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.

Gammarus fasciatus
Gammarus fasciatus
(a freshwater amphipod)
Native Transplant

Copyright Info
Gammarus fasciatus Say, 1818

Common name: a freshwater amphipod

Taxonomy: available through www.itis.govITIS logo

Identification: The body of Gammarus fasciatus is laterally compressed and white or transparent in color. The body has 7 free thoracic segments and an abdomen with 6 segments. The thoracic segments each have segmented legs. The first set of legs are specialized legs called gnathopods which are used for grasping.  Gills begin where the leg and thorax and run from the second to sixth pair of legs on the thorax. The first three abdominal segments have paired pleopods, which are specialized legs for swimming. The last three abdominal segments have paired uropods which form the tail fin. Two pairs of antennae are attached to the cephalothorax (fused head and thorax). The first set of antennae, are typically longer than the second antennae and exhibit a 2–7 segmented accessory flagellum. Females have oostegites on the inside of their legs, which are large pouches for carrying eggs. Males typically have larger gnathopods than females. (Pennak 1989; Peckarsky et al. 1993; Clemens 1950).

Size: to 14 mm in length

Native Range: Gammarus fasciatus is native to the Mississippi drainage and the Atlantic coast of North America from the Atlantic coastal plain to North Carolina, including such drainages as the Hudson, Delaware, and Chesapeake river systems. It is reported as native to Lake Erie and Lake Ontario but its native status in the remaining Great Lakes drainage is unknown (Van Overdijk et al. 2003; Dermott et al. 1998; Mills et al. 1993 Pennak 1989).

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

Nonindigenous Occurrences: Colorado (EPA 2017) Nevada (La Rivers 1962)
Gammarus fasciatus is a cryptogenic range expander in the Great Lakes. Grigorovich et al. 2003 has referred to new populations of Gammarus fasciatus in Lake Superior as ‘expanded range’.

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 Gammarus fasciatus are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
CO200920091Roaring Fork
MI187420154Lake Huron; Lake Michigan; Lake Superior; St. Marys
MN200120202Lake Superior; St. Louis
NV194119621Havasu-Mohave Lakes
NY187418741Lake Ontario
OH187418741Lake Erie
WI200120203Beartrap-Nemadji; Lake Superior; St. Louis

Table last updated 7/15/2024

† Populations may not be currently present.

Ecology: Gammarus fasciatus is a freshwater benthic amphipod that can tolerate very low levels of salinity. It occurs in both rivers and lakes, is particularly abundant in shallow well oxygenated areas, and is frequently associated with thick macrophyte beds. In the St. Lawrence River, the abundance of Gammarus fasciatus is positively correlated with the biomass of Cladophora spp., macrophytes, and pH. In some ponds in Ontario, it occurs at pH above 7 (Palmer and Ricciardi 2004). Gammarus fasciatus survives well at water temperatures around 10–15°C but it becomes increasingly intolerant of temperatures increasing past 20°C. The length of time Gammarus fasciatus can tolerate a specific water temperature above 20°C decreases with increasing temperature. Temperatures of 34–35°C and greater cause relatively rapid mortality. Gammarus spp. were found to be absent in the presence of oil pollution ( Borgmann et al. 1989; Thibault and Couture 1980, 1982; Pennak 1989; Van Maren 1978; Hart and Fuller 1974; Sprague 1963; Pentland 1930).   

Gammarus fasciatus mate between April and November and individuals only mate once. Males will pair with females by grasping them and carrying them on their backs until the female has molted and is ready to mate. At this point the male will reposition the female and use his pleopods to insert sperm into the female's brood pouch. Eggs of Gammarus fasciatus are carried by the mother until they have hatched and juveniles have developed appendages. Typically eggs hatch 2-4 weeks to hatch and 8-23 offspring are produced. Young develop through a series of molting. The first five instar phases (periods in-between molting) are considered juvenile phases where the two sexes are indistinguishable. At the sixth instar the sexes are visually distinguishable. Individuals become sexually mature two months after hatching and have a lifespan of approximately one year (Kestrup and Riccardi 2010; Van Overdijk et al. 2003;Pennak 1989;Clemens 1950).   

Gammarus fasciatus function as both predators and shredders feeding on detritus, coarse and fine particulate organic matter, filamentous algae, diatoms, animal matter, its own species, and zooplankton such as Daphnia spp.  Smaller individuals feed on detritus more frequently. Gammarus fasciatus can be a common food item for many fish species, including yellow perch (Perca flavescens). Amphipods support an “amazing” population of algae and sessile Protozoa on their external body surfaces (Swiss and Johnson 1976; Borgmann et al. 1989; Weisberg and Janicki 1990; Delong et al. 1993; Brent Summers et al. 1997; Pennak 1989; Gonzalez and Burkart 2004).    

In Lake Ontario G. fasciatus is potentially one of the hosts for the nematode Cosmocephalus obvelatus, which infects the oesophagus of gulls. In the St. John estuary, New Brunswick, it is host to the nematode Capillospirura pseudoargumentosa, which develops to the infective stage in the amphipod and then infects shortnose sturgeon. The swim bladder nematode Cystidicola farionis develops to the 3rd stage in this species, and then eventually infects fish species. G. fasciatus is intermediate host to other aquatic parasites as well, including some acanthocephalans (Johnson 1975; Smith and Lankester 1979; Wong and Anderson 1982; Appy and Dadswell 1983).            


Means of Introduction: Unknown. If Gammarus fasciatus is an introduced species in the Great Lakes, possible means of introduction could include transport in either solid or liquid ballast, arrival on aquatic plants, arrival with stocked fish, dispersal via canals, and/or introduction via fish bait (Mills et al. 1993; Hogg et al. 2000). Amphipods have been observed to be dispersed via mammals and several species of Gammarus have been observed to cross from one drainage to another after construction of canals  (Havel and Shurin 2004).

Status: Cryptogenic.  Gammarus fasciatus was first recorded from the Great Lakes around the late 1800s to early 1900s and is known to occur throughout the drainage. It is unknown whether or not it is native to the Great Lakes. It is particularly difficult to find clear information on its distribution before 1940. Mills et al. (1993) concluded the species was probably introduced to the Great Lakes, however it was noted natural distribution cannot be determined. Van Overdijk et al. (2003) states the western Lake Erie population is native and Grigorovich et al. (2003) has referred to new populations of Gammarus fasciatus in Lake Superior as ‘expanded range’.

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: Gammarus fasciatus and the introduced amphipod Echinogammarus ischnus both increase in density in the presence of invasive Dreissena spp. in the St. Lawrence River, probably due to refugia and increased food resources from mussel pseudofaeces. However, in the presence of the introduced round goby, Neogobius melanostomus, the abundance of Gammarus fasciatus has decreased in eastern Lake Erie by up to 85%. In some parts of the Detroit River, Niagara River, and Lake St. Clair, Echinogammarus ischnus is replacing Gammarus fasciatus, probably due to a stronger affinity of the former for Dreissena spp. substrate in these water bodies. In spite of this, Gammarus fasciatus does still increase in the Great Lakes in the presence of invasive mussels through increased habitat heterogeneity and increased food from mussel pseudofaeces (Dermott et al. 1998; Stewart et al. 1998a, b; Van Overdijk et al. 2003; Barton et al. 2005; Limen et al. 2005; Palmer and Ricciardi 2005).           

There is little genetic variation between and within populations of G. fasciatus throughout the Great Lakes. There is more variability in populations found in the St. Lawrence River. This would lend evidence to the hypothesis that the Great Lakes’ populations of Gammarus fasciatus were relatively recent introductions, possibly from systems such as the St. Lawrence, Hudson, Chesapeake, or Delaware drainages. However, it is still unclear whether or not this species is native to the Great Lakes (Hogg et al. 2000).

References: (click for full references)

Appy, R. G. and M. J. Dadswell. 1983. Transmission and development of Capillospirura pseudoargumentosa (Nematoda, Cystidicolidae). Canadian Journal of Zoology 61(4):848-859.  

Barton, D. R., R. A. Johnson, L. Campbell, J. Petruniak, and M. Patterson. 2005. Effects of round gobies (Neogobius melanostomus) on dreissenid mussels and other invertebrates in eastern Lake Erie, 2002-2004. Journal of Great Lakes Research 31(2):252-261  

Berezina, N.A. and V.E. Panov. 2003. Establishment of new gammarid species in the eastern Gulf of Finland (Baltic Sea) and their effects on littoral communities. Proceedings of the Estonian Academy of Sciences. Biology, Ecology 52(3):284-304.

Borgmann, U., K. M. Ralph, and W. P. Norwood. 1989. Toxicitiy test procedures for Hyalella azteca, and chronic toxicity of cadmium and pentachlorophenol to H. azteca, Gammarus fasciatus, and Daphnia magna. Archives of Environmental Contamination and Toxicology 18:756-764.  

Cave, C.S. and K. Strychar. 2014. Decline Of Diporeia in Lake Michigan: Was Disease Associated with Invasive Species the Primary Factor? Funded Articles 61. http://scholarworks.gvsu.edu/oapsf_articles/61.

Clemens, H. P. 1950. Life cycle and ecology of Gammarus fasciatus Say. Contributions of the Stone Laboratory, Ohio University 12:1-63.  

Delong, M. D., R. B. Summers, and J. H. Thorp. 1993. Influence of food type on the growth of a riverine amphipod, Gammarus fasciatus. Canadian Journal of Fisheries and Aquatic Sciences 50(9):1891-1896.  

Dermott, R., J. Witt, Y. M. Um, and M. Gonzalez. 1998. Distribution of the Ponto-Caspian amphipod Echinogammarus ischnus in the Great Lakes and replacement of native Gammarus fasciatus. Journal of Great Lakes Research 24(2):442-452.  

Gonzalez, M. J. and G. A. Burkart. 2004. Effects of food type, habitat, and fish predation on the relative abundance of two amphipod species, Gammarus fasciatus and Echinogammarus ischnus. Journal of Great Lakes Research 30(1):100-113.  

Grigorovich, I. A., A. V. Korniushin, D. K. Gray, I. C. Duggan, R. I. Colautti, and H. J. MacIsaac. 2003. Lake Superior: an invasion coldspot? Hydrobiologia 499:191-210.  

Hart, C.W. Jr., S.H. Fuller. 1974. Pollution Ecology of Freshwater Invertebrates. Academic Press, New York, NY.

Havel, J.E. and J.B. Shurin. 2004. Mechanisms, effects, and scales of dispersal in freshwater zooplankton. Limnology and Oceanography 49:1229-1238.

Hogg, I. D., Y. de Lafontaine, and J. M. Eadie. 2000. Genotypic variation among Gammarus fasciatus (Crustacea: Amphipoda) from the Great Lakes – St. Lawrence River: implications for the conservation of widespread freshwater invertebrates. Canadian Journal of Fisheries and Aquatic Sciences 57(9):1843-1852.

Holsinger, J. R. 1976. The freshwater amphipod crustaceans (Gammaridae) of North America. USEPA, Cincinnati, OH, 89 pp.

Johnson, C. A. III. 1975. Larval acanthocephalan parasites of 3 species of estuarine amphipods in North Carolina, USA. ASB Bulletin 22(2):59.  

Kelly, D.W., J.T.A. Dick, and W.I. Montgomery. 2002. The functional role of Gammarus (Crustacea, Amphipoda): shredders,predators, or both? Hydrobiologia 485:199-203.

Kestrup, A., A. Riccardi. 2010. Influence of conductivity on life history traits of exotic and native amphipods in the St. Lawrence River. Fundamental and Applied Limnology 176:249-262.

Kunz, P.Y., C. Kienle, and A. Gerhardt. 2010. Gammarus spp. in Aquatic Ecotoxicology and Water Quality Assessment:Toward Integrated Multilevel Tests.

La Rivers, I. 1962. Fishes and fisheries of Nevada. Nevada State Print Office, Carson City, NV.

Limen, H., C. D. A. van Overdijk, and H. J. MacIsaac. 2005. Food partitioning between the amphipods Echinogammarus ischnus, Gammarus fasciatus, and Hyalella azteca as revealed by stable isotopes. Journal of Great Lakes Research 31(1):97-104.

Messick, G.A., R.M. Overstreet, T.F. Nalepa, and S. Tyler. 2004. Prevalence of parasites in amphipods Diporeia spp. from Lakes Michigan and Huron, USA. Diseases of Aquatic Organisms 59:159-170.

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 Research. 19(1):1-54.

Palmer, M. E. and A. Ricciardi. 2004. Physical factors affecting their relative abundance of native and invasive amphipods in the St. Lawrence River. Canadian Journal of Zoology 82(12):1886-1893.  

Palmer, M. E. and A. Ricciardi. 2005. Community interactions affecting their relative abundance of native and invasive amphipods in the St. Lawrence River. Canadian Journal of Fisheries and Aquatic Sciences 62(5):1111-1118.  

Peckarsky, B. L., P. R. Fraissinet, M. A. Penton, and D. J. Conklin Jr. 1993. Freshwater Macroinvertebrates of Northeastern North America. Cornell University Press, Ithaca, New York State. 442 pp.

Pennak, R. W. 1989. Fresh-water invertebrates of the United States, 3rd ed. John Wiley & Sons, New York, 628 p.

Pentland, E. S. 1930. Controlling factors in the distribution of Gammarus. Transactions of the American Fisheries Society 60(1):89-94.  

Smith, J. D. and M. W. Lankester. 1979. Development of swim bladder nematodes 1979. Development of swim bladder nematodes Cystidicola spp. in their intermediate hosts. Canadian Journal of Zoologoy 57(9):1736-1744.  

Sprague, J. B. 1963. Resistance to four fresh water crustaceans to high temperatures and low oxygen. Journal of the Fisheries Research Board of Canada 20:387-415.  

Stewart, T. W., J. G. Miner, and R. L. Lowe. 1998a. An experimental analysis of crayfish (Orconectes rusticus) effects on a Dreissena-dominated benthic macroinvertebrate community in western Lake Erie. Canadian Journal of Fisheries and Aquatic Sciences 55(4):1043-1050.  

Stewart, T. W., J. G. Miner, and R. L. Lowe. 1998b. Quantifying mechanisms for zebra mussel effects on benthic macroinvertebrates: organic matter production and shell-generated habitat. Journal of the North American Benthological Society 17(1):81-94.  

Summers, B., R., M. D. Delong, and J. H. Thorp. 1997. Ontogenetic and temporal shifts in the diet of the amphipod Gammarus fasciatus, in the Ohio River. American Midland Naturalist 137(2):329-336.

Swiss, J. J. and M. G. Johnson. 1976. Energy dynamics of 2 benthic crustaceans in relation to diet. Journal of the Fisheries Research Board of Canada 33(11):2544-2550.  

Thibault, Y. and R. Couture. 1980. 24 hour median lethal temperature of Gammarus fasciatus (Crustacea, Amphipoda) acclimated to various temperature levels. Revue Canadienne de Biologie 39(3):149-152.  

Thibault, Y. and R. Couture. 1982. The upper thermal resistance limit of Gammarus fasciatus, Say (Crustacea, Amphipoda) and its utilization in thermal effluent situations. Canadian Journal of Zoology 60(6):1326-1338.  

Van Maren, M. J. 1978. Distribution and ecology of Gammarus tigrinus and some other amphipod Crustacea near Beaufort, North Carolina, USA. Bijdragen tot de Dierkunde 48(1):45-56.  

Van Overdijk, C. D., I. A. Grigorovich, T. Mabee, W. J. Ray, J. J. Ciborowski, and H. J. MacIsaac. 2003. Microhabitat selection by the invasive amphipod Echinogammarus ischnus and native Gammarus fasciatus in laboratory experiments and in Lake Erie. Freshwater Biology 48(4):567-578.  

Weisburg, S. B. and A. J. Janicki. 1990. Summer feeding patterns of white perch, channel catfish, and yellow perch in the Susquehanna River, Maryland. Journal of Freshwater Ecology 5(4):391-405.  

Winn, R.N., and D.M. Knott. 1992. An evaluation of the survival of experimental populations exposed to hypoxia in the Savannah River estuary. Marine Ecology Progress Series 88(2-3):161-179.

Wong, P. L. and R. C. Anderson. 1982. The transmission and development of Cosmocephalus obvelatus (Nematoda: Acuardioidea) of gulls (Laridae). Canadian Journal of Zoology 60(6):1426-1440.

Other Resources:
Great Lakes Waterlife

Author: Kipp, R.M. and K. Hopper

Revision Date: 1/16/2024

Citation Information:
Kipp, R.M. and K. Hopper, 2024, Gammarus fasciatus Say, 1818: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=26, Revision Date: 1/16/2024, Access Date: 7/16/2024

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.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [7/16/2024].

Contact us if you are using data from this site for a publication to make sure the data are being used appropriately and for potential co-authorship if warranted.

For general information and questions about the database, contact Wesley Daniel. For problems and technical issues, contact Matthew Neilson.