Through this program, IRWA volunteers collect data on “benthic macroinvertebrates” – a biological term that means an organism without a backbone (invertebrate), that can be seen with the naked eye (macro), and lives on the river bed rather than in the water column (benthic). Benthic macroinvertebrates include insects such as larval damselflies, dragonflies, and midges, as well as crustaceans, mollusks, etc. that live in the streambeds of fresh water rivers like the Ipswich.
Macroinvertebrates, or “macros” for short, are an important part of the ecology of the Ipswich River. They can also be used as an indicator of water quality based on their preferences and tolerances. For example, certain macros such as mayfly larvae can only thrive in waters with relatively high dissolved oxygen. Therefore, the presence of mayfly larvae in a river segment is an indicator of high dissolved oxygen. However, if that river segment only contained macros that can tolerate low dissolved oxygen (such as damselfly larvae) we could conclude that the dissolved oxygen levels are too low to support a diverse range of macros.
Sampling, sorting and identifying macroinvertebrates is a fun activity for volunteers. To find out how to get involved in this program and for information of when these events take place, contact the Program Coordinator Ryan O’Donnell at firstname.lastname@example.org
Macroinvertebrate Sampling Sites
Information for Volunteers:
- Macroinvertebrate Monitor Description (pdf)
- Macroinvertebrate Monitoring Manual (pdf)
- Macroinvertebrate Monitoring Quality Assurance Project Plan 2013-2015 (pdf)
Major Group Biotic Index
Biotic index is a measure of the pollution tolerance of the macroinvertebrate community at a site. More groups of pollution tolerant aquatic macroinvertebrates are an indicator of poorer water quality. The effect of impervious cover on water quality in sub-basins of the watershed is also shown for comparison to the macroinvertebrate data. This map was created by Kristen Thiebault.