Back to GLANSIS home page

GLANSIS Overview

The Great Lakes have a long history of aquatic nonindigenous species (ANS) introductions – both intentional and unintentional. As of 2016, over 180 nonindigenous species have been reported to have reproducing populations in the Great Lakes basin, i.e. lakes Superior, Michigan, Huron, St. Clair, Erie, Ontario, and their connecting channels and water bodies within their respective drainages (Mills et al. 1993, Ricciardi 2001, Ricciardi 2006, Ricciardi unpubl. data). The most recent ANS reported and verified established in the Great Lakes basin is Thermocyclops crassus.

The number of Great Lakes aquatic nonindigenous species documented in GLANSIS must be interpreted as a minimum. Identification depends on our ability to find, recognize, verify, and document new species, which is, in turn, dependent on our ability to adequately sample the Great Lakes ecosystem.

NAS Partnership

GLANSIS functions as a Great Lakes specific node of the USGS NAS (Nonindigenous Aquatic Species) national database. Information entered for GLANSIS automatically appears in NAS and vice versa, though we maintain overlapping species lists. GLANSIS provides targeted access to the information – especially collection records – for established Great Lakes nonindigenous species in the NAS Database. GLANSIS serves additional information on risk assessment, management and control (relative to the Great Lakes basin only) that are not served by NAS.

Additional information on aquatic invasive species related to the Great Lakes region that are not included in GLANSIS – e.g., species which have been reported but not established, failed introductions, cryptogenic species for which evidence is considered insufficient and species native to the Great Lakes which have invaded other regions of the U.S. may be available through USGS NAS.

Back to GLANSIS home page

GLANSIS Criteria

Species are assessed for inclusion in the database on a case-by-case basis. The present database does not include waterfowl, mammals, amphibians or reptiles.

The present GLANSIS database consists of three lists:

  • A core list of species nonindigenous to the Great Lakes basin (not native to any part of the basin)
  • A list of range expansion species (native only to a portion of the basin)
  • A watchlist (not currently found in the Great Lakes but assessed in the peer-reviewed scientific literature as of 2010 as likely to invade via current pathways)

GLANSIS Definitions and Criteria for Listing (Nonindigenous and Range Expansion)

Based on the following criteria, the list of aquatic nonindigenous species found via GLANSIS is subject to constant revision.

Geographic criterion (established): Only species which are established in the Great Lakes basin below the ordinary high water mark -- including connecting channels, wetlands and waters ordinarily attached to the Lakes -- are included in the GLANSIS database. Species which have invaded inland lakes within the Great Lakes basin but not meeting the above geographic criterion are not included in the established list, but should be available via the watchlist.

Aquatic criterion: GLANSIS includes only aquatic species. USDA wetland indicator status (click here for more information) is used as a guideline for determining whether wetland plants should be included in the list - OBL, FACW and FAC wetland plants are included in this list as aquatic; FACU and UPL plants are not.

Nonindigenous criterion: The species included in the GLANSIS nonindigenous list are those which are considered nonindigenous within the Great Lakes basin by meeting at least 3 of the following criteria (based on Ricciardi 2006):

  1. the species appeared suddenly and had not been recorded in the basin previously;
  2. it subsequently spreads within the basin;
  3. its distribution in the basin is restricted compared with native species;
  4. its global distribution is anomalously disjunct (i.e. contains widely scattered and isolated populations);
  5. its global distribution is associated with human vectors of dispersal;
  6. the basin is isolated from regions possessing the most genetically and morphologically similar species.

Note: Although widely used, the term 'invasive' is vague and subject to widely inconsistent usage. Biologically it is often related to the relative ability of a species to spread and establish in new areas, while legislatively and politically it is used to characterize a nonindigenous species “whose introduction does or is likely to cause economic or environmental harm or harm to human health” (Executive Order 13112, February 1999). Thus, the term 'invasive' has multiple meanings and requires a subjective judgment. We avoid using the term 'invasive', but may use the word 'invader', in the context that a nonindigenous species that has successfully established a reproducing population is an 'invader'. 'Exotic' is a commonly used synonym for 'nonindigenous'.

Range expansion criterion: The species included in GLANSIS on the range expansion list are those which are considered nonindigenous to a portion of the Great Lakes basin according to the above nonindigenous criterion but which have been identified in the peer-reviewed literature and/or by consensus of expert review to be native or cryptogenic in some portion of the basin.

Cryptogenic species are those species that cannot be verified as either native or introduced (after Carlton, 1996). These include species that may have been identified as invasive by one researcher, but for which a literature review reveals conflicting opinions. The range expansion list includes cryptogenic species when the population is clearly nonindigenous to a portion of the basin or if the population suddenly expanding (e.g., formerly rare species becoming dominant), or changing growth form indicating the possibility a non-native strain is invading (e.g., solitary species becoming colonial, etc). When searching for species nonindigenous to a particular lake or basin (e.g., species nonindigenous to Lake Superior) select nonindigenous + range expanders to ensure inclusion of these species in your search.

Established criterion: A nonindigenous species is considered established if it has a reproducing population within the basin, as inferred from multiple discoveries of adult and juvenile life stages over at least two consecutive years. Given that successful establishment may require multiple introductions, species are excluded if their records of discoveries are based on only one or a few non-reproducing individuals whose occurrence may reflect merely transient species or unsuccessful invasions.

GLANSIS Definitions and Criteria for Listing (Watchlist)

The GLANSIS Watchlist represents a synthesis of research conducted between 1998 and 2012. As a result, it may not fully reflect the effect which regulations established during that period have had or will have on vectors of introduction (e.g., ballast water, aquaculture, live food trade, bait). The watchlist is intended to be precautionary; if there is debate about a species probability of invasion (introduction, survival, establishment, and spread) in the Great Lakes, the preference is for inclusion on this list until such doubt is resolved.

Geographic criterion: Lives in a known donor region1 (e.g., rivers adjacent to Great Lakes, inland lakes in the Great Lakes region, western Europe, the Ponto-Caspian region) or in a zone with high specialization, species pool, or climate conditions that match the Great Lakes1.

Aquatic criterion: Within the context of the Great Lakes Aquatic Nonindigenous Species Information System (GLANSIS), the criterion of including only aquatic species is unchanged. USDA wetland indicator status is used as a guideline for determining whether wetland plants should be included in the list OBL, FACW, and FAC wetland plants are included in this list as aquatic; FACU and UPL plants are not. Waterfowl, amphibians, reptiles, and mammals spending significant time in and dependent on the water are not currently included.

Established criterion: NOT already established in the Great Lakes, but assessed as 'likely' to become so in peer-reviewed literature or via our assessment (TM-169). Watchlist-specific criteria:2

  1. a transport vector currently exists that could move the species into the Great Lakes
  2. the species is likely to tolerate/survive transport (including in resting stages) in the identified vector
  3. the species has a probability of being introduced multiple times or in large numbers
  4. the species is likely to be able to successfully reproduce in the Great Lakes
  5. the species has been known to invade other areas


The species has been identified in one or more peer-reviewed scientific publications3 as having high probability for survival, establishment, and/or spread if introduced to the Great Lakes.

1This list is not comprehensive, as most published studies have been on the Ponto-Caspian region; very little information is currently available for other areas of the world with similar habitats or from which shipping traffic arrives to the Great Lakes (e.g., Asia, Central and South America).

2Species included on this watchlist meet at least three of these five criteria.

3Criteria and methods employed in these peer-reviewed publications vary but are generally consistent with the specified watchlist criteria.


Bailey, R.M., and G.R. Smith. 1981. Origin and geography of the fish fauna of the Laurentian Great Lakes basin. Can. J. Fish. Aquat. Sci. 38: 1539-1561.

Bryan, M.B, D. Zalinski, B. Filcek, S. Libants, W. Li, and K.T. Scribner. 2005. Patterns of invasion and colonization of the sea lamprey. Mol. Ecol. 14: 3757-3773.

Daniels, R.A. 2001. Untested assumptions: the role of canals in the dispersal of sea lamprey, alewife, and other fishes in the eastern United States. Env. Biol. of Fishes 60: 309-329.

Mandrak, N.E., and E.J. Crossman. 1992. Postglacial dispersal of freshwater fishes into Ontario. Can. J. Zool. 70:2247-2259.

Mills, E.L., J.H. Leach, J.T. Carlton, and C.L. Secor. 1993. Exotic species in the Great Lakes: a history of biotic crises and anthropogenic introductions. J. Great Lakes Res. 19: 1–54.

Moroz, T.G. 1994. Aquatic Oligochaeta of the Dnieper-Bug estuary system. Hydrobiologia 278: 133-138

Ricciardi A. 2001. Facilitative interactions among aquatic invaders: is an “invasional meltdown” occurring in the Great Lakes? Can. J. Fish. Aquat. Sci. 58: 2513-2525.

Ricciardi A. 2006. Patterns of invasion in the Laurentian Great Lakes in relation to changes in vector activity. Divers. Distrib. 12: 425-433.

Smith, S. H. 1995. Early changes in the fish community of Lake Ontario. Great Lakes Fishery Commission Technical Report 60, Ann Arbor.

Spencer, D.R. and P.L. Hudson. 2003. The Oligochaeta (Annelida, Clitellata) of the St. Lawrence Great Lakes region: an update. J. Great Lakes Res. 29: 89-104

Trebitz, A.S., J.R. Kelly, J.C. Hoffman, G.S. Peterson, and C.W. West. 2009. Exploiting habitat and gear patterns for efficient detection of rare and non-native benthos and fish in Great Lakes coastal ecosystems. Aquatic Invasions 4: 651-667.

Back to GLANSIS home page


Executive Committee:
  • NOAA-GLERL - Ed Rutherford, Ashley Baldridge Elgin, Doran Mason
  • NOAA-NCCOS - Felix Martinez
  • NOAA-GLSGN - Rochelle Sturtevant
Web Development: Joeseph Smith, CIGLR

Student Support: Peter Alsip, Kylan Hopper, Thomas Makled, CIGLR

Volunteer: Michele Wensman, CIGLR

Collaborators: Pam Fuller (USGS, Gainesville, Florida)
  • Expert Review: Anthony Ricciardi (Chair), Sarah Bailey (Fisheries and Oceans Canada), Hunter Carrick (Central Michigan University), Susan Galatowitsch (University of Minnesota), Jeff Gunderson (Minnesota Sea Grant), Rex Lowe (Bowling Green), Nicholas Mandrak (Fisheries and Oceans Canada), and Robin Scribailo (Purdue), Pat Chow-Fraser (McMaster University, ON, Canada), Hugh MacIsaac (University of Windsor, ON, Canada), Eugene Stoermer (University of Michigan), Steve Hensler, Tim Campbell, Titus Selheimer, Kevin Irons, Blake Ruebush, and Lisa Huberty Ken Phillips, Leah Elwell, Bernd Blossey, Norman Yan, Mark Burrows, Andy Dzialowski, Richard Barbiero, David Barton, Melania Cristescu, Jaimie Dick, Pat Hudson, Gerald Mackie, Calum MacNeil, Marten Koops, Robert Wakeman, John Gannon, Thomas Nalepa, and Henry Vanderploeg
  • NOAA: David F. Reid, David Raikow, James Liebig, Erynn Maynard
  • Past Collaborators: Anthony Ricciardi (McGill University, QC, Canada) and Rebekah M. Kipp (McGill University, Montreal, Canada), Donna Kashian (Wayne State University), Alisha Dahlstrom (Wayne State University)
  • Past Research Associate: Abigail Fusaro
  • Past Student Support: Emily Baker, Alex Bogdanoff, Ling Cao, Jane Li, Mary Hejna, Ling Jie Gu, Katie Thompson, Kyle Dettloff, Katherine Hanson, Julie Larson, Mary McCarthy, Rachel Nagy, Gabriela Núñez, Renee Spencer, Lauren Berent, Thomas Makled, Karim Alame, Marie Arnaout, Mitra Asgari, Ahmed Michael Beydoun, Emily Byrnes, Jacob Dombroski, Tiana Dudley, George Ibrahim Fakhouri, Aimee Faloppa, Mavis Gappy, Abbas Jamaluddin, Arjewan Talib Jassim, Christopher Kramb, Christina Kassis, Cathy Kelly, Abhin Kumar, Julie Larson, Marc Narcisse, Cody Narlock, Carly Nowicki, Chandani Patel, Douglas Putt, Ahmed Saad, Jomana Shayota, Heather Siersma, Cherish Stottlemyer, Amy Szczepanski, Madelyn Tucker, Viviana Veber, Holly Witman, Whitney Conard, and Susannah Iott