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Students Use Macroinvertebrates as Indicators of Stream Quality


Increased awareness concerning imperiled insect populations may be driving interest in invertebrate-themed programming.  This past fall, CEES received multiple requests for the Aquatic Biodiversity program, a unit that focuses intensely on insects. 


Pool and riffle habitats in Hare Creek (Ritchey Woods). Photograph by V. Schmalhofer.


Aquatic Biodiversity guides students through the process of using aquatic invertebrates (insects, worms, snails, crawdads, etc.) as a mechanism to assess the health of streams and ponds.  Because tolerance to various physical factors - such as temperature, pH, pollution level, etc. - differs among species, and because invertebrates tend to be more sensitive than vertebrates to variation in the physical environment, the invertebrate species present in an aquatic habitat can be used as a proxy of system health/condition.  Presence of pollution intolerant species, for example, indicates a healthier (i.e. less polluted) environment.  The program can also be used to investigate how different types of aquatic organisms are found in different habitats, such as pools (deeper, slower moving water) and riffles (shallower, faster moving water).


High school AP Environmental Science students collect aquatic invertebrates from Hare Creek at Ritchey Woods.  Photograph by V. Schmalhofer.


Using dip nets and rock sampling, students collect a variety of invertebrates to assess the habitat.  As part of the activity, students learn basic invertebrate identification skills, as well as categories of pollution tolerance of various types.  Depending on how in-depth an investigation is desired, physical parameters of the environment may also be measured.  Aquatic Biodiversity concentrates on larvae of insects - such as mayflies, damselflies, stoneflies, midges, mosquitos, and caddisflies - but snails, flatworms, and other invertebrates are examined, too.  While it is not a full immersion program (hand-collecting aquatic invertebrates works best in shallower water!), Aquatic Biodiversity does encourage students to get their feet wet - and with the extended summer temperatures that prevailed this autumn, students enjoyed a day in the stream!


Aquatic Biodiversity is suitable for middle school science classes, as well as various high school courses, such as Freshman Biology, AP Environmental Science, AP Biology, and Ecology.



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