Broad-backed (Taeniopterygidae) stoneflies found at Eight Mile and Telegraph

Since 2002, Friends of the Rouge (FOTR) has coordinated a program to sample Rouge River tributaries every winter for the larvae of the sensitive aquatic insect called a stonefly.  Finding stoneflies is significant because their presence is an indication of good water quality.

Stoneflies are regularly found in tributaries and branches of the Middle and Lower Rouge River and occasionally in the Upper Rouge.  Three different types have been found:  slender winter stoneflies (Capniidae) (most common), Perlodid stoneflies (Perlodidae), and an occasional Nemourid stonefly (Nemouridae).  Despite repeated sampling, no stoneflies of any type had been found in the Main Branch of the Rouge River or its tributaries.  This year was different.

On February 9, 2010 a team from the Wayne County Department of Public Services Water Quality Management Division (WC) positively identified a broad-backed stonefly (Taeniopterygidae) in the Main Rouge at Eight Mile Road and Telegraph.  This type of stonefly had not been found before in the Rouge AND stoneflies had never been found in the Main Branch before.  "It is really exciting that this sensitive aquatic insect survives so far downstream on the Rouge River!" said Sally Petrella, Volunteer Monitoring Program Manager for Friends of the Rouge. 

The Main branch of the Rouge River begins in Rochester Hills, travels through western Troy, a sliver of Bloomfield Township, Birmingham, Beverly Hills and Southfield before it reaches Eight Mile Road at Telegraph.  Over the past ten years, water quality has been improving due to a program that has reduced combined sewer overflows through retention basins and sewer separation.

All types of stoneflies are very sensitive to pollution as they rely on gills or skin diffusion to obtain oxygen directly from the water.   They require heavily vegetated riverbanks and prefer boulders, pebbles, large pieces of wood and decaying leave in the stream. Pollution and increased temperatures can rob the water of oxygen and the removal of streamside vegetation and logs can make it difficult for these animals to survive. Broad-backed stoneflies (Taeniopterygidae) are less sensitive than the more commonly found slender winter stoneflies and are often found at larger river sites, which may explain why they were found at this particular site.  

The Annual Winter Stonefly Search is part of a long-term monitoring program coordinated by Friends of the Rouge and supported by the Alliance of Rouge Communities.  WC partners with FOTR to sample additional sites, especially deeper downstream sites that are more difficult to sample.  For a full report, click here.

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