Lessons from the Bay : About the Watershed—An Instructional Framework

V. The Chesapeake Bay Watershed as an Ecological System
 
 
  1. Each watershed has characteristic life forms.
     
    1. The environment created and shaped by natural forces and modified by humans determines what life forms can occupy a watershed.
       
    2. Each species occupies a niche within the range of environments in which the species is found.
       
    3. All life forms show adaptations to the environments in which they live.
       
  2. All living elements of an ecological system are interdependent.
     
    1. Plants and animals in ecological systems live in a web of interdependence in which each species contributes to the functioning of the overall system.
       
    2. Food webs, energy chains, and the water cycle illustrate the interrelationships of all living things.
       
    3. In a healthy, functioning ecosystem, life forms and environmental factors interact to keep the Chesapeake Bay watershed populations in a long term dynamic equilibrium with each other and with their habitats.
       
    4. Diverse plant communities tend to support diverse wildlife in the Chesapeake Bay watershed communities.
       
    5. Some of the plants and wildlife populations living in the Chesapeake Bay watershed exhibit cyclic patterns over time.
       
    6. Water is necessary for all organisms, not just those living in water.
       
    7. Natural laws are binding on human populations and the Chesapeake Bay watershed.
       
  3. Variation and change occur in all ecological systems.
     
    1. All forms of life are affected by changes in their environments.
       
    2. The numbers and species of life forms within the Chesapeake Bay watershed are not static but are constantly changing.
       
    3. There may be a trend of continuous replacement of one natural community of life by another.
       
    4. Natural events and human activities affect the rate and direction of succession.
       
  4. Adaptation is continuous within all ecological systems.
     
    1. Plants and animals are adapted to living in different parts of a watershed: forests, fields, headwater or first order streams, wetlands, ponds, lakes, rivers, salt marshes, estuaries, and oceans.
       
    2. Each habitat is suitable only to those life forms that have adapted, over a number of generations, to its ecological conditions.
       
    3. Life forms adapt to their environments in ways that enable them to survive and maintain their numbers.
       
    4. Species with very specific habitat requirements tend to be less able to adjust to environmental change.
       
    5. Isolated ecosystems such as islands may develop specialized life forms, thus making these systems more vulnerable to environmental change.
       
  5. Living things tend to reproduce in numbers greater than their habitat can support.
     
    1. A population tends to increase in size until limited by one or more factors.
       
    2. Various mortality factors, such as disease, predation, climatic conditions, pollution, accidents, and shortages of life’s necessities, will cause a percentage of any population to die each year.
       
  6. Each area of land or water, and ultimately the planet, has a carrying capacity (the maximum number of individuals that a given environment can support without having detrimental effects) of plants and animals.
     
    1. Carrying capacity is determined by climatic, geological, biological, and/or behavioral factors along with human activities.
       
    2. Carrying capacity may vary from season to season and year to year.
       
    3. The numbers, health, and distribution of plants and animals within the Chesapeake Bay watershed are related to carrying capacity.
       
    4. The different elements within a watershed dictate the distribution of organisms within the watershed.

Resources
Bridging the Watershed.
<http://www.bridgingthewatershed.org/students.html>.

Online Field Guides. eNature.com. National Wildlife Federation.
<http://www.enature.com/>.

Plants and Animals. Chesapeake Bay Program.
<http://www.chesapeakebay.net/baybio.htm>.

Water Resources. U.S. Geological Survey.
<http://water.usgs.gov/education.html>.

What Is a Watershed, Anyway? Chesapeake Bay Foundation.
<http://www.cbf.org/site/PageServer?
pagename=back_watershed>.

What’s a Watershed? Conservation Technology Information Center, Purdue University.
<http://www.ctic.purdue.edu/KYW/glossary/whatisaws.html>.


Next: VI. Conservation, Restoration, and Stewardship of the Chesapeake Bay Watershed

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“About the Watershed” includes:
  I.  The History of the Chesapeake Bay and
  its Watershed
  II.  Geology of the Chesapeake Bay Watershed
  III.  Water and Sediments
  IV.  Elements of a Watershed
  V.  The Chesapeake Bay Watershed as an
  Ecological System
  VI.  Conservation, Restoration, and Stewardship
  of the Chesapeake Bay Watershed
  VII.  Chesapeake Bay Watershed Issues and
   Trends: Alternatives and Consequences
  VIII.  Careers for Water Enthusiasts
 

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Lessons from the Bay includes:
 · Process Model
 · About the Watershed—An Instructional Framework
 · Lesson Plans
 · Project Action Guide
 · Glossary of Wetland Terms