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Wetland Ecology
Wetlands – lands covered with
water all or part of a year
• Hydric (saturated) soils – saturated long enough to
create an anaerobic state in the soil horizon
• Hydrophytic plants – adapted to thrive in wetlands
despite the stresses of an anaerobic and flooded
environment
• Hydrologic regime – dynamic or dominant presence
of water
Wetland Classification Chart
Major Categories
General Location
Wetland types
Marine (undiluted salt
water)
Open coast
Shrub wetland, salt
marsh, mangrove swamp
Estuarine (salt/freshwater
mix)
Estuaries (deltas,
lagoons)
Brackish marsh, shrub
wetland, salt marsh,
mangrove swamp
Riverine (associated w/
rivers and streams)
River channels and
floodplains
Bottomlands, freshwater
marsh, delta marsh
Lacustrine (associated w/
lakes)
Lakes and deltas
Freshwater marsh, shrub
and forest wetlands
Coastal Wetlands:
Inland Wetlands:
Palustrine (shallow ponds, Ponds, peatlands,
misc. freshwater wetlands) uplands, ground
water seeps
Ephemeral ponds, tundra
peatland, ground water
spring oasis, bogs
Physical/Hydrological Functions of Wetlands
• Flood Control
– Correlation between wetland loss and downstream
flooding
– can capture, store, and slowly release water over a period
of time
• Coastal Protection
– Serve as storm buffers
• Ground Water Recharge
– Water has more time to percolate through the soil
• Sediment Traps
– Wetland plants help to remove sediment from flowing
water
• Atmospheric Equilibrium
– Can act as ‘sinks’ for excess carbon and sulfur
– Can return N back to the atmosphere (denitrification)
Chemical Functions of Wetlands
• Pollution Interception
– Nutrient uptake by plants
– Settle in anaerobic soil and become reduced
– Processed by bacterial action
• Toxic Residue Processing
– Buried and neutralized in soils, taken up by
plants, reduced through ion exchange
– Large-scale / long-term additions can exceed a
wetland’s capacity
– Some chemicals can become more dangerous in
wetlands (Mercury)
Mercury Chemistry
• Elememental mercury (Hg0)
– Most common form of environmental mercury
– High vapor pressure, low solubility, does not
combine with inorganic or organic ligands, not
available for methylation
• Mercurous Ion (Hg+)
– Combines with inorganic compounds only
– Can not be methylated
• Mercuric Ion (Hg++)
– Combines with inorganic and organic
compounds
– Can be methylated  CH3HG
Methylation
• Basically a biological process by microorganisms in
both sediment and water
– Mono- and dimethylmercury can be formed
– Dimethylmercury is highly volatile and is not
persistent in aquatic environments
• Influenced by environmnetal variables that affect both
the availability of mercuric ions for methylation and
the growth of the methylating microbial populations.
– Rates are higher in anoxic environments,
freshwater, and low pH
– Presence of organic matter can stimulate growth
of microbial populations, thus enhancing the
formation of methylmercury (sounds like a
swamp to me!)
Methylmercury Bioaccumulation
• Mercury is accumulated by fish, invertebrates,
mammals, and aquatic plants.
• Inorganic mercury is the dominate environmental
form of mercury, it is depurated about as fast as it is
taken up so it does not accumulate.
• Methylmercury can accumulate quickly but depurates
slowly, so it accumulates
– Also biomagnifies
• Percentage of methylmercury increases with
organism’s age.
Chemical Functions of Wetlands
• Waste Treatment
• High rate of biological activity
• Can consume a lot of waste
• Heavy deposition of sediments that bury waste
• High level of bacterial activity that breaks
down and neutralizes waste
• Several cities have begun to use wetlands for
waste treatment
Biological Functions of Wetlands
• Biological Production
– 6.4% of the Earth’s surface  24% of total global
productivity
– Detritus based food webs
• Habitat
– 80% of all breeding bird populations along with
>50% of the protected migratory bird species rely
on wetlands at some point in their life
– 95% of all U.S. commercial fish and shellfish
species depends on wetlands to some extent
Wetland Life – The Protists
• One celled organisms (algae, bacteria)
– Often have to deal with a lack of oxygen
• Desulfovibrio – genus of bacteria that can use
sulfur, in place of oxygen, as a final electron
acceptor
– Produces sulfides (rotten-egg smell)
• Other bacteria important in nutrient cycling
– Denitrification
Phytoplankton
• Single celled
• Base of aquatic food web
• Oxygen production
Photosynthesis:
Solar Energy + CO2 + H20  C6H12O2 + O2
CO2 + H20  H2CO3  H+ + HCO3-  2H+ + CO3 2-
As CO2 is removed from the water pH increases.
General Types of Aquatic Macrophytes
• Submergent – Plants that grow entirely under water.
Most are rooted at the bottom and some may have
flowers that extend above the water surface.
• Floating-leaved – Plants rooted to the bottom with
leaves that float on the water surface. Flowers are
normally above water.
• Free Floating – Plants not rooted to the bottom and
float on the surface.
• Emergent – herbaceous or woody plants that have the
majority of their vegetative parts above the surface of
the water.
Coontail
Hydrilla
Parrotfeather
Floating-Leaved
Plants
Free Floating
Plants
Emergent
Plants
Special Adaptations
Wide at
the base
Called a
buttress
Tupelo
Cypress
Previous
Student
Wetland Trees
I won this boat
Benefits of Aquatic Plants
• Primary Production
– Wildlife Food
– Oxygen Production
• Shelter
– Protection from predation for small fish
• Fish Spawning
– Several fish attach eggs to aquatic macrophytes
– Some fish build nests in plant beds
• Water Treatment
– Wetland plants are very effective at removing
nitrogen and phosphorous from polluted waters
Submerged macrophytes can provide shelter for
young fish as well as house an abundant food
supply.
Some fish will attach
their eggs to aquatic
vegetation.
Alligators also build
nests from vegetation.
Too many plants can sometimes be a bad thing!
•Block waterways
•Deplete Oxygen