Piloting Macroinvertebrate Surveys to Assess Water Quality & Biodiversity
CRC has long maintained a focus on water quality through monitoring, advocacy, and restoration projects. We are growing our programmatic focus on the ecology and biodiversity of our underwater neighbors dependent on good water quality, all with an eye to fostering connection, stewardship, and interest in our watershed community. At the intersection of water quality and ecology are aquatic macroinvertebrate communities.
What is an aquatic macroinvertebrate?
It is an organism that lives in the water, is large enough to be seen and collected without special equipment such as a microscope, and does not have a backbone. Macroinvertebrate communities are composed of a wide variety of organisms, from crustaceans like crayfish and amphipods (scuds), to mollusks like snails, or the most numerous group typically found: insects. This includes mostly aquatic insects in the larval or nymph stages such as the commonly collected stoneflies, caddisflies, dragonflies, or mayflies, but can also include adult life stages of insects like riffle beetles.
In 2026 CRC took our first steps towards building a volunteer macroinvertebrate monitoring program—inspired by our dedicated and numerous water quality volunteers—by conducting community science macroinvertebrate surveys in multiple tributaries in NH, including the Wild Ammonoosuc (Bath), Twin Brook (Chesterfield), California Brook (Chesterfield), and an unnamed tributary to Grant Brook (Lyme). Benthic macroinvertebrate surveys offer insight into the health of aquatic ecosystems. Community composition (what species are found), species diversity (how many different types of macroinvertebrates are found), and abundance (how many of each type are found) all provide information about water and habitat quality, pollution effects, and general ecological condition of the water body in which the macroinvertebrates are sampled.
Some species, like mayflies and stoneflies, are more sensitive to degraded water conditions, while others, like worms and midges are tolerant of poor water quality. Many other commonly found groups, including dragonfly and damselfly nymphs, bivalves, and crayfish fall somewhere in between in their ability to persist in impacted habitats. A common metric used for judging water quality is “EPT species richness” an index that calculates the relative abundance of mayflies (taxonomic order: Ephemoptera), stoneflies (Plecoptera), and caddisflies (Trichoptera) in a sample. Within each broad taxonomic category the species found can inform about water, community, and food web health. For example, stoneflies in general are indicative of higher quality water, but giant stoneflies are even more sensitive to pollution than winter stoneflies. Changes over time in macroinvertebrate community metrics can provide a lot of useful information about the state of the water body and how it is reacting to and recovering from perturbances. Macroinvertebrates are also critical components of the aquatic food web, serving as food for larger aquatic and terrestrial organisms from fish to bats and all things in between – their huge importance to aquatic ecosystems is inverse to their small size (despite being call “macros”).
Macroinvertebrate surveys are used extensively in biomonitoring, and importantly, are easy to conduct and adapt for use with volunteers, students, or professionals. Yet, long term and widespread macroinvertebrate data for the Connecticut River tributaries are lacking. This fall, CRC collaborated with the Chesterfield and Bath schools to implement sampling protocols with students and also hosted a non-student volunteer collection event in Lyme, NH with the Upper Valley Land Trust. We’re grateful to Upper Valley Land Trust for permitting access to Lyme Hill Conservation Area for this project. Learn more about UVLT’s work at UVLT.org.
These pilot sampling events allowed staff members including myself, Kate Buckman, as well as Stefanie Farrington and Melissa Langley to test out different methods used by other organizations and state agencies and receive feedback from participants. This will help shape a protocol for CRC community scientists to implement in NH and beyond in future years that works well for CRC’s needs, while generating data useful outside of CRC as well. We hope to develop committed long-term macroinvertebrate volunteers, similar to those who power our successful e. coli water sampling program in the northern CT, MA, and southern VT portions of our watershed. Please feel free to reach out if you are interested in learning more.
