Starry stonewort (Nitellopsis obtusa), a macroalgae native to Europe and Asia, has made its way into Vermont. First found in the United States in 1978 (likely a result of transport via ballast water), this species is known from waters in 8 states, including Vermont’s Lake Memphremagog and Derby Pond.
Starry stonewort can quickly reach nuisance levels – mats of this species up to two meters thick can impede boating, fishing, and other recreational activities. This species’ capability to reproduce by fragmented vegetation or bulbil (see photo) makes it especially hard to control.
There are three areas in the Vermont portion of Lake Memphremagog where starry stonewort is known – Scotts Cove (2015), and South Bay and an area adjacent to Scotts Cove in the main lake (2016). Additionally, starry stonewort was found in 270-acre Derby Pond in Derby in 2016.
So, what is being done to stop the spread of this species? On May 26, 2017, the channel linking Scotts Cove to Lake Memphremagog will be temporarily closed and continue for 90 days in an effort to reduce the risk of spread of starry stonewort from the cove. According to the Vermont Use of Public Waters Rules (Section 4.1b) the Secretary of the Agency of Natural Resources (or designee) is authorized to implement a temporary closure of an area less than 10% of a lake’s surface area or 50 acres, whichever is less. Scotts Cove is an area of 24 acres, 0.4% of the 5,966-acre Lake Memphremagog area in Vermont.
The Lakes Program will also continue to monitor the population of starry stonewort in Lake Memphremagog and Derby Pond, and search other lakes and ponds in Vermont that are at risk of starry stonewort invasion; evaluate future management options and the factors that influence successful outcomes; stay abreast of current research; incorporate starry stonewort identification specifics into trainings; and deploy Program-staffed, portable decontamination systems at Vermont public access points on Lake Memphremagog and on other regional waterbodies including Lake Derby.
What can you do to help stop the spread of starry stonewort? The best way to prevent further spread of this and other aquatic invasive species is to practice Clean, Drain, Dry – check for hitch hiking aquatic invasive species before launching and leaving access points, drain boat bilges and live wells, and decontaminate any equipment used on a waterbody after use or allow the equipment to dry in the sun for five days. These simple steps can prevent aquatic invasive species from spreading to new areas in and outside of Vermont, and can reduce the impact of species such as starry stonewort in already invaded waters.
For more information on starry stonewort or Clean Drain Dry, Lakes Program’s, aquatic invasive species webpage.