Living Micro-Reefs
Bring Excitement to the Classroom
Science educators teach aquatic ecology through innovative techniques
Lacy crust bryozoan. Photograph, Adam Frederick
Marine engineer Chris Tollini with a rack of disks. Photograph, Nicole Lehming
Marine engineer Chris Tollini pulls up a rack of discs that became encrusted with marine life after they were immersed for six months in the murky waters of Baltimore's Inner Harbor. One of the discs might shelter a lacy crust bryozoan, shown here with its colonial plumes (top). Photographs, J. Adam Frederick (top) and Nicole Lehming (above)

ON A WARM SEPTEMBER MORNING in Baltimore's Inner Harbor, the traffic steadily moving along on Pratt Street, Chris Tollini is perched on a ledge just above the harbor's murky water. He's pulling up the first of thirteen PVC pipes, each with stacks of black-encrusted discs along the length of the pipes. These acrylic discs were clean when first lowered into the water nearly six months before — now they are teeming with life: mussels, barnacles, and other organisms such as bryozoans and hydroids. These living microcolonies are destined for high school labs and students who are studying the ecology of this polluted urban harbor.

Tollini is with the Institute of Marine and Environmental Technology (IMET) Aquaculture Research Center housed steps away in the Columbus Center, which fronts onto Pratt Street. This morning he's with the supervisor of science education for Carroll County's public schools, Jim Peters, who will put the pipes and discs in coolers and deliver them to county science teachers.

By explaining how these marine colonies got started in the first place and thrived in contaminated waters, teachers will be able to guide their students in hands-on research about complex ecological processes.

A Toehold for Life

More than twenty years ago, Adam Frederick and his colleagues at the Center of Marine Biotechnology (IMET's predecessor) conceived the idea of hanging discs in the harbor in order to collect organisms that could be used by Maryland pupils to study aquatic biology. Now Maryland Sea Grant's assistant director for education, Frederick began collaborations with other research scientists at the center.

White anemone (top left); bryozoans (top right); a whip mud worm (bottom left); and stentors (bottom right). Photograph, Adam Frederick
Once immersed in the Inner Harbor, the bare acrylic discs quickly attract a plethora of small, invertebrate marine creatures, including a white anemone (top left); bryozoans (top right); a whip mud worm (bottom left); and stentors (bottom right). Photograph, Adam Frederick

This effort grew into the Biofilms and Biodiversity Project, a program which uses biofilm discs and an interactive web resource to educate students and teachers who visit the Columbus Center. There they are invited to examine the colonized discs in a learning lab, called SciTech, which is run by Towson University. Teachers also participate in professional development workshops given by Frederick.

Earlier in his career, Frederick taught high-school courses in biology and environmental science, and he still speaks of the living discs with the zeal of a teacher eager to share new worlds with his students. The discs, he says, are not only inexpensive but an effective tool for teaching nonscientists about the harbor's marine life.

"You look at these discs under the microscope, and it is like seeing a miniature reef," Frederick says. In this small space, many interesting-looking animals live together in a community. The mussels dominate, opening and closing their shells as they filter food particles from the water. You can see barnacles extending their feeding legs, tiny worms, perhaps anemones, and even the occasional mud crab.

In examining the disc-bound communities, students and visitors learn about the coating of life that forms the foundation for the entire colony. Though not visible to the eye, this coating consists of microorganisms — bacteria and diatoms — that are the first colonizers. Once established, they send out chemical signals that attract mussel larvae and other life forms that settle and attach themselves. It's like hanging out a sign, "Free land for settlers!"

Project-based Learning
Marissa Harbison and Judy Plaskowitz with a rack of disks. Photograph, Nicole Lehming
Mytilopsis leucophaeata on a disk. Photograph, Nicole Lehming
Marissa Harbison, (top) a senior at South Carroll High School in Sykesville, Maryland, examines one of the biofilm discs in her Science Research class, guided by the teacher, Judy Plaskowitz. A disc (bottom) shows how in the Inner Harbor, dark false mussels (Mytilopsis leucophaeata) usually outcompete other species for living space. Photograph, Nicole Lehming

Over the years, the biofilm discs have become a vehicle for educational outreach beyond the Columbus Center, and Jim Peters has become one bridge for that outreach. After filling two large coolers with the PVC pipes and their discs, he delivered them to seven high schools in Carroll County. Science teachers were ready and waiting: all had prepared aquariums in their classrooms with water containing salinity at 11 parts per thousand — the same level found in the waters of the Inner Harbor when the discs were collected. These saline conditions would keep the colonies alive until science classes later in the week.

The discs fit well in a broader approach routinely used by Carroll County science teachers that emphasizes hands-on learning. Students record their observations and collect specific data. Unlike conventional biology where pupils may do microscopic studies of prepared slides and dissect animals furnished by a biological supply house, the biofilms project gives them an unusual opportunity. "They rarely get to see living things from an environment like the harbor, let alone a community of living things," says Frederick. "The level of engagement is high — the school bell could ring, and they're still engaged."

In Carroll County, the discs are the basis for a lesson in an elective course called Science Research that offers students an intensive series of project-based science learning activities, some of them focused on aquaculture, the cultivation of fish in tanks. Students take this course in addition to others in physics, chemistry, and biology. For two decades, Frederick has worked with Peters and the county's science teachers to help refine the Science Research course curriculum.

"I feel incredibly lucky to have this program," says Judy Plaskowitz, who teaches the class at South Carroll High School in Sykesville. One reason it has prospered, she says, is the technical support she and other teachers receive from Frederick and other scientific experts working at IMET. Peters adds, "We couldn't sustain any of this without their help."

The day after Peters's special delivery to Plaskowitz, 25 students file into her Science Research class. Safety first: she has the students put on protective gear — latex gloves and goggles. The Inner Harbor's water can contain potentially harmful bacteria.

Plaskowitz had removed 12 discs from the PVC shaft, placed each in a separate glass bowl, and spread them around the classroom. "They know that Baltimore Harbor is really polluted, but I don't know if they know the life you can find there," she tells a visitor before groups of two or three students take their places around each bowl.

"Here are examples of things you might see on the discs," Plaskowitz says, pointing to a set of photos on a screen titled "Rogues Gallery," an illustration from Maryland Sea Grant's Biofilms and Biodiversity website that shows classes of marine organisms, such as bryozoans with their feathery tentacle crowns, hydroids with branching plumes, transparent anemones.

She tells the students about random sampling, a critical tool in ecological science for estimating the abundance of species in a particular space. She helps the students to identify and count species on each side of the disc at ten randomly chosen locations. Each location is only a fraction of the disc's surface area, about 78 square centimeters per side. From measurements made at the ten locations, the students can extrapolate to estimate abundances across the entire disc — or an even larger area.

"You get to go deeper in this class — it's more hands-on," says Marissa Harbison, a senior. "Hands-on makes it interesting. . . . It's dope!"

Mussels were the most abundant species she and her classmates counted. And that, Frederick says later, offers a key lesson about the harbor's ecology. "It's an example of a principle that ecologists have known about for a long time called dominance diversity," he says. "That's what we have in Baltimore Harbor because it's a stressed environment — you end up with a few species that dominate the space and crowd out everything. You see more well-balanced biodiversity in less-stressed environments."

Some Carroll County students in the Science Research class have seen those kinds of differences first-hand: they have analyzed biofilm discs they deployed in other, less-stressed aquatic settings, including freshwater ponds around Carroll County and saltier water adjacent to Ocean City, Maryland.

Sharing the Model

For some years now, Frederick has been spreading the word among Maryland educators about the value of biofilm discs for teaching science. Any Maryland science teacher can ask him to deploy discs in the Inner Harbor. Besides supplying them to Carroll County, he's also provided a source for discs for teachers in Baltimore City and Baltimore County. In addition, a series of lesson plans created by Frederick and his colleagues can be downloaded from his program's Biofilms and Biodiversity website. These pages are among the most viewed on Maryland Sea Grant's website.

Students looking at oysters on an REU cruise. Photograph, Sandy Rodgers

A core mission for Maryland Sea Grant is preparing students to succeed in science. To address the national need for science education, Maryland Sea Grant develops innovative approaches to improving science education from middle school though graduate school.  more. . . .

Over the years Frederick has also helped science educators in California, Hawaii, Rhode Island, South Carolina, and Texas get started using biofilm discs for teaching.

In fact, his work has gone international: Frederick led an effort to connect science educators in the United States with their counterparts in Europe who want to use biofilm discs to help secondary-school students learn about marine biodiversity. The project, which began in 1997, is called the Virtual University Education project or VIRTUE; partners include the University of Gothenburg, in Sweden; institutions in Germany and Spain; and Maryland Sea Grant through the University of Maryland Center for Environmental Science. Participating faculty members have collaborated to create lesson plans, and the University of Gothenburg created an online portal for students and teachers to share data about their projects. As part of a research field experience, Swedish high-school students connected with VIRTUE have traveled to South Carolina's Grice Marine Laboratory, where they examined biofilm discs removed from Charleston's harbor.

VIRTUE is based on a premise that students, whether they examine discs pulled from Baltimore's Inner Harbor or Scandinavia's Baltic Sea, can learn principles about aquatic biodiversity that are important to understanding ocean and coastal waters everywhere. In this way, each acrylic disc encompasses its own little world, as well as a piece of the wider world.

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