Transcript Wetlands

Fresh Water Systems
• Fresh water systems are classified as
either lotic (meaning moving water)
or lentic (meaning standing water)
Freshwater Systems
• Frayer Diagram
Ponds and Lakes
Ponds and lakes are considered lentic
water systems. These are standing water
systems.
Activator
• Bill Nye's Lakes and Ponds
Lakes are formed in at least 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
or craters formed from meteorites can
leave depressions for lakes to form.
5. Lakes known as reservoirs are man-made and can be used to store
drinking water such as the one at Memorial Lake.
Ponds
• Generally, ponds are shallower than lakes. This allows sunlight to
reach the bottom so that more vegetation can grow in a pond often
attracting a greater biodiversity of life.
• 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.
Threats to Water Systems
Lake Erie
• 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
to support life.
Lake Turnover (demo)
•
Particularly in cool, northern areas of North America, many lakes undergo changes
with the seasons. In the summer, the sun warms the upper layer of water in the lake.
The warm water floats on top of the cooler, dense lower layer. In fall, the top layer
cools off, too. As the water cools, it becomes denser and sinks. This causes the lake
waters to mix together. As the water mixes, minerals, plant matter, and other
nutrients rise from the lake bottom to the surface. This is called lake turnover helps
refresh the supply of nutrients throughout the lake.
Another type of lentic system is a
Wetlands
An area of land that is covered
with a shallow layer of water
during some or all of the year
Why are wetlands important?
•
Long regarded as wastelands, wetlands are now recognized as
important features in the landscape that provide numerous benefits
for people, fish, and wildlife.
1. Flood Control – Wetlands function like natural sponges, storing water and
slowly releasing it. This process slows the water’s momentum and erosive
potential, reduces floods heights, and allows ground water to recharge.
2. Natural Filtration – After being slowed by a wetland, water moves around
plants, allowing suspended sediment to drop out and settle to the wetland
floor. In many cases, this filtration process removes much of the water’s
nutrients and pollutant load by the time it leaves the wetland.
3. Habitat – Wetlands are some of the most biologically diverse ecosystems in
the world, comparable to a rainforest or coral reef in regards to the amount
of life in which it can support. The nutrient-rich habitat is home to many
different types of plants and animals.
There are at least fourteen
different types of wetlands
Here are some of them…
Freshwater Marsh
periodically saturated or flooded with water; filled with many herbaceous
(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
Wetland Concept Map
Everglades Ecosystem
Hurricane Katrina/wetlands?
• PBS predicts Hurricane Katrina Disaster
What can be done to protect
lentic 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.
Bill Nye’s Wetlands
• Wetlands