My principal area of interest encompasses the distribution, ecology, taxonomy, and systematics of aquatic macroinvertebrates, with focus on the oligochaetous Clitellata ('Oligochaeta') and other freshwater Annelida - the true worms. Other interests include the preservation of habitat utilized by federal- and state-listed endangered, threatened, and/or rare species of aquatic organisms; the distribution of freshwater mussels, Nematomorpha, Turbellaria, other lesser known groups of non-insectan macroinvertebrates, and aquatic insects. In addition to my work on the annelid fauna of Illinois, I am compiling distributional and ecological data for Annelida occurring in several states and provinces.
- - Short summaries for several of my collaborative projects are presented below:

Aquatic oligochaetes and other annelids occurring in the Huron Mountain region, Marquette County, inthe upper peninsula of Michigan.
In 2010, I received a small grant from the Huron Mountain Wildlife Foundation to support a preliminary inventory of freshwater oligochaetes occurring in aquatic and semi-aquatic habitats in the Huron Mountain region northwest of Marquette, Michigan. Our limited surveys at 21 sites in July 2010 yielded 25 species representing four orders, four families, and 22 genera; additional taxa (10-15) were represented by immature specimens only. In April 2011, additional funding was received to support a second year of research. In July 2011, collections were made at 18 additional sites. A third year of funding was received in March 2012, supporting surveys for aquatic and semi-aquatic oligochaetes at 16 lentic and lotic sites in July 2012. Future surveys may focus on the terrestrial oliogchaetes (megadriles) in this area.

Integrated Taxonomic Information System (ITIS).
In 2002, I was asked by ITIS personnel to serve as a steward for the aquatic oligochaetes. In late 2010, I was awarded a small grant from ITIS to provide an current, annotated list of freshwater oligochaetes occurring in North America. This includes a hierarchy, accepted names with authority(ies), recent synonomies, one or more (commonly 3-4) citations for publications documenting each valid taxon (order, family, subfamily, genus, species, subspecies), and supportive information to resolve nomenclatural issues that have been perpetuated in the historical and recent literature.

Aquatic Oligochaetes of the Great Smoky Mountains National Park.
In September 1999, we began a preliminary inventory of the freshwater oligochaetes occurring in or adjacent to the Great Smoky Mountains National Park (GSMNP). This project is being underwritten by small grants received in 1999, 2000, 2001, 2002, 2003, and 2004 from Discover Life in America, Inc. (DLIA), a not-for-profit organization administering the All Taxa Biodiversity Inventory (ATBI) program in the Park. This project is being conducted with the collaboration of Peggy Morgan (FL DEP) and many other researchers associated with the ATBI.

An extensive website summarizing our surveys for aquatic oligochaetes in the Park is available HERE. This site presents an introduction to the ATBI program and our research; by using the site navigation bar at the bottom of each page you can view a map of the Park noting sites from which specimens have been collected, specific locality information for those sites, field and laboratory methodologies used in the collection, processing, and identification of taxa, annotated checklist of aquatic oligochaetes and other annelid species known or thought likely to occur in the Park, project hightlights, goals, and sources of funding, in-kind contributions, and leveraged research support. A preliminary checklist of the freshwater Annelida (including the Aeolosomatida, Branchiobdellida, Hirudinida, and oligochaetous Clitellata) known to occur in North Carolina, South Carolina, Tennessee, and adjacent states, and a summary of work conducted to date, are posted at this site.

In late November 2007, an updated summary of our annelid research and discoveries was published (Wetzel and Morgan 2007) in a special issue of the journal Southeastern Naturalist [vol. 6 (special issue 1): 153-158] -- focusing on the on diverse research and educational programs affiliated with the ATBI in the Park; a full citation for this paper (and special issue) is included on the webpage accessible via the 'Publications' link in the navigator bar at the bottom of this page). During 2008, identifications of over 3,000 specimens (from collections made in 2003 and 2004) increased the number of known species of freshwater oligochaetes in the Park from 19 (as published in 2007) to 30!

Nomenclatura Oligochaetologica (N.O.)
In late 2000, Dr. John Reynolds (Oligochaetology Laboratory, Kitchener, Ontario) invited me to co-author Nomenclatura Oligochaetologica - Supplementum Quartum: a catalogue of names, descriptions and type specimens of the Oligochaeta. This fourth supplement (N.O.S.Q.) was to update (Addenda Editioni Primae) and correct (Corrigenda Editioni Primae) generic, subgeneric, specific and infra-specific names of oligochaetes published in the first three supplements -- N.O. Supplementum Primum (N.O.S.P.), N.O. Supplementum Secundum (N.O.S.S.), and N.O. Supplementum Tertium (N.O.S.T.), and include new taxa described through 2012.

However, in mid-2012, we decided to forego a fourth supplement, instead directing our efforts to compile a Second Edition of this Nomenclator -- bringing together all accounts and corrigenda presented in the original and three supplements with new accounts for taxa described since publication of the third supplement (N.O.S.T.). We hope to finalize this second edition by the end of 2013, or before, and present it as an on-line document with open access. By presenting the second edition in the virtual arena, we can easily correct oversights in our editing, and add the accounts for newly described taxa as soon as they have been published.

As of January 2013, over 10,000 accounts have been included (families, genera, subgenera, and species).

The Terrestrial Oligochaetes (Annelida, Clitellata) of North America.
In March 2004, Dr. John Reynolds and I published a guide to the terrestrial oligochaetes occurring in North America north of Mexico [in the journal Megadrilogia, vol. 9(11): 71-98]. That paper summarizes the extensive distributional information for this group, much of which has been published over the past 50+ years on a state, provincial, and/or regional basis in North America. In addition to a global perspective on megadrile earthworms and a summary of published historical and recent distributional information, we included summaries on the general biology of earthworms, recommended field and laboratory techniques, suggested keys for use in identification, an annotated checklist to species, and an extensive literature section. We currently recognize 10 families, 37 genera, and 161 species of megadrile earthworms in North America; of these, 116 are considered native and 45 considered to have been introduced.

In December 2008, we published an update of this 2004 publication, with new records for the U.S. and Canada, and expanded to include distributional records for Mexico, Hawaii, Bermuda, and Puerto Rico. This was published in the journal Megadrilogica, vol. 12(12): 157-208.

In July 2012, the second update in this series was published in the journal, Megadrilogica, vol. 15(8): 191-211.

The Earthworms (Annelida, Clitellata) of Illinois.
The first publication in over 50 years focusing on the earthworms in Illinois was published by Reynolds and Wetzel (2011) in the journal, Megadrilogica, vol. 15(4): 35-67. This survey increased the number of species known to occur in the state to 38, including three that represented new records for Illinois. Of these 38 species, 18 are considered native to North America, and 20 are considered introductions.

Aquatic Oligochaetes of the Colorado River, Grand Canyon National Park.
In November/December 1991, I (and with the assistance of many other volunteers during river trips) began an inventory of the freshwater oligochaetes and other annelids occurring in a variety of habitats within the Grand Canyon National Park in Arizona. Field work was conducted while participating in a 13-day research expedition to study sediment transport and energy flow in the river downstream of the Glen Canyon Dam. During this 226-mi rafting trip, We focused on collections for freshwater annelids occurring in both the Colorado River proper and several of the tributaries that flow into it within the Park. Subsequent collecting trips were made in August/September 1993 (12 days), June 2001 (11 days), and July 2006 (9 days). To date, collections for freshwater annelids and other invertebrates have been taken from 78 sites within the Park, including the Colorado River proper, 24 direct tributaries, backwater marshes, and several spring, seep, drip pot, and hanging garden sites. This project is in collaboration with Drs. Dean Blinn (now retired) and Joe Shannon. A more extensive project summary, including specific collecting locality information, is available HERE.

I have also been collaborating with scientists in other states (AZ, FL, NC, TN, TX) on the study of aquatic oligochaetes and other fauna associated with springs and groundwater habitats.

The primary source of funds that support my research at the Illinois Natural History Survey (INHS) are provided to me by the Illinois Department of Transportation (IDOT), as an Aquatic Zoologist with the INHS / IDOT Further Studies Program. Funds supporting my research on the biodiversity and hydrogeology of Illinois springs have been provided by the Illinois Nature Preserves Commission, Illinois Groundwater Consortium, and the Illinois Department of Natural Resources Environmental Protection Trust Fund Commission. Funds supporting my research on the distribution of the freshwater Annelida of the Colorado River and its tributaries in Grand Canyon National Park were provided in part by the Bureau of Land Management through the Glen Canyon Environmental Studies group, the National Park Service, and Northern Arizona University. Funds supporting my research on the distribution of freshwater Annelida in southern Sweden was provided in part by the World Wildlife Fund. Funds supporting research in the Great Smoky Mountains National Park have been provided in part by Discover Life in America, Inc. (DLIA) for the years 1999-2006. Funding to conduct limited suveys for aquatic oligochaetes in the Upper Peninsula Michigan was received from the Huron Mountain Wildlife Foundation (2010-2012).

Workshops. A non-construction grant from the U.S. Environmental Protection Agency, through the North American Benthological Society (NABS) Technical Issues Committee, was instrumental in underwriting an all-day taxonomic workshop at the 48th annual NABS meeting in Keystone Resort, Colorado, on 28 May 2000. This workshop was co-presented by Mark J. Wetzel, R. Deedee Kathman (Aquatic Resources Center, College Grove, TN), Steven V. Fend (U.S. Geological Survey, Menlo Park, CA), and Kathryn A. Coates (Bermuda Biological Station for Research, Inc.). These funds also supported the preparation and publication of a workshop workbook (Wetzel et al. 2000).

During 2005, we expanded this workbook to include the Enchytraeidae, Parvidrilidae, megadriles that are commonly collected in aquatic habitats, and branchiobdellidans; significant updates were also incorporated into all chapters. This updated workbook was prepared initially for use during two 3-day workshops presented during 2006: 1) in February, to aquatic biologists working with the Florida Department of Environmental Protection (presented by K.A. Coates, S.V. Fend, S.R. Gelder, and Wetzel, at the FDEP laboratory facility in Tallahassee), and 2) in May, to members of the Florida Association of Benthologists (presented by Wetzel, at the University of Florida Department of Entomology and Nematology, Gainesville). This workbook was updated in late 2008 (and again during 2009) for use during 3-day oligochaete taxonomy workshops presented by Wetzel in 2009: 1) University of Missouri, Columbia (6-8 January), 2) EcoAnalysts, Inc., Moscow, Idaho (3-5 March), and 3) Watershed Assessment Associates, Schenectady, NY (17-19 November).