General Information
Species Name: Daphnia lumholtzi
Also Known As: African spiny water-flea, water-flea
Family: Daphniidae (Common Water Flea)
Life Span: 6-9 days generation time, up to 30 days
Life Cycle: Under stress, daphnids produce resting eggs or ephippia. Ephippia are resistant to adverse environmental conditions and can lay dormant in sediment where they persist for many years delaying hatching until optimal conditions are present. As a result, the absence of waterflea from a body of water it has previously been found in does not necessarily indicate that it has been extirpated. The ephippia of waterflea are especially well adapted for dispersal. The ephippia of waterflea have hairs and spines along the dorsal edge of the egg that could grip boats or other objects and thus aid dispersal
Origin: Asia, Africa, Australia
Injurious: No
Category 2: Priority Aquatic Invasive Species
Why Are They Invasive?
Waterfleas may have a detrimental effect on fish that depend on zooplankton in their larval and juvenile stage. It is also feared that Daphnia lumholtzi will replace native Daphnia and cause a shift in pelagic communities of both zooplankton and fish.
What Do They Look Like?
The most distinguishing characteristics of waterflea is its long helmet and tail spines. Its anterior helmet is larger than that produced by any native species, although similar in form. The tailspine is normally at least as long as the body length. Native species have a tail that is much shorter than its overall body length. Other distinct characteristics are the fornices that extend to a sharp point instead of being smooth and rounded like native Daphnia. The ventral carapace margin has approximately 10 prominent spines while native species have weak spinescence.
Photos
Where Do They Live?
Waterflea inhabits reservoirs, river oxbows (''billibongs''), and deep tectonic lakes. Most water bodies invaded by D. lumholtzi, reservoirs in the southern regions of the U.S., tend to be more eutrophic than lakes and reservoirs in the north. This species has rapidly invaded a wide variety of habitats, including flood-plain lakes, large rivers and one of the Great Lakes. Waterflea takes advantage of late summer thermal niches when the water temperature surpasses 25 C, but performs poorly at water temperatures below 10 C.
How Do They Spread?
D. lumholtzi was first detected in a Texas reservoir in 1990. It is now found in the Great Lakes region as well as the Southwest USA and its distribution is expanding. It is uncertain how D. lumholtzi was introduced into the U.S. It is suspected that it may have been transported with shipments of Nile perch from Lake Victoria in Africa where it is a dominant zooplankter. Nile perch were originally introduced into Texas as early as 1983. The continuing discovery of D. lumholtzi in new locations could be due to contaminated stockings of fish through international commercial trade. At the same time, the close proximity of affected reservoirs in Missouri and in Texas might lead to the conclusion that D. lumholtzi may have spread by recreational boating from the initially infested reservoirs. D. lumholtzi can be transported through construction equipment. It most likely D. lumholtzi was brought to North America with African fish imported for the aquarium trade or to stock reservoirs.
How Do I Control Them?
Management of invasive aquatic animals involving either mechanical removal or application of chemicals to public waters requires a permit. Contact the Contact the Nebraska Game and Parks Commission for more information.
CLEAN your watercraft, trailer, angling gear and other equipment. Remove all aquatic vegetation and animal species from your equipment.
DRAIN your watercraft at the ramp by removing the boat plug and draining all live wells and ballast tanks.
DRY your watercraft, trailer and other equipment for at least 7 days before visiting another waterbody.
DON'T DUMP BAIT. Dispose of bait by emptying bait buckets on dry land, away from waterbodies or in a trash receptacle. Moving a live organism from one waterbody to another is illegal, even if you are planning to use the organism as bait.
DON'T LET IT LOOSE. Do not release or transport exotic or non-native fish species to new ecosystems. It is unlawful to release any aquatic species into a waterbody other than the one from which it was harvested. Doing so can promote the spread of AIS.
What Should I Do If I See Them in Nebraska?
If you see waterflea in Nebraska, you should report them to the Nebraska Game and Parks Commission's Aquatic Invasive Species (AIS) Program using their AIS Report Form. For guidance on what information to include in your report, check out our reporting tips.
References and More Information
An Image-Based Key To The Zooplankton Of North America
Center for Invasive Species and Ecosystem Health
Global Invasive Species Database
Nebraska Game and Parks Commission
Smithsonian Environmental Research Center
Summary of Species Currently Listed as Injurious Wildlife under (18 U.S.C. 42) Lacey Act