive changes in salinity and
water level, due to changes in amount of
freshwater inflow and tidal fluctuations in
water level.
C. Texas wetland ecosystems are divided into 6 regions.