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

Coastal Wetlands

: General Location Marine (undiluted salt water) Estuarine (salt/freshwater mix) Open coast Estuaries (deltas, lagoons) Wetland types Shrub wetland, salt marsh, mangrove swamp Brackish marsh, shrub wetland, salt marsh, mangrove swamp

Inland Wetlands

: Riverine (associated w/ rivers and streams) Lacustrine (associated w/ lakes) River channels and floodplains Lakes and deltas Palustrine (shallow ponds, misc. freshwater wetlands) Ponds, peatlands, uplands, ground water seeps Bottomlands, freshwater marsh, delta marsh Freshwater marsh, shrub and forest wetlands 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 (Hg 0 )

– –

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



CH 3 HG

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 ( swamp to me!

) sounds like a

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 + CO 2 + H 2 0



C 6 H 12 O 2 + O 2 CO 2 + H 2 0



H 2 CO 3



H + + HCO 3 -



2H + + CO 3 2 As CO 2 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.

Hydrilla Coontail Parrotfeather

Floating-Leaved Plants

Free Floating Plants

Emergent Plants

Special Adaptations

Wide at the base Called a buttress Cypress Tupelo 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.

Alligators also build nests from vegetation.

Some fish will attach their eggs to aquatic vegetation.

Too many plants can sometimes be a bad thing!

•

Block waterways

•

Deplete Oxygen