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Transcript of Water Resources
There are four major abiotic factors that impact water quality. (What does abiotic mean?)
The watershed is the region that drains into a stream system. As the rain falls on this area it follows the slope of the land to the low point, usually a river or lake and then it collects in that body of water. How the land is used in the area will have an impact on the quality of that ecosystem. How does development in the watershed affect water quality??
Water Quality Classification
Water quality is based on several aspects such as light penetration, productivity, dissolved oxygen, etc. There are two basic categories: Oligotrophic and Eutrophic
When we look at the distribution of rainfall world wide we see that it is not distributed evenly. The amount of rainfall in an area gives an indication of the amount of freshwater that is available for us to use.
Where is the water & what affects the quality?
What affects our water?
There are several factors that affect the quality of water. These are both biotic and abiotic. We will look at each factor and the impact it might have.
Energy is important to the production of aquatic plants and therefore animals. Even aquatic systems need to have a producer base in order to flourish. If there is not enough solar energy then the aquatic plants cannot be as productive as they should be and this can lead to a decline in the aquatic ecosystem.
However, too much solar energy can be just as bad if not worse. Warmer temperatures tend to lead to increased disease spread, can cause some species of animals to leave the system, and it causes a decrease in the amount of oxygen available.
Cloudy days decrease sunlight
Sediment can make the water cloudy and light wouldn't go as far
Deeper lakes tend to have less energy throughout the water
Composition is the material that makes up the bottom, or bed, of a body of water.
Sandy = more sediment floating in the water
Rocky = more habitat for organisms
Another important abiotic aspect of a water body is the amount of dissolved oxygen (DO) available in the system. Dissolved oxygen is vital to the survival of all organisms in the system. The amount of DO in the water will affect the types of organisms that will inhabit the area.
Biological Oxygen Demand (BOD)
This tells how much oxygen is needed by the organisms.
Higher BOD = less Dissolved Oxygen
High BOD usually indicates many bacteria and decomposers
The last abiotic factor that we will consider is nutrients. Nutrients are required by all plants and algae to grow and reproduce. More nutrients in a system, whether it’s aquatic or terrestrial, means more productivity. Generally this is a good thing, however in an aquatic system too much productivity can lead to lower water quality. Lots of algae means less light penetration.
The biotic factors of the aquatic system is both inside and out. The riparian corridor (the vegetation on the shores) is vital to the health of the system.
Decreased evaporation, lower temperature, shelter, and erosion control from the banks.
Check out this video on the watershed.
When you look at the watershed of the Grand River you may notice that it includes several urban areas and agricultural areas. These will increase runoff and nutrients into the Grand River.
The Grand River Watershed
Oligotrophic (Oh-li-go-tro-fic) systems are generally younger systems. They tend to have clear, cold waters, high dissolved oxygen, high diversity and low productivity. Lower productivity in an aquatic system is good because it decreases the amount of vegetation and decomposition the system will have.
A eutrophic (U-tro-fic) system is one that is usually older. It tends to have warmer waters, more productivity, cloudy water and low diversity. Many of these waters may have started out as oligotrophic but turned into eutrophic over time due to increased nutrient load into the system.
Do we cause eutrophication? We can, and often do, cause what is labeled as cultural eutrophication. Basically this is a speed up version of natural aquatic succession. The use of fertilizers increases nutrients (causing an increase in algae), pesticides (lower diversity), grass clippings and sewage (increase decomposition and lowers DO) and other runoff like salt, sediment, etc will affect the light penetration and diversity of organisms. An increase in these items leads to faster eutrophication of a body of water.
Water Resources Continues....
Make sure to go through the Water Module and go through the Water Resources Part 2 lesson.