Carrie Jones
Lesson Plan #1- Pre-workshop assignment
What is a salt marsh and how are they beneficial to our environment?
A. Standards
National—Content standard A: Science as Inquiry
Content standard C: Life Science
State—B-6: The student will demonstrate an understanding of the interrelationships
among organisms and the biotic and abiotic components of their environments
B. Performance objectives
Following completion of this lesson, students will be able to:
 Understand the ecosystem of a salt marsh and how a salt marsh functions
 Identify the benefits of a salt marsh
 Define eutrophication and the process of how it occurs
 Conclude ways to reduce pollution
C. Lesson Plan
1. Concept Exploration
Present the students with blue crab data to illustrate that many organisms
are suffering and ask the students why they think the population is doing so
poorly (www.chesapeakebay.net/crabs.aspx?menuitem=15241). More than
1/3 of the nation’s blue crab catch comes from the Chesapeake Bay and it is a
very important economic fishery for Maryland and Virginia.
“Since the early 1990s, there has been a dramatic decrease in Bay-wide blue crab landings.
Commercial crabbers have also increased their fishing effort, but are catching fewer crabs per
amount of effort than in years past. These occurrences likely relate to recruitment overfishing, when
large removals of adults from the stock result in fewer juveniles being produced.
The 2007 Chesapeake blue crab harvest of 44.2 million pounds was among the lowest recorded
since 1945. The low harvest corresponds with low stock abundance, but also reflects restrictive
management measures in place since 2001 and 2002. While the crab harvest remains near record
lows, the percentage of Bay crabs harvested remains high: an estimated 60 percent of the Bay's
available blue crabs were caught in 2007—considerably more than the target harvest of 46 percent.
How is habitat loss a pressure on blue crabs?
Reduced acreage of underwater bay grasses due to poor water quality and irregular weather
conditions has also been linked to the decline of blue crabs. Bay grass beds provide important
habitat for blue crabs by protecting juveniles, molting adults and feeding adults from predators.
Field experiments have shown that underwater bay grasses substantially reduce predation on
juvenile blue crabs, and also result in higher growth rates compared to crabs living in unvegetated
areas.
In addition to habitat loss, debate has grown over the effect of increased predation on the blue crab
stock. Predatory fish like striped bass and Atlantic croaker—whose populations are currently very
high—may rely on juvenile blue crabs as part of their diet, affecting the abundance of blue crab
recruits (age 0 crabs). “
Taken from www.chesapeakebay.net
This should introduce the concept of pollution.
Engage them with the event that an oil factory is being built right next to the
ocean and it is their job to figure out what type of natural barrier substrate will
help prevent pollution. Present the students with four graduated cylinders,
each filled with a different material such as mud, sand, gravel and mud with
vegetation. Ask the students to touch the materials and hypothesize which
material they think will allow the most water to go through the material and
why they think that. Introduce the term porosity and show them a sponge or
another object with open spaces and have them experiment with beakers of
water and pouring the water in the different materials to see which material
has the most open spaces. Possibly have some other materials they can
choose from to experiment with.
2. Concept Introduction
Ask the students how many people have been to a salt marsh or to name
an example of where a local salt marsh is located. Salt marshes occur where
the land and sea meet, usually behind an estuary or sound and only on the
coasts. South Carolina has the most marsh acreage of any other Atlantic coast
state (344,500 acres of salt marsh)
(http://www.dnr.sc.gov/marine/pub/seascience/dynamic.html). They are
among the most productive ecosystems and contain specific types of plants
which are salt-tolerant and regularly exposed to wet and dry conditions since
the marsh is influenced by the tides. Because of these conditions, these plants
are limited to just salt marshes, which is a good way to identify you are in a
salt marsh. Smooth cordgrass (Spartina alterniflora) dominates the low
marsh. There are also different zones of the salt marsh where different plants
and animals are found. The low marsh is the area directly next to the water
and floods twice daily. The high marsh only floods during storms and
unusually high tides, so there is more of a variety of different kinds of plants
such as needlerush, salt meadow cordgrass and short-form smooth cordgrass.
Animals don’t really eat the plants, but the plants decompose and provide
nutrients to the many organisms found in the salt marsh. The marsh serves as
a nursery ground and refuge for many fish, shellfish, crustaceans and
plankton. They also are beneficial as they act as a buffer against storms. The
numerous, hardy plants help keep the soil in place and protect the shoreline.
In the porosity experiment, the students should have observed depressions in
the mud when they poured the water in. The mud with the vegetation should
have held in place better. Not only does the mud and marsh plants hold the
sediment in place, but also helps to buffer against coastal pollution and runoff.
Ask the class to brainstorm causes of pollution and write them on the board.
Then, have the students go online and answer the questions on the worksheet
provided at the end of the lesson plan. Have the students work in groups to
complete the questions but walk around and make sure all members are
participating. The websites are:
www.knowitall.org/sclife/test.html
www.epa.gov/owow/estuaries/kids/
3. Concept Application
The problem is: salt marshes are disappearing. Many marshes have been
filled in or dredged in order to create more land. Over half of the United
States population has moved towards the coastal areas, which has increased
pollution and runoff to our coastal ecosystems. If the salt marshes are
disappearing, the impact of pollution on the ecosystem without a buffer can be
considerable. Excess nutrients, such as from fertilizers and runoff causes
eutrophication, which results in excessive plant growth and decay. Observe
how this process occurs by building a mini ecosystem in a plastic tray. Use
gravel and clay to build roads and houses on one side of the tray and the other
side of the tray represents a body of water. Remind the students of the oil
factory event at the beginning of the lesson and tell them to build a system
which will prevent the most amount of oil from entering the ocean. Provide
all the materials needed such as plants, sticks, sponges and paper. Use
different types of food, paper, oil and food coloring to represent pollution.
Then pour water on the land to see where the pollution goes. Then ask what
household item that you’ve provided may represent the salt marsh. Pour the
polluted water out into a beaker. Each group should pour a set amount of
pollution (such as 50ml veg. oil, 10 sprinkles, 5 drops of food coloring, and 5
pieces of paper) and see which group prevents the most amount of pollution
from entering the ocean.
D. Review/Evaluation
Review their understanding from the worksheet and discussion on pollution.
Discuss the activity and who had the best ecosystem and why.
Include in the discussion:
How are we contributing to salt marsh loss and what can we do to reduce our
impact?
What laws or regulations should be in place to help protect these ecosystems?
What are the functions and benefits of a salt marsh?
What negative effects could eutrophication have on the organisms in the
ecosystem?
Can eutrophication also occur naturally?
Sources:
www.cheapeakebay.net
www.knowitall.org
www.epa.gov
http://crd.dnr.state.ga.us/content/displaycontent.asp?txtDocument=22
http://www.dnr.sc.gov/marine/pub/seascience/dynamic.html
Worksheet #1
Go to www.knowitall.org/sclife/test.html. Click each part of the salt marsh and
answer the following questions.
1. What is an estuary?
2. Whose footprints were in the marsh and what does it eat?
3. What are the 3 vegetation “zones” of the marsh and which is more abundant?
4. Who are the main decomposers of the marsh?
5. What are 3 threats to the marsh?
6. What’s the saltiest place of the salt marsh?
7. What animals live their whole lives as plankton?
8. Why are the tides higher sometimes and lower at different times of the month?
9. Why do oysters build reefs?
10. What are some of the top predators in the marsh?
Now go to www.epa.gov/owow/estuaries/kids/.
Click on “Take a tour” and choose 1 of the estuaries.
1. What are 3 things you did not know about this estuary?
2. What are 3 threats to this specific estuary?
Next, click “About estuaries” and read “why are estuaries important” and “what
challenges do our estuaries face” in order to answer the questions in the games and
activities.
Click “Games and Activities” and play “Who am I?” and “Solve a mystery”