Objectives

In this lesson, students will:

• be introduced to the history and culture of oystering on the Chesapeake Bay
• become familiar with the life cycle of the oyster
• be able to describe the importance of oysters to the ecosystem of the Chesapeake Bay
• sketch the vessels and equipment used to harvest oysters
• compare the Eastern oyster and the Pacific oyster
• view aquaculture techniques that are used to cultivate oysters
• form opinions about the possible introduction of the Pacific oyster to the Chesapeake Bay

MSPP Outcomes:

Outcome #1: Students will demonstrate their acquisition and integration of major concepts and unifying themes from the life sciences.

• Individuals and groups of organisms interact with each other and the environment.
• The organisms and groups of organisms best suited to an environment survive and reproduce.

Science - Grade 8

Outcome #6: Students will demonstrate the ability to apply science in solving problems and making personal decisions about issues affecting the individual, society, and the environment.

• Take a position relative to an issue that affects society and use your knowledge of science to defend that position.
• Relate personal actions you can take to address an issue and demonstrate support for your position. Identify and evaluate risks with benefits associated in science and technology both in the present and in the past.

Social Studies

Geography: Grades 4-5

• demonstrate a sense of personal responsibility for environmental decisions made at the state and national levels

Geography: Grades 6-8

• Students will be able to evaluate environmental issues and recommend ways of protecting the environment while meeting human needs.

Materials Needed:

• Internet access
• copies of the Oyster Observations Worksheet for each student
• copies of the Bringing 'Em Home Worksheet for each student
• copies of the Oyster Dilemma Worksheet for each student

Optional materials:

• several live oysters, in their shells (available from local seafood market, keep cool)
• several shucked oysters (sold in pints and quarts at local seafood markets)*
• an empty 5-10 gallon aquarium
• Bay water (or prepared saline water, directions follow)

*Do not feed raw oysters to students. Raw oysters can contain harmful bacteria. Wash hands after handling all oysters.

Teacher Background

We once thought that the Eastern oyster supply was bottomless, but today fewer and fewer watermen can make a living harvesting oysters. In recent years the population of the Eastern oyster has declined dramatically, with only 1% of its historic population still available for harvest. Oysters used to grow in huge reefs, called "bars" or "rock" that rose above the water line. Just as a note of interest, the famous Maryland striped bass like to "hang around" oyster beds so it came to be called a "rockfish". These oyster reefs were navigational hazards: Captain John Smith reported seeing oysters that were the size of dinner plates! Today much smaller oysters struggle to live in flattened "beds," largely due to overharvesting and habitat problems.

The harvesting of oysters from the Bay was a huge business, particularly after the Civil War. Men actually fought over oyster beds and with marine police. By the early 1900's overharvesting had taken its toll on the oyster population. There were calls for conservation and oyster "farming" even then. Your students might enjoy researching this colorful time period on the Chesapeake Bay.

The decline of the Eastern oyster has had a much greater impact than just on the wallets of watermen and our stomachs. The oyster is thought of as one of the most important animals in the Bay. The reefs oysters create provide homes and habitat to lots of Bay creatures, including baby crabs, fish, grass shrimp, mussels, sponges, barnacles, and other tiny critters. Oyster spat (baby oysters) must locate a hard substrate (surface) to attach to in order to grow to maturity.

The oyster's most significant contribution to the Bay is its filtering capacity. As it passes water over its gills in search of food (algae), it removes sediments (dirt), excess nutrients (nitrogen and phosphorus), and toxics from the water. These small filter feeders then deposit wastes in tiny clumps on the bottom. When oysters were very plentiful they could actually filter the entire Bay in three to six days! Now in an entire year isn't enough time for the remaining oysters to filter the whole Bay.

Hurricane Agnes (1973) brought huge amounts of fresh water and sediment into the Bay, suffocating many oysters. Pollution has also weakened the oyster, and lowered oxygen levels in the water. Parasitic diseases like MSX and Dermo kill oysters just as they reach harvestable size. Today's remaining oysters are smaller and far less plentiful than they were a hundred years ago.

Today many people are joining in efforts to help the oyster by "oyster gardening" alongside docks. The oysters grown in floats or mesh bags can be "planted" in sanctuary reefs to grow and reproduce. Aquaculture techniques are not new; people worldwide have been cultivating fish and shellfish for thousands of years. If diligent efforts to save the oyster continue, Marylanders may be able to save this valuable resource.

Your students will be posed with the dilemma of whether or not the Pacific oyster should be introduced to the Bay. It is thought that the Pacific oyster might be able to thrive here, thus helping to filter water and provide habitat for other Bay critters. Some scientists feel that it may be too late for the Eastern oyster to "recover" and again be a vital part of the Bay's ecosystem. However, the introduction of a non-native species, like the Japanese oyster, requires serious consideration. The potential consequences are unknown.

Please follow the student lesson prior to your students so that you can learn more about the incredible, edible oyster.

Teaching tips and options for this lesson

An even better suggestion is to conduct the following experiment so that students can actually see the filtering capacity of the oyster. (This demonstration was taken from Chesapeake Choices and Challenges curriculum lesson "Oysters and a Clear Bay", written by the Chesapeake Bay Foundation. The lesson comes with an oyster filtering video, an oyster history timeline activity, and a hands-on investigation where students try to design a filter to out-filter the oyster.):

Oysters can filter the water in the Bay as shown in this simple experiment. The oysters are placed in a tank of cloudy water (left). As they filter the water for food, the clarity improves steadily. At the end of two hours the water is clear (right).

Setting up the demonstration:

• You may use one or two aquariums. If you use two aquariums, one will serve as a control for the demonstration. Obtain live oysters from a local seafood market or grocer. Fill the aquarium(s) with water from the Bay or from a river that supports oysters. If you do not have access to a body of water that supports oysters, you may use stream or dechlorinated tap water mixed with sea salt to the correct salinity for oysters. Oysters can survive in salinities ranging from 12 ppt. (parts per thousand) to full salt water. Add at least 12 ml of salt for every liter of water in the aquarium. Sea salt is available at most pet and aquarium supply stores.
• Allow your oysters to acclimate to the aquarium for 24 hours so that they will be ready to filter when you do your demonstration. Oysters can be temperamental when they have been out of their natural habitat for some time.
• If you plan to keep your oysters in the aquarium for more than a day or so, you should set up a bubbler system to oxygenate the water and a filter to get rid of toxic ammonia. Since oysters require massive amounts of algae to survive, we suggest that you do not keep them long, unless you feed them with algae paste.

• Add your oysters to one aquarium; leave the other (if you are using two aquariums) without oysters to serve as a control. Once your oysters have acclimated to the salinity, have your students add algae (if available) and/or small amounts of dirt and silt to the aquarium(s) until the water is cloudy. Oysters can filter sediments and algae that are suspended in the water, but they will not filter sand or clay.
• If your oysters are healthy (and not traumatized from their move) they should filter the water crystal clear within hours of when they begin filtering. Each oyster filters, on average, two gallons per hour.
• To determine the rate at which oysters filter, students should begin timing when the oysters open their shells to start filtering and stop timing when the water is clear.

• Introduction: This section sets the stage for the dilemma that your students will face at the conclusion of the lesson. If you can have several of the resources listed at the end of the lesson on hand for students who have more questions, that would be great.
• Part 1 - What's and Oyster, and is it a Good Neighbor?: The web sites listed in this part of the lesson serve to introduce your students to the life cycle of the oyster, and to familiarize them with its ecological impact. Again, extra resource books might come in handy for the curious student who wants to learn more. Your students will need copies of the the Oyster Observation Worksheet to complete as they visit the web sites in this part of the lesson. They should hold on to the worksheet for reference in Part 5.
• Part 2 - Bringing 'Em Home!: This part of the lesson explores the rich culture and history of oystering in the Chesapeake Bay. If you are very pressed for time, this part of the lesson could be omitted without compromising the issue being studied. Your students will need copies of the Bringing 'Em Home Worksheet for this part of the lesson. In this part of the lesson the students will sketch a dead-rise workboat, a skipjack sailing vessel, the oyster dredge, and oyster tongs.
• Part 3 - Pals in the Pacific: In this part of the lesson students will learn about the Pacific oyster and begin to make comparisons to the Eastern oyster. There is no written component to this part of the activity, but look for information gained from the Web sites in their final oyster dilemma answers.
• Part 4 - Amazing Aquaculture!: This part of the lesson introduces your students to aquaculture. The specific methods used to cultivate oysters are explored. This part of the lesson does not have a written component, but you may want to discuss oyster cultivation when you conduct a final class discussion. A guest speaker from the Chesapeake Bay Foundation or the Oyster Recovery Partnership could really bring aquaculture to life here.
• Part 5 - The Oyster Dilemma: This final part of the lesson poses a question and allows students to "vote" to show their choice. Each student will need a copy of the Oyster Dilemma Worksheet. The dilemma is whether or not Pacific oysters should be introduced to the Bay. After the students have completed the lesson you may want to have them research the effects of the introduction of other non-native animal species to the Bay. Examples that would be easy to research are the mute swan and the nutria. Both of these animals have had detrimental effects to the Bay ecosystem, but this should not be used to necessarily sway the students' decisions about the introduction of the Pacific oyster. Folks from US. Fish & Wildlife, Annapolis, MD or Maryland Department of Natural Resources, Annapolis, MD can be of help in researching the introduction of non-native species to Maryland. Finally, it would be very helpful to conduct a class discussion of the dilemma, allowing students to share the reasons that they wrote below their "vote." Also, share the total vote tally with the class, either before or after the discussion.

How will you know if the students have done a good job?

Possible extensions

• Create oyster life cycle charts to post in the classroom.
• Build an oyster "reef" bulletin board with your students using cutout oysters (a fast way is to use a copier to make lots of paper oysters to cut out). Add other creatures that would live in and around the reef, using the resource books listed below for reference.
• Visit the National Aquarium in Baltimore.
• Go out on a field trip with the Chesapeake Bay Foundation. They offer hands-on experiences for students that highlight oystering on their Baltimore Harbor SnowGoose workboat and Annapolis Stanley Norman skipjack trips. For further information contact the Education Coordinator of the Chesapeake Bay Foundation at 1-800-445-5572.
• Involve your students in an oyster gardening/restoration service learning project, beginning in the fall of '98, through the Chesapeake Bay Foundation. (You will need water access.) For more information contact the Maryland Restoration Coordinator of the Chesapeake Bay Foundation at 1-800-445-5572.
• Contact the Chesapeake Bay Foundation about their supplementary curriculum project Chesapeake Choices and Challenges. Classroom MSPAP-assessment style activities and service learning projects about oysters and other Bay creatures are offered at no cost through teacher workshops. For more information contact the Maryland Curriculum Facilitator of the Chesapeake Bay Foundation at 1-800-445-5572.
• Contact the Oyster Recovery Partnership to involve your school in their oyster restoration work, or to arrange the services of their Speaker's Bureau. For more information contact them by phone at 410-269-5570, or by mail at P.O.Box 6775, Annapolis, MD 21401.

Good reference books to have on hand for your students

• Chesapeake Bay - A Field Guide, by Christopher White
• Life in the Chesapeake Bay, by Alice Jane Lippson & Robert L. Lippson
• Awesome Chesapeake, Tidewater Publishers (very simple text)
• On an Island in the Bay, by Patricia Mills (This is a beautiful photo essay book with very simple text.)

Other books/articles for teacher reference

• "Oystering in the Chesapeake Bay", The Washington Post, Horizon section, January 14, 1998 (This one illustrated selection is a great, concise article that covers the history, culture, and current conditions of oystering in the Bay.)
• The Oyster Wars of the Chesapeake Bay, John Wennerstein
• This was the Chesapeake Bay, by Robert H. Burgess
• Sunup to Sundown: Watermen of the Chesapeake, by Mick Balckistone
• Harvesting the Chesapeake, Tools and Traditions, by Larry S. Chowning
• Blacks of the Chesapeake, by Vincent O. Leggett (phone: 410-269-7815)

Photo Credits

• Color photographs courtesy of the Oyster Recovery Partnership, Chesapeake Appreciation, Inc., P.O. Box 6775, Annapolis, MD 21401 (410-269-5570)
• Black and white photographs of oystermen from Blacks of the Chesapeake, by Vincent O. Leggett
• Black and white photos of the oyster experiment from "Oysters: Food, Filters, Fish Habitat" from the Chesapeake Bay Foundation.