The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Bythotrephes longimanus
Bythotrephes longimanus
(spiny waterflea)

Copyright Info
Bythotrephes longimanus

Common name: spiny waterflea

Synonyms and Other Names: Formerly known as Bythotrephes cederstroemii (Berg and Garton, 1994; Yan and Pawson, 1998; Berg et al., 2002; Therriault et al., 2002).  spiny water-flea

Taxonomy: available through www.itis.govITIS logo

Identification: Bythotrephes longimanus is a large cladoceran distinguished by a long straight tail spine that is twice as long as its body and has one to three pairs of barbs. Parthenogenically produced animals have kink in middle of their spine and sexually produced animals lack the kink. Bythotrephes appearance is similar to Cercopagis pengoi, another Great Lakes invader, except Bythotrephes is larger with a more robust spine that lacks a hook at the end.

Size: can reach 15 mm

Native Range: Northern Europe and Asia

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Bythotrephes longimanus are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
IL198620113Chicago; Lake Michigan; Little Calumet-Galien
IN198619881Lake Michigan
MI1984201712Betsie-Platte; Betsy-Chocolay; Dead-Kelsey; Keweenaw Peninsula; Lake Huron; Lake Michigan; Lake Superior; Michigamme; Ontonagon; Pere Marquette-White; St. Marys; Thunder Bay
MN1987201812Baptism-Brule; Big Fork; Cloquet; Lake of the Woods; Lake Superior; Little Fork; Lower Rainy; Rainy Headwaters; Rainy Lake; Rum; St. Louis; Vermilion
NH202320231Winnipesaukee River
NY1985201910Hudson-Hoosic; Lake Champlain; Lake Erie; Lake Ontario; Mettawee River; Mohawk; Oneida; Sacandaga; Upper Allegheny; Upper Hudson
OH198520193Lake Erie; Tuscarawas; Walhonding
PA199820132Lake Erie; Upper Allegheny
VT201420141Lake Champlain
WI1986201912Bad-Montreal; Beartrap-Nemadji; Door-Kewaunee; Flambeau; Lake Michigan; Lake Superior; Lower Fox; Menominee; Middle Rock; Namekagon; St. Louis; Upper Wisconsin

Table last updated 4/18/2024

† Populations may not be currently present.

Ecology: Bythotrephes longimanus is found among the zooplankton in the upper water column of large and small temperate lakes. They can tolerate brackish water, and are most abundant in late summer and autumn. Occurrence and density of Bythotrephes populations are determined mainly by water temperature and salinity; Bythotrephes is limited to regions where water temperature ranges between 4 and 30°C and salinity is between 0.04 and 8.0 parts per thousand, but it prefers temperature between 10 and 24°C and salinity between 0.04 and 0.4 ppt (Grigorovich et al. 1998). Temperature plays a major role in determining the abundance and location of Bythotrephes in the Great Lakes, as they prefer cooler water and cannot tolerate very warm lake temperatures (Berg and Garton 1988, Garton et al. 1990, Brown and Branstrator 2004). Bythotrephes occurs in oligotrophic and mesotrophic lakes and has a lower tolerance to low dissolved oxygen concentrations than the native cladoceran Leptodora kindtii (Sorensen and Branstrator, 2017). Bythotrephes can reproduce both asexually and sexually; unfertilized eggs are carried in a brood pouch, and fertilized eggs are cast in the fall, hatching the following spring (Evans, 1988). The intensity and type of predation pressure appears to affect the size of Bythotrephes, its spine length, and the extent of its diel migrations (Straile and Halbich, 2000).

Bythotrephes longimanus is a visual predator, using its large compound eye to detect zooplankton (Azan et al., 2015). They consume 75% of their body weight each day in prey items (Lehman et al., 1997).

Means of Introduction: Bythotrephes was probably introduced from ship ballast water (Sprules et al. 1990, Berg et al. 2002) and possibly as diapausing eggs from sediment in ballast tanks (Evans 1988). 

Status: Bythotrephes is established in all of the Great Lakes and many inland lakes in the region. Densities are very low in Lake Ontario, low in southern Lake Michigan and offshore areas of Lake Superior, moderate to high in Lake Huron, and very high in the central basin of Lake Erie (Barbiero et al., 2001; Vanderploeg et al., 2002; Brown and Branstrator, 2004).

Impact of Introduction:
Summary of species impacts derived from literature review. Click on an icon to find out more...


It has caused major changes in the zooplankton community structure; invasion history; reproduce rapidly; competes directly with small fish and can have impact on zooplankton community (USEPA 2008).

The first noticeable impact of Bythotrephes was to fisherman. The tail spines of Bythotrephes hook on fishing lines, fouling fishing gear. Bythotrephes consumes small zooplankton such as small cladocerans, copepods, and rotifers, competing directly with planktivorous larval fish for food (Berg and Garton 1988, Evans 1988, Vanderploeg et al. 1993). There is concern that Bythotrephes could increase bioaccumulation of contaminants by lengthening the food chain (Vanderploeg et al. 2002). Bythotrephes has been implicated as a factor in the decline of alewife (Alosa pseudoharengus) in Lakes Ontario, Erie, Huron, and Michigan (Evans 1988). Bythotrephes also competes with, and possibly preys on, Leptodora kindtii and may be a causal factor in the decline of Leptodora (Branstrator 1995). Bythotrephes and Leptodora abundances are often negatively correlated (Garton et al. 1990, Branstrator 1995). There is speculation that Bythotrephes may control the abundance of Cercopagis pengoi though competition and predation (Vanderploeg et al. 2002). Bythotrephes is a food source for fish including yellow perch, white perch, walleye, white bass, alewife, bloater chub, chinook salmon, emerald shiner, spottail shiner, rainbow smelt, lake herring, lake whitefish and deepwater sculpin (Bur et al. 1986, Makarewicz and Jones 1990, Branstrator and Lehman 1996). 

Remarks: Deweese et al (2021) report on preliminary microfossil evidence for the presence of Bythotrephes in 4 inland lakes of the Great Lakes region which would place the introduction dates for this species signficantly earlier.  The authors still speculate whether the data may be an artefact (albeit of a common method), and should be considered preliminary at best. If these corroborated, earliest dates of reported microfossils should be 1934 (Lake Kabetogama, MN), 1908 (Mille Lacs, MN), 1900 (Lake Nipissing, Ontario) and 1650s (Three Mile Lake, Ontario).  Such early records call into question both the presumed means of introduction for this species (ballast water) as well as the possibility that the species should be considered native.  

References: (click for full references)

Barbiero, R.P., R.E. Little, and M.L. Tuchman. 2001. Results from the US EPA's biological open water surveillance program of the Laurentian Great Lakes: III. Crustacean zooplankton. Journal of Great Lakes Research 27:167-184.

Barbiero, R.P. and D.C. Rockwell. 2008. Changes in the crustacean communities of the central basin of Lake Erie during the first full year of the Bythotrephes longimanus invasion. Journal of Great Lakes Research 34(1):109-121.

Barbiero, R.P. and M.L. Tuchman. 2004. Changes in the crustacean communities of Lakes Michigan, Huron, and Erie following the invasion of the predatory cladoceran Bythotrephes longimanus. Canadian Journal of Fisheries and Aquatic Sciences 61:2111-2125.

Barbiero, R.P. and G.J. Warren. 2011. Rotifer communities in the Laurentian Great Lakes, 1983-2006 and factors affecting their composition. Journal of Great Lakes Research 37(3): 528-540.

Berg, D.J., and D.W. Garton. 1988. Seasonal abundance of the exotic predatory cladoceran, Bythotrephes cederstroemi, in western Lake Erie.  Journal of Great Lakes Research 14(4):479-488.

Berg, D.J., and D.W. Garton. 1994. Genetic differentiation in North American and European populations of the cladoceran Bythotrephes. Limnology and Oceanography 39:1503-1516.
Beyer, J., P. Moy, B. De Stasio. 2011. Acute upper thermal limits of three aquatic invasive invertebrates: hot water treatment to prevent upstream transport of invasive species. Environmental Management 47(1):67-76.
Bourdeau, P.E., K.L. Pangle, and S.D. Peacor. 2011. The invasive predator Bythotrephes induces changes in the vertical distribution of native copepods in Lake Michigan. Biological Invasions 13(11):2533-2545.   
Berg, D.J., D.W. Garton, H.J. MacIsaac, V.E. Panov, and I.V. Telesh. 2002. Changes in genetic structure of North American Bythotrephes populations following invasion from Lake Ladoga, Russia. Freshwater Biology 47:275-282.
Branstrator, D.K. 1995. Ecological interactions between Bythotrephes cederstroemi and Leptodora kindtii and the implications for species replacement in Lake Michigan. Journal of Great Lakes Research 21:670-679.
Branstrator, D.K., and J.T. Lehman. 1996. Evidence for predation by young-of-the-year alewife and bloater chub on Bythotrephes cederstroemi in Lake Michigan. Journal of Great Lakes Research 22:917-924.
Brown, M.E., and D.K. Branstrator. 2004. A 2001 survey of crustacean zooplankton in the western arm of Lake Superior. Journal of Great Lakes Research 30:1-8.
Bunnell, D.B., B.M. Davis, D.M. Warner, M.A. Chriscinske, and E.F. Roseman. 2011. Planktivory in the changing Lake Huron zooplankton community: Bythotrephes consumption exceeds that of Mysis and fish. Freshwater Biology 56: 1281-1296.
Bur, M.T., D.M. Klarer, and K.A. Krieger. 1986. First records of a European cladoceran, Bythotrephes cederstroemi, in Lakes Erie and Huron. Journal of Great Lakes Research 12:144-146.
Cullis, K.I., and G.E. Johnson. 1988. First evidence of the cladoceran Bythotrephes cederstroemi Schoedler in Lake Superior. Journal of Great Lakes Research 14:524-525.
DeWeese, N.E., E.J. Favot, D.K. Branstrator, E.D. Reavie, J.P. Smol, D.R. Engstrom, H.M. Rantala, S.P. Schottler. 2021. Early presence of Bythotrephes cederstromii (Cladocera: Cercopagidae) in lake sediments in North America: evidence or artifact? J Paleolimnol 2021:xx. https://doi.org/10.1007/s10933-021-00213-w.

Evans, M.S. 1988. Bythotrephes cederstroemi: its new appearance in Lake Michigan. Journal of Great Lakes Research 14(2):234-240.
Fernandez, R.J., M.D. Rennie, and W.G. Sprules. 2009. Changes in nearshore zooplankton associated with species invasions and potential effects on larval lake whitefish (Coregonus clupeaformis). International Review of Hydrobiology 94:226-243.
Foster, S.E., and W.G. Sprules. 2009. Effects of the Bythotrephes invasion on native predatory invertebrates. Limnology and Oceanography 54(3):757-769.
Garton, D.W., D.J. Berg, and R.J. Fletcher. 1990. Thermal tolerances of the predatory cladocerans Bythotrephes cederstroemi and Leptodora kindtii: relationship to seasonal abundance in western Lake Erie. Canadian Journal of Fisheries Aquatic Sciences 47:731-738.
GLMRIS. 2012. Appendix C: Inventory of Available Controls for Aquatic Nuisance Species of Concern, Chicago Area Waterway System. U.S. Army Corps of Engineers.
Grigorovich, I.A., O.V. Pashkova, Y.F. Gromova, and C.D.A. Van Overdijk. 1998. Bythotrephes longimanus in the Commonwealth of Independent States: variability, distribution and ecology. Hydrobiologia 379:183-198.
Hoskin, R. - U.S. Corps of Engineers, Pittsburgh District, Kinzua Dam & Allegheny Reservoir, Warren, Pennsylvania.
Hovius, J.T., B.E. Beisner, K.S. McCann, and N.D. Yan. 2007. Indirect food web effects of Bythotrephes invasion: responses by the rotifer Conochilus in Harp Lake, Canada. Biological Invasions 9:233-243.
Jacobs, M.J., and H.J. MacIsaac. 2007. Fouling of fishing line by the waterflea Cercopagis pengoi: a mechanism of human-mediated dispersal of zooplankton? Hydrobiologia 583(1):119-126.
Jokela, A., S.E. Arnott, and B.E. Beisner. 2011. Patterns of Bythotrephes longimanus distribution relative to native macroinvertebrates and zooplankton prey. Biological Invasions 13:2573-2594.
Lange, C., and R. Cap. 1986. Bythotrephes cederstroemi (Schoedler) (Cercopagidae: Cladocera): A new record for Lake Ontario. Journal of Great Lakes Research 12:142-143.
Lehman, J.T., and C.E. Cáceres. 1993. Food-web responses to species invasion by a predatory invertebrate: Bythotrephes in Lake Michigan. Limnology and Oceanography 38(4):879-891.
Lui, K., M. Butler, M. Allen, E. Snyder, J. Da Silva, B. Brownson, and E. Ecclestone. 2010. Field guide to aquatic invasive species, 3rd edition: identification, collection and reporting of aquatic invasive species in Ontario waters. Ontario Ministry of Natural Resources.
Makarewicz, J.C., and H.D. Jones. 1990. Occurrence of Bythotrephes cederstroemi in Lake Ontario offshore waters. Journal of Great Lakes Research 16:143-147.
Nordin, L.J., M.T. Arts, O.E. Johannsson, and W.D. Taylor. 2008. An evaluation of the diet of Mysis relicata using gut contents and fatty acid profiles in lakes with and without the invader Bythotrephes longimanus (Onychopoda, Cercopagidae). Aquatic Ecology 42:421-436.
Pangle, K.L., and S.D. Peacor. 2006. Non-lethal effect of the invasive predator Bythotrephes longimanus on Daphnia mendotae. Freshwater Biology 51(6):1070-1078.
Ontario's Invading Species Awareness Program. Spiny and Fishhook Waterfleas. http://www.invadingspecies.com/invaders/invertebrates/spiny-and-fishhook-waterflea/. Accessed on 05/31/2013.
Pangle, K.L., S.D. Peacor, and O.E. Johannsson. 2007. Large nonlethal effects of an invasive invertebrate predator on zooplankton population growth rate. Ecology 88(2):402-412.
Pichlová-Ptácníková, R., and H.A. Vanderploeg. 2011. The quick and the dead: might differences in escape rates explain the changes in the zooplankton community composition of Lake Michigan after invasion by Bythotrephes? Biological Invasions 13(11):2595-2604.
Pothoven, S.A., H.A. Vanderploeg, J.F. Cavaletto, D.M. Krueger, D.M. Mason, and S.B. Brandt. 2007. Alewife planktivory controls the abundance of two invasive predatory cladocerans in Lake Michigan. Freshwater Biology 52(3):561-573.
Rennie, M.D., A.L. Strecker, and M.E. Palmer. 2011. Bythotrephes invasion elevates trophic position of zooplankton and fish: implications for contaminant biomagnification. Biological Invasions 13(11): 2621-2634.
Sorensen, M.L., and D.K. Branstrator. 2017. The North American invasive zooplanktivore Bythotrephes longimanus is less hypoxia-tolerant than the native Leptodora kindtii. Canadian Journal of Fisheries and Aquatic Sciences 74:824-832. http://dx.doi.org/10.1139/cjfas-2016-0188.
Sprules, W.G., H.P. Riessen, and E.H. Jin. 1990. Dynamics of the Bythotrephes invasion of the St. Lawrence Great Lakes. Journal of Great Lakes Research 16: 346-351.
Stewart, T.J., W.G. Sprules, and R. O’Gorman. 2009. Shifts in the diet of Lake Ontario alewife in response to ecosystem change. Journal of Great Lakes Research 35(2):241-249.
Straile, D., and A. Halbich. 2000. Life history and multiple antipredator defenses of an invertebrate pelagic predator, Bythotrephes longimanus. Ecology 81:150-163.
Strecker, A.L., and S.E. Arnott. 2008. Invasive predator, Bythotrephes, has varied effects in ecosystem function in freshwater lakes. Ecosystems 11(3):490-503.
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Vanderploeg, H.A., J.R. Liebig, and M. Omair. 1993. Bythotrephes predation on Great Lakes zooplankton measured by an in situ method: implications for zooplankton community structure. Archiv für Hydrobiologie 127:1-8.
Vanderploeg, H.A., T.F. Nalepa, D.J. Jude, E.L. Mills, K.T. Holeck, J.R. Liebig, I.A. Grigorovich, and H. Ojaveer.  2002. Dispersal and emerging ecological impacts of Ponto-Caspian species in the Laurentian Great Lakes. Canadian Journal of Fisheries Aquatic Sciences 59:1209-1228.
Yan, N.D., and T.W. Pawson. 1997. Changes in the crustacean zooplankton community of Harp Lake, Canada, following invasion by Bythotrephes cederstroemi. Freshwater Biology 37:409-425.
Yan, N.D., and T.W. Pawson. 1998. Seasonal variation in the size and abundance of the invading Bythotrephes in Harp Lake, Ontario, Canada. Hydrobiologia 361:157-168.

Author: Liebig, J., A. Benson, J. Larson, T.H. Makled, A. Fusaro, and K.M. Reaver

Revision Date: 10/6/2021

Citation Information:
Liebig, J., A. Benson, J. Larson, T.H. Makled, A. Fusaro, and K.M. Reaver, 2024, Bythotrephes longimanus: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=162, Revision Date: 10/6/2021, Access Date: 4/18/2024

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.


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Citation information: U.S. Geological Survey. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [4/18/2024].

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