|The fishhook waterflea (Cercopagis pengoi) is pictured at top. The other species is also an invasive|
Though small, this waterflea is rather formidable. A predatory species, it eats all sorts of native zooplankton and has been linked to large drops in the numbers of many known prey species in its introduced range. It also competes with native species that also eat zooplankton and fouls fishing equipment, nets especially. Fishhook waterfleas also will eat very young fish, particularly those that normally feed on phytoplankton. This can lead to major ecological changes, including changes in upper-level predation and increases in the intensity of algal blooms that occur. It's believed that the trophic changes that these small creatures cause will prove problematic for fish stocks, which, combined with equipment fouling, does not bode well for fisheries. Apparently, there have also been allergic reactions reported in fishermen that handle materials that have become fouled by these animals.
There is currently no known way to kill off these crustaceans, and the only management methods that are being done are really to prevent further spread of the animal. This includes better control of ballast water and regulations on the proper disposal and cleaning of equipment that has been in water known to house populations of the fishhook waterflea.
This species is currently on the list of 100 World's Worst Invasives at #21.
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