Selecting Freshwater Macroinvertebrate Taxa List

By Dr. John Morse, Clemson University

The number of freshwater macroinvertebrate taxa occurring in eastern North America is much greater than the number imaged and annotated in this project.
​How were the project’s taxa chosen?

1. The families and genera for which we provide images and annotations are relatively common and occur throughout most or all of eastern North America—less-common taxa and taxa with more-restricted ranges are not included. The number of taxa for which we provide images and the smaller number of taxa for which we provide annotations are also limited by the resources available for the project.
2. We include only freshwater macroinvertebrate taxa encountered in eastern North America that are commonly used for estimating an Index of Biological (or Biotic) Integrity (IBI). As noted in the US EPA's guiding reference (Barbour et al. 1999), IBIs typically include insects, crustaceans, snails, bivalves, annelids, mites, and a few other macroinvertebrates that are rarely seen. We concentrate on insects, but, for completeness, we also include some examples of non-insect macroinvertebrates. The reason for restricting the list of non-insect macroinvertebrates is that a longer list often will require imagery and annotation for structures that are visible only with dissection and special preparation (e.g., special stains, mounting on microscope slides, etc.), activities that citizen stream-watch participants are not likely to attempt.
3. Many interesting macroinvertebrate taxa occur in lakes, ponds, swamps, etc., with most of these taxa occurring exclusively in such habitats. However, there are no standard protocols for using macroinvertebrates to assess water quality in lentic (still-water) habitats. The above-mentioned EPA reference pertains only to "streams and wadeable rivers," generally smaller lotic (flowing water) habitats. This means that both professional biologists and citizen stream-watch groups currently focus their freshwater biomonitoring efforts on flowing surface water. Therefore, freshwater taxa that occur only in lentic habitats are not included in this project.

Why are annotations provided sometimes for a genus, sometimes for less-refined levels of taxonomy such as a family or an order? What criteria were used to decide the amount of detail provided in the annotations?

At a minimum, the level of annotation provided for each taxon is the level needed to distinguish it from other taxa imaged in this project. At the level of order and family, our annotations will often distinguish the taxon from all other North American taxa, but for families with multiple genera we did not attempt to annotate genera sufficiently to distinguish them from other North American genera that are not imaged.

Reference cited:
Barbour, M.T., J Gerritsen, B.D. Snyder, & J.B. Stribling. 1999. Rapid Bioassessment Protocols for Use in Streams and Wadeable Rivers: Periphyton, Benthic Macroinvertebrates, and Fish. Second Edition. EPA 841-B-99-002. U.S. Environmental Protectin Agency, Office of Water, Washington, D.C.
*Available from https://nepis.epa.gov/Exe/ZyPDF.cgi/20004OQK.PDF?Dockey=20004OQK.PDF