Rapid Bioassessments, Grand River, Macorinvertabrates, River Metabolism


Biology | Life Sciences


Eric Snyder


The Grand River is the longest river in Michigan and has been greatly impacted by human activities, particularly logging in the mid-1800s, which when coupled with 20th-century urbanization and continued agricultural use, led to historically poor river health. Despite this, actions throughout the past 50 years by federal, state, and local citizen involvement, have resulted in increased river health and broader water quality monitoring within the watershed. During the summer of 2021, rapid bioassessments targeting benthic macroinvertebrates were conducted along the Grand River, with the primary goal of following up on prior state-led surveys conducted at different locations along the mainstem of the river in 2009 and 2014. Using the Michigan standard rapid bioassessment protocols for both wadeable and non-wadeable streams (P51 and P22 methodologies), assessments at seven locations were carried out along with metabolism measurements. Initial macroinvertebrate and habitat survey results indicate a decline in general water quality as one travels downstream, likely due to riparian impacts and cumulative pollution. This pattern was consistent with the state survey data. Metabolism was assessed at each location using a one station method, with estimations following closely with what is predicted by the river continuum concept. Headwaters and mouth/lower segments were largely heterotrophic, while the middle orders/segments were mainly autotrophic. Looking forward, this information provides a comparison for future biological monitoring efforts within the Grand River to assess changes in its ecological health.

Available for download on Saturday, April 29, 2023

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