Macroinvertebrate Monitoring

Volunteer collecting macroinvertebrates in Gravelly Brook, Ipswich.

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.

 

 

 

 

 

 

The presence of different types of benthic macroinvertebrates are good indicator of water quality.

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 rodonnell@ipswichriver.org

Macroinvertebrate Sampling Sites

Information for Volunteers:

Monitoring Results:

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.

Percent Model Affinity

Percent model affinity measures the similarity of the types of macroinvertebrates found at each site to an unimpacted, model community. A higher degree of similarity means there are fewer impacts to water and habitat quality at that site. 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.