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 Coastal Wetlands: 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 Inland Wetlands: 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 Palustrine (shallow ponds, misc. freshwater wetlands) Ponds, peatlands, 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) Mercurous Ion (Hg+) 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 Mono- and dimethylmercury can be formed 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 Solar Energy + CO2 + H20  C6H12O2 + O2 Photosynthesis: 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

Wetland Trees Wide at the base Tupelo Called a buttress 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