Aquatic Annelida of Grand Canyon National Park – Introduction


In 1990, the Glen Canyon Environmental Studies Program in cooperation with the Department of Biology, Northern Arizona University, Flagstaff (NAU), began a long-term study of the benthic dynamics of the Colorado River and its tributaries located in the Grand Canyon National Park (GCNP), Coconino and Mohave counties, Arizona.  For several years, this project was directed by Drs. Dean W. Blinn and Joseph P. Shannon (NAU), with assistance from Dr. Larry E. Stevens (Grand Canyon Monitoring and Research Center); more recently (after Dr. Blinn retired from the faculty of NAU), the project has been directed by Dr. Shannon.  In early 1991, M.J. Wetzel was invited by Drs. Blinn, Stevens, and Shannon to participate in an upcoming river trip (November-December), specifically to assist the program with its field sampling program, and to focus as time permitted on the aquatic annelid fauna present at sites located on the Colorado River and on selected tributaries.  The collection of aquatic annelids continued during three additional river trips (September 1993, June 2001, and July 2006).

  photos to be added here soon. 

Photos (© M.J. Wetzel, INHS) taken during our 20-30 June 2001 trip on the Colorado River in Grand Canyon National Park (GCNP), Arizona [Colorado River (COR) river mile (RM) noted].

Numerous taxonomists and systematists with expertise in one or more groups of plants and animals are participating in this project, and are being assisted by ecologists, data specialists, aquatic and terrestrial biologists, teachers, students, and regional volunteers.  My primary focus for this project was to identify freshwater oligochaetes, leeches, and any other aquatic or semi-aquatic annelids that I and others collected from the Colorado River, its direct tributaries, and other unique habitats within the GCNP during this project.  I especially welcome any specimens that others may have collected from aquatic habitats within the GCNP, and published records of aquatic and terrestrial Annelida from this region.  Your findings (with credit) will be incorporated into this website, and your publications will be included in the literature cited section of this document if you forward a reprint to me. Suggestions for and comments on this project are welcome.

These expeditions would not have been possible without the professional field assistance of many others, listed below.  Each of the four trip headings, below, link visitors to more specific information associated with sites visited during each of the trips.

1991 river trip (20 November–03 December)

Collaborators on this 1991 river trip included: Joseph P. Shannon, Michael L. Shaver, Jeanette Macauley, Clay Runck, Alla Sineeva, Candace Stewart, Tom Martin, Molly & Peter Absolon, Marcy Demillion, Teresa Yates, Dennis Silva, Mary Moran, OC Davis, Bob Grusy, Jano Kempster, Monte Becker, Lew Steiger, Stephanie Trimmer, Jim Thomas,  and several other volunteers.  INHS lab assistant M.L. Biyal was responsible for the sorting and processing of macroinvertebrate samples collected in 1991, the slide mounting of oligochaete specimens sorted from samples, and database entry of pertinent project information.

 1993 river trip (01–12 September)

Collaborators on this 1993 river trip included: Joseph P. Shannon, Michael L. Shaver,  Larry E. Stevens, Michelle L. Biyal, Susan J. Hueftle, Fredric R. ‘Frederheic’ Govedich, Emma L. Benenati, Bonnie Ellis, Connie L. Graham, Jack Stanford, G. Richard Marzoff, Jeff Pflueger, T. Brinton, and several other volunteers.  INHS lab assistant M.L. Biyal was responsible for the sorting and processing of macroinvertebrate samples collected in 1993, the slide mounting of oligochaete specimens sorted from samples,  and database entry of pertinent project information.

2001 river trip (19-29 June)

Collaborators on this 2001 river trip included: Emma L. Benenati, Nelleka DeVane, Allen Haden, Pat Haden, Carolyn Link, Chris Niebuhr, Joseph P. Shannon, Kristin Straka, Susie Vogel, and Kevin Wilson, and GCMRC personnel Carol ‘Fritz’ Fritzinger, Park Steffensen, and Jake Tiegs. Peggy Morgan (Florida Department of Environmental Protection), assisted me with the collection of oligochaetes during this trip, and was instrumental in our ability to concentrate on the diversity and uniqueness of habitats (especially the spring, seep, and COR tributaries), particularly when our time was limited at sites because of time-dependent aspects of the multiple research projects supporting this trip, and also because of schedules associated with river flow, hydroelectric discharge from the Glen Canyon dam, and other characteristics of the COR and its tributaries.

2006 river trip (10-18 July)

Collaborators on this 2006 river trip included: Nick Ballew, Emma L. Benenati, Chris Blattel, Steve Marlatt, Peggy Morgan, Bob Murphy, John Rihs, Jeff Scoggins, and Joseph P. Shannon. I thank Tim Grooms and other personnel of Yellow Springs Instrument Company, Inc. for the loan of the model YSI 556 multiparameter handheld meter (dissolved oxygen, DO % saturation, water temperature, conductivity, hydrogen ion concentration [as pH], ORP, resistivity, and barometric pressure); this meter performed flawlessly, affording a convenient and time-saving approach to accurate measurement of several physical / chemical water quality parameters amidst the relatively extreme conditions present in the Grand Canyon at this time of year. [I have used numerous meters in the YSI product line for over 30 years, and they have been extremely reliable; although I cannot provide specific endorsements of commercially available products, the Model 556 meter did serve flawlessly in an ’emergency field situation’ after a comparable meter (manufactured by a competing company) failed to ‘meet expectations’.]


All research associated with this project in the GCNP complies with and has been / is being conducted under the following Scientific Research and Collecting Permits issued by the USDI-NPS: GRCA1993AHRR (issued to Dr. Dean Blinn, Northern Arizona University, Flagstaff); and GRCA1999-20-11, GRCA-1997-SCI-071, and GRCA-2000-0071 (all issued to Dr. Joseph Shannon, Northern Arizona University, Flagstaff).   All of the trips were affiliated directly with continuing projects – – monitoring of the effects of interim flows on the aquatic food base [Cladophora, and amphipods, chironomids, oligochaetes, and several other dominant invertebrate taxa] in the Colorado River downstream of the Glen Canyon Dam, Arizona.  If you have additions or corrections to the information presented below, please forward them to me via E-mail, at: * mjwetzel{AT}

Collecting Sites

All collecting sites sampled during the river trips of 1991, 1993, 2001, and 2006 are located in either Coconino or Mohave counties in Arizona. Colorado River river mile (COR RM, or RM) coordinates are taken from Stephens (1983). All other locality information, including Universal Transverse Mercator System (UTM) coordinates, has been taken from U.S. Geological Survey 7.5 minute series topographic quadrangle maps (USGS tqm); the North American Datum (NAD) of 1927 applies to all maps.  The edition (year of publication, photorevision, and photoinspection, when applicable) is noted in each site description. Township, Range, and Section information, when available, is governed by the Gila & Salt River Meridian (G&SRM).  UTM coordinates recorded for the 2001 collections were obtained using a Garman GPS III Plus.  Latitude and longitude coordinates will be added to site information as time permits.

Note:  By placing your cursor over the homepage for this project under the Research link in the navigator bar at the top of this webpage, you can access:

  • Pages with locality information for collection sites that were sampled during the four research trips,
  • A preliminary checklist of the aquatic Annelida occurring in the Colorado River (COR) and its tributaries in Grand Canyon National Park, Arizona (GCNP)
  • Literature cited and selected references pertinent to this research project.

Field sampling and laboratory methodologies

Physical and chemical parameters were measured at each site immediately prior to habitat characterizations and biological collections.

Parameters measured included: ambient and water temperatures (in °Celsius, using red liquid thermometer); dissolved oxygen (in mg/l), percent dissolved oxygen saturation, conductivity, hydrogen ion concentration (as pH), ORP, and barometric pressure – – all measured simultaneously using the Yellow Springs Instruments Model 556 MPS multimeter.

Aquatic oligochaetes (and other macroinvertebrates) were collected qualitatively using standard D-ring dip nets and small, fine-meshed aquarium dip nets.  Dip net collections for specimens were supplemented by the hand-picking of various natural substrates (gravel, cobble, boulders, sticks, branches, logs, leaf packets, and root mats).  Riffle, run, pool, backwater, and cascade habitats were agitated by hand and foot, with dislodged material drifting into dip nets.  Additionally, aquatic vegetation, detritus, and other substrates (gravel, cobble, detritus) were rinsed in buckets of habitat water to dislodge oligochaetes, followed by the straining of rinse water through fine-meshed Nytex cloth or an aquarium net.

Most samples containing oligochaete specimens were relaxed immediately after collection in a weak ethanol solution, then fixed with buffered formalin.  Aquatic insects, when separated from other material after capture in the nets or buckets, were preserved in 70% ethanol.  Mollusks, when observed, were preserved in 70% ethanol; ancylids, sphaeriids, and a few gastropod species were collected from several  sites, but neither live specimens nor shell material of the pelecypod families Unionidae, Corbiculidae, and Dreissenidae was observed a any of the sites visited in 1991, 1993, or 2001.

A priority during our surveys was to minimize physical disturbance to streams and other sites from which aquatic macroinvertebrates were collected – maintaining our ‘leave-no-trace’ approach to field research to the best of our abilities.  In particular, extreme care was taken during our abbreviated collecting efforts for aquatic macroinvertebrates in the finite habitats associated with the small streams and rock pools.  Every effort was made to cull live vertebrate specimens (fishes and amphibians) from netted material, immediately returning them to the specific habitat from which they were obtained.After field samples were brought to the INHS laboratory, and initial processing of samples was completed, all samples were labeled and stored in 80-85% ethanol in  vials or jars appropriate for the specimen.

In the lab, oligochaetes were dehydrated through an ethanol series, cleared for 1+ hours in a 1:1 ethanol-xylene solution, then mounted under coverslips on glass slides in Canada Balsam or Permount.  Specimens were identified using Olympus BH-2 or BX-50 compound microscopes equipped with Nomarski differential interference contrast (DIC) optics.

Nomenclature and taxonomic interpretations follow Reynolds and Cook (1976, 1981, 1989, 1993), Kathman and Brinkhurst (1998), Reynolds and Wetzel (2021), Wetzel et al. (2009), Reynolds and Wetzel (2023), and those published in recent literature.  All specimens obtained during this study are deposited in the Illinois Natural History Survey Annelida Collection in Champaign, Illinois USA.


Funding for this research, in part, has been provided by the U.S. Department of the Interior through the Bureau of Reclamation, Glen Canyon Environmental Studies Program, and the Grand Canyon Monitoring and Research Center–U.S. Geological Survey, in cooperation with the Grand Canyon National Park, Glen Canyon National Recreation Area, and Northern Arizona University.  I also thank the Ancestral Puebloans, the People of the Havasupai Nation – Havsuw Baaja, or “People of the Blue-Green Waters,” and the People of the Hualapai Nation – “People of the Tall Pines” and “Keepers of the Canyon.” Finally, I acknowledge the continuing support of my institution, the Illinois Natural History Survey. I am particularly grateful to Drs. Dean Blinn and Joe Shannon, directors of this project, for their support and encouragement, and for the opportunity to participate in this outstanding project.  Effective collection of annelid specimens during the 1991, 1993, 2001, and 2006 river expeditions would not have been possible without the professional field assistance of numerous colleagues and friends.

Literature Cited

Citations for the literature referenced in the text, above, are presented HERE.

Questions, Comments, Suggestions, or Ideas?
Please E-mail them to me at:   
mjwetzel{AT} *

 Copyright 2000-2024, by Mark J. Wetzel; All Rights Reserved.  This website established and maintained by Mark J. Wetzel, Research Scientist-Curator and Collections Manager, INHS Annelida Collection, Illinois Natural History Survey (INHS), Prairie Research Institute at the University of Illinois Urbana-Champaign, Champaign, Illinois 61820 USA

This website contains original, copyrighted material; it is being provided here as a professional courtesy, exclusively for your private, non-commercial use. Reference to or redistribution of any part of the information contained herein – whether it be through oral, printed, electronic, or other tangible medium of expression – shall acknowledge the Illinois Natural History Survey (INHS) and this website as its source, and shall acknowledge the U.S. Department of the Interior Bureau of Reclamation, Glen Canyon Environmental Studies Program, the Grand Canyon Monitoring and Research Center, U.S. Geological Survey, Grand Canyon National Park, and Glen Canyon National Recreation Area, and Northern Arizona University for their long-term support of this research. Should you have any questions whatsoever regarding the warranty, liability, or proprietary rights of, or credits for information contained within this website, please refer to the INHS License Agreement. [To the best of my knowledge – and with the exception of the INHS logo – all icons, line breaks, dots, arrows, and globes are not copyrighted.]

* The ‘@’ symbol in my E-mail address has been replaced with ‘{AT}’ to deter the ‘mining’ of these webpages by spammers who use programs to collect valid E-mail addresses; a recent study released by the Federal Trade Commission found that 86% of E-mail addresses posted on webpages and in internet news-groups eventually end up on lists used by spammers. You must replace the ‘{AT}’ with the ‘@’ symbol in order for your E-mail message to be sent and received.

Suggested citation for this webpage:
Wetzel, M. J. 2024. The Aquatic Annelida of the Colorado River and its tributaries, Grand Canyon National Park, Arizona.
World Wide Web URL: [ ]. 17 March 2024.

[page update: 20Jul2021; 14, 15,16,26Nov2021; 01Jan,05feb2023; 17mar2024; mjw ]