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This case study is used to teach undergraduate students about hydraulic fracturing (hydrofracking), a controversial method for extracting methane from shale. The controversy arises from claims that chemicals used in the fracking process and the methane itself find their way into drinking water and are also sometimes found at dangerous levels in the air. The case study begins in a college chemistry class where a student inquires about a news item he saw about residents setting their tap water on fire. The instructor uses this as an opportunity for the students to research hydrofracking and natural gas, and she then integrate these topics into their present study of isotopes. The class first examines what isotopes are by using a guided inquiry based activity. The students then learn how mass spectrometry, which uses the principles just learned about isotopes, is employed to determine the source of methane in contaminated wells. This case study is designed for freshman chemistry students and students in environmental studies.

This case study explores the controversy surrounding Yellowstone bison (Bison bison) and the relationship between wildlife management and pluralist democracy. In the late 1960s Yellowstone National Park suspended the policy of strictly managing bison by culling in favor of "natural processes" management. This led to dramatic herd growth and to bison exiting the park in winter in search of forage. Montana cattle ranchers reacted angrily for fear that the animals would infect their cattle with brucellosis. Since 2000, several government agencies have administered the Interagency Bison Management Plan, which uses culling to manage the population at around 3,000 head. The resumption of culling has upset environmental groups, while the recently approved expansion of bison habitat beyond park boundaries continues to upset ranchers.  The ongoing political battle between ranchers, environmentalists, Native American tribes and government agencies shows how difficult it can be to balance legislative mandates, ecological values, and conflicting public demands. The case study may be employed in a variety of courses, including American Government, Public Policy, Interest Groups, Environmental Studies and National Parks.

This case study presents the fictional tale of two neighboring towns that have recently experienced a growth boom and are now suffering the environmental consequences. The case provides an opportunity to explore a wide variety of anthropogenic causes of natural capital degradation. Students are assigned the role of scientists working for the regional Department of Environmental Resources Management, and it is their job to discover the underlying causes for a wide variety of citizen complaints and to suggest reasonable and cost effective solutions. The case may be assigned as a recap activity after teaching a unit on natural capital degradation. The case includes a PowerPoint presentation as well as three lab activities that are included in the teaching notes. The case would be appropriate for high school or lower level undergraduate ecology or environmental science courses.

This case study examines a variety of biological factors that may have been involved in the 2013 dolphin "unusual mortality event" (UME) on the East Coast of the United States. The story follows a news reporter and four different scientists who are preparing their notes for speaking at a public hearing about the dolphin die-off event. After reading the story, students assume the roles of these scientists and use the jigsaw method to gather, analyze, and share information.  Due to the interdisciplinary nature of environmental toxicology, this case study exposes students to four main topics: ecology of ecosystems, endocrine system/chemical messaging, immune system function, and virus biology.

Polar bears are an iconic symbol of climate change, but regionally relevant examples of susceptible biota are needed to highlight how global forces impact local environments. In this interrupted case study, students follow a young naturalist as she explores why saltmarsh sparrows are increasingly rare in coastal wetlands of the northeastern United States. In small groups, students diagram how sea-level rise may alter saltmarsh sparrow habitat and analyze a graph to determine if there is evidence to support sea-level rise. The social implications of rising sea levels induced by climate change can also be explored with an optional jigsaw activity. Students who successfully complete this case study will integrate key concepts related to sea level rise, interpret scientific data and draw conclusions about environmental change, and evaluate alternative management decisions. Originally developed for an undergraduate ecology course, the case could easily be adapted by college or high school instructors for an introductory biology or an environmental science course.

Lauren is an Environmental Studies graduate from NYU and former Sustainability Manager at the NYC Department of Environmental Protection, and the amount of trash that she has produced over the past three years can fit inside of a 16 oz. mason jar. Lauren Singer is author of the Zero Waste blog, Trash is for Tossers and founder of organic cleaning product company, The Simply Co. Through her blog, she has empowered millions of readers to produce less waste by shopping package-free, making their own products and refusing plastic and single-use items.

To what extent should corn be used for the production of ethanol? Are we better off producing corn for food or producing corn for fuel? This case study uses a technique called "intimate debate" (also known as "constructive controversy") in order to examine this issue. Each student participates in a set of mini-debates for which there is no audience. Students are paired with a teammate; these teams then take turns arguing each side of the issue while seated across from their opponents who do the same. The session concludes with opposing teams reaching consensus. Detailed instructions are included in the case handout to prepare students for the experience before debate day. This case was used successfully in a sophomore/junior level, general education, environmental biology course. It would fit appropriately into any college course that discusses environmental issues related to farming practices, land use, alternative fuels, renewable energy, or sustainability.

This case study presents a realistic example of drinking water contamination within a fictional local community and leads students through an abbreviated human health risk assessment. Students are provided background information about the extent of the contamination and a description of the contaminated site and are then required to calculate both the cancer and non-cancer risks to the community. This exercise is appropriate for an environmental toxicology or environmental risk assessment course. It works well after a lecture on the basics of risk assessment including how to calculate exposure intakes and risk estimates.

With increasing U.S. government support for biofuel production in the late 2000s came increased pressure to convert more land to cornfields for ethanol. To make way for more corn, millions of acres of prairie grassland were plowed under, destroying an extremely diverse wildlife habitat that also served as a large carbon reservoir. This case study focuses on the reasons for and consequences of large carbon losses when prairie grasslands are converted to agricultural lands. Many students are challenged when faced with linking together energy flows, decomposition, and nutrient cycles.  This case gives students the opportunity to consider different pools in the carbon cycle and the fluxes between them in order to model (on paper) an integrated picture of why carbon is lost when prairie grasslands are plowed and planted to cornfields.  Students also consider ways that carbon loss from land conversion due to ethanol production might be avoided via government incentive programs or mitigated via changes to farming practices. This case study was developed for an introductory ecology, environmental science, soil science, or agriculture course.

In this case study students are provided with information for piecing together the story of how forest fragmentation and biodiversity loss can affect the risk of Lyme disease transmission to humans. The case introduces the dilution effect, a widely accepted theory-and one of the most important ideas in disease ecology-which suggests that disease risk for humans decreases as the diversity of species in an area increases. It also explains how landscape fragmentation, one of the most common threats to biodiversity, can influence the risk of Lyme disease for humans. Students interpret and discuss various figures to develop a concept map that connects all the individual results of the story. Students gain an appreciation for the complexity of species interactions in an ecosystem, the effects of forest fragmentation on these interactions and the possible consequences for human health. This activity was developed for an undergraduate introduction to environmental sciences course under the topic of biodiversity and conservation, but would also be suitable for interdisciplinary studies interested in examining the connections between conservation and public health.

This case study uses a jigsaw activity to introduce students to four specific plant responses to climate change: elevational range shifts, phenology shifts, community shifts, and changes in biodiversity. Students become "experts" on one of these responses by reading an article (from Nature, Science, or American Journal of Botany; not included with the case) on their assigned topic and then sharing their expertise with others in class. In order to hone their understanding and increase retention on these topics, students then learn about plant communities found in a specific system-vernal pools or seasonal wetlands typical of Mediterranean climates (a PowerPoint presentation on this topic is included). Students accomplish several small group tasks to assess how different vernal pool plant communities have responded to fluctuations in annual weather patterns and predict how these communities may respond to greater weather variability resulting from future climatic change. This case was written for mid- to upper-level ecology, plant ecology, botany, or environmental studies courses. The material covered may also be suitable for classes examining the role of weather variability/climate change in relation to plants.

Humans construct boundaries -- around our homes, our neighborhoods, and our nations -- to bring order to a chaotic world. But we rarely consider how these boundaries affect other creatures. In this episode of Think Like A Scientist, we meet conservation photographer Krista Schlyer, who has spent the last seven years documenting the environmental effects of the U.S./Mexico border wall, and biologist Jon Beckmann, who studies how man-made barriers influence the movement of wildlife. Schlyer and Beckmann have seen damaging impacts of the border wall firsthand, but they remain optimistic. Humans probably won't stop constructing walls and fences any time soon, but planning our boundaries with wildlife in mind can help prevent these structures from causing environmental harm.

The external environment's effects upon genes can influence disease, and some of these effects can be inherited in humans. Studies investigating how environmental factors impact the genetics of an individual's offspring are difficult to design. However, in certain parts of the world in which social systems are highly centralized, environmental information that might have influenced families can be obtained. For example, Swedish scientists recently conducted investigations examining whether nutrition affected the death rate associated with cardiovascular disease and diabetes and whether these effects were passed from parents to their children and grandchildren (Kaati et al., 2002). These researchers estimated how much access individuals had to food by examining records of annual harvests and food prices in Sweden across three generations of families, starting as far back as the 1890s. These researchers found that if a father did not have enough food available to him during a critical period in his development just before puberty, his sons were less likely to die from cardiovascular disease. Remarkably, death related to diabetes increased for children if food was plentiful during this critical period for the paternal grandfather, but it decreased when excess food was available to the father. These findings suggest that diet can cause changes to genes that are passed down though generations by the males in a family, and that these alterations can affect susceptibility to certain diseases. But what are these changes, and how are they remembered? The answers to questions such as these lie in the concept of epigenetics.

When an elementary school teacher calls in sick to work, she finds out that she is not the only one who will be missing school that day.  Children from her fifth grade class have also become ill and parents are calling to report the absences. The concerned principal of the school finds out the fifth grade class had a field trip to one of the local parks the day before. The case shows the areas visited by the class and provides discussion between the principal and a physician that teaches the readers about water quality and EPA standards for bacteria levels in recreational water. The case has an optional lab component that provides the theory for three methods that can be used to conduct microbial water analyses.  Procedures are included for teachers to lead a lab activity to test water to identify which location in the park caused the illness. This case study and accompanying laboratory activity are recommended for an environmental engineering course or a lower level science course.

This "clicker case" gives students an opportunity to apply their understanding of three different types of selection (directional, stabilizing, and disruptive) to a variety of model systems. The case describes each type of selection in detail, presents a paradigm case of each, and then uses clicker questions to test whether students can identify the mode of selection in other systems (answers included in the teaching notes).  Nine different studies are presented so that students gain a broad understanding of selection and how environmental factors can impact species differently. The case concludes with an optional discussion activity (also discussed in the teaching notes) to deepen understanding. Although designed for a high school classroom, it could easily be used in a lower-level college course as an engaging introduction or review of concepts. The case could be used at the beginning of an evolution unit, but it would be helpful if the students were familiar with natural selection before completing the activity.

This interrupted case study tells the story of Miles, a freshman in college, who volunteers to help with the composting program on campus. Miles is excited about composting but his mother is hesitant to try it at home. Miles learns about the key ingredients for successful composting and his mother eventually begins to see its value. This case is presented in four parts, and can be used with or without the PowerPoint presentation and associated clicker questions (see Supplemental Materials). First, students are asked to analyze waste that they generate at home and identify any material that is compostable. Next, students explore the science of composting. Finally, students explore the topic of human manure to consider composting to the extreme. The case was designed for an environmental science course for non-majors; no prerequisite knowledge is assumed.

This interrupted case study, designed for an introductory biology or environmental science course, introduces students to the complexity of ecosystems by examining changes in trophic interactions and abiotic factors in a freshwater ecosystem as a result of human actions. The case narrative describes the recent and undesirable appearance of decomposing algae (Cladophora glomerata) on a public beach in the Laurentian Great Lakes. Students are asked to use the scientific method by creating hypotheses and examining observational data to describe biotic and abiotic components of the Great Lakes ecosystem. The case requires students to differentiate between benthic and pelagic environments (e.g., the influence of depth and phytoplankton density on light availability, and the availability of phosphorus) and the interactions between organisms in both environments. Students also examine shifts in these interactions as a result of the newly introduced zebra and quagga mussels, which have ultimately resulted in the algae's presence on the beach. There are also opportunities to discuss the impact of these ecosystem changes on people who own property and/or visit the beach.

In this interrupted case study students analyze the complexities surrounding identification and confirmation of cancer clusters. The case challenges students to consider the evidence from two different perspectives; a local family physician representing the community, and a cluster investigation officer who has worked on several cancer cluster investigations. This case was inspired by the discussion about a possible cancer cluster in Clyde, Ohio, where around 20 cases of childhood cancer since 2001 fueled public concern, leading to an investigation by the Ohio department of health in 2006. This case was designed for introductory courses in biology and environmental sciences, taken by both science majors and non-science majors. In addition to introductory college classes, this case could also be used in advanced high school biology classes.

This interrupted case study introduces basic modeling to investigate a decline in an American marten population on an island in Southeast Alaska. Two summer field technicians working on a long-term field ecology project for one of their professors notice that there are fewer marten captures this year. Through discussions with their professor, conversations with a local fur trapper, and based on their own observations, they develop a plan to model the population and the potential causes of the decline to solve the mystery. Students use Excel or other database software along with life tables and introductory population ecology to investigate three potential causes of the marten population decline. This case was developed for use in an environmental science or wildlife management course but could also be used in an advanced science high school course or general ecology course. It would be beneficial for students to have some background in statistics including how to interpret R-squared values, p-values, and 95% confidence intervals.

Sheep ranching has destroyed habitat and decimated species in many areas of the world, but in Patagonia declining wool prices provide an opportunity to turn the tide. This case study places students in the role of advisor to an international NGO that has funds to advance conservation goals. A PowerPoint slideshow is used to present the Patagonian landscape, species, and variables that should be considered in conservation decisions.  After the presentation, students are given two maps: the first shows park boundaries, topography, roads, and major land forms; the second includes land prices overlaid on the first. Student groups are assigned a budget, and with the help of a set of guiding questions, students identify and defend a potential land purchase to develop as a protected area. The case is intended for use in an undergraduate class in conservation biology, environmental science or ecology, and presupposes another case in our collection, "The Great Patagonia Land Grab" by C.E. Quinn and J.E. Quinn