Biologist and integrated environmental scientist Dr. Sarah Krejci’s compelling narrative illustrates the impact of humans on the natural environment.
Assistant Professor of Biology and Environmental Sciences, Bethune-Cookman University in Daytona Beach, Florida
PhD in Oceanography, MS and BS in Marine Biology, minor in History
Chicago is a long way from the sunny shores of Daytona Beach, where Dr. Sarah Krejci now delights students with her vivid lectures about seahorses and other aquatic life. However, her love for the ocean was sparked in that Midwest city by her father, who instilled in her a passion and respect for nature. “My dad was a mechanic,” recalls Krejci. “But there was a drive to recycle, to conserve food. He was always very environmentally conscious.”
Today, as a professor at Bethune-Cookman University, Krejci strives to share that reverence with students in her Introduction to Environmental Science class. One way she does this is by tapping into one of her personal favorite areas of study—seahorses.
Krejci, who refers to herself as “Seahorse Sarah” on her personal website, discovered her love of these creatures while working at Chicago’s Shedd Aquarium, where she learned about the seahorse’s unique qualities, including the fact that males carry the babies in a specialized pouch and give birth. Also, unlike most fish, they propel themselves with a fluttery dorsal fin and prehensile tail, not a caudal (tail) fin. And there is no denying that they are transfixing to watch as they move through the water.
“What I really love about seahorses is that there are so many messages you can share through them, because they are charismatic. They attract people. They draw people in,” she says.
Below, she shares some of the ways she has centered her lessons on conservation and climate change around a seahorse-studded slide show that makes science concepts easier to understand and absorb.
“Highlighting socioscientific issues impacting seahorses offers opportunities to develop critical thinking and evidence-based reasoning in students.”— Sarah E. Krejci, PhD
Course description: An introduction to basic concepts concerning the relationships among the physical, chemical, and biological components of the environment, and the impact upon them due to the activities of our own populations. The interaction between humans and the environment will be explored from organismal, ecosystem, and global perspectives.
See resources shared by Sarah E. Krejci, PhDSee materials
How Krejci uses seahorse stories as a teaching tool
The initial PowerPoint presentation that Krejci shares with her introductory environmental science class begins with some basic tips on note taking and studying, but by slide 5 (shown below), her favorite creature, the seahorse, makes its initial appearance. “There’s a lot you can do through using the seahorse as a model for how humans interfere with the environment,” she says. “Because they’re incredibly attractive, people have this connection, and it gives you an opening to talk about larger socioscientific issues.” Here are a few lessons she teaches, using seahorse stories as the common theme.
The study of biology versus environmental science
Krejci uses the seahorse to help illustrate the differences between the study of biology and the study of environmental science. A biologist studies the organism itself, she explains, by examining the five factors listed in the slide above. To illustrate the study of reproduction, behavior, and survival through the lens of biology, she introduces the fascinating story of seahorse mating. Some of the more interesting factors here include that the male, which has testes and sperm, carries the young in his uterus-like pouch for about two weeks until contractions expel them, leaving them to fend for themselves—which leads to the topic of survival.
The environmental scientist, she explains, looks at how the environment affects all of these elements of seahorse biology, such as growth and biochemical changes at the cellular level. For instance, some seahorses grow cirri—projections like those shown on the organism in the slide—to camouflage themselves. A change of environment can cause them to lose their cirri, she says, asking students to consider this: “Why would they lose them?” Krejci asks her students to predict and describe what type of habitat seahorses with cirri are blending into based on how the seahorse looks. The cirri branches on the seahorse mimic highly branched algae that can grow independently or on seagrass blades. As water currents increase in seagrass beds, these fragile algae can be knocked off the seagrass blades or their holdfasts and carried away in currents.
Currents can also trigger a shift in algal growth, which produces a morphology with fewer branches and reduced drag, allowing the algae to stay anchored. The physical forces of the currents acting on the algae are also acting on the seahorse, which may reduce the growth of cirri; or seahorses may respond by reducing cirri formation, since there is no ecological advantage to having them in an area with less branched algae to blend into. A variety of biological and ecological factors may explain how and why seahorses grow and lose cirri, and there is no consensus on whether genetics, the environment, or both are the controls.
An environmental scientist has to understand the biology and environmental conditions that can lead to changes in species. This one seahorse example serves to illustrate how complex the study of environmental science can be.
The effects of climate change on aquatic life
Next, Krejci explains how temperature will impact the reproductive capacity, behavior, and survival of these delicate creatures.
Seahorses exist in endangered ecosystems—seagrass beds, mangroves, and coral reefs—that are highly vulnerable to human disturbance, including climate change. Rising ocean temperatures can reduce the seahorse gestation period, leading to premature births and shortened seahorse snouts. “I utilize this storytelling element of the impacts of climate change on seahorses to demonstrate the complexities of science and the influence we have on the environment,” she explains.
The impact of human behavior and commerce
“Every year, 37 million seahorses are removed from their habitats. They are taken out, dried up, ground up, and made into powder to treat asthma and sexual dysfunction, used as curios in souvenir shops, and collected as pets in home aquariums,” Krejci tells students. Seahorses have had international protection regulating their collection since 2002, which has reduced wild collection and increased their price. Seahorses are now so prized, in fact, that they can sell for $300 apiece in the United States for the aquarium market. Students are always astounded to hear this—and they can clearly understand the effects of human economic activity on the environment.
The difference between comparative and controlled experiments
Seahorses also help Krejci explain comparative versus controlled experiments. Comparative experiments can compare groups in the natural environment, with a variety of variables present, whereas controlled experiments generally happen in a laboratory, with one variable being the focus of the study. An example of a comparative experiment, she says, would be going into the wild once a month to collect samples of the water where seahorses live, then comparing the levels of plankton and the water quality (variables such as temperature and weather may differ widely across collections). A controlled experiment would involve bringing seahorses to the lab and changing the pH of the water for some of them and leaving the control group at the same pH as their native habitat, while making sure all other factors (such as food, lighting, and water quality) remained the same across treatments.
Krejci’s tips for bringing stories into slideshows
Because there is such a consistent narrative running through her introductory lecture and PowerPoint presentation, students feel more invested in the material, says Krejci. (For her online students, she has made a recording of this narrative to go with the slides.) “Instead of memorizing facts, students are understanding a concept, connections, and a big-picture message,” she explains. “They’re learning vocabulary and content in a storytelling fashion.”
Here are some tips she offers to educators who would like to intertwine their own personal interests with the lectures and concepts they are required to convey in a course:
Look for topics that break your heart
Because Krejci has modeled to her students her fascination with and love of seahorses, they feel more invested in the lessons, she says. “They want to know: Why is the water so important to a seahorse? When we get into the specifics of dog waste or septic water going into their environment, they can picture this organism. It gives them a place to start. It’s a central theme that allows them to connect,” she says.
Krejci can then hone in on specific lessons relating to water pollution, habitat loss, overharvesting, and aquaculture—all of which become more heart-wrenching when students can picture these delicate creatures as the victims. “It’s important to provide time in these discussions for students to reflect on their own actions that impact the environment, such as littering and carbon footprint—and follow up with solutions for reducing these impacts,” says Krejci.
Illustrate your point with pictures
Krejci’s presentations rely heavily on clip art, graphics, and animations found (for free) online or that she creates in Photoshop or PowerPoint. “Don’t be too wordy,” she advises. “My PowerPoints do not contain a lot of text. I use graphics to convey my message [visually], because I want the students to listen to me. However, be intentional with your graphics. Don’t crowd a slide with too many pictures and images at once, since students need time to process the information you are trying to convey visually and verbally. Utilize PowerPoint animation features to bring in graphics and text slowly as you lecture.”
Bookend your presentation with questions
Before launching into her seahorse PowerPoint presentations, Krejci asks preview questions, giving students plenty of time to ask their own questions of her. For example, before defining environmental science, she asks, “What do you think environmental science is?” Then she allows students to think for a few moments and jot down some ideas. She also provides summary questions at the end of the PowerPoint presentation—a few for each section—so students can be sure they have grasped all of the key concepts (see below).
“I think professors should be given the freedom to make connections between their research and passion and use it in a course to illustrate examples,” Krejci concludes. “Don’t be afraid to talk about hard science. Your students will be interested because you’re so interested.”