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III. Save the Oyster Reef!

Summary

Oysters are a valuable part of estuary ecosystems. They help purify the 

water, control erosion, and provide habitat for numerous other species. 

In this activity, students will investigate a hypothetical scenario in a 

town on the Chesapeake Bay, and devise a management plan to “Save 

the Oyster Reef”.

Learning Objectives

Students will be able to:

• Explain the water quality requirements for healthy oyster 

populations.

• Given water quality data, determine whether the water 

quality will allow oyster growth and spawning.

• Suggest 3 management practices that can be used to 

improve water quality for oyster growth and reproduction. 

K-12 Oysters in the Chesapeake Bay

Module 2

Grade Level: Middle 

School 

Teaching Time: 1-2 class 

periods

Materials:

Copies of the Student 

Data Sheets

Water quality 

parameters, data, and 

best practices 

information from 

previous activities.
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Background Information

Since colonial times, the Chesapeake (meaning "great shellfish Bay" in Algonquin) has lost more 

than 98 percent of its oysters. Gone are the days when oyster reefs posed navigational hazards to 

Chesapeake Bay explorers. Their reefs defined the major river channels. The reefs extended to near 

the water surface and often posed a navigational hazard to ships sailing up the Bay. Now, after 

decades of damage to reefs from harvest, increased disease, falling salinity due to the increased 

runoff that accompanies increased impervious surface, and increased sedimentation from runoff, a 

significant amount of hard bottom habitat has been lost. The oyster population in the Bay is less 

than 1% of what it once was. The native Eastern oyster—Crassostrea virginica—plays an important 

role in the Bay's ecosystem, as both a habitat for a variety of sessile plants and animals and freeswimming fish and shellfish, and as filter feeders because they feed upon phytoplankton (algae).

Key Words

Oyster Management – Among other strategies, restoration, monitoring efforts and the 

management of private and public grounds, work together to address the issue of poor water 

quality in the Bay with strategies to meet the criteria in all of the Bay’s tributaries. Improved water 

quality is a critical factor in supporting a vibrant oyster resource.

Sessile – Organism permanently attached to a hard surface and not freely moving. 

Water Quality Regulations - Water quality standards are provisions of state, territorial, and 

authorized tribal or federal law approved by EPA that describe the desired condition of a water

body. These standards form a legal basis for controlling pollution entering the waters of the 

United States from a variety of sources (e.g., industrial facilities, wastewater treatment plants, 

and storm sewers). States, territories, and authorized tribes may adopt policies and provisions 

regarding water quality standards implementation.

Activity Procedure

Engagement

Have students read about the problem in the town of Wando from Student Data Sheet: Save 

the Reef! 

“Something is wrong in the town of Wando on a small river in the Chesapeake Bay. The 

normally successful local oyster harvesters have seen a reduction in their annual oyster harvest 

in the last few decades and the level of oyster harvest is very low. Now the number of tourists 

who come to the island to eat the delicious oysters has started falling off. What’s even worse is 

that this year, for the first time ever, local residents had to order oysters from hundreds of 

miles away to use in their traditional oyster roasts. Can you help the good folks of Wando 

decide what regulations need to be put in place to stop the decline in their local oyster reef 

population?”
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Students have collected a lot of information in previous lessons about the value of oysters to 

water quality, best management practices, and the requirements of oysters in order to build 

and maintain healthy reef systems. They should have access to the data sheets from Water, 

Water, Land Use and Water Quality, and Oyster Harvest Simulation in order to discuss potential 

regulations that might protect and increase the oyster reefs near the town of Wando. 

Exploration 

Students receive information about water quality at Wando, and at a town upstream, Hamburg. 

They should review the parameters and look for ones that are not conducive for oyster growth. 

Have them keep notes in the data tables that display water quality readings for both towns on June 

1, and answer the follow-up questions with evidence from previous lessons on the Student Data 

Sheet. 

 Water Quality Data on June 1

 Parameter Wando Hamburg

Salinity 12 ppt 8 ppt

Water 

Temperature 700 F 650F

Dissolved oxygen 6.9 mg/L 4 mg/L

pH 7.9 8.6

Turbidity High Very high

1. Is the water quality in Wando adequate for healthy oysters? Yes

Evidence: All of the parameters are within the ranges for oyster growth, but if the turbidity is 

high over time, oyster reefs can be covered up. 

2. Is the water quality in Hamburg adequate for healthy oysters? No

Evidence: High turbidity, salinity lower than 10, low dissolved oxygen. pH is high. 

3. Which water quality parameters might be harmful to oysters or prevent oyster spawning?
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Oysters can tolerate a large range of pH and salinity, but the low dissolved oxygen caused 

oyster death; very high turbidity may be causing the low dissolved oxygen, and; reducing the 

growth of phytoplankton (food) is critical to oysters. 

Salinity - Oysters are generally happier and produce more spat at higher levels of salinity, and 

can live in water with levels between 2-30 ppt. The ideal salinity range for growth and 

development is 10 to 22 ppt.

Water Temperature - Oysters spawn at temperatures greater than 60.0F. Adult oysters grow 

well at 500 to 800F, or higher, but the most favorable temperatures are 770 to 790F.

Dissolved oxygen - Oysters and most animals that live on oyster reefs need at least 2-3 ppm DO 

to survive. Normal dissolved oxygen concentrations for the Bay is (about 7 milligrams dissolved 

oxygen/liter; mg/L) Low dissolved oxygen can result in oyster mortality. In shallow waters 

where nutrient pollution runs high, oxygen levels can plummet to nearly zero at night. Oysters 

living in these zones are far more likely to pick up the lethal Dermo disease. 

pH - The Bay generally has a pH between 7.0-9.0, which is neutral to slightly basic. More acidic 

conditions in key parts of Chesapeake Bay reduce rates of juvenile oyster shell formation and 

growth. The Eastern oyster can spawn in water with a pH between 7.8 and 8.2.

Inputs of nutrients from sewage systems and agriculture promote increased phytoplankton 

populations in the upperpart of the Bay. As these plants grow, they absorb large amounts of carbon 

dioxide from the water column, thereby making waters in that region less acidic. As phytoplankton

are carried toward the ocean by the Bay's currents, they are eaten by animals and bacteria. The 

respiration of this phytoplankton organic material results in the release of the same carbon dioxide 

taken up by the phytoplankton, which remains dissolved in the water making it significantly more 

acidic.

Turbidity – Water clarity is heavily influenced by weather events, such as droughts and rain storms,

and it fluctuates a great deal. When rains fall in the watershed, it runs off the ground carrying 

sediments into local rivers that eventually lead to the Bay. This sediment combines with other 

materials like decaying plant and animal waste, and sewage to form suspended solids in the water. 

The solids cause the water to scatter light resulting in increased turbidity. Clear waters are a 

reflection of a healthier Bay. 

Explanation 

Tell your students that now it is their turn to make a Plan of Action to save the oyster reefs. 

Divide the class into small groups of (3) to propose at least two new regulations that the 

officials can put into practice to slow or stop the decline in the oyster reef population. Each 

group should discuss potential management practices and determine which ones would make a 

significant difference in the water quality and improve oyster populations. They will choose the 

top 2 practices and write a regulation for each one. Each regulation should include the action, 

who is responsible to vote this into law, and who will be responsible for enforcing compliance. 
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Ask each student group to present an explanation of their regulations to the class through any 

multimedia format.

Extension 

The class can compile the regulations and discuss the potential outcome. Would the people of 

Wando be happy with their oyster populations in 10 years? Additionally, students can participate 

in an oyster reef restoration project or monitor a local site on a periodic basis. 

http://www.cbf.org/oysters or http://oysterrecovery.org/

Students can also track water quality parameters at a local buoy. 

http://buoybay.noaa.gov/observations/data-graphing-tool

Evaluation 

Monitor the participation of students in this group activity. Each should be contributing to the 

discussion and development of the regulations. Students should record their observations and 

evidence on the Student Data Sheet. They should provide evidence for their management 

decisions and prepare a short presentation to their peers outlining the reasoning for their choices. 

This rubric may help assess the students’ presentations of their management ideas. (15 points 

total)

Below Standard

 1-2 points

Approaching Standard

 3-4 points

 At Standard

 5 points

Points

Explanation 

of ideas and 

Information

Uses too few or irrelevant 

descriptions, facts, details, 

or examples to support 

their management 

Ideas. 

Missing some key 

supporting ideas, 

conclusions, details, or 

explanations. 

Uses relevant, 

well-chosen descriptions, 

and details; 

findings fully support 

their management ideas.

Organization

Information is not 

presented in a logical 

order, and explanations 

are not clear.

Information has a logical 

progression but the 

explanations are not 

clear. 

Information is clear,

complete and 

presented in a logical 

sequence. 

Science 

Content 

Presentation contains 

many inaccuracies in 

science content or 

incorrect conclusions.

Presentation has a few 

inaccuracies or an 

incorrect conclusion. 

Presentation includes 

accurate information and 

good science reasoning.

 Total
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Three Dimensional Learning How the Dimensions are 

Addressed

Core Disciplinary 

Idea(s)

LS2.A Interdependent 

Relationships in Ecosystems 

Organisms and populations of 

organisms are dependent on 

their environmental interactions 

both with other living things and 

with non-living factors.

Growth of organisms and 

population increases are limited 

by access to resources. 

ESS3.C - Human activities have 

significantly altered the 

biosphere, sometimes damaging 

or destroying natural habitats. 

Students have learned about the 

abiotic factors critical to oyster 

populations, they will examine water 

quality readings at (2) locations, and 

determine whether the data will limit 

oyster growth and reproduction. 

Students will examine the human 

activities that are responsible for poor 

water quality and determine courses 

of action to improved water quality 

parameters.

Science/Engineering 

Practice(s)

Analyzing and Interpreting Data

Analyze and interpret data to 

provide evidence for 

phenomena. 

Engaging in Argument from 

Evidence

Construct an oral and written 

argument supported by 

empirical evidence and scientific 

reasoning to support an 

explanation for a phenomenon 

or solution to a problem. 

Students will analyze water quality 

data and determine a course of action 

through management plans that will 

improve water quality parameters for 

increased oyster production. 

In the culminating activity, students 

construct two regulations. A 

presentation to their classmates 

requires that they deliver sound 

evidence and scientific reasoning to 

solve the problem of poor water 

quality. 

Cross-cutting 

Concepts

Patterns can be used to identify 

cause and affect relationships.

Cause and Effect 

Cause and effect relationships 

may be used to predict 

phenomena in natural systems. 

Students review data and information 

that they have collected to construct 

an explanation that includes

relationships between the oyster 

population and water quality 

parameters. Given new data sets, 

they determine whether the water 

quality parameters will support oyster 

populations. 
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Ties to Common 

Core

Speaking and Listening 8.4

Students present claims and 

findings emphasizing salient 

points in a focused, coherent 

manner with relevant evidence, 

sound and valid reasoning and 

well-chosen details. 

A presentation of the results of their 

group decision about management 

regulations to their classmates 

requires that they deliver sound 

evidence and scientific reasoning to 

solve the problem of poor water 

quality. 

Ties to MD 

Environmental 

Literacy Standards

Standard 4. Populations, 

Communities, and Ecosystems

The student will use physical, 

chemical, biological, and 

ecological concepts to analyze 

and explain the 

interdependence of humans 

and organisms in populations, 

communities, and ecosystems. 

The students will use chemical and 

biological criteria and data about 

oyster populations to provide 

evidence for the effects of water 

quality on ecosystem health and 

organism populations. 

Module References 

http://www.oyster-restoration.org/related-links/

http://estuaries.noaa.gov/teachers/pdf/06_oysters_tg.pdf

http://buoybay.noaa.gov/investigating-turbidity

https://www.sciencedaily.com/releases/2010/06/100610104619.htm

Maryland Environmental Literacy Standards

http://marylandpublicschools.org/programs/Documents/Environmental/MDEnvironmentalLitStan

dards.pdf

Additional Resources

http://www.oyster-restoration.org/related-links/