3WetlandsBogs, swamps, and marshes are wetlands. All wetlands have waterlogged soil. Bogs and swamps are flooded, but a marsh is wet only part of the year. Some wetlands are flooded with salty ocean water; others are covered with fresh water from rivers and lakes.
7Wetland climateUnlike some other biomes, wetlands do not have a characteristic climate. They exist in polar, temperate, and tropical zones, although usually not in deserts. However, they are very sensitive to changes in climate, such as a decrease in precipitation (rain, sleet, or snow). The amount of precipitation and changes in temperature affect the growth rate of wetland plants. Some wetlands are seasonal, which means that they are dry for one or more seasons of the year.
8Wetland soilWetland soils are known for their wetness but they should also be known for their high organic content. Most wetland soils have a higher amount of organic material than terrestrial soils.
9Wetland plantsMore than 5,000 species of plants live in or near wetlands. Wetlands have high biological productivity (the rate at which life forms grow in a certain period of time).The kinds of plants that may be found in a wetland are determined by several factors, especially the type of soil and the quantity of water.Some plants grow only in water or extremely wet soil. Other plants need moist but not saturated soil. When a wetland dries up, the area fills with plants adapted to life in dry habitats and can survive where other wetland plants would wilt.
12AnimalsWetlands have been called "biological supermarkets." Besides animals that live there permanently, many nonwetland animals visit for food and water.Wetland conditions make it necessary for the animals that live there permanently to adapt in special ways.
16RiversThese are bodies of flowing water moving in one direction. Streams and rivers can be found everywhere—they get their starts at headwaters, which may be springs, snowmelt or even lakes, and then travel all the way to their mouths, usually another water channel or the ocean. The characteristics of a river or stream change during the journey from the source to the mouth.
18Conditions in RiversThe temperature is cooler at the source than it is at the mouth. The water is also clearer, has higher oxygen levels.Towards the middle part of the stream/river, the width increases, as does species diversity—numerous aquatic green plants and algae can be found.Toward the mouth of the river/stream, the water becomes murky from all the sediments that it has picked up upstream, decreasing the amount of light that can penetrate through the water. Since there is less light, there is less diversity of flora, and because of the lower oxygen levels, fish that require less oxygen.
19River plantsIn fast streams and rivers many plants have special structures that keep them from being carried away by the water. Some aquatic plants have strong roots that keep them anchored securely, while others have stems that bend easily with the movement of the water. Certain mosses are able to cling to rocks.
24LakesThese regions range in size from just a few square meters to thousands of square kilometres. Scattered throughout the Earth. Many ponds are seasonal, lasting just a couple of months while lakes may exist for hundreds of years or more. Ponds and lakes may have limited species diversity since they are often isolated from one another and from other water sources like rivers and oceans.
26Conditions in LakesThe zone, which is closet to the shore is host to a wide variety of species due to its warm, shallow environment. Various species of invertebrates, crustaceans, plants and amphibians thrive in this environment, and in turn provide food for predators such as birds, reptiles and other creatures inhabiting the shoreline.The open water near the surface of a lake or pond, is home to a variety of phytoplankton, and zooplankton, which play an important role in the food chain. Several species of freshwater fish such as bass and lake trout can also be found this area, mainly feeding on insects and plankton. The deeper region of a lake is shrouded in darkness, and serves as a repository for dead plankton, and is inhabited by creatures which feed mostly on decaying organisms.
27Lake plantsUnderwater plants need to stay close to the water's surface so sunlight can reach them. Some freshwater plants, such as water lilies, grow flowers and leaves that float on the water's surface.
29Lake animalsMany types of animals live in ponds because they are not in danger of being swept away by a current. Insects, birds, turtles, frogs, and fish are some of the animals you can find in ponds and lakes.In regions with colder climate some animals have to hibernate during winter.
32People IWithout freshwater biomes we would not be alive. Freshwater ecosystems are important because they provide us water for drinking; energy and transportation.Dams may provide pollution-free energy, and create lakes for people to enjoy, but they can also damage the environment. Salmon are a species that use rivers to spawn, and are often hurt by dams.Wetlands are also an important type of freshwater ecosystem. They may be soggy and stinky, but they provide critical habitat for tons of plants and animals, help clean our water, control floods, and provide food for humans.By fertilizing the lawn with chemicals and allowing our cars to drip nasty oils and fluids we are polluting freshwater biomes. The rain carries these pollutants into rivers, streams, lakes and ponds.