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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.