Benthic macroinvertebrates are those organisms that are large enough to be seen without the aid of magnification and that live in close association with substrate particles within flowing and nonflowing bodies of water. Their mobility is limited enough (i.e., tens of meters), and their life spans are of sufficient length (a few months to more than a year) to make them ideal for evaluating ecological conditions and recovery from short-term and chronic perturbations in localized or general areas. Benthic macroinvertebrates provide a sensitive measure of the effectiveness of remedial actions on both spatial and temporal scales.
Collection methods vary depending upon study objectives. Qualitative and semiquantitative methods (e.g., aquatic kicknet) are generally used for screening studies. In studies requiring a greater degree of statistical confidence, such as those associated with compliance monitoring or risk-based analyses, quantitative collection techniques are used (e.g., Surber or Hess samples in streams, and Ekman or petite ponar grabs in standing waters). Sampling frequency varies, but at least two seasons are sampled whenever possible (spring and fall). Invertebrates are sorted and identified to lowest practical taxon in a laboratory.
Examples of the results for some of the major benthic macroinvertebrate community studies that have been conducted since 1985 are presented for the following locations.
For more information regarding Benthic Macroinvertebrate Monitoring, please contact John G. Smith.
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