Invasive Algae Removal Scheduled This Week

Alliance Project Manager Taylor West identifies invasive starry stonewort while surveying in Ashville Bay. Submitted photo

A pilot project to tackle invasive starry stonewort in Ashville Bay is scheduled to begin Tuesday.

Town of Chautauqua Mobitrac vessels will work alongside Chautauqua Lake Association skimmers to test a new removal method for this invasive, which is an increasing problem on the lake. Overseeing the work will be Chautauqua Watershed Conservancy Director of Conservation Twan Leenders, who last week secured a permit from the Department of Environmental Conservation for the removal of around 1.5 acres. The pilot test marks a major milestone in the efforts to contain a new species of concern in our local waters. It stems from an intensive tracking of the algae over the past two seasons, following the identification of two large fields of new growth in the fall of 2022. This ongoing monitoring is now being paired with action, as stakeholders take the first steps towards strategic management in coordination with state officials.

A relative newcomer on the scene, many lakes in the Northeast are still trying to figure out the best ways to tackle starry stonewort infestations. While it is really an algae, this species looks and acts like a lot of the invasive weeds many are concerned with. Growing to maturity later in the summer, it can form dense stands that choke out native plants and fish populations, in addition to causing recreational problems. One of the main challenges in managing starry stonewort, and one of the reasons why guaranteed control methods are elusive, is that it comes apart and spreads quite easily. When pieces of the algae are broken up by waves or chopped by boat props, each fragment can begin growing again on its own. Another challenge for long-term control is the importance of removing not just the upper section of the algae, but also lower portions that are embedded in the lake bottom. While surveys have found smaller amounts of it scattered within our lake since around 2009, Leenders and the CWC-led Aquatic Invasive Species Early Detection Program identified around seven total acres of this invasive growing in stands at Ashville Bay and Prendergast Point last year. These two locations underwent a doubling of acreage this year, and lakewide plant surveys by North Carolina State University have also detected additional populations elsewhere in the lake.

As a result, this plan to test mechanical removal is being put into action as a first step, while other tools are being considered including chemical treatment, diver assisted suction harvesting, or combined approaches.

This initial pilot program intends to take advantage of the geography in Ashville Bay as well as the capabilities of the Mobitracs. Timing is also an important factor, as the algae usually begins reproducing from October to November. The project area is a relatively shallow section of the lake–around three feet deep. This terrain is well suited to the Mobitracs, which can use their front rakes to extract material from near the lake bottom onto support vessels. The proposed removal area is also in the interior of a larger plant field, where a vegetated perimeter will remain untouched at the boundary of the work site. The outer border is intended to act like a natural fence, which will contain fragments of starry stonewort. The terrain of this area may also help with the effectiveness of the pilot program, as wind and wave action tend to push material south to the shoreline, rather than out into the lake. In preparing for the removal, Leenders and Alliance staff surveyed and mapped the area last week. Mobitracs are equipped with onboard GPS units and operators will use these maps to guide their work.

These pilot removal efforts are intended to yield more concrete options for larger-scale management of this non-native invader. This will take a coordinated approach with multiple groups working together to achieve the best possible outcome. Groups working to address starry stonewort include the Chautauqua Lake Partnership, Solitude Lake Management, NC State, Chautauqua County, the Town of Chautauqua, Town of North Harmony, NYSDEC, CWC, CLA, the Alliance, and others. A press release covering the 2022 infestations and plans for management can be found on the Alliance website at chautauquaalliance.org/news/press-release-starry-stonewort/. Additional updates will be published as this work moves forward.


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