FRESHWATER (Lentic v Lotic)

Freshwater ecosystems are important for maintaining the water cycle and providing a habitat for organisms and drinking water for us.  Find more information HERE.

Freshwater systems are typically divided into 2 groups: still (LENTIC) and moving (LOTIC) water systems. 

Abiotic factors such as light and nutrients will determine the diversity and life of a lake or pond.  Ponds are defined as smaller bodies of water where the light can reach the bottom. 
Lakes are larger bodies and have different divisions or zones in which organisms can survive. 

Lakes have life spans that are affected by other abiotic factors such as pollution from runoff or groundwater seeping in. Lakes that have little extra nutrients are called oligotrophic vs. lakes with excess nutrients, resulting in high plant growth and great biodiversity (for a while).
 Zones of Life in Oligotrophic

 Zones of life in Eutrophic Lake

The sides of a lake are known as the littoral zone--this is where many plants grow, either as submerged, emergent or floating plants. 
Lakes are filled by rainwater and groundwater, but also by rivers and streams which converge into one large depression in the land or where humans have impacted the environment by damming the river. 

Rivers and streams bring the water from the highest point of the watershed (the divide) into the lakes and ponds within the drainage area. Rivers are important shapers of the earth... carving channels and valleys over time. A vast majority of rivers originate in hills and mountains or are formed as a result of melting glaciers. Rain water and the melting snow fall down the mountains in the form of multiple streams that meet at a confluence where the water body becomes large and gets transformed into a river. This water forces down because of gravity and finally becomes slow on reaching the ground. Rivers are deeper than streams.River carries the sediments brought into it by streams into larger water bodies such as ocean or a lake. Unlike streams, rivers flow within wider banks.
Another important zone on the edges of streams and rivers is called the Riparian Zone.
In many areas, once rivers begin to come close to the coast or ocean, they begin to slow down and often spread out into widespread WETLAND areas.  Wetlands can also develop on the edges of lakes where rivers and streams enter or exit that part of the watershed. 

These areas are very important in many ways. 
Freshwater Careers

Subpages (1): Frog Dissection
Christy Croll,
Oct 15, 2015, 9:18 AM
Christy Croll,
Oct 15, 2015, 9:19 AM