Transcript Wetlands
Standing Water Systems • Freshwater systems are classified as either lotic (meaning moving water) or lentic (meaning standing water) One type of lentic system is a Wetland An area of land that is covered with a shallow layer of water during some or all of the year What you should know about wetlands • Two groupings – salt water and freshwater, • Salt water wetlands house organisms that can tolerate the muddy bottoms and levels of salinity (salt) • Freshwater wetlands can vary greatly in amounts of water, acidity, and types of plant life ranging from trees to moss to grasses • There are at least 14 different types of wetlands; however, we will focus on the main five Functions and Values of Wetlands • Flood control – wetlands function like natural sponges, storing water and slowly releasing it • Natural Filtration – After being slowed by a wetland, water moves around plants, allowing the suspended sediment to drop out and settle to the wetland floor • Habitat – Wetlands are some of the most biologically productive ecosystems, comparable to the rainforests or coral reefs. This nutrient-rich habitat is home to many different types of plants and animals Freshwater Marsh periodically saturated or flooded with water; filled with many (non-woody) plants adapted to wet soil Bog freshwater wetland characterized by spongy peat deposits, a growth of evergreen trees and shrubs; and a floor covered with sphagnum moss. They tend to be acidic. Swamp freshwater swamp is fed primarily by surface water inputs dominated by trees and shrubs; they have very wet soils during the growing season and standing water during certain times of the year Saltwater Marsh A wetland that is high in salt content; influenced by the tides so life in it must be very tolerant of saline and changing conditions in and out of water for part of the day. Usually filled with many different types of grasses such as cord grass, salt-grass, and glasswort Estuary a wetland filled with brackish water (water that mixes salt and freshwater); very rich in nutrients and a wide diversity of life; a place where freshwater stream puts into the ocean Mangrove Swamp a wetland that also is found along the coast; brackish water; environment characterized by special salt-tolerant trees, shrubs, and other plants capable of growing in such conditions; trees have special roots that help anchor the tree against tropical winds and storms Ponds and Lakes • Like wetlands, ponds and lakes are considered lentic water systems. Ponds • Not all ponds exist year-round. For example, in the northern and western US some ponds appear only in the spring when runoff from spring rains and melting snow collect in low areas. The ponds often dry up in midsummer as the shallow water quickly evaporates. These are often called vernal ponds. • Ponds in colder climates often freeze over in the winter. Living things in the pond survive in the liquid water below the frozen ice. Lakes are formed in five ways. 1. A cut-off river meander may become an oxbow lake. 2.Ice sheets melted from glaciers may created lakes in the depressions of the Earth’s crust due to the heavy layers of ice. 3. Movements in the Earth’s crust may create deep valleys allowing lakes to form such as Lake Tanganyika in Africa. 4. Empty craters (known as calderas) may be formed from volcanic eruptions such as Crater Lake in Oregon. 5. Lakes known as reservoirs are man-made and can be used to store drinking water , such as the one at Memorial Lake. Threats to Water Systems • 1. Mankind- People are one of the greatest threats to a standing water system due to pollution, over-developing an area, changing the surface of the land (such as putting in more roads, etc.). Threats continued • 2. Too many nutrients - Put into a standing water system, this poses a great threat through a process called eutrophication. • This process can be caused naturally or unnaturally (by man). The process begins as algae and other organisms add nutrients to a lake. These nutrients support plant life. If too many nutrients are added, then the algae begins to crowd out the lake creating lots of decaying matter and robbing this system of the necessary oxygen to support the life within it. Finally, the plants completely fill the lake creating a grassy meadow. In a moving water system this process may also occur creating an area known as a dead zone unable to support life. What can be done to protect these systems? • Beginning in the 1970s, government enacted laws to protect wetland habitats. In PA for every acre of wetland you destroy you must create two acres of wetlands. • Effective drainage systems can direct run-off water so that it can get the wetland areas. IN addition, retention ponds are also being created. This is a type of manmade wetland where large volumes of water can be held and then slowly released back into a water system. • Creating effective sewage treatment plants and revising our farming practices to cut down on excess nutrients from entering the system. • As consumers, we can elect to purchase eco-friendly products such as shampoos and cleaners that reduce the phosphates or nitrates we pour down the drain. • Plant more trees and shrubs to help hold back soil and excess nutrients. This is known as a riparian buffer.