Eubosmina coregoni

The distribution of E. coregoni varies seasonally in the Great Lakes. In Lake Michigan, it occurs in the nearshore region at 5–10 m from the surface in fall and winter, but more frequently at 20–30 m depth in the height of the summer. In the same lake, it is relatively uniformly distributed horizontally in fall and winter, but in summer it occurs significantly more frequently in water 0–18 km from shore than in open water. When it occurs predominantly at the surface in Lake Michigan, E. coregoni is an important food item for such fish species as bloater (Coregonus hoyi) (Gannon 1975, 1976; Evans et al. 1980; Crowder and Crawford 1984).            

In eutrophic lakes in Europe, E. coregoni is often dominant in spring and fall. However, in the Great Lakes it is almost completely absent in spring and is more abundant in summer, potentially reaching densities of around 69,000 per m² in western Lake Erie and around 44,500 per m² in Lake Ontario. It has also been recorded at high densities in the fall in Lake Ontario and Lake Michigan (Roth and Stewart 1973; Geller and Müller 1981; Johansson and O’Gorman 1991; Barbiero et al. 2001).        

Eubosmina coregoni filter feeds and feeds raptorially, selecting specific phytoplankton in the water column. It specifically selects particles of 0.5–5 μm in size and thus is much more tolerant of eutrophic conditions and the presence of cyanobacteria such as Cylindrospermopsis raciborskii than many larger Daphnia spp. Larger cladocerans experience difficulty feeding in the presence of cyanobacteria because they do not feed selectively and longer algae filaments clog their filtering apparatuses (Henning et al. 1991; Mayer et al. 1997; Cyr 1998; Donabaum et al. 1999).            

Reproduction in E. coregoni can occur either between sexual females and males, or parthenogenetically in asexual females. The mean number of eggs found per individual from 1981–1986 in Lake Ontario ranged from around 0.4–1.2. E. coregoni can produce resting eggs that can stay dormant in the sediments for long periods of time. These eggs will hatch under the influence of specific environmental conditions. For example, E. coregoni was once recorded to emerge from resting eggs after a drought and the re-acidification of a lake in Sudbury, Canada (Johansson and O’Gorman 1991; Arnott and Yan 2002; Lord et al. 2006).            

Changes in this species’ morphology with season, or cyclomorphosis, may be related to predation and/or temperature. Further studies need to be carried out to test these hypotheses, especially in North America. Most studies have been carried out in Europe, but different forms of this species occur in Europe in comparison with North America (Kappes and Sinsch 2002).            

This is a freshwater species. It can experience mortality at salinities of 3‰ (Nauwerck 1991).

Suchy and Hann (2007) suggested that the transfer of E. coregoni in the digestive tract of rainbow smelt (Osmerus mordax) may be responsible for introducing the species to water bodies west of the Laurentian Great Lakes, demonstrating how waterflea resting eggs may transform biological predation from a form of control to a vector for transport.

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

Environmental	Beneficial

It is possible that the presence of E. coregoni and zebra mussel (Dreissena polymorpha) veligers in Lake Ontario could have aided the establishment of the exotic blueback herring (Alosa aestivalis; Ricciardi 2001).Eubosmina coregoni serves as a significant Great Lakes food item of introduced alewife (Alosa pseudoharengus) and the introduced spiny water flea (Bythotrephes longimanus) (Grigorovich et al. 1998, Mills et al. 1995).

There is little or no evidence to support that Eubosmina coregoni has significant socio-economic impacts in the Great Lakes.

There is little or no evidence to support that Eubosmina coregoni has significant beneficial effects in the Great Lakes.

When congregated at the surface of Lake Michigan, E. coregoni is an important food item for such fish species as bloater (Coregonus hoyi) (Crowder and Crawford 1984).

Note: Check federal, state/provincial, and local regulations for the most up-to-date information.

Control

Biological
Young-of-year bloaters (Coregonus hoyi) have been shown to surface feed on Eubosmina coregoni in Lake Michigan, but their effectiveness as a control is unknown, especially because they have been documented moving to the benthos earlier to avoid competition from the invasive alewife (Alosa pseudoharengus) (Crowder and Crawford 1984). Bythotrephes spp. are known to consume E. coregoni in Russia and the U.S. (Grigorovich et al. 1998), and E. coregoni populations declined significantly immediately following the invasion of the waterflea Bythotrephes longimanus in the Laurentian Great Lakes Michigan, Huron, and Erie, with direct predation by B. longimanus the most likely explanation (Barbiero and Tuchman 2004). E. coregoni levels in B. longimanus-invaded areas have remained at low levels, indicating a significant population-wide impact, but the long-term effectiveness of B. longimanus as a biological control method is unknown (Barbiero and Tuchman 2004).

Physical
E. coregoni may be transported over land by recreational boaters (Suchy and Hann 2007). Though it is not as likely to foul gear and attach to equipment as the more commonly known spiny waterflea (Bythotrephes longimanus) and fishhook waterflea (Cercopagis pengoi), the same responsible maintenance and cleaning methods are recommended to prevent spread between water bodies, including cleaning all aquatic equipment with high pressure water (>250 psi) or hot water (>50°C) after each use (Ontario’s Invading Species Awareness Program). Electron beam irradiation and ultraviolet light treatments have been used to control spiny and fishhook waterfleas in aquatic pathways, and are likely effective against E. coregoni (GLMRIS 2012). Another possible non-selective pathway control is high water turbidity, which may decrease zooplankton (especially cladoceran) abundances due to the negative effects of suspended clay particles on filtering and assimilation rates (Suchy and Hann 2007).

Chemical
E. coregoni is a freshwater cladoceran. Mortality has been documented quickly at salinities >3% (Nauwerck 1991). Gemza (1995) documented a shift from copepods to cladocerans as dominant zooplankton at increasingly eutrophic sites in Severn Sound, Lake Huron. Zooplankton biomass generally increases with increasing eutrophication, so reduction of excessive nutrient pollution causing abnormal eutrophication could help control E. coregoni (Gemza 1995). A study of the effects of cadmium and zinc on Lake Michigan zooplankton found that E. coregoni was significantly reduced by separate and combined treatments of 2 µg Cd/L and 100 µg Zn/L, with negative effects primarily due to zinc (Marshall et al. 1981). A more recent study on the effects of copper sulfate (used to control algal biomass in eutrophic water bodies) and Carbaryl (used to control aquatic pests) on zooplankton found that levels of 50 µg/L Cu and 20 µg/L Carbaryl individually reduced E. coregoni biomass by >50% (Havens 1994).

Note: Check state/provincial and local regulations for the most up-to-date information regarding permits for control methods. Follow all label instructions.

Although the current name listed for this species by the Integrated Taxonomic Information System is Eubosmina coregoni, the most current suggested name is currently Bosmina (Eubosmina) cf. coregoni based on Kotov et al. (2009) (Whitmore and Bailey pers comm. 2019). Species names that include cf are often subject to change or updates, so GLANSIS and NAS are waiting until a consensus is reached before updating this species' name.