Understanding the enemy
ST. PAUL — Aquatic invasive species continue to expand their ranges within Minnesota but state officials have taken an aggressive approach in efforts to slow the spread.
So far, the Bemidji area lakes are thought to be free of AIS, but invasive species have been discovered in nearby waters, including Leech and Lake Winnie.
Among the species the state officials are hoping to contain are:
— Faucet snail: Already established on Winnie and other area water bodies, the snail is host to a trematode that has killed scaup and coot on Lake Winnie and other northern lakes.
The snail also competes with native snails and usually wins the battle because it can obtain food by filtering the water as well as by scraping the vegetation.
They also have little difficulty finding new homes within a water system because they can easily spread by hitching a ride on an aquatic plant or on stationary objects such as a boat anchor.
— Spiny waterflea: The spiny waterflea already has a foothold in Lake of the Woods and the Rainy River. Clumps of the tiny crustacean (less than one-half inch long) look and feel like gelatin but individuals are difficult to distinguish without magnification.
— Zebra mussels: Averaging between one-half inch and two inches, the zebra mussel is among the more obvious invaders because of the tendency to gather on an object, including our native mussels. Last winter, zebra mussel veligers were found in water samples taken from Lake Winnie.
— Eurasian watermilfoil: A major threat to the Bemidji area lakes, Eurasian watermilfoil has gained a foothold in Leech Lake, among other bodies of water. Unlike the native milfoil, Eurasian watermilfoil forms dense mats that interfere with boating and swimming.
— Curly leaf pondweed: Another aggressive plant, curly leaf pondweed comes up in early spring and has the ability to outcompete native plants to the point where it can kill the native vegetation.
It also forms weed mats and when it dies back in mid-summer, the plant releases nutrients, which can cause algae blooms.