Starry Stonewort
This invasive macro-algae can grow in dense beds that outcompete and displace native plants, thus reducing aquatic biodiversity. The dense beds can also cover areas that fish would use to spawn. The thick growth can be a nuisance for recreation activities like swimming, fishing, and boating.
Common Name: Starry stonewort
Scientific Name: Nitellopsis obtusa
Native Range: Widespread across Europe and Asia
Background
Starry stonewort is a macro-algae that has relatively straight, bright green branches that are arranged in whorls from the stem nodes. The “star” in the plant’s name refers to the creamy white bulbils (asexual reproductive structures) that are star shaped and occur at the substrate-water interface and on the branches of the main axis nodes. Starry stonewort can grow in dense mats up to seven feet in depth, forming large, pillow-like masses that originate from the substrate.
Habitat
Starry stonewort grows in freshwater lakes and brackish bays with slow moving water.
NYS Distribution Map
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Identification
Starry stonewort has a white, star-shaped bulbil, a pattern of nodes, and whorled branching.
Impact
This invasive macro-algae can grow in dense beds that outcompete and displace native plants, thus reducing aquatic biodiversity. The dense beds can also cover areas that fish would use to spawn. The thick growth can be a nuisance for recreation activities like swimming, fishing, and boating.
Prevention and Control
Starry stonewort is a difficult species to remove once it is established because it can spread by fragmentation and growth beneath the bottom substrate. Mechanical harvesting (hand and diver assisted suction harvesting) has been used to reduce starry stonewort biomass in local areas. Chemical treatment with pesticides that kill algae have also been used.
