AA DDaayy oonn tthhee RRiivveerr

A film by Tom Fitz

Classroom Discussion Guide High School Version (9-12)

Content created for Schoolyard Films, Inc. by Cypress Curriculum Services, LLC

Film Overview

"Partly cloudy skies and clear water"—it's a perfect day on Central Florida's Rainbow River. Join Florida naturalists Tim Walsh and Steve DeCresie as they set out on a misty morning to explore the underwater world of the Rainbow River. These energetic and passionate naturalists share their understanding of the river—in the river—offering an intimate view of aquatic wildlife in their element. "You get a different view of wildlife underwater" says Tim, and this is aptly demonstrated as he mingles underwater with a surprisingly graceful snapping turtle.

Winner of the 2010 International Wildlife Film Festival Best Internet and Best Children's Program, A Day on the River offers a springboard for classroom discussion on many environmental and science topics such as wildlife ecology, resource conservation, and the nature of science. The film's leading roles are played by some of nature's more distinctive animals—turtles. These fascinating reptiles are one of the great success stories of animal evolution. For over 200 million years, turtles have humbly and unhurriedly made their way with very little change to their body structure—a strong case that "taking your shelter with you" is an excellent survival strategy. But turtles are now on the decline worldwide, and despite the great interest in understanding these animals, they still hold many secrets about their biology and behavioral ecology. With stunning imagery and an engaging narrative, A Day on the River offers an intimate look at a delicate river ecosystem and the turtles that make it their home, in an informative yet charming short film.

Teachers can use this guide to supplement a study of the Florida Sunshine State Standards in Science, specifically on content standard topics such as scientific investigation, structure and function of living things, the processes and diversity of life, interactions between living organisms and their environments, and the impact of scientific knowledge and technology on communities, cultures and societies.

Key Terminology

Be sure that students are comfortable with these terms either before the film, or as part of discussion after the film. If the students are doing writing prompts, provide these terms as a "word bank" to help guide their writing.

abiotic, adaptation, biodiversity, biotic, carnivore, competition, consumer, dependent variable, ecosystem, environment, food chain, food web, habitat, herbivore, impact, independent variable, inherited, instinctual, life cycle, limiting factor, model, omnivore, organism, population, predator, prey, producer, sample, society, species National Standards Correlations

Discussion Guide Element Unifying Science as Science in Personal Life Science History and Concepts and Inquiry and Social Nature of Processes Perspectives Science Discussion Question #1 • • Discussion Question #2 • • • • Discussion Question #3 • • • Discussion Question #4 • • Discussion Question #5 • • Activity 1: Turtles of Florida and Where They Thrive: A Literature Review and • • • • • Field Visit Project Activity 2: Mark and Recapture: Simulating Turtle Population Monitoring • • • • •

Sunshine State Standards Correlations

Discussion Guide Element Sunshine State Standards

Discussion Question #1 SC.912.L.15.4 SC.912.L.15.6 SC.912.L.15.7 Discussion Question #2 SC.912.L.17.2

Discussion Question #3 SC.912.L.17.7

Discussion Question #4 SC.912.L.17.8 SC.912.L.17.16 SC.912.L.17.18 Discussion Question #5 SC.912.N.4.1 SC.912.N.4.2 Activity 1: Turtles of Florida and Where SC.912.L.17.20 They Thrive: A Literature Review and Field Visit Project Activity 2: Mark and Recapture: SC.912.L.17.1 Simulating Turtle Population Monitoring SC.912.L.17.13 SC.912.N.4.1 SC.912.N.3.5 SC.912.N.4.1

Discussion Questions/Writing Prompts

Use the following questions as a springboard to stimulate classroom discussion or use them as writing prompts. Either way, the goal is to foster discussion on the level of synthesis and analysis. Below each question, you will find possible areas of discussion to guide the teacher.

1. a) To what chordate class do turtles belong? Describe the features of turtles that are distinguishing characteristics for most members of this class. What are some characteristics of turtles (Order Testudines)?

 Turtles belong to the diverse chordate class Class Reptilia, which also includes the crocodilians, birds, tuataras, snakes, and lizards. The evolutionary relationship of turtles to other reptiles is not well understood, but molecular studies suggest that they are closely related to the crocodilians.  Like many members of Reptilia, turtles have amniotic eggs and most have skin with scales, plates, or similar structures formed from the protein keratin. For example, turtles have scutes--bony plates formed from the turtle's skin. Birds have feathers which are thought to be derived from scale-like structures of earlier ancestors.  Obviously, the carapace and plastron are unique to the Testudines. Also, turtles do not have teeth and most turtles can withdraw their head and neck inside their shell.

b) One of the biologists in the film describes the unique morphological features of turtles. From what bone does the carapace develop? Compare and contrast the position of the "ribs" in turtles, other reptiles, and humans.

 The carapace develops from ribs. The result is that the "ribs" encapsulate the scapula, which is inconsistent with the body plans of every other vertebrate.  If class time allows, find picture examples of each body plan to do a simple verbal compare and contrast.

c) As you heard in the film, turtles have existed for approximately 200 million years and have changed very little over that time. From an evolutionary perspective, what does this suggest about the basic body plan of the turtle?

 Review concept of animal adaptations—changes in behavior, physiology, and body structure, which allow animals to survive in their environment.  Prompt students to consider the differences between divergent body plans among four- limbed vertebrates and how these differences relate to survival strategies. Examples: i) Canines: long legs, sharp teeth, agile bodies—body plan is adapted to chasing and killing prey ii) Birds: bipedal, winged, feathers, light-weight skeleton—body plan is adapted to flight; allows birds to rapidly flee from predators or, as predators, to chase prey. iii) Turtles: short limbs, protective shell around body, retractable or folding neck—body plan relies on physical protection from predators; rather than overcoming prey or outrunning predators, turtles adopt a "hide and wait" defensive approach.  Ask students if the turtle body plan seems to be "inferior" or "poorly adapted" compared to the other body plans discussed. Point out that the persistence of the turtle body plan over 200 million years suggests that the protective shell and associated behavior are successful adaptations for the turtle.

d) Can you think of other animals with armor that serves as protection from predators? Are any of these species closely related to turtles?

 Examples include: i. Armadillo (means "little armored one" in Spanish) ii. Pill millipede and pill bug iii. Snail iv. Mollusk  Define convergent evolution as the attainment of similar traits in unrelated species. Explain that similar solutions to biological challenges may evolve independently among unrelated lineages. In this case, the solution of physical protection through armor evolved separately in reptiles, insects, mammals, and mollusks.

e) Can you think of adaptations among the world's turtles species that help them survive in their particular environment?

 Webbed feet: Like other aquatic four-limbed animals, freshwater turtles have skin between their digits to help move them through water.  Paddle-like limbs: Sea turtles need more than webbed feet to swim in strong ocean currents. Their forelimbs are modified into flippers for fast swimming.  Worm-shaped appendage: The alligator snapping turtle has a worm-like appendage on its tongue that it wiggles to attract prey.  Strong front legs and claws: Burrowing turtles such as the gopher tortoise have very strong forelimbs and claws that help them dig into soil.

2. One of the conservationists in the film explains that the primary water source for the Rainbow River is the direct flow of water from the Floridan Aquifer. How do you think water quality in the Rainbow River compares to rivers that originate primarily from surface waters (i.e. runoff from land)? In what ways might these differences affect the distribution and types of aquatic organisms in each type of river? Formulate a testable hypothesis to explain why one of these water quality differences occurs.

 Ask students to consider differences and similarities in the following areas: water clarity, temperature variation, pH, nutrient levels. Prompt students to consider how identified differences translate to differences in plant and/or wildlife composition.

3. Many factors contribute to the unique characteristics of an ecosystem. These may be abiotic (non-living) or biotic (living). Can you identify abiotic and biotic characteristics of spring-fed freshwater ecosystems like Rainbow River? How do these factors influence the characteristics of this type of ecosystem?

 Ask students to consider abiotic factors first. Possible responses may include: current velocity, temperature, substrate chemistry (e.g., limestone influence on pH), dissolved nutrient levels, dissolved oxygen concentrations  Before considering interactions, ask students to identify biotic factors. Students should group biotic elements into two broad groups—autotrophs (producers) and heterotrophs (consumers). Autotroph examples include: phytoplankton, submerged macrophytes, floating macrophytes, emergent macrophytes. Heterotroph examples include zooplankton, aquatic insects, mollusks, larger vertebrate herbivores, omnivores, and carnivores (e.g., manatees, turtles, and bass).  Ask students to consider how the identified biotic and abiotic factors affect the ecosystem, particularly focusing on interactions of these factors. Discussion points include: i. How does temperature constancy influence the stability of the ecosystem? Does this abiotic factor influence species composition or diversity? ii. How might increased nitrogen levels (from human activity) influence the productivity of phytoplankton and how might an increase in phytoplankton affect other abiotic and biotic factors (water clarity, plant species composition, herbivore food availability, etc)?

4. a) In the film, we see how humans have become a major part of the Rainbow River environment. Can you give specific examples of human activities that adversely affect the river ecosystem? Explain how these activities harm or alter the ecosystem.

 Responses will vary, but two major factors should be discussed—reduction in ground water from consumptive use and increased levels of nutrients and other pollutants. Students may not be aware that a characteristic feature of spring-fed rivers is ecosystem stability. Unlike rivers which are principally surface water driven, spring fed rivers maintain relatively constant flow and water temperature. As a result, the ecosystem can be sensitive to changes in environmental conditions.  These aquatic systems are nitrogen limiting and nutrient loading from human activities in the watershed can be a major problem for ecosystem stability, especially when coupled with reductions in available water. The result can be significant algal growth followed by decreases in plant productivity, biodiversity, and water quality.  Other human impacts include: 1) habitat loss, 2) erosion and turbidity from shoreline disturbance, 3) accumulation of toxic substances associated with boating, 4) introductions of non-native invasive species, 5) over fishing, and 6) animal hazards from littering.

5. a) The film's epilogue states that since filming the program, the State of Florida banned the commercial harvest of freshwater turtles from the wild. What role do you think science had in determining the need for this law? What questions were likely addressed using scientific methods?

 Explain that science is often used to inform decision making by state agencies. In this case, state regulatory agencies responsible for natural resource protection relied on science to determine if regulatory protection for turtles was needed.  Science was likely used to answer questions at all levels of this issue. Examples include: i. Are freshwater turtle populations declining? ii. If so, is human harvest of freshwater turtles a major factor in the decline? iii. How many turtles are needed to maintain stable populations in the wild? iv. How much harvesting can turtle populations tolerate, if any? v. Does the population recover once a commercial harvesting ban is implemented?

b) Is the Florida turtle harvesting ban fair to the hunters who made their livelihood by selling turtles? Is there a need to consider the impact on commercial turtle hunters when deciding to make this law?  Encourage class discussion on the rights of commercial turtle hunters, the rights of society to enjoy turtles and other wildlife, and the "rights" of turtles themselves.  Explain that most legal decisions are preceded by an analysis of cost and benefits. Such cost-benefit analyses must include consideration of economic and social impacts and must weigh these impacts against the benefits to society and natural resources.

c) How will scientists and policy makers know if the ban is having the intended effect of protecting Florida's freshwater turtle population?  Discuss the need to assess management decisions to determine if the intended objective is reached.  Prompt students to consider ways scientists might measure changes in turtle populations. Would it be necessary to take measurements before the harvesting ban?  Encourage class discussion on possible approaches to turtle monitoring. Prompt students to consider pros and cons of proposed monitoring methods. Activity Two of this guide explores capture and release methodology for estimating animal populations.

Suggested Activities for Further Study

Activity One: Turtles of Florida and Where They Thrive: A Literature Review and Field Visit Project

Turtles live in many different types of habitats. The type and range of habitats that a turtle can thrive in depends upon the species. Some species live entirely in upland forests; other species utilize both uplands and wetlands (semi-aquatic), while others spend most of their life in an aquatic environment.

In this activity, students will investigate habitat requirements of common turtle species through both classroom and field exercises. Students will gain a better understanding of habitat features, observe turtles in their habitats, discuss human impacts on habitat and turtle populations, and explore things that humans can do to better protect turtle populations in Florida.

What are the habitat needs of the species listed below? Conduct a literature review to complete the table. Find public lands in your area that appear to meet the habitat requirements for at least one of the species in this table.

1) Begin with an overview of the turtle life cycle and the various habitat types where turtles can be found in Florida. [Note: Sea turtles, salt marsh turtles and certain freshwater turtles that spend most of their time submerged are not included in this exercise.] Major topics to cover in the overview include diversity of diet among and within species, nesting behavior, aestivation, thermoregulation, predators, defense mechanisms, and an overview of habitat types. There are several excellent online resources to develop the overview: http://plants.ifas.ufl.edu/guide/turtles.html http://www.corkscrew.audubon.org/wildlife/turtles.html

http://myfwc.com/WILDLIFEHABITATS/SpeciesInfo_FreshwaterTurtles.htm

2) Supply students with copies of the turtle habitat table (provided below). Working in groups, students conduct a literature review to complete the table for all species known to occur in your area. In addition, students should obtain printouts of color photos for each species. These photos should be sufficient to assist with field identification activities later in this activity. Students should keep records of their information sources.

3) While students are conducting literature research or in preparation of the activity, the teacher should identify nearby locations with habitat necessary for each species. Ultimately, the field trip should include a number of sites with and without all habitat needs.

4) As a class, compile all data into a single table. If any habitat facts are either inconsistent with other teams’ data or questionable based on the teacher’s knowledge of species, ask the team to provide their source. This will give the class a chance to validate information and critically assess data quality. Discuss how scientists often report different information and the need for review and confirmation of results. When choosing which species to look for, be sure you use the information on active periods to determine if you are likely to spot the species at that time of year.

5) Arrange a field trip to these locations and conduct a survey to determine if the species are present. a) Discuss safety and the importance of minimizing disturbance at the site. b) In addition to personal effects for outdoor activities (e.g. hat, sunscreen, field shoes), students should have clipboards, copies of the completed habitat data table, and paper and pencils to record observations. If available, binoculars are very helpful for species identification. Students should make observations to answer the following questions: i) Which habitat type did you visit? ii) Was there evidence of nesting habitat? Describe. iii) Was there evidence of basking habitat? Describe. iv) Was there evidence of threats to turtle populations? Describe. v) Did you observe turtles? What species? vi) If you find the species but cannot identify the “required” habitat "requirement", develop a hypothesis to explain how this species survives in this habitat without the missing environmental element. vii) If you do not observe any of the targeted species, evaluate the site and identify missing habitat elements that could explain the absence of the turtle. What other factors beside habitat might explain the absence of the species?

Florida Turtle Literature Review Florida Habitat Nesting Basking 4 Active Common Other Habitat Common Name Species 1 2 3 Diet 5 6 7 Region type Habitat habitat Months Threats requirements Florida Softshell Apalone ferox All Turtle NE, Spotted Turtle Clemmys guttata Central Deirochelys Chicken Turtle All reticularia

Gopher Tortoise Gopherus polyphemus All

River Cooter Pseudemys concinna NW, Central

Pseudemys floridana Pond Cooter All floridana Florida Red- Pseudemys nelsoni All bellied Cooter Loggerhead Sternotherus minor NW,NE,

musk turtle minor Central Common Musk Sternotherus odoratus All Turtle Common Box Terrapene carolina All Turtle Yellow-bellied Trachemys scripta NW Slider scripta Striped Mud Kinosternon baurii All Turtle Kinosternon Mud Turtle All subrubrum Pseudemys Peninsula Cooter Central peninsularis 1Habitat Types Active Months Deep Ditches & Canals Months when turtles are actively feeding Farm Pond and nesting. Use this information to Floodplain Swamp determine the best time to watch for this Frequently Flooded Ditches species in the wild. Freshwater Marsh Isolated Seasonal Wetland Common Threats Lakes Agricultural pesticides Mixed Hardwood Forest Alligator predation Old Field Feral hogs Pine Forest Fire ants River or Large Reservoir Fire suppression Stream or Spring Human harvest Wet Meadow or Bog Reduced upland nesting habitat Roads & habitat fragmentation 2Nesting Habitat Wetland draining Deep sandy soil Uplands adjacent to wetlands Other Habitat Requirements Uplands immediately adjacent to wetland Any other conditions necessary for this species that is documented in the 3Basking Habitat literature. Cypress knees Logs Partially submerged branches Rocks Sandy shoreline Sparsely vegetated upland

4Diet Algae Amphibians Aquatic vegetation Berries Crayfish Fish Grasses Leafy plants mollusks Mushrooms Seeds Small inverts Small mammals Snails Worms

Activity Two: Mark and Recapture: Simulating Turtle Population Monitoring

This activity is a modification of the popular population estimation simulation using the mark and recapture of beans. In this version of the activity, students will use dry pasta to conduct a desktop population count of the "loggerhead musk turtle" in the Rainbow River. Students will learn the basic principles of mark and recapture monitoring method, utilize skills in basic statistical calculations, and learn how sample size affects the accuracy and precision of a population estimate. Follow-up questions will allow students to consider the reasons scientists conduct monitoring.

Materials: Each pair of students will need: • 1/2 cup small pasta shells (roughly 100 shells) • 1 small cup or small paper bag • black marker • calculator • data sheet

Background for Teachers:

Scientists commonly use sampling plots or aerial imagery to monitor plants. With only rare exceptions, plants “cooperate” in monitoring programs—they patiently sit still while the scientist takes measurements. But how does one monitor organisms that move around and almost always run and hide from well-meaning field biologists?

Wildlife ecologists devised the mark and recapture method to estimate population size. The concept of the method concerns the probability of catching an individual in a population twice and how this probability of recapture relates to the actual population. Mark and Recapture monitoring involves the following steps: 1) capturing a sample of the population, 2) marking these individuals with unique identifiers (e.g., tags), 3) releasing the captured animals to redistribute in the population, and 4) re- sampling the population to determine the number of recaptures. Using mathematical models, the researcher can then calculate an estimate of the true population.

This activity is a desktop simulation of the mark and recapture method. A simulation like this provides an excellent, interactive opportunity to emphasize Sunshine State Standards at all levels surrounding the big idea “The Practice of Science.” It can be used to discuss method, scientific reasoning, how and why different groups got different results, etc. Teachers can use the discussion questions (and even create additional inquiry-based questions) with this activity to meet the individual needs of a variety of students and classroom settings.

Introduction to Class:

1. Purpose/problem statement:

In this activity, you will conduct a classroom simulation of a monitoring program for loggerhead musk turtles living on the Rainbow River. Your objectives are to:

a. estimate the number of loggerhead musk turtles on the Rainbow River b. determine the effect of sample size on population estimation error

Background: Amateur naturalists have reported a decline in loggerhead musk turtle sightings along the Rainbow River in recent years. As a state biologist, you need to verify that these observations are accurate and then investigate possible causes. This activity will deal with your first step— estimate the current population size. This will establish an estimated baseline population, which you can compare to future population estimates to determine whether a declining trend is present.

How can you determine the number of turtles on the river? Obviously, capturing every turtle in the river would be very costly, time consuming, and disruptive to the turtle population you are trying to protect. Wildlife biologists use a sampling technique known as Mark and Recapture to estimate the population size. Here is how it works. Biologists place live traps in the study area and capture a certain number of animals. All captured animals are marked with an identification tag, and then released. After a period of time, the biologists repeat the trapping activity and 1) count the total number of captured animals and 2) make note of how many were previously caught (have ID tags). With these data, biologists can calculate the estimated population size.

Calculations: The mathematical formula for estimating the turtle population is:

=

푅 퐶 X = Estimate of total turtle population 푀 푋 M = # turtles captured and marked during first sample C = # turtles captured in second sample R = # turtles captured in first sample that were recaptured in second sample

If we solve for the estimated population size, :

푋 = 푀퐶 푋 2. Procedure: 푅

Work in pairs for the first part of the exercise.

a. Place approximately 1/2 cup (approx. 125 mL) of shells in your cup and return to your desk. The cup represents the Rainbow River and the shells represent ALL the yellow-bellied turtles currently living in the river.

Conduct 1st Sampling Event: b. Remove 20 "turtles" from the river by removing them from the cup. These represent turtles captured in the Rainbow River on your first sampling event. This number is already recorded under First Sample Total (M) on the data sheet. c. Mark each of these captured "turtles" with a marker. d. Release the marked "turtles" back to the "river" by placing the shells back into the cup. e. Gently, but thoroughly, mix the marked turtles with the other turtles in the river. You don't want to break their shells!

Conduct 2nd Sampling Event: f. Randomly remove a second small handful of turtles from the cup. It is important to pull the sample randomly (e.g. close your eyes and remove shells or slowly pour shells into hand). g. Record the number of captured turtles under Second Sample Total (C) on the data sheet. h. How many turtles did you recapture? Count the number of turtles in this sample that were recaptured from the 1st sampling event (turtles with marks). Record this under Total Recaptured (R). i. Now count all turtles in the river (including the turtles from your second sample) and record under Actual Population (P). This is the actual population of yellow-bellied turtles in the Rainbow River.

Tally Results and Analyze j. All groups now report their results for M, C, and R to the class. Each team should record the other groups' data in their own data sheet. k. Calculate the estimated population size (X) and percent difference from the actual population (% Difference) for all groups' data. l. What is the effect of sample size on the accuracy of population estimates? Make a scatter plot of Estimated Population (X) and percent difference from the actual population (% Difference) and draw a best fit line through the data points.

3. Discussion Questions:

a. How did your estimate compare with the actual population size? Did you over-estimate or under-estimate the population? b. Was there a lot of variability in the accuracy of estimates among groups? c. How did the average difference between the estimate and real population value compare to your groups alone? What does this suggest about the number of sample events that are necessary for accurate estimates? d. Were you able to detect a relationship between sample size and estimation accuracy? e. What other factors might affect the accuracy of the estimate? f. Does this seem like an effective method for monitoring turtle populations at Rainbow River? Why not simply count all the turtles you see from a canoe? g. Did this mark and recapture exercise simulate an experiment or an observational study? How can you tell? h. What can this data tell us about the causes of changes in the population over time?

Rainbow River Mark & Capture Simulation

Estimated Population (X) % Difference First Sample Second Total × Actual Total Sample Total Recaptured Population Group (M) (C) (R) 푀 퐶 (P) × 100 푅 푋 − 푃 1 20 푃 2 20 3 20 4 20 5 20 6 20 7 20 8 20 9 20 10 20 11 20 12 20 13 20 14 20 15 20 16 20 17 20 18 20 19 20 20 20 Sum % Differences ÷ Number of Groups = Average % Difference

Relationship between Sample Size and Estimation Accuracy in a Mark and Recapture Simulation

True Population and Estimate Difference Population(%) True andEstimateDifference

Second Sample Size (C)