Species that are considered high risk have a well-documented history of invasiveness in at least one location globally, and a high or medium climate match to the contiguous United States.
Daphnia lumholtzi is a cladoceran native to parts of Africa, Asia, and Australia. It has recently become established in numerous locations in the United States, as well as scattered locations in Canada, Mexico, Brazil, and Argentina. Although competition between D. lumholtzi and native Daphnia in the U.S. is reduced by differences in phenology, competition can occur in certain circumstances and differential predation may reinforce the effects of competition. D. lumholtzi has also been associated with declines in the zooplankton Diaphanosoma. D. lumholtzi is less available to juvenile fish predators than native Daphnia because of its larger size and prominent spines. Climate match is very high and potential pathways of introduction are not well understood or managed, so further range expansion in the United States is likely. Overall risk posed by D. lumholtzi is high.
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High Risk
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