water-flea, water flea

The North American and European subspecies have hybridized in the Great Lakes basin. Morphologies and genetics of hybrid D. g. galeata x D. g. mendotae tend more toward the European D. g. galeata form in Lake Erie and more towards the North American D. g. mendotae form in the Lake Ontario drainage (Taylor and Hebert 1993).

Mature parthenogenetic females of European D. galeata can reach a maximum of 2.8 mm in length, although most females range from 1.3–2 mm. Males grow up to 1.4 mm but most are around 1.2 mm. The hybrid D. g. galeata x D. g. mendotae is slightly larger than native D. g. mendotae, which can grow up to a maximum of around 1.75–2.5 mm, depending on conditions, but is usually around 0.6–1.6 mm long (Heisey and Porter 1977; Flobner and Kraus 1986; Glagolev 1986; Lynch et al. 1986; Dodson 1988; Leibold and Tessier 1991; Taylor and Hebert 1993; Boersma 1995).

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

Environmental

D. g. Galeata genetically affects the native species Daphnia galeata mendotae through hybridization; hybrid forms of these two species are much more successful than the North American species representing 90-100% of swarms in lakes where hybrids are present (Taylor and Hebert, 1993)

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

D. g. galeata are not known to pose a threat to human health. They have not been found to damage infrastructure or affect water quality. They do not harm any economic sectors or the perceived aesthetic of the waters they inhabit.

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

Daphnia spp.  have some value as a model organism for genetic and medical research, however they are not a high research priority (Stollewerk, 2010). D. g. galeata does not remove toxins or pollutants from the water. They have no recreational or commercial value. They may act as a diet item for important prey fish, however they replace native cladocerans that occupy this same niche (Taylor and Hebert, 1993).

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

Control
There is little control information available on a species-specific level for Daphnia galeata galeata, especially as related to its presence in North America. However, many control methods used for more commonly known waterfleas may work for D. g. galeata as well.

Biological
Various parasites have been shown to reduce host density and population survival in experimental Daphnia populations in Europe (Ebert 2005). However, it is unclear whether parasites regulate natural Daphnia populations, as all experiments have been completed under lab conditions. Research on D. galeata galeata is lacking, but many invertebrates are likely predators of Daphnia spp. where they occur in Europe and North America, including Great Lakes species such as the predacious phantom midge Chaoborus flavicans, the waterfleas Leptodora spp. and Bythotrephes longimanus, (Lysebo 1995).  Many small fish of species such as yellow perch (Perca flavescens), three-spined stickleback (Gasterosteus aculeatus), alewife, bluegill and ciscos have been documented consuming daphnids and other zooplankton in Canada and the U.S. (Hulsmann and Mehner 1997; Post and McQueen 1987; Mills and Forney 1983).

Physical
Electron beam irradiation has been used to control microorganisms in aquatic pathways, including Daphnia galeata galeata (GLMRIS 2012). Electron beam irradiation is a non-selective control method which exposes water to low doses of radiation using gamma-sterilizers or electron accelerators, breaking down DNA in living organisms while leaving behind no by-products (GLMRIS 2012). Ultraviolet (UV) light can also effectively control microorganisms including D. g. galeata in water treatment facilities and narrow channels, where UV filters can be used to emit UV light into passing water, penetrating cell walls and rearranging DNA of microorganisms (GLMRIS 2012).

Chemical
There are no known chemical control methods for this species

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