biomagnification, the magnification of concentrations of toxins as
they move up the food chain.
Remaining class time can be used to conduct a class discussion
about biomagnification. Students might work in groups to complete an Observation Worksheet on the lesson’s main concepts
(see Supplemental Materials), and then the class can discuss their
To extend the lesson for a longer period of time or a more advanced
grade level, connections could be made to human physiology
through the health effects of biomagnifying substances like methylmercury and PCBs (EPA, 2016a, 2016b). Discussing different biomagnifying substances could also provide classes the opportunity
to discuss how different substances accumulate in different body tissues and what the implications of these differences in bioaccumulation might be. Higher grade levels could also practice scientific
literacy and data interpretation by examining case studies of biomagnification (e.g., Bargagli et al., 1998; Strandberg et al., 1998).
This lesson plan can also accommodate classes of different sizes.
For a class of seven to 24 students, instructors can simply place
fewer students at each level of the food chain, as long as each
secondary consumer can still eat at least two zooplankton, and each
tertiary consumer can eat at least two secondary consumers. For a
class of greater than 25 students, instructors might consider breaking
the class into two groups.
Although zooplankton and copepods are found in essentially
all aquatic ecosystems, our choices of secondary and tertiary consumers are relatively specific to the Chesapeake Bay. Consequently,
these elements of the lesson could be adapted to other locally relevant aquatic ecosystems. For example, in freshwater ecosystems,
minnows, herring, or shad could be substituted for the secondary
consumer, and bass, trout, or salmon for the tertiary consumer.
For saltwater ecosystems, minnows, mackerel, and sardines might
be more relevant secondary consumers, and salmon or tuna could
serve as the tertiary consumer. However, in adapting this lesson
to other ecosystems, it is important not to conflate secondary consumers with omnivores or tertiary consumers with carnivores; for
example, while mummichogs and minnows are omnivores, herring
and shad are not and should therefore not consume plant material
in the second stage of the lesson.
When we field-tested this activity in a middle school classroom,
students remained engaged and were particularly excited to consume their classmates and excrete the waste. Moreover, based on
responses to the Post-Activity Worksheet (see Supplemental Materials), the lesson was successful at conveying the main concepts
of biomagnification, particularly in relation to the food chain and
as distinct from bioaccumulation.
We would like to thank the students at Spring Ridge Middle School,
who participated in our field-testing, as well as the Science Education
class at St. Mary’s College of Maryland for their feedback on this activity.
Bargagli, R., Monaci, F., Sanchez-Hernandex, J. C., & Cateni, D. (1998).
Biomagnification of mercury in an Antarctic marine coastal food web.
Marine Ecology Progress Series, 169, 65–76.
Kim, H.-T. & Kim, J. G. (2013). How do high school science textbooks in
Korea, Japan, and the U.S. explain bioaccumulation-related concepts?
Science Education International, 24, 416–436.
EPA. (2016a). Basic information about mercury. Available at https://www.
EPA. (2016b). Learn about polychlorinated biphenyls (PCBs). Available at
National Science Teachers Association. (2013). Disciplinary core ideas
in the Next Generation Science Standards (NGSS) final release.
Retrieved from http://nstahosted.org/pdfs/ngss/20130509/
Strandberg, B., Bandh, C., van Bavel, B., Bergqvist, P.-A., Broman, D., Näf, C.,
Pettersen, H., & Rappe, C. (1998). Concentrations, biomagnification and
spatial variation of organochlorine compounds in a pelagic food web
in the northern part of the Baltic Sea. Science of the Total Environment,
ADELINE SCHLUSSEL ( firstname.lastname@example.org) is a graduate of the
Department of Biology, ALEXANDER RHOADES ( email@example.com) is a
graduate of the Department of Chemistry and Biochemistry, KELLY Y. NEILES
( firstname.lastname@example.org) is an Assistant Professor in the Department of
Chemistry and Biochemistry, and SAMANTHA L. ELLIOTT (slelliott@smcm.
edu) is an Associate Professor in the Department of Biology, all at St. Mary’s
College of Maryland.