2023 Early Hearing Detection & Intervention Conference

March 5-7, 2023 • Cincinnati, OH

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5/21/2019  |   10:00 AM - 10:15 AM   |  A COMPARISON OF MACROINVERTEBRATE DRIFT IN A 4TH ORDER REACH OF THE AU SABLE RIVER, MI.   |  250 DE

A COMPARISON OF MACROINVERTEBRATE DRIFT IN A 4TH ORDER REACH OF THE AU SABLE RIVER, MI.

The Au Sable River (MI) is a 4th order blue ribbon trout stream that has experienced an array of changes during the past 50 years, including diversion of sewage effluent and removal of a low-head dam. We evaluated invertebrate drift for 24 hours at 3 sites on 3 dates to replicate drift studies conducted in 1969 and 1996. Drift typically peaked between midnight and 5 am and was dominated by mayflies. Drift was lowest during day light hours. Total drift abundance at a single sample location was reported to be 8,489 organisms day?¹ net?¹ before the sewage diversion (1969) and 4,535 organisms day?¹ net?¹ after effluent diversion (1996). In comparison, we estimated drift in 2018 to be 11,418 organisms day?¹ net?¹ at the same site. Although effluent diversion significantly reduced nutrient loading, 2018 invertebrate drift exceeded previous drift abundance suggesting that nutrient reductions have not diminished invertebrate drift.

  • Bioassessment
  • Monitoring
  • Secondary Production

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Presenters/Authors

Barney Boyer (), Grand Valley State University, boyerb@mail.gvsu.edu;


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