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Chesapeake Bay

Grades 9-10 | Informative | Source-Based

Source Lexile®: 1100L-1140L

Learning Standards

 

 

 

Prompt: Today you will read two texts, “The Chesapeake Bay Ecosystem” and “Saving the Blue Crab.” You will also analyze data from three graphs representing the relationships between nutrients entering the Bay, amount of algae growth, and population trends for oysters and blue crabs.

 

Write an essay that serves as an action plan for a proposal to restore the health of the Bay and the types of activities that need to be modified to achieve a successful restoration. Be sure to reference the texts and graphs in your response addressing the following focus points:

  • Types of human activity that affect the Bay’s health.

  • The importance for restoring the Bay’s health.

  • Action plans or steps that could be taken to restore the health of the Bay.

 

Use evidence and data presented in the texts and graphs to support and enhance your response.

 

 

 

Source 1

"The Chesapeake Bay Ecosystem"
From dnr.maryland.gov

 

Human Impact on the Chesapeake Bay

 

  1. Like a human, plant or animal, the Chesapeake Bay watershed is a complex, living system. Interconnected habitats and living things like this are called ecosystems. The Bay is a very large ecosystem. It is made up of smaller ecosystems including forests, streams and marshes. Ecosystems work through the plants and animals that live in them. In a healthy ecosystem, plants and animals can benefit each other in a cycle of energy. Plants use solar energy to grow, transforming nutrients from the decay and waste of other living things. Animals eat the plants and recycle the nutrients, through their wastes and by their death and decay, for the use of other living things. The same process occurs on the land, in terrestrial ecosystems, and in the water, in aquatic ecosystems. Ecosystems continue to thrive when the energy from the nutrients in this cycle is not wasted or lost, but is stored and recycled.
     
  2. More humans in an ecosystem means more energy is diverted for our use. Residential developments replace wetlands, forests and meadows. Every day, new development is bringing new housing, shopping malls and office buildings to the Bay watershed. Producing electricity, diverting water for human uses, and building roads, houses and sewage treatment plants put stress on the ecosystem of the Chesapeake Bay. Each action, be it turning on a faucet, paving a road, or cutting down a tree, represents a change in the natural balance of the Bay’s ecosystem. Actions far away from the Bay but within its watershed affect it.
     
  3. In 17th and 18th century Europe, only landowners could use natural resources, and only royalty and aristocrats were landowners. An average citizen could not cut down a tree and use it for firewood or catch a fish to eat. Early European settlers thus came to America with a strong sense that natural resources necessary to support life, like wildlife and firewood, should belong to everyone. They also believed that anyone should be able to own property. These ideas were imposed on a Native American culture that held all natural resources to be common property.
     
  4. The new found freedom to make individual decisions on the use of land and resources has resulted in unintended environmental consequences. Large tracts of land were cleared for various uses, leading to loss of forests and habitat. Intensive hunting practices led to the serious decline or extinction of some species like bison, turkeys, wolves and certain fish. The cumulative effect of our land use practices is now most in evidence in the degraded condition of the Bay.

 

Attack of the Soil
 

  • Towns along the Bay and its rivers, like Georgetown, Bladensburg, and Port Tobacco, originally served merchant ships which came to pick up tobacco and other crops to take to Europe. Many of these towns are far upstream on the Patuxent, Potomac and other rivers. Today, we could not imagine a ship coming up this far because the rivers are now so shallow. They are shallow because of sedimentation, which means that the soil from the land washed into the rivers and filled them with sediment. When the settlers cut down forests to make tobacco and corn fields, the soil was washed into the rivers, and eventually the Bay, by the rain. Urban and suburban development has also contributed sediment to the Bay. As land development has occurred, soil has continued to wash into the Bay and its rivers, covering up oysters and fish spawning areas.
     
  • Other things are carried into the Bay from these areas when it rains, like chemicals from the tar on roads; fertilizers and pesticides from lawns and farms; soap from people washing their cars; and trash that is thrown on the ground. These are called non-point source pollutants because they run off the land and do not come from particular, identifiable places.

 

Pollution Solution

  • Many industries that rely on water for cooling like power plants and steel factories, settled in the Chesapeake Bay watershed. They heat the water before returning it to the Bay or its tributaries. This has been found to change the habitat for some fish species and contribute to the growth of algae. Excessive algae block sunlight from the Bay’s underwater plants, which are needed for food for fish and wildlife. Industries along the Bay and its tributaries also produce chemicals that cause harm to animals and plants that need the water to live. And waste from people’s homes, stores and offices is also treated and discharged into the Bay and its rivers. Wastewater that is discharged into the Bay is called point-source pollution because it comes from a particular place. For many years, most people thought that enough water could dilute any kind of pollution. By the 1920's fish, crabs and oysters began to die in the Chesapeake Bay as well as other estuaries in the U.S. People became concerned. We now know that water is not a solution for pollution; now Federal, state and local governments have programs to protect and restore the Bay’s water. Today, we have new technologies and informed and caring citizens to help solve pollution problems. We can recycle waste and conserve water. We restrict point source pollutants and require stormwater management in new developments to slow down rainwater and help keep it from washing materials into the Bay. We have smart growth laws that help make development more compatible with the environment and we require forest conservation for areas that are disturbed by development. These measures have begun to improve the health of the Bay, but we can still do a lot more.

 

Plants and Animals Respond
 

  • Although the effect of our human actions on the plants and animals and their diversity is not as visible as polluted air and water, we must remember that while certain animal species can adapt to a human-dominated landscape, many species cannot. Today, elk, wolves and cougars are extinct in Maryland. Less noticeable, but no less devastating to the Chesapeake Bay ecosystem, has been the decline or extinction of plants like the atamasco lily - only one small population is left on Maryland’s Coastal Plain.
     
  • We have seen, in the more recent past, a decline in rock fish (striped bass), migratory Canada geese, and canvasback ducks. A combination of overuse, habitat loss and pollution led to these declines. Allowing these resources to recover, by cleaning up their habitat and regulating hunting and fishing, has resulted in success for rock fish and is expected to help other species. And in recent years, pelicans and cormorants have made a comeback. Beaver were once extinct in Maryland and now are very common, even in residential developments.

 

 

 

Source 2

"Saving the Blue Crab"

 

 

Excess Nutrients in the Chesapeake Bay Make Survival Difficult

 

Recently, the blue crab has been in the headlines because of reduced catches by commercial and recreational Chesapeake Bay crabbers. While harvesting is a major factor in affecting the crab population, loss of habitat has also contributed to the problem. To understand how this loss of habitat occurs, it is first necessary to understand how excess nutrients affect the Bay. The Chesapeake Bay is like a soup. Both are composed of many ingredients.
 

But just as too much of any ingredient can spoil the flavor of the soup, too much of a particular substance can harm the Bay. The current problem with the Bay is too many nutrients. Nutrients are substances that help plants grow. The most important nutrients are nitrogen and phosphorus. Plant and animal matter (including human waste), fertilizer, and even deposition from car exhaust and power plants all contain nutrients. If not treated, these nutrients will find their way into creeks, rivers and eventually the Bay.

 

How Excess Nutrients Harm the Bay

 

Once the nutrients are in the Bay, they become food for plants. But excess nutrients cause too much plant growth, especially algae (microscopic floating plants). When there is too much algae, the water becomes cloudy and blocks the light needed by underwater plants called submerged aquatic vegetation (SAV). Algae can also coat the leaves of the SAV, further reducing the amount of light received by the plants. SAV are very important to blue crabs because they provide food, shelter and nursery areas. Research has shown that the density of juvenile crabs is ten times greater in SAV beds than in unvegetated Bay areas.
 

An excess amount of algae can also cause other problems. When the algae die, they settle to the bottom where they are naturally decomposed by bacteria. During this normal decompositional process, the bacteria use dissolved oxygen from the Bay's bottom waters. When large amounts of algae are decomposed by bacteria, the removal of dissolved oxygen is substantially increased. This dissolved oxygen is needed by blue crabs and other organisms living on and near the bottom. The resulting low dissolved oxygen concentrations drive blue crabs from their preferred habitat and kill many of the small bottom organisms on which the blue crabs feed. This situation worsens in the summer when several natural factors act to further lower the amount of dissolved oxygen in the Bay's water. The low dissolved oxygen conditions caused by excess nutrients are the primary reason large bottom sections of the Bay are unsuitable as blue crab habitat.

 

 

 

 

 

What is Being Done about Excess Nutrients

 

Reducing nutrient pollution has been a priority of the Chesapeake Bay cleanup for over a decade. Progress is being made due to the combined efforts of citizens, industry and the government. Since 1985, Maryland has greatly reduced phosphorus and nitrogen pollution. We are already seeing results in the Bay and its tributaries such as cleaner water and more Bay grasses. These improvements show that the cleanup is on the right track.

 

 

 

 

Source 3

"Breakdown of Nutrients Entering the Bay" (graph)
From virginiaplaces.org

 


 

 

 

 

Source 4

"Blue Crab Population in the Chesapeake Bay" (graph)
From ecosystemsontheedge.org

 

 

 

 

Source 5

"Oyster Landings & Floating Algae/Sea Floor Algae Ratio in the Chesapeake" (graph)
From amnh.org


 

 

 

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