Aquatic Insects: Indicator Species of Urban Watershed Health

Date: January 3, 2019 Author: EcoSpark Categories: Latest

Aquatic Insects: Indicator Species of Urban Watershed Health

This blog was contributed by guest writers Bethany Linton, Scott Robertson, Nicole McClennan and Peter Sourges.

Benthic Macro Invertebrates (BMI’s) are important environmental indicators of the health and integrity of watersheds and for this reason, can be effectively utilized in urban stream studies. EcoSpark assembles preserved BMI study sets that are used to teach students how to collect and identify these species. During stream studies, students tally the number of BMI species found and calculate the productivity of the watershed using the Hilsenhoff Index. EcoSpark’s standardized stream assessment protocol was used to compare different urban stream environments between the Humber River in the Greater Toronto Area (GTA), Jennings Creek in Kawartha Lakes and Jackson’s Creek in Peterborough. This comparative stream study was conducted by Fleming College students from the Ecosystem Management Technology program in collaboration with EcoSpark.

The Humber River has a long history in Toronto with a section running alongside the Old Mill. The Old Mill was first established in 1793 as one of the first industrial sites in Toronto as a sawmill. Since then, the Old Mill has been damaged and reconstructed numerous times and now stands as the Old Mill Toronto Hotel, including the Humber Banquet Hall and a Wedding Chapel. The Humber River is recognized as a Canadian Heritage River and acts as habitat for a wide range of migratory songbirds, over 60 fish species, and monarch butterflies.

EcoSpark has recorded BMI data at the Humber River since 2010 and uses an assessment tool called the Hilsenhoff Biotic Index (HBI). The HBI is an index which estimates the overall tolerance of a community given the abundance of each taxonomic group of BMIs. The Humber River was first classified as an “Unimpaired” site in the Fall of 2010.. Another evaluation in Fall of 2015 established that the Humber River was “Potentially Impaired” receiving an HBI  value of 5.19, indicating that there is likely a fair amount of pollution occurring. In the Fall of 2016, the evaluation showed it was “Potentially Impaired” once more receiving an HBI value of 6.14, showing that there was substantial pollution. Both Jackson’s Creek and Jennings Creek were evaluated by the Fleming College students this past fall season. Jackson’s Creek was evaluated and was shown to be “Potentially Impaired”, receiving an HBI value of 4.65 (Table 1.3), showing that there was probably pollution. Jennings Creek was shown to be “Potentially Impaired” receiving an HBI value of 6.01 (Table 1.2), showing substantial pollution occurring.

The HBI increase in the Humber River effectively shows the increase of impairment, this is likely due to the constant development occurring in the GTA, as this would likely affect the diversity and production of the watershed. For both Jennings and Jackson’s Creek there are subdivision developments occurring nearby, with runoff and agitation to the watershed contributing to it’s impairment.


Data Analysis Calculator. (2018). EcoSpark. Retrieved from:

Discover Humber River, Old Mill & Marshes Guide. (2018). City of Toronto. Retrieved from;

Historical Lower Humber River BMI Data. (2018). Provided by EcoSpark.

History of Old Mill area at Humber River. (2018). Old Mill Toronto. Retrieved from;

Image retrieved from:

 A Note about the Authors:

Bethany Linton, Scott Robertson, Nicole McClennan and Peter Sourges currently attend Sir Sandford Fleming College and are in the Ecosystem Management Technology program. They all have a strong passion for the environment and love getting hands on experience in aquatic and terrestrial field work. To further develop their skills, they have completed a variety of certificates and species identification courses. As a team they have a lot of experience in outreach and education programs on informing others on the importance of ecology and sustainability.