Mission: Water quality bioassessment


Research Question

How healthy are our freshwater systems?

You’re Invited

Go pick up some rocks, kick up some sediment, dance in your favorite stream! The native benthic macro-invertebrates (or BMIs) you find hiding on the bottom of streams and rivers tell us a lot about the quality of the water. Based on whether you find or don’t find certain species, you can gauge the health of your stream or river.


Mission Steps

  1. Choose a fresh body of water to conduct your investigation.
  2. Gather your materials for fieldwork, including:
  3. In the field, collect macroinvertebrates using a kicknet or by just looking around.
  4. Tally what you find on your Bioassessment datasheet and calculate water quality and health scores.
  5. Go to your My Vital Signs page to add your macroinvertebrate "found" or "not found" observations. Put your bioassessment score in your field notes.
    • If you’re working alone and have limited time, choose 1 or 2 species to add to the database
    • If you’re working as a class, each team can enter one of the species you found or a species you expected to find
  6. Post your Macroinvertebrate Bioassessment datasheet to the Project Bank! (How do I do that?)

Why this Mission Matters

Streams and rivers are valuable aquatic resources in the state of Maine. BMIs are a useful tool in monitoring the quality of these water bodies. By tracking their presence or absence over time, we can understand if there were disturbances to the stream or river. These disturbances could range from climate change to pollution to invasive species. By monitoring the BMI populations in the same water body over time, scientists can gauge whether water quality and ecosystem health are improving or declining. Armed with this information, scientists and resource managers can ask better questions and make better decisions to protect the resource.

Why BMIs are great water quality indicators:

  • BMIs can’t move very far. If pollution enters a water body, the BMIs are stuck there. Fish can easily escape pollution, so they can be poor water quality indicators.
  • The BMIs can be easily grouped into pollution tolerance classes that help us determine the quality of the water. The diversity of BMIs is just as important as the presence of pollution intolerant species.
  • BMIs have a short lifespan; so one season’s pollutants will directly affect them.
  • Though you might not think so now, BMIs are easy to identify (especially when compared to other pollution indicator organisms like algae).

Dive Deeper!

Contribute to more cutting-edge macroinvertebrate research with these related field missions:


I was wondering what you're looking for when the materials say Weed Weasel? I have gone on line but I either get a jig for fishing or a garden tool. Is one of these what the materials are referring to or is it something completely different? Thanks

Hey there hoffert7,

A weed weasel is a fun contraption made with a few garden rakes and some rope. Here are instructions on how to make them - https://lakestewardsofmaine.org/wp-content/uploads/2013/11/2013-How-to-m... (we use smaller hand rakes instead of the full rakes). Depending on how many you need we may have some you can borrow.

-The VS Team-

I am hoping to get students out in a pond behind our school in the next two weeks. Because of our limited class periods I will be taking them all out one day to collect macros and will not be sorting/identifying until the next day. How do you suggest doing the data sheets? I would like students to work in groups of 3, but then can each group enter their info from their data sheets online? This is my first experience with Vital Signs, so I will probably have a lot of questions! But I am very excited to get the students out!


I think having two days for this activity is a great idea. When you are out in the pond on Day 1, I would suggest taking all of your photos (site photo, methods photo, evidence photos) to then use when you upload your data. Also, by taking some really clear evidence photos, you won't need to take the living macroinvertebrates back with you to the classroom (which could get messy for both you and the BMIs!).

This Mission is a little different than most because it uses both the normal Vital Signs data sheets and a special one, designed to calculate the overall health of the water body. I would give students the species survey sheet (http://vitalsignsme.org/sites/default/files/content/level1_freshwater.pdf) on Day 1 because they can then fill in some of the sheet (the first page and a half) without having identified the species yet. Once you identify the species on Day 2, the students can then complete the sheet and create an observation with all of the information. Students can enter this data directly into the online form in groups of three (or however big/small you want).

For the second data sheet (the Macroinvertebrate Bioassessment Sheet on this Mission page), you will compile ALL of the data from all classes and use it to fill in that sheet with the correct information (to then allow students to see the overall health of the water body). This sheet can then be uploaded onto Vital Signs via the Project Bank and your data will be available to scientists and future students. This sheet is great as you complete this activity over many years--students can then compare their data to the data of previous years.

Also, if you need anything for identification when you are out in the field, check out this website: http://vitalsignsme.org/macroinvertebrates. The Identification Sheet on the top is very, very helpful. I'd suggest making a few copies of that and using them for identification either in the field or classroom.

Have fun, and feel free to post with any questions (or if this explanation did not help at all, in which case I can try again!).



So glad you're excited about this mission!

Schools across the state seem to be jumping on already! Check out data from Dover-Foxcroft from last week. Here's one observation that they posted - http://vitalsignsme.org/species-trichoptera-order-was-found-mrspovak-201....

Can't wait to see what you all find :)

I am so excited about this mission! The identification resources are fantastic! I can't wait to get started with my students.


I'm so glad you are excited about this mission! Getting out--and getting wet--in a stream is so much fun for students (and teachers!). I would recommend, when you get your class out into the stream, taking single sheets for identification of macroinvertebrates. I really like the "Department of Environmental Protection Macroinvertebrate ID-Guide" and also the "Missouri Stream Team Stream Insects and Crustaceans" sheet (http://www.mostreamteam.org/documents/vwqm/bugcard1.10.pdf). Laminating a few copies of each of these sheets is great, and they highlight specific characteristics of each BMI for proper identification. Both of those sheets are extremely helpful! (Species cards are also awesome, but bringing out lots of species cards can get a little cumbersome sometimes out in the stream. This summer, Vital Signs will release a one-sided identification sheet that can be used as an "all-in-one" species card for BMIs.)

If you and your students get really into this mission, I would strongly recommend getting a copy of the Streamkeeper's Field Guide. It has a great BMI dichotomous key in it, and it also contains a lot of information regarding chemical testing (if you want to go that route, eventually) and watersheds in general (so then your students can begin assessing WHY the stream's health is the way it is ... because a stream is a reflection of its watershed, understanding the watershed is key to understanding the stream, and visa versa). It is definitely a worthwhile investment.

Also, grab a few ice cube trays before you go out. They make awesome places to store and hold BMIs while you are working on identifying them (and they allow for easy organization of the different species).

If you have any questions about identification, stream work, or the mission, please let us know! Also, if you have any comments/concerns regarding the mission, that information is also welcome.

Thanks so much, and have an awesome time out in the stream! I hope it goes swimmingly.