The Minnesota Department of Natural Resources has announced on Friday, Aug 28 that the state's lakes have been invaded by the invasive starry stoneworth. In Wisconsin, 23 lakes located in the southeast part of the state have already been surveyed and the Wisconsin Department of Natural Resources and other affiliated organizations plan to investigate on 35 more.

Starry stonewort (Nitellopsis obtusa) is a submerged macroalgae under the Charales order, characterized by its whorls that contain about four to six leaves with dull edges, and arranged along its main stem.

The green algae reproduces through the help of the bulbils, which is the primary identifying markers of the algae. The bulbils are vegetative fragments developed at nodes that are three to six millimeters in width and are shaped like a star with at least five points.

Starry stonewort are usually situated in slow-moving waters or lakes that are typically one to six meters in depth. The species are commonly located in chalky waters containing calcium carbonates, which are frequently proximal to the sea. With this, it is believed that starry stonewort prefer to stay in saline environments. The species are also said to thrive in surroundings with minimal light supply.

The green algae may cause annoying disturbances as evidenced by the conditions it has cause Michigan, New York and Indiana. Because it can outdo other vegetation and form its own stands, places where fish can reproduce may become limited. The species may also damage motor equipment made for the water.

Starry stonewort was first found in the United States at the St. Lawrence River in 1978 and have then spread throughout the US northeast lakes. The species were first confirmed in Wisconsin in 2014. During the announcement made on Friday, the Minnesota officials confirmed that the green algae have infested Lake Koronis and Mud Lake, found in Stearns and Meeker counties respectively. Investigation ensued after property owners in Lake Koronis reported massive vegetation in the lakes to the Department of Natural Resources. After investigating the place, the staff of the agency have discovered that about 53 acres of the lake have been infested by starry stonewort.

Photo: Kristian Peters | Wikimedia Commons