Aquatic Macro Invertebrates

Northeastern Illinois University, DePaul University, & the Chicago Metropolitan Water Reclamation District

Macroinvertebrates, the unsung heroes of river ecology, are organisms including aquatic insect larvae, small mollusks, crustaceans, aquatic worms, and essentially anything tiny that lacks a backbone but is still visible without a microscope.

Why care about macroinvertebrates? Because they care about you, and do a LOT of stuff for you because of it! They break down organic debris and helping recycle the nutrients back into the ecosystem, mostly by getting eaten (a thankless task). Aquatic macroinvertebrate populations are routinely used as indicators of stream health, and by studying the changes in macroinvertebrate populations surrounding our islands, we can determine if our islands are supporting more diverse and abundant macroinvertebrate populations, as we would suspect to happen. We measure this by deploying “Hester-Dendy” apparatuses - macroinvertebrate habitats that we leave in the river for 6-8 weeks. As the gaps fill up with sediment, macroinvertebrates crawl in. We then pull the whole structure up and assess the contents, which allows us to get a snapshot of the community living in the river.

Northeastern Illinois University and DePaul University have supported work from undergraduate researchers Steph Mueller and Sam Garcia. Steph has developed our internal Bugs in Urban Rivers Program (BURP) which is our continuous monitoring program at the Wild Mile, Bubbly Creek, and River Park. The analysis of our samples from this research is conducted by trained volunteers, making it an exciting community science project!

Initial data collection after the installation of our pilot gardens demonstrated higher species diversity as measured by the Shannon Diversity Index for samples taken near our artificial floating wetlands, versus those collected in areas with seawall. These promising initial results are outlined in a 2023 publication, and support the necessity of wetland and riparian ecosystems for this crucial category of river organisms.