How to use algae to evoke inquiry and establish interdisciplinary connections Claudia Bode, Mary Criss, Andrew Ising, Sharon McCue, Shannon Ralph, Scott Sharp, Val Smith, and Belinda Sturm E very year, high school students hunch over microscopes and peer at a plethora of tiny creatures. Swimming single-celled protists and whirling multicellular rotifers often steal the show, preventing students from noticing the static algae. However, these frequently overlooked, ordinary algae are inspiring research all over the world as scientists contemplate the idea of using algae as a renewable alternative to fossil fuels. By shifting the focus of their timeless microscope activities, teachers can introduce students to this idea. This article provides an overview of several algae activities that teachers can incorporate into their microscope activities to engage high school students in authentic inquiry—whether in a general or advanced biology, environmental-science, pre-engineering or biotechnology elective or in a summer enrichment course. Teachers can use individual lessons or a combination to encourage a wide variety of interdisciplinary connections—building bridges between biology, chemistry, environmental science, engineering, geography, physics, social studies, and language arts. A complete description of each activity is available online (see “On the web”). February 2014 43 Why algae? Most people tend to think of algae as the green, hairlike fibers that muck up ponds, but the microscopic varieties may have the most potential as an extraordinary energy source. Microscopic algae, or microalgae, are rich in oil molecules called triglycerides. Just like oils from soybeans and peanuts, a transesterification reaction can chemically convert algal oils into biodiesel (Chisti 2007). There are many benefits to microalgae as a fuel source. For example, algae avidly consume carbon dioxide during photosynthesis, which helps mitigate greenhouse gas effects. Algae can also grow in areas unsuitable for standard agriculture, so they don’t compete or interfere with food production. Whereas soybeans yield about 446 liters of biofuel per hectare annually, microalgae could yield more than 58,000 liters (Chisti 2007). A real-world mystery Despite the potential of algae-derived fuel, many questions remain. For example, how can scientists and engineers grow huge quantities of algae and minimize water usage, energy consumption, and cost? How can they extract algae’s oils without using harmful organic solvents? From feedstock to tailpipe, scientists and engineers are working together to turn algae into a viable fuel in the following ways: ◆◆ ◆◆ ◆◆ ◆◆ ◆◆ Ecologists and environmental engineers are searching for ways to grow algae without compromising land and water resources. Chemists and chemical engineers are searching for benign methods to extract oil from algae and convert it to fuel. Mechanical engineers are optimizing how engines perform with alternative fuels. Environmental engineers are testing emissions to see how renewable fuels compare to fossil fuels. Chemists and chemical engineers are identifying ways to turn by-products from algae processing and conversion (e.g., glycerol from biodiesel production) into paints, plastics, fibers, and other consumer products. Because practical solutions to these challenges are still uncertain, this area of study is ripe for inquiry—allowing high school students to work on some of the same key problems as practicing engineers and biologists. Along the way, students engage in the practices of engineering design, allowing “them to better engage in and aspire to solve the major societal and environmental challenges they will face in the decades ahead” (NGSS Lead States 2013, p. 1). Algal Awareness activity Teachers can use the microscope to introduce students to algae and its potential as a biofuel feedstock. In the Algal Awareness activity (see “On the web”), students examine pond water samples and learn about a variety of algal species, such as the spikey green rods of Ankistrodesmus and the spherical clusters of Pediastrum (Figure 1). (See “On the web” for a link to other freshwater algal images.) This activity serves as the starting point for further inquiry. How to grow algae To set the stage for inquiry, teachers can ask students to think about how to grow algae. Most students recognize that algae need light, nutrients, water, and air. But how much light should be provided? What amounts and types of nutrients? Will a single algal strain grow better than a pond water mixture of multiple algal species? With so many variables to consider, students can explore various conditions and maybe even make new discoveries. Four review articles can provide students useful background knowledge: Demirbas 2008; Mascarelli 2009 a, b; Pienkos and Darzins 2009. Students can investigate how to grow algae by using the Green Machine activity (see “On the web”) and the Maximizing Algal Growth activity (see “On the web”). Alternatively, described below is an open-ended inquiry approach where students design and build their own photobioreactors. The class can work together on a single investigation or divide into small groups. Building photobioreactors Designing and building photobioreactors is more timeconsuming than a guided lab, but it exposes students to an authentic engineering experience. This process gives students the skills to become independent, creative problem-solvers. Fun with photobioreactors. Photobioreactors provide many opportunities for further research and side projects—the only limiting factors are time and student interest. For example, students can use three tanks to test the impact of climate change, air pollution, and water pollution on algal growth. This can help them gain a better understanding of population dynamics and ecosystem health. 44 The Science Teacher Pond Power FI G U R E 1 Collecting algae from pond water. CLOCKWISE FROM FAR LEFT: MARY CRISS; WIKIMEDIA; PETER SIVER, CONNECTICUT COLLEGE. Clockwise, from left: Sharon McCue, biology teacher, collects algae from a local pond during her summer research at the University of Kansas; Pediastrum; Ankistrodesmus. The cost and time investment for growing algae varies. Though this activity works best as a monthlong project, as little as one week can be effective since microalgae can grow rapidly, often doubling in 24 hours. Teachers should allow one lab period to set up the photobioreactors and 10 minutes twice a week for measuring growth. The supplies (e.g., aquaria, pumps) cost from $10 to $50. The goal of this inquiry is to find a way to maximize algal growth. After introducing the potential for algae as a biofuel, teachers ask students to take an hour and plan their own experimental investigation and photobioreactor setup by answering the following questions (for a handout, see Project Guide Worksheet “On the web”). Teachers must approve the plan before students proceed to the next step. 1. Inquiry: What question do you intend to answer with this project? Some possible questions include: a. How does the light source or intensity affect algal growth? b. What is the ideal nutrient composition, water tem- perature, pH, or dissolved oxygen level? c. Will providing aeration, extra carbon dioxide, or other nutrients accelerate growth? 2. Project design: How will you answer your question? List each step as specifically as possible and then sketch the experimental design. (Note: Students’ responses to this question are typically too general; they struggle to think through each step and forget to consider details like variable control, the location of the light source, and how to hang the light source. Figure 2 (p. 46) lists possible supplies.) 3. Data collection: What data will you collect and how often? How will you present your data? Sketch graphs, tables, or charts for your data collection. See the following section for how to measure algal growth. Also, what safety or ethical concerns exist? How will you deal with each of these? (Safety note: Students must follow safe lab procedures, including wearing eye protection, wash- February 2014 45 ing hands, wearing gloves when handling hazards like fertilizers, avoiding skin contact with organisms, disposing of materials appropriately, using caution with electric equipment near water sources, and using caution when collecting samples from outdoor ponds or streams [don’t use septic ponds].) Monitoring algal growth Students need 10–20 minutes per class period to measure algal population changes and record observations such as color, smell, and degree of clarity. To monitor algal growth, students can use turbidity tubes, turbidity meters, spectrophotometer absorbance at 684 nanometers, and hemocytometers. Two high school teachers in our program correlated turbidity data with cell count data from a dozen different pond water samples (Figure 3) and found that turbidity tubes are reliable. Students can construct their own turbidity tubes for about $7 each (see “On the web” for construction details and a general discussion of turbidity). Assessment There are many ways to assess this activity. To build communication skills, we ask students to explain their research in a formal presentation to family, friends, classmates, teachers, and even professors and students from area universities (for a rubric, see “On the web”). In addition, teachers can ask their students to use social media sites, write blogs, create posters, and write articles for various outlets (e.g., newspapers, science magazines, peer-reviewed journals). In our experience, students often struggle to graph data without step-by-step directions, so we spend extra time critiquing graphs for appropriate axes labels, scales, legends, and titles in their presentations. We also ask students to reflect on the experience FI G U R E 2 Supplies for photobioreactors. MARY CRISS Clockwise, from top, left: Aquaria of microalgae, fluorescent lights to promote algae growth, light timer, air stone for diffusing air, and gang valve to distribute air from pump to aquaria. Other supplies, not pictured, include algae source, water source, containers for collecting algal samples, nutrient source, and dissolved fertilizer. Safety note: Electrical components near water tanks must have ground fault circuit interrupters to prevent electrical shock. 46 The Science Teacher Pond Power by answering the following questions: 1. Collaboration: Identify the people who improved your project’s quality, and describe their contributions. Collaborators may include classmates, school staff, family and community members, and professionals. F IG UR E 3 Correlation between cell count and turbidity. 2. Conclusion/analysis: What answer(s) did you get to your question? What trends did you notice? What data stood out? What additional knowledge did you gain? 3. Reflection: What difficulties did you encounter with your project, and how did you deal with challenges? What new questions do you have as a result of your project? Top-Down Trophic Cascade activity One of the problems with growing algae for biofuel production in open ponds is that grazing zooplankton—such as Daphnia, which are transparent crustaceans or “water fleas”—eat it. Scientists are searching for ways to limit this feeding frenzy, and biology or environmental studies students can help investigate such food chain effects by manipulating a simulated ecosystem with the Top-Down Trophic Cascade activity (see “On the web”; Smith 2011). Begin the activity by establishing four thriving algae tanks, two of which serve as unmanipulated controls. To each of the other two tanks, add 10 Daphnia, available from biological supply companies. Students monitor and graph algal growth for three weeks, then add one or two goldfish, which eat the Daphnia, to each experimental tank. As the algae thrive, students observe how different organisms interact with each other and their environment, bringing to life environmental issues and solutions. seaweed, filamentous “pond scum”), which often bloom in ponds and streams because of fertilizer runoff and other forms of pollution. Macroalgae typically have fewer lipids than microalgae (3–4% of the total algal dry weight compared to 40%) and consist mainly of carbohydrates. Scientists can manually rake macroalgae, which are easy to harvest, out of the water and then ferment them to make ethanol or burn it to heat stoves or furnaces. Though scientists don’t use macroalgae to make biodiesel, they can still dry them and turn them into a fuel source. We developed an inexpensive apparatus and lab activity for this process (Figure 4, p. 48). Assessment Teachers can use the following questions to promote classroom discussion or serve as pre- and posttest assessments: ◆◆ Macroalgae: Pond scum or energy source? In the Drying Algae and Calorimetry activities (see “On the web”), students can investigate macroalgae (e.g., kelp, ◆◆ Can scientists turn unwanted pond scum into a cheap source of renewable energy? How? What are the differences between macro- and microscopic algae? Which is easier to harvest? Unexpected drama in the “Top-Down Trophic Cascade” activity. In one of our classes, students wondered what would happen if we added a crayfish, named Mr. Pinchers, to one of the Daphnia- and algae-filled tanks. The teacher consented, and the Daphnia clustered around Mr. Pinchers, as if seeking shelter from the goldfish predator. The teacher eventually rescued Mr. Pinchers from the tank, and the goldfish ate all the Daphnia over the weekend. The experiment was a success, even if no one witnessed it. February 2014 47 FI G U R E 4 Drying chamber for dewatering macroalgae. MARY CRISS Make the chamber using a Styrofoam cooler, small box, hair dryer, and window screen. Spread algae evenly on the drying screen. Record the mass at time zero. Blow-dry for one minute and record the mass. Repeat until mass levels out (about 10 minutes). Pelletize the dried algae using a 5-milliliter syringe. After compressing the syringe as hard as possible, use a paper clip to push the pellet away from the end of the syringe. Remove the plunger and allow the pellet to dry overnight. If desired, use a calorimeter activity (see “On the web”) to calculate the energy content of the algae pellet. (Safety note: Styrofoam product should be flame retardant [check label]. Only run dryer on lowest setting. Monitor at all times and do not overheat. Have an ABC fire extinguisher handy and know how to use it.) 48 The Science Teacher Pond Power In these activities, students discover that pond scum is mostly water, with only about 10% biomass. This observation leads to a thought-provoking dilemma that makes a good written report or classroom discussion: Though macroalgae are cheap and abundant, are they worth all the trouble (and energy) to harvest and dry? If harvesters manually collect macroalgae from polluted areas, how might this affect the harvesters’ health or that of the ecosystem? We ask students to perform a qualitative benefits verses barriers analysis to see how engineering and biological concepts incorporate socioeconomic and global issues. Though macroalgae present many clear limitations as a fuel source, students can brainstorm creative, innovative solutions to these barriers. Interdisciplinary connections In much the same way that Weyman (2009) described the interdisciplinary connections of biofuels, teachers can use the activities described here to connect neighboring intellectual terrain, foster problem-solving skills, and help students develop appreciation for ethical and environmental concerns. Students use skills from the following subjects: ◆◆ ◆◆ physics: to test the effects of light intensity and transmission, chemistry: to calculate molar concentrations for nutrient-rich media, ◆◆ math: to graph data and perform statistical analyses, ◆◆ English: to write reports, and ◆◆ social studies and geography: to appreciate regional socioeconomic concerns and climate and land-use issues. Conclusion From microscope to photobioreactor, algae is an effective tool to relate common biology concepts to real-world challenges like renewable energy. The area is not only ripe for inquiry, but students can make observations, pose questions, and gather and analyze data. n Claudia Bode ([email protected]) is an education director at the University of Kansas in Lawrence; Mary Criss (mcriss@usd259. net) is a biology teacher at Wichita North High School in Wichita, Kansas; Andrew Ising ([email protected]) is a biology teacher at Olathe North High School in Olathe, Kansas; Sharon McCue ([email protected]) is a biology teacher at Wichita Northeast Magnet High School in Wichita, Kansas; Shannon Ralph ([email protected]) is a biology teacher at Dodge City High School in Dodge City, Kansas; Scott Sharp ([email protected]) is a biology teacher at De Soto High School in De Soto, Kansas; Val Smith ([email protected]) is a professor at the University of Kansas in Lawrence; and Belinda Sturm ([email protected]) is an associate professor at the University of Kansas in Lawrence. About the project The activities described here were developed at a National Science Foundation Research Experiences for Teachers program called Shaping Inquiry from Feedstock to Tailpipe (NSF EEC-0909199). With funding from the American Recovery and Reinvestment Act, this program engages high school and community college instructors in biofuel-related projects at the University of Kansas. On the web Algae research rubric: http://bit.ly/1bfmWNx Algal Awareness activity: http://bit.ly/1bdK6Hq Algal blooms at the 2008 Olympics video: http://bit.ly/1k6WOd7 Calorimeter activity: http://bit.ly/1jhpbrB Daphnia: Birth of the Next Generation video: http://bit.ly/1eM2Wq5 Daphnia videos from Video Image and Data Access: http://bit. ly/1jhppyW Directions for making a turbidity tube: http://bit.ly/1av5EMj Drying algae activity: http://bit.ly/1eM3g8d Freshwater algae images: http://fmp.conncoll.edu/Silicasecchidisk/ LucidKeys/Carolina_Key/html/Group_List.html Guppies Eating Daphnia video: http://bit.ly/1k6XKhE Maximizing Algal Density activity: http://bit.ly/18f2FuI Project guide worksheet: http://bit.ly/1iwe2VX The Green Machine: Making Algae Grow activity: http://bit.ly/ IqtMcV Top-down trophic cascade activity: http://bit.ly/1cjC2Gx References Chisti, Y. 2007. Biodiesel from microalgae. Biotechnology Advances 25 (3): 294–306. Demirbas, A. 2008. Production of biodiesel from algae oils. Energy Sources, Part A 31 (2): 163–168. Mascarelli, A.L. 2009a. Algae: Fuel of the future? Environmental Science and Technology 43 (19): 7160–7161. Mascarelli, A.L. 2009b. Gold rush for algae. Nature 461 (7263):460–461. NGSS Lead States. 2013. Next Generation Science Standards: For states, by states. Washington, DC: National Academies Press. Pienkos, P.T., and A. Darzins. 2009. The promise and challenges of microalgal-derived biofuels. Biofuels, Bioproducts & Biorefining 3 (4): 431–440. Smith, V.H. 2011. The ecology of algal biofuel production. ActionBioscience.org, www.actionbioscience.org/biotech/smith. html Sturm, B.S., E. Peltier, V. Smith, and F. De Noyelles. 2012. Controls of microalgal biomass and lipid production in municipal wastewater-fed bioreactors. Environmental Progress & Sustainable Energy 31 (1): 10–16. Weyman, P.D. 2009. The interdisciplinary study of biofuels. The Science Teacher 76 (2): 29–34. February 2014 49