Starry stonewort (Nitellopsis obtusa) note the star-shaped reproductive bulbils (Photo: Minnesota DNR)

The Frog Blog – Aquatic Weed Wednesday

Welcome to Wednesday! For today, we will be looking into another aquatic macroalgae (like Chara) but this one is a recent invader into Ohio waters: Starry stonewort (Nitellopsis obtusa).

The invasive macroalga starry stonewort may look similar to the native Chara and Nitella spp. but, we would highly suggest against supporting in your ponds and lakes. Originally native to Eurasia, this alga is commonly moved from one waterbody to another via fragments on boat trailers. Its most defining feature that separates it from similar looking macroalgae species are its star-shaped bulbils used for reproduction. It is easy to confuse Nitellopsis, Nitella, and Chara. However, if you are unsure of whether you have a Nitella sp. or a Chara sp. Look toward the touch and smell of it as well; Chara has a “musky” smell to it and a gritty feel while Nitella is smoother and lacks the smell. Additionally, Nitella will not have a rigid appearance like Chara typically does. Then see if the bulbils are present when they form later in the growing season to separate out Nitellopsis.

Starry stonewort may be a difficult macrophyte to find in your pond or lake since it inhabits the bottom (or benthos) and rarely finds its way to the surface. This can also make management of this invasive specie difficult as well since many control techniques focus from the top of the water column relative to the bottom. A good way to check and see if you have Starry stonewort in your pond or lake would be to utilize a macrophyte sampling rake: a device that is simply two metal rakes attached together with their teeth facing away from one another attached to a rope. Throw the rake into your waters and slowly retrieve it back, gathering aquatic plants and algae along the way. Then observe and identify what you find.

By: Edward Kwietniewski

Aquatic Biologist

AQUA DOC Lake and Pond Management

Edward Kwietniewski graduated from The State University of New York College of Environmental Science and Forestry (SUNY ESF) with a Bachelor’s degree in Aquatics and Fisheries Science. He also has a Master’s degree in Lake Management from the State University of New York College at Oneonta (SUNY Oneonta). He has a love for all things aquatic and is an avid fisherman. Content goes here


Resources and External Links

Borman, Susan. Through The Looking Glass: a Field Guide to Aquatic Plants. Stevens Point, Wis. :Wisconsin Lakes Partnership, 1997. Print.

Minnesota Department of Natural Resources (DNR). “Starry stonewort (Nitellopsis obtusa)” Web. Accessed 5 March 2018.