Invasion History

First Non-native North American Tidal Record: 2007
First Non-native West Coast Tidal Record: 2007
First Non-native East/Gulf Coast Tidal Record:

General Invasion History:

Bosmina coregoni is a freshwater cladoceran species or species complex, first described from Britain, and believed to be native to Eurasia and introduced to North America (Haney and Taylor 2003; Kotov et al. 2009). It was first detected in North America in the Great Lakes in 1966, probably introduced in ballast water (Mills et al. 1993). It has spread to smaller lakes in the Great Lakes drainage; and to Lake Winnipeg, Manitoba; and reservoirs in Missouri (Mabee 1998; De Melo 1994a; USGS Nonindigenous Aquatic Species Program 2013). In 2008, B. coregoni was first collected on the West Coast of North America in the lower Columbia River estuary at Astoria, Oregon. It was also found in Lake Washington, Seattle in 2011, and in reservoirs in the interior Columbia River basin, in eastern Washington in 2012 (Smits et al. 2013). As a result of the difficulty and confusion in the systematics and identification of Bosmina spp., it is probably frequently overlooked and sometimes erroneously reported (De Melo and Hebert 1994b). Currently, it is found in 13 states, in the Atlantic, Pacific, Mississippi, and Great Lakes watersheds (Beaver et al. 2018).

North American Invasion History:

Invasion History on the West Coast:

Bosmina coregoni was first collected in November 2008 near Astoria, Oregon in the Columbia River Estuary. It occurred at very low densities, up to 0.123 animals L-1, and was present through 2011 (Smits et al. 2013). It occurred in an assemblage dominated by native and introduced fresh and brackish-water copepods (Eurytemora affinis, Diacyclops thomasi, Pseudodiaptomus forbesi, Limnoithona tetraspina, Sinocalanus doerrii) (Bollens et al. 2012; Smits et al. 2013). Bosmina coregoni also occurred in nontidal freshwater in the Pacific Northwest region, in Lake Washington (Seattle, WA) in June 2011 through July 2013, reaching peak densities of 10.5 animals L-1, and in reservoirs in eastern WA, in the upper Columbia basin, in August 2012 (Smits et al. 2013). Identifications were confirmed by molecular methods and examination of males (done by Drs. Alexey A. Kotov and Derek Taylor) (Smits et al. 2013). In long-term sampling (2005-2013) from a pier in Vancouver, Washington, on the tidal Columbia river, it comprised 0.5 % of zooplankton individuals and reached a peak abundance of 846 m-3, but declined to low levels (7 m-3) by 2013 (Dexter et al. 2015). Bosmina coregoni appears to have had a 'boom-and-bust' invasion in the Columbia River. It is likely that that B. coregoni is more widespread in western North America, beyond these three collection sites. Ballast water is an unlikely vector to the Columbia estuary, since this species is not known to occur in eastern Asia (Kotov et al. 2009). Other possible vectors are those that have been suggested for interior lakes, including: stocked fishes, fishing gear, boats, aquatic plants, and natural dispersal by waterfowl (Smits et al. 2013).

Invasion History on the East Coast:

Bosmina coregoni is probably more widespread than published records indicate. It is reported on several species lists for freshwater tributaries of Chesapeake Bay (Brownlee and Jacobs 1987; Steinberg and Condon 2009), but these records may have resulted from use of a European zooplankton key (George Mateja 1998, personal communication). We have no reliable records from East Coast tidal waters.


Cladocerans of the genus Bosmina have an oval carapace covering the body and legs, and a distinct head, with a prominent median eye. The first antennae are rigidly fixed to the head, tapered to a point and curved, resembling elephant tusks. They have several sensory hairs about halfway between the tip and base, but none at the tips. The second antennae, the primary appendages for locomotion, are biramous, with one branch having three segments and the other with four. The posterior part of the intestine is sharply angled ventrally, and terminates with a postanal claw and a set of spines called the pecten. Adult parthenogenetic females have a dorsal brood pouch. Under favorable conditions, parthenogenetic females predominate in the population, and males are quite rare. Males lack eggs in the brood pouch, have longer antennule and setae than females, and have a copulatory hook. Fertilized females produce large, thick-walled eggs, enclosed in the cast-off brood-chamber, called an ephippium. Description based on Barnes 1983, Thorp and Covich 2001, and De Melo and Hebert 1994b.

Bosmina (Eubosmina) coregoni is distinguished by the absence (or greatly reduced size) of a mucro, a spine in the corner of the postanal angle of the carapace. The carapace is arched, and the post-abdominal claw has only a proximal pecten. The pecten consists of four short spines, followed by a row of longer spines, increasing in height distally. There is a sensory bristle near the tip of the rostrum. The first antenna is at least 50% of the body length. Females are 432-757 µm long (De Melo and Hebert 1994b).

The relationship among named forms of the subgenus Eubosmina, including B. coregoni, are uncertain because of the high phenotypic variability of these animals to environmental cues, including temperature, day length, and predation. Haney and Taylor (2003) considered B. longispina to be the ancestral form of the subgenus, arising in Eurasia, giving rise to a variety of species (B. longispina, B. maritima, B. obtusirostris, B. kessleri, and B. thersites), and colonizing northern North America. Kotov et al. (2009) treat Bosmina c.f. coregoni as a species complex which includes forms identified as B. coregoni gibberum, B. longispina, B. obtusirostris, B. kessleri, and B. thersites. A brackish water form (called variously B. maritima, B. longispina maritima or B. coregoni maritima), from the Baltic Sea, may be conspecific with B. coregoni, but was treated as a separate species by De Melo and Hebert (1994b).

Some sources (Kotov et al. 2009; Appeltans et al. 2013) treat all or most of these forms as conspecific. However, European and North American populations of B. coregoni are genetically similar, indicative of a recent (~ 40 years ago) invasion (De Melo and Hebert 1994a; De Melo and Hebert 1994b), which corresponds with the appearance of 'mucro-less' Bosmina in plankton samples and Great Lakes sediment cores. European and North American B. longispina show greater divergence, consistent with a Pleistocene invasion, and a probable distinct species status for the North American longispina (Haney and Taylor 2003). The status of European and North American B. maritima and B. kessleri is more uncertain (Kotov et al. 2009).


Taxonomic Tree

Kingdom:   Animalia
Phylum:   Arthropoda
Subphylum:   Crustacea
Class:   Branchiopoda
Superorder:   Diplostraca
Order:   Cladocera
Infraorder:   Anomopoda
Family:   Bosminidae
Genus:   Bosmina
Species:   coregoni


Eubosmina coregoni (None, None)

Potentially Misidentified Species

Bosmina freyi
Bosmina (Bosmina freyi) is widely distributed in eastern North America, including the Great Lakes, and also has been collected in California lakes. It is one of the dominant zooplankton in the tidal freshwater Hudson estuary (Pace et al. 1998), and in the Mattaponi River, Virginia, a tributary of the Chesapeake Bay (Hoffman et al. 2008). This cladoceran has a prominent mucro (De Melo and Hebert 1994b; Kotov et al. 2009).

Bosmina hagmamni
Bosmina (Neobosmina) hagmani was described from the Amazon, and collected by De Melo and Hebert (1994b) in Connecticut and Massachusetts. It has a prominent mucro.

Bosmina huaronensis
Bosmina (Neobosmina) huaronensis was described from Peru, and collected by De Melo and Hebert (1994b) in Texas and eastern Mexico. It has a prominent mucro.

Bosmina liederi
Bosmina (Bosmina) liederi is widespread in eastern North America, including the Great Lakes, and is also found in Bass Lake, California and Lake Washinton, Washington (De Melo and Hebert 1994b; Kotov et al. 2009; Smits et al. 2013). It has a prominent mucro (De Melo and Hebert 1994b).

Bosmina longirostris
Bosmina (Bosmina) longirostris was described from Europe. Although this species has been casually reported throughout North America, De Melo and Hebert (1994b) collected specimens fitting that description, only from one lake in California. Kotov et al.(2009) were skeptical of records outside western Eurasia. This species has a prominent mucro (De Melo and Hebert 1994b).

Bosmina longispina
Bosmina (Eubosmina) longispina has nominal populations in Eurasia and northern North America, including the Great Lakes; Lake Washington, Washington (WA), and eastern WA reservoirs. It has a prominent mucro (De Melo and Hebert 1994b; Smits et al. 2013). North American populations probably represent a separate species (Haney and Taylor 2003; Kotov et al. 2009).

Bosmina maritima
Bosmina (Eubosmina) maritima is a brackish-water form native to the Baltic Sea, and reportedly introduced to the Great Lakes. This form, with a prominent mucro, is often treated as a subspecies of B. longispina (De Melo and Hebert 1994b). Its status as a distinct species or subspecies is uncertain (Kotov et al. 2010).

Bosmina oriens
Bosmina (Eubosmina) oriens is known from freshwaters of northeastern North America (Newfoundland to Massachusetts). It has a prominent mucro (De Melo and Hebert 1994b).

Bosmina tubicen
Bosmina (Neobosmina) tubicen was described from Venezuela and was collected in Ontario, New Brunswick, Texas, and eastern Mexico by De Melo and Hebert (1994b). It has a prominent mucro.



Cladocerans of the genus Bosmina can develop parthenogenetically from unfertilized eggs in a female's brood pouch. The juveniles have the basic form of miniature adults, and molt and grow as they feed. After a period of growth, parthenogenetic eggs are deposited in the female's brood pouch. For the closely related B. maritima at 10-15 C, the eggs were produced 10.6-5.9 days after birth, and took 7.3- 4.3 days to develop (Kankaala and Wulff 1981). When the embryos hatch, the female molts, and a new batch of eggs are deposited in the brood pouch. A female may have several successive broods. Female B. maritima at 10-15 C, on average, had 2 broods, consisting of 1.3-3.3 eggs each. This Swedish Baltic population of B. maritima had a generation time of 18.3-10.2 days (Kankaala and Wulff 1981). Freshwater populations of B. coregoni, acclimated to higher temperatures, probably have much more rapid rates of population growth.

Bosmina spp. can reach high population densities by parthenogenetic reproduction, developing populations that are all female or female-dominated. Environmental factors such as temperature, day-length, the presence of predators, etc., appear to stimulate the production of males. Females, when fertilized, produce large resting eggs, in pairs, enclosed in a capsule formed by modifications of the brood chamber (called an ephippium). The ephippium is cast off when the female molts. It settles into the sediment, but may be stimulated to develop by favorable conditions of light and temperature. Sexual reproduction of resting eggs provides a means of surviving winter, droughts, or other adverse conditions, as well as providing new genotypes for potentially altered conditions (Barnes 1983; Kankaal 1983). We are not aware of studies on specific cues affecting sexual reproduction, or hatching of resting eggs in B. coregoni. In B. maritima in Sweden, resting egg production was greatest in late summer and fall, with extensive, but unsuccessful mis-matched hatching in October and November, and successful hatching in the spring, leading to a planktonic population (Kanakaala 1983).

Taxonomic problems make it difficult to define the range and habitat of B. coregoni, but studies using genetics and detailed morphological examination indicate that it is native to northern and eastern Europe, from Scandinavia to central Europe and eastern Russia (Demelo and Hebert 1994a; Kotov et al. 2009). Records from tropical and subtropical regions (Brazil, Iran, Florida- Zoological Record search) are presumed to be misidentifications. This cladoceran appears to be adapted to a temperate climate, and its introduction into the Great Lakes, Lake of the Woods, and Lake Winnipeg indicate its tolerance to long winters and cool summer waters (Demelo and Hebert 1994a; Suchy and Hann 2007; Suchy et al. 2010). Bosmina coregoni sensu stricto is a freshwater species, and information on its salinity tolerance is limited. Nauwerck (1991) reports an upper salinity tolerance for B. coregoni from lakes on the Baltic coast of Sweden. The closely related (possibly conspecific) Baltic form B. maritima tolerates salinities up to 12.5 PSU (Ackefors 1971). In a simulated ballast water exchange experiment, B. coregoni tolerated an hour at 8 PSU but died at 14 PSU (Ellis et al. 2009).

Bosmina sp. are filter-feeders, creating a current and filtering phytoplankton, detritus, and bacteria in the water column. They have some capacity for selective feeding (Barnes 1983; Sellner et al. 1993; Pace et al. 1998; Hoffman et al. 2008). Bosmina spp. are less sensitve to blooms of colonial toxic cyanobacteria than larger cladocerans, such as Daphnia spp., possibly in part because their smaller carapace and weaker filtering current excludes large colonies, and partly because of greater tolerance to cyanobacterial toxins (Fulton and Paerl 1987). Bosmina coregoni in the Great Lakes is prey for planktivorous fishes, such as Alosa pseudoharengus and whitefishes (Coregonus spp.), and for the introduced predatory cladocerans Bythotrephes longimanus and Cercopagis pengoi (Laxon et al. 2003; Barbiero et al. 2004).


Phytoplankton, bacteria, detritus


Copepods, mysids, fishes


Cladocerans, copepods

Trophic Status:

Suspension Feeder



General HabitatUnstructured BottomNone
General HabitatNontidal FreshwaterNone
Salinity RangeLimnetic0-0.5 PSU
Salinity RangeOligohaline0.5-5 PSU
Tidal RangeSubtidalNone
Vertical HabitatPlanktonicNone

Tolerances and Life History Parameters

Minimum Salinity (‰)0This is a freshwater species.
Maximum Salinity (‰)3Nauwerck 1991, experimental, animals from Baltic coastal lakes, Swedem. However the closely related Bosmina maritima, sometimes considered conspecifc, in the Baltic Sea tolerates salinities up to 12 PSU (Ackefors 1971).
Minimum Reproductive Temperature10Bosmina maritima (closely related) Sweden, parthenogenetic production of juveniles, resting egg production at lower temperatures (Kankaala and Wulff 1981)
Maximum Reproductive Temperature15Bosmina maritima (closely related) Sweden , parthenogenetic production of juveniles, mortality at 18 C (Kankaala and Wulff 1981)
Minimum Length (mm)0.4Adult females (Demelo et al. 1994b)
Maximum Length (mm)0.8Adult females (Demelo et al. 1994b)
Broad Temperature RangeNoneCold temperate-Warm temperate
Broad Salinity RangeNoneNontidal limnetic-Oligohaline

General Impacts

The freshwater cladoceran Bosmina coregoni has become one of the dominant zooplankters of the Great Lakes, particularly in Lake Erie but was reduced to low levels of abundance after the invasion of the predatory cladoceran Bythotrephes longimanus (Mills et al. 1993; Barbiero, et al. 2004). The extent to which B. coregoni has affected native zooplankton composition or food webs is unclear. The very low abundances of this cladoceran in the Columbia River estuary (Smits et al. 2004) indicate that detectable impacts are unlikely, at this time.

Regional Distribution Map

Bioregion Region Name Year Invasion Status Population Status
P260 Columbia River 2007 Def Estab
GL-I Lakes Huron, Superior and Michigan 1966 Def Estab
GL-II Lake Erie 0 Def Estab
GL-III Lake Ontario 1968 Def Estab
LWINNI Lake Winnipeg 1994 Def Estab
LNIPIGON Lake Nipigon 1995 Def Estab
L115 _CDA_L115 (Salmon-Sandy) 1992 Def Estab
L050 _CDA_L050 (Kalamazoo) 1966 Def Estab
L043 _CDA_L043 (Door-Kewaunee) 1969 Def Estab
L127 _CDA_L127 (English-Salmon) 1994 Def Estab
L013 _CDA_L013 (St. Louis River) 2001 Def Estab
L065 _CDA_L065 (Lone Lake-Ocqueoc) 1998 Def Estab
L093 _CDA_L093 (Ottawa-Stony) 1998 Def Estab
L113 _CDA_L113 (Irondequoit-Ninemile) 1998 Def Estab

Occurrence Map

OCC_ID Author Year Date Locality Status Latitude Longitude


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Smits, Adrianne P.; Litt, Arni; Cordell, Jeffery R.;Kalata, Olga; Bollens, Stephen M. (2013) Non-native freshwater cladoceran Bosmina coregoni established on the Pacific coast of North America, BioInvasions Records published online: corrected proof

Soors, Jan; Faasse, Marco; Stevens, Maarten; Verbessem, Ingrid; De Regge, Nico;Van den Bergh, Ericia (2010) New crustacean invaders in the Schelde estuary (Belgium), Belgian Journal of Zoology 140: 3-10

Steinberg, Deborah K.; Condon, Robert H. (2009) Zooplankton of the York River, Journal of Coastal Research SI 57: 66-79

Suchy, Karyn D.; Hann, Brenda J. (2007) Using microfossil remains in lake sediments to examine the invasion of Eubosmina coregoni (Cladocera, Bosminidae) in Lake of the Woods, Ontario, Canada, Journal of Great Lakes Research 33: 867-874

Suchy, Karyn D.; Salki, Alex; Hann, Brenda J. (2010) Investigating the invasion of the nonindigenous zooplankter, Eubosmina coregoni, in Lake Winnipeg, Manitoba, Canada, Journal of Great Lakes Research 36(1): 159-166

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