Daphnia lumholtzi

D. lumholtzi is native to Africa, Asia, and Australia (Havel et al., 1995). It was first reported in North America in 1990 (Sorenson and Sterner, 1992), and Brazil in 2000 (Zanata et al., 2003). The ability to thrive in riverine habitats (Soeken-Gittinger et al., in review) and produce large numbers of resting eggs (Acharya et al., 2006) may enhance the spread and invasiveness of this species. Spines afford D. lumholtzi some protection from predation (Swaffar and O’Brien, 1996), but many fish species actively feed on D. lumholtzi during the warm summer months when D. lumholtzi become abundant and native Daphnia are normally scarce. Thus, D. lumholtzi may provide a supplemental food resource for zooplanktivorous fish (Lemke et al., 2003; Linesch and Gophen, 2005; Havel and Graham, 2006) rather than reducing the food base via competitive exclusion of native Daphnia. D. lumholtzi is listed in the ISSG Global Invasive Species Database, but not included in the ISSG “Worst 100” list.

Because of the clonal structure of many Daphnia populations, and the fact that some clonal lines are obligate parthenogens (asexual only), invasions can occur at both the species and clonal level. The invasion of North America by D. lumholtzi is an example of invasion at the species level whereas the invasion of Africa by a single genotype of D. pulex is an invasion at the clonal level. D. lumholtzi is native to three continents: Africa, Asia, and Australia (Havel et al., 1995) and tolerant of a wide range of environmental conditions. It was first reported from North America in 1990 and spread rapidly throughout the continent during the next ten years (Havel and Shurin, 2004). Compared to native North American Daphnia species, D.lumholtzi is more tolerant of riverine conditions (Stoeckel et al., 1996, Soeken-Gittinger et al., in review), warm temperatures (Yurista, 2004), and tends to invest heavily in resting eggs (Acharya et al., 2006).

In stark contrast to the relatively benign (thus far) invasion of North America by D. lumholtzi, an invasion of Africa by a North American clone of D. pulex has resulted in the complete displacement of all native D. pulex clones. The invading clone is hypothesized to have been accidentally introduced with a largemouth bass stocking program in the late 1920s and now appears to be the only D. pulex genotype occurring in Africa (Mergeay et al., 2006). This is an alarming example of a cryptic invasion that was only detectable using modern genetic techniques, but has had a devastating impact on the native genetic diversity of the native population.

Daphnia spp. can be found in almost any permanent body of water. They are mainly freshwater and densely populate most lakes and ponds. They live as plankton in the open water of lakes, or live either attached to vegetation or near the bottom of the body of water (Miller, 2000).

Genetics

D. lumholtzi has been DNA sequenced, please see Elias-Gutierrez et al. (2008).

Environmental Requirements

There is a lack of papers providing complete environmental tolerance ranges of D. lumholtzi. Most published studies on this subject tend to state that D. lumholtzi is associated with “high” or “low” values of a given parameter, depending on the range of values encountered in the study. I have therefore provided ranges of water quality parameters for lakes/reservoirs where D. lumholtzi were present. The ranges given here for each parameter fall within the tolerated range, but do not represent the entire tolerated range.

Also see datasheet on Daphnia spp.

Many fish species actively feed on D. lumholtzi, and the invader does not appear to be replacing native daphnia species. Rather, D. lumholtzi becomes most abundant during periods of warm water temperatures when native Daphnia are normally rare. Thus, D. lumholtzi may be providing a supplementary food resource for zooplanktivorous fish during the warm summer months (Lemke et al., 2003; Linesch and Gophen, 2005; Havel and Graham, 2006).

General

• Research model

D. lumholtzi is easily distinguished from native North American species by the presence of large head and tail spines (Havel and Hebert, 1993). Initial fears that these spines would afford D. lumholtzi a competitive advantage over native species via protection from predation appear to be largely unfounded.

1. Lethal values for many water quality parameters such as DO, nitrate, ammonia, etc. are currently lacking.

2. Thorough surveys of distribution in native habitat are needed, particularly on the African continent.

3. Impacts on native communities (positive and negative) are still poorly understood.

Switzerland: IUCN (The World Conservation Union), Rue Mauverney 28, Gland 1196, Gland, Switzerland, http://www.iucn.org/

USA: United States Geological Survey: Nonindigenous Aquatic Species, Florida Integrated Science Center (FISC), Gainesville, FL 32653

06/03/08 Original text by:

James Stoeckel, Auburn University, Dept. of Fisheries & Allied Aquacultures, 203 Swingle Hall, Auburn, Alabama 36849, USA