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Severn Sound Environmental Association

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Tributary Ecosystem Health Monitoring Program

Stream benthic community composition has long been used to assess stream quality in the Severn Sound watershed. The Tributary Ecosystem Health Monitoring Program (TEHMP) has been ongoing since 1996 and utilizes several standard biomonitoring protocols in the Severn Sound streams. The TEHMP approach taken in Severn Sound has been to rely most on qualitative collection methods to determine presence/absence of benthic macroinvertebrates (identified to as low a taxonomic level as practical) at a number of sites across the watershed. The collection of quantitative samples using a T-sampler at selected sites provides an indication of year-to-year changes due to natural fluctuations and to remedial efforts (SSRAP 2002).

 Questions and Answers

What is Biomonitoring?

Biomonitoring is a collection method known as biological monitoring. It is the systematic use of living organisms or their responses to assess the aquatic environment

What are benthic invertebrates?

Benthic invertebrates (aquatic bottom dwelling organisms without a backbone) live in, crawl upon, or attach themselves to the bottom sediments of a body of water. They include such things as various larval stages of dragonflies, damselflies, mosquitoes, mayflies, black flies, crayfish, snails, clams and aquatic worms. Benthic invertebrates perform many important functions in the river ecosystem such as decomposing organic matter and are a food source for many fish species.

Why does SSEA monitor benthic invertebrates?

There was concern that standard water quality protocols (chemical and bacterial) just show a point in time (a snapshot) and are unreliable predictors of overall stream health throughout the season. Collecting benthic invertebrates can provide an understanding of aquatic habitat health. Because many benthic invertebrates live in the stream year-round and sometimes over multiple years, their presence or absence provides valuable information about a stream's health over time. Changes in water quality lead to changes in the community structure and species. Polluted areas, often only support a few pollution tolerant species versus a diverse community found in unimpaired areas. This tool enables SSEA to locate where stewardship activities may be needed or areas to protect within the watershed.

Where does SSEA monitor benthos in the severn sound area?

Seventeen long-term monitoring stations are sampled yearly (July/August) within the Severn Sound watershed. It represents eight sub-watersheds includes Avon River, Coldwater River, Copeland Creek, Hogg Creek, North River, Silver Creek, Sturgeon River, and Wye River. (View the SSEA Monitoring Stations Map....Look for the white circle symbol), Additional sites are monitored seasonally depending on projects within the watershed.

How does SSEA monitor invertebrates in the Severn Sound area?

Two sampling protocols are used for the collection of benthic invertebrates. The first protocol involves two people conducting a 15 minute search of all habitats in a 15 meter stream reach using hand sieve and forceps to collect a qualitative collection. Habitats included sand, silt, gravel, rip-rap, large rocks, logs and vegetation.

The second protocol is a quantitative method using a t-sampler within the riffle area of a stream. This method was selected to calculate the density of invertebrates within the diameter of the t-sampler. It provides valid comparisons between samples, by relative abundance and will show any species and density changes at a location. The open end of the sampler is placed into the current and the substrate inside the t-sampler is agitated for one minute and allowed too clear. The flow of the water through the t-sampler will carry any invertebrates through the net and into the catch bottle.

Contents of the catch bottle are placed in a white field tray and all specimens are picked from the tray and net. The specimens are preserved in seventy percent alcohol and taken back to the lab for identification using a stereo microscope.



In the spring of 1998 a hands-on educational program was created by SSEA and local high schools. The program involves grade ten students completing a stream evaluation in four local streams. The evaluation involves collecting benthic invertebrates (qualitative method), assessing in-stream and riparian vegetation, chemical analysis (hach kits), flow measurements, temperature (air and water) and a site sketch. The benthic invertebrate samples that where collected by the students are brought back to the classroom for identification. Four sites were selected for the study: two headwater and two mouth stations. This enabled the students to learn the different species that are present in a headwater station (unimpaired water quality) compared to mouth (impaired water quality) station.

For more information about the TEHMP, contact:           
 Paula Madill, Ecosystem Technologist
705-527-5166 ext. 203