Description Description Students will first explore a salt marsh habitat with opportunities to ask questions about the organisms and phenomena observed. Students will then participate in a week-long research project studying the effects of bycatch reduction devices on commercial crab pots on a diamondback terrapin community. Keywords Keywords: salt marsh, diamondback terrapin, crab pot, community, ecosystem, research Age rangeTime required Age range : 15-18Time required: 1 week Target audience: biology educators, students Context Context: classroom, local salt marsh habitat
Technical Requirements Technical Requirements (Get local aid from organizations & universities! ) Access to transportation to and from marsh, canoes/oars, life vests, crab pots, chicken wire, stakes, bycatch reduction devices, permission to handle animals and perform research on salt marsh site, measuring devices (calipers, rulers, & field scales) and computers to record & plot data. Connection with the curriculum Connection with the curriculum: ecology: interactions within an ecosystem (predator-prey, population dynamics, etc.), habitat, biodiversity, and connections to the process of scientific investigation Learning Objectives: Learning Objectives: to enhance the critical thinking skills and the ability of students to think and act as research scientists; to demonstrate how knowledge is constructed; to demonstrate the potential impact of human alterations of the natural environment; to give students a fuller understanding of the complex interactions within an ecosystem.
Guidance for preparation In the salt marsh, organisms experience a wide range of environmental pressures due to periods of varying tide, sunlight, wind, and variable salinities. Many organisms have specialized structures or behaviors that allow them to live in this constantly changing and often harsh environment. Some of the animals commonly seen in the salt marsh are the blue crab, fiddler crabs, periwinkle snails, herons and other wading birds, and diamondback terrapins. Due to the number of exciting observations in the environment, the salt marsh is an intrinsically interesting location to incite active learning and an excellent place to conduct an inquiry exploration. Research Background Commercial crab traps (called pots) are designed in such a way to maximize blue crab catch in the southeastern coast of the United States. Unfortunately, crabs are not the only organism that get captured in the pots. The diamondback terrapin (declared endangered by certain states) is a naturally curious creature, and often gets caught and drowns inside the crab pots. Initial research studies have shown that attaching bycatch reduction devices (basically plastic rectangles) to the entry points of the crab pots successfully excludes most diamondback terrapins from entering without significantly impacting the crab catch. These devices are not currently being used regularly by commercial crabbers, so research conducted by the students could actually contribute to a relevant body of evidence in the discussion about whether or not to require the use of bycatch reduction devices on pots.
The research element of the inquiry pathway provides a novel avenue for students to experience excitement about science in a way that they may never have had before. Students are afforded the opportunity to increase personal ownership of the lessons and biological information because they have a large part to play in the development and implementation of the research project. The students largely design the experiment, collect their own data, and develop their own conclusions after organizing and analyzing the data. **This type of inquiry pathway could be applied more generally to other distinct ecosystems besides the salt marsh. Tips for Success Visit the salt marsh site to find safe and adequate locations to bring students Acquire the necessary materials/animal handling licenses in advance by contacting local organizations and/or universities with marine science programs for help Give a safety lecture to prepare students for proper canoe & animal-handling behavior Inform the students from the beginning of the semester that a big project will be occurring that will require some outside class time. Have a sign-up sheet for students to select which day after school they will collect data.
Inquiry-based Teaching Model Phase 1: Question Eliciting Activities Exhibit curiosity Define questions from current knowledge Phase 2: Active investigation Plan & conduct simple investigation Propose preliminary explanations or hypotheses Phase 3: Observation / Experiment Gather evidence from observation Phase 4: Discussion Consider other explanations Phase 5: Reflection Communicate explanation
Phase1: PROVOKE CURIOSITY Provide a little background information about the salt marsh ecosystem before the students embark on the class field trip to the salt marsh exploration together (explaining how tidal cycles work, osmotic pressure due to salinity, predator-prey relationships in the salt marsh, relationships between soil, vegetation, & hydrology, etc.) Show a film (http://www.rkwalton.com/sea/salt_marsh.php)in the classroom that shows the biodiversity of salt marsh organisms after teaching students about introductory ecology. Conduct initial trip to salt marsh to explore the site and allow students to formulate their own questions about the different parts of the ecosystem (tidal cycles, animals, plants, salinity, etc.). If time permits, the teacher could bring along a few field guides (for organism identification) and allow students to attempt to identify and learn about the creatures they see in the ecosystem.
Phase 1: DEFINE QUESTIONS FROM CURRENT KNOWLEDGE Tell students about crab pots and how they are used to catch blue crabs in the east coast of the US. Describe the problem that diamondback terrapins are frequently caught accidentally and drown in the pots because they cannot get air to breathe. Ask students: Why do the terrapins get trapped in the pots? What impact would a decreased terrapin population have on the salt marsh ecosystem? Main Question: Can you think of any way that commercial crabbers could continue to catch blue crabs without causing the accidental deaths of the diamondback terrapins? Main Question: Can you think of any way that commercial crabbers could continue to catch blue crabs without causing the accidental deaths of the diamondback terrapins?
Phase 2: Active Investigation PROPOSE PRELIMINARY EXPLANATIONS OR HYPOTHESES Ask probing questions to encourage critical thinking in proposing explanations to the previous questions: How is it that the blue crabs get caught in the pots? What is the difference between blue crabs and terrapins? What role do terrapins play in the salt marsh? What do terrapins eat? What eats terrapins? Is there anything about the crab pots that could be altered to exclude terrapins from being caught? (here the teacher’s questioning should lead the students to discover the concept behind the bycatch reduction device that can be attached to the entrances to the crab pots). Is there anything about the crab pots that could be altered to exclude terrapins from being caught? (here the teacher’s questioning should lead the students to discover the concept behind the bycatch reduction device that can be attached to the entrances to the crab pots). Is there any way to alter the pots so that the terrapins that do get caught won’t drown? (here the teacher’s questioning should lead the students to discover the concept of the chimneys that can be attached to the crab pots to allow terrapins to breathe when caught in the traps). Is there any way to alter the pots so that the terrapins that do get caught won’t drown? (here the teacher’s questioning should lead the students to discover the concept of the chimneys that can be attached to the crab pots to allow terrapins to breathe when caught in the traps).
Teaching Phase 2: Active Investigation PLAN AND CONDUCT SIMPLE INVESTIGATION Ask students to propose possible research designs for the suggested ideas (explaining how they will be implemented). Some ideas may include: Using chicken wire to create chimneys to put on the crab pots Attaching bycatch reduction devices to entrances to crab pots Securing crab pot chimneys to stakes to hold them in place against the water current Measuring the turtles and crabs caught in order to see if there is a difference in size between the crab pot with the bycatch reduction device and the crab pot without one. Having a control and experimental crab pot to see if there is a difference in terrapin catch between the two Create the modified crab pots with students during class—if time permits—or after school. Have students sign-up for time slots to go the research site after school (each student should go one day during the week, ideally in groups of 3-5 per research outing with the teacher). Have a mandatory safety/information session before any student goes out in the canoes.
Teaching Phase 3: Creation GATHER EVIDENCE FROM OBSERVATION First, ask students to predict what they will find in the different crab pots with and without different-sized bycatch reduction devices and explain their reasoning. Then, implement the research project! Bring a different small group of students each day of the week after school and have students check the crab pots for blue crabs and terrapins (making whatever measurements the students determined should be made to aptly answer the question of whether or not bycatch reduction devices were effective at excluding terrapins and not significantly decreasing the crab catch). Spend 5 minutes each day of class to discuss what the previous day’s 3-5 students found in the pots. Have small group discussions about whether their original predictions have changed or stayed the same.
Phase 4: Discussion EXPLANATION BASED ON EVIDENCE Collect all data (measurements determined by class—probably terrapin size, gender, etc.), organize in one place on the web so all students can access all data. Have students create graphs to visualize data. There won’t be any pre-determined answer, although recent research studies have shown that middle-sized bycatch reduction devices (4.5x12”) do successfully exclude most terrapins without impacting commercial crab catch. Let the data collected by the students drive the conclusions (this is a real research project! Not just replicating an experiment that has a pre-determined result). Separate students into small groups to work on explaining the trends observed (for the purpose of presenting ideas/conclusions to the class).
Teaching Phase 4: Discussion CONSIDER OTHER EXLANATIONS Offer students a few web resources to look at when formulating conclusions to present to class in order to compare other scientific ideas to their own. Examples: http://www.dtwg.org/Bibliography/Publications/wood%201997.pdf Wood, R. C. 1997. The impact of commercial crab traps on northern diamondback terrapins, Malaclemys terrapin terrapin. Pages 21-27. In J. Van Abbema editor. Proceedings: Conservation, Restoration, and Management of Tortoises and Turtles--An International Conference. New York Turtle and Tortoise Society, New York, USA. Wood, R. C. 1997. http://www.dtwg.org/Bibliography/Publications/Roosenburg%20and% 20Green%202000.pdf http://www.dtwg.org/Bibliography/Publications/Roosenburg%20and% 20Green%202000.pdf Roosenburg, W. M. and J. P. Green. 2000. Impact of a bycatch reduction device on diamondback terrapin and blue crab capture in crab pots. Ecological Applications 10:882-889 Roosenburg, W. M. and J. P. Green. 2000.
Teaching Phase 5: Reflection COMMUNICATE EXPLANATION Have small groups present conclusions to class, explaining why they came to that particular conclusion (can be formal or informal presentation). Discuss any differences of opinion among the class after each group has presented(or similarities if most came to the same conclusion).
FOLLOW UP ACTIVITIES AND MATERIALS Ask students how the research study could be expanded in the future Test students on aspects of ecosystem with open- ended questions so they can use their experience in the field as examples of different ecosystem dynamics. Maybe have open-house night bringing in parents to watch students present their research & findings with photos, etc.?
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