Gammarus fasciatus
Say, 1818
Common Name:
A freshwater amphipod
Synonyms and Other Names:
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).
Great Lakes Nonindigenous Occurrences:
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. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, 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.
Full list of USGS occurrences
Table last updated 4/24/2024
† Populations may not be currently present.
* HUCs are not listed for areas where the observation(s) cannot be approximated to a HUC (e.g. state centroids or Canadian provinces).
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).
Great Lakes 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).
Great Lakes 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. G. fasciatus in the Great Lakes likely is a mix of native and introduced populations. Most sources consider the species native to Lakes Erie and Ontario (Van Overdijk et al. 2003; Dermott et al. 1998; Mills et al. 1993 Pennak 1989). However, it is still unclear whether or not this species is native to the Great Lakes as a whole, particularly for the more northern populations (Hogg et al. 2000). There is little genetic variation between and within populations of G. fasciatus throughout the Great Lakes. There is more variability within populations found in the St. Lawrence River. This would lend evidence to the hypothesis that the Great Lakes’ populations of G. fasciatus were relatively recent introductions, possibly from systems such as the St. Lawrence, Hudson, Chesapeake, or Delaware drainages.
Great Lakes Impacts:
Summary of species impacts derived from literature review. Click on an icon to find out more...
Current research on the environmental impact of Gammarus fasciatus in the Great Lakes is inadequate to support proper assessment. There remains a lack of fish predation studies that identify Gammarus on a species level. Gammarus spp. have a wide range of physiochemical tolerance, habitat needs, and susceptibility to replacement. Further study is needed to understand Gammarus spp. and their place in the food web (Macneil et al. 1999). Gammarus fasciatus likely competes with other native and non-native gammarids (Berezina and Panov 2003), but specific studies focused on pairwise interactions seem limited primarily to interactions with Echinogammarus ischnus, which is non-native to the Great Lakes and able to displace G. fasciatus (Limen et al 2005).
In Lake Ontario, Gammarus fasciatus is potentially one of the hosts for the nematode Cosmocephalus obvelatus, which infects the oesophagus of gulls (Wong and Anderson 1982). Gammarus is also an intermediate host to Microsporidia spp., a pathogen that has been found within the tissues of native amphipod Diporeia (Cave and Strychar 2014). However, the role that Microsporidia has played in the decline of Great Lakes Diporeia remains unclear (Messick 2004).
There is little or no evidence to support that Gammarus fasciatus has significant socioeconomic impacts in the Great Lakes.
Gammarus fasciatus has a moderate beneficial effect in the Great Lakes.
Gammarus fasciatus serve as shredders, predators, and detritivores, and also act as a common source of food for many fish species. Gammarids’ presence in freshwater streams is important because macroinvertebrate feeding is a major rate-limiting step in the processing of stream detritus (Pennak 1989; Kelly et al. 2002; Kunz et al. 2010). Gammarus fasciatus is known to feed on nuisance Cladophora and has been reported to occupy Cladophora substrata extensively in Lake Erie (Van Overdijk et al. 2003; Delong et al. 1993).
Management:
Regulations There are no known regulations for this species.
Note: Check federal, state, and local regulations for the most up-to-date information.
Control
Physical
Temperatures of around 34–35°C and more cause relatively rapid mortality of Gammarus fasciatus (Sprague 1963). Oxygen saturation levels below 30% were shown to be lethal to amphipods within hours to days of exposure (Winn and Knott 1992).
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 reference list)
Author:
Kipp, R.M. and K. Hopper
Contributing Agencies:
Revision Date:
1/16/2024
Citation for this information:
Kipp, R.M. and K. Hopper, 2024, Gammarus fasciatus Say, 1818: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI, https://nas.er.usgs.gov/queries/greatlakes/FactSheet.aspx?Species_ID=26&Potential=N&Type=0&HUCNumber=DHuron, Revision Date: 1/16/2024, Access Date: 4/25/2024
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.