"What Makes a Quality Lake? "

Answer Key

Name: ________________________________________________________

Class Period:______________________ Date:______________________


1. The rapid growth in Florida’s population has affected many lakes. List three changes that have occurred in Florida lakes due to rapid population growth.  

  a. less wildlife

  b.  changes in water quality from increased nutrients

  c. increased sediments in lakes


2. Lakes have many different uses in Florida. List several examples of these uses.         

Recreational fishing, commercial fishing, boating, skiing, swimming, bird watching                            


3. List key concept ideas for the following words:  


4. There are four trophic state categories used to describe lakes. Define each of them briefly.


5. Explain the effects of nitrogen and phosphorous on a lake's water quality:

Nitrogen and phosphorous are nutrients that enable plants to grow, including algae. When these two nutrients are increased, water clarity usually decreases due to a greater abundance of algae. More nutrients also means there might be a greater abundance of large plants (macrophytes). 


6. Describe how water flush rates affect the nutrient levels in a lake.

A fast flush rate doe not allow the nutrients to be used by the plants, whereas a slow flush rate allows more nutrients to be taken up by algae and large plants (macrophytes).


7. Several different factors can affect the sedimentation rates in a lake. Please discuss how the following two factors might influence sedimentation.


Increased nutrients: Increased nutrients from lawn fertilizers, agriculture, and other sources contribute to increased nutrients in the lakes via runoff.  The increase in nutrients promotes more plant growth. As plants grow and then degrade, the rotting materials settle to the bottom of the lake, increasing muck layers (sediments).


Flushing rate: a fast flushing rate in a lake decreases the nutrients available for plant growth, therefore there are not as many plants or algae.  With fewer plants, degradation of materials is not as great and there is less sedimentation.


8. Humans can have a direct impact on lakes. Examples include housing development, recreational boating activities, industry, agriculture and aquaculture.  What are some of the changes that occur in lakes due to human impact?

Nutrient levels may increase from more lawns being fertilized and algae blooms will reduce water clarity; sediments may increase from nearby construction sites or land-clearing activities, reducing water clarity;  wildlife habitats are altered when plants and trees are removed for development; wildlife often leave the area for lack of habitat or food; or in some instances, a lake may actually become more productive from the nutrients and wildlife may be increased.

9. Water clarity in a lake can be affected by various factors. Explain how the following two factors can change water clarity.



10.  Fill in the blanks:

a. The presence of aquatic plants will generally not improve water quality unless at least 50%  of the bottom is covered with submersed plants.

b. A eutrophic lake is not a dead lake. Instead it is a productive lake.

Center for Aquatic and Invasive Plants, UF/IFAS

A collaboration of the UF/IFAS Center for Aquatic and Invasive Plants
and the Department of Environmental Protection, Bureau of Invasive Plant Management.
HS/EA 6/08/06
SSS: SC.F.1.4, SC.G.1.4, SC.G.2.4, SC.H.1.4, SC.H.2.4, SC.H.3.4, LA.A.1.4, LA.B.1.4, LA.B.2.4