WATERFLEAS (ORDER CLADOCERA)
Fishhook and spiny waterfleas have three competitive advantages over our native waterfleas. First, they’re slightly larger than native waterfleas they prey upon. In fact, these waterfleas are not very choosey and are able to eat a wide variety of plankton. Their barbed tail spines discourages fish and insects from eating them. When predators avoid eating invading cladocerans, they dominate the zooplankton community, depriving small fish and other plankton feeders of food. This, in turn, also reduces food for larger fish and predators. And because waterfleas can produce offspring parthenogenically (asexually) with many generations in a season, they are capable of reaching astounding densities very quickly! Now that these invasive waterfleas have been introduced to North America they are easily carried to new locations on fishing equipment or in live wells of boats.
2010 Distribution of fishhook waterfleas
2010 Distribution of spiny waterfleas
and Sexual Generations in Water Fleas
The interesting way in which waterfleas reproduce makes them very adaptable to environmental change. Most cladocerans can reproduce by parthenogenesis, with females producing asexual eggs that hatch into genetically identical daughters. As a result, males are not present in the population for much of the year. As long as environmental conditions remain favorable, females will continue to produce female offspring. If the environment starts to deteriorate due to overcrowding, cooling weather, lack of food or oxygen depletion, eggs are produced that develop into males and females, capable of sexual reproduction. In this generation, females mate with males to produce resting eggs that can survive through winter and periods of drought. In the spring or when environmental conditions are again favorable, the resting eggs all hatch into parthenogenic females.
Waterfleas tangled on fishing line
Thoroughly clean all fishing tackle, diving gear, nets, boats, and anything else that may hold water before moving from one body of water to another. Drain water from boat motors, livewells,bilges, and transom wells before leaving an access area. Always empty bait buckets on land; do not release live bait into the water or transfer live animals from one body of water into another. Discard contaminated fishing line and nets that can not be cleaned.
To read more, view the Pennsylvania Sea Grant spiny and fishhook waterflea fact sheet
FOR MORE INFORMATION ON WATERFLEAS