Aquatic Nuisance Species
An aquatic nuisance species (ANS) disrupts ecological processes because it is not indigenous to the ecosystem. Invasive organisms have become a major cause of species extinction, with the highest extinction rates occurring in freshwater environments. In Yellowstone, three ANS are having a significant detrimental effect:
• Lake trout (Salvelinus namaycush), illegally introduced in Yellowstone Lake where they feed on the native Yellowstone cutthroat trout;
• Myxobolus cerebralis, a parasite that causes whirling disease in cutthroat trout and other species; and
• New Zealand mud snails (Potamopyrgus antipodarum), which form dense colonies and compete with native species.
Other ANS likely to arrive in the area are:
• Eurasian watermilfoil (Myriophyllum spicatum), which can create dense mats on calm water surfaces, shading out and displacing native plants; and
• Zebra and quagga mussels (Dreissena polymorpha and D. rostriformis bugensis) native to eastern Europe, which consume plankton and algae, reducing their availability for native species.
