Diver assisted suction harvesting and chemical treatments are expected to be two new tools used to fight invasive starry stonewort this summer. Photo by Taylor West.

Management of the invasive algae starry stonewort is a top priority for Chautauqua Lake this season. Over the past several years, new infestations of this species have cropped up in high use areas, prompting the need for increased monitoring and removal efforts. Now, new tools such as diver assisted suction harvesting and chemical treatment are expected to be used in 2025, as Alliance Members continue to collaboratively address this emerging problem within the lake.

While technically an algae, starry stonewort looks and acts like an aquatic plant when it enters the height of its growing season in late summer. Fibrous strands form dense underwater mats, which can choke out native species of plants and fish, impede recreation, and spread easily when pieces of the algae are broken off. Thanks to early detection surveys led by the Chautauqua Watershed Conservancy, large fields of starry stonewort have been identified near high traffic areas at Prendergast Point and Ashville Bay. So far, these areas have seen management attempts by manual or mechanical removal, either using workers in the water or machines like Mobitracs and skimmers. Because of the challenges that this species presents, new techniques are on the docket this year.

The Towns of North Harmony and Chautauqua each have state funding in hand to perform diver assisted suction harvesting of the algae at the two main fields of growth. This is a process that looks to minimize potential spread by having divers enter the water and suck out the algae while leaving native plants and fish relatively unaffected. Bags of starry stonewort are loaded onto a boat and ferried to shore for disposal. Permits to perform this work were secured late in the year in 2024, however, weather conditions and safety concerns prevented the contractor from starting DASH last fall. Now, with permits, funding, and better weather in hand, divers plan to start addressing the two large fields of growth when the algae emerges this year.

AJ Reyes, a certified lake manager with GEI Consultants, explained at the Alliance’s May Annual Member Meeting that starry stonewort can be a particularly difficult species because different techniques may or may not work in different environments. There is no one tried-and-true method. Therefore, the Chautauqua Lake Partnership is also planning to test the effectiveness of several different chemical treatments on the algae. Three smaller areas of growth in the lake’s South Basin have been identified and mapped by researchers from North Carolina State University, and CLP intends to work with Ready Scout LLC to apply different products and monitor the results. These treatments were planned and permitted in 2024, however the algae was not found growing in significant quantities (a testament to the fickle nature of this species), so the pilot test did not take place. Similar to DASH last year, the expectation is that this chemical pilot can move forward in 2025 if conditions allow. Dr. Rob Richardson, a leader in invasive species research, spoke to the public about starry stonewort at the County’s Lake Symposium in March, and outlined the work that N.C. State is continuing to do in order to monitor its growth over time.

As we are in the early stages of determining what management will work best for starry stonewort on Chautauqua Lake, we are also thinking about how these different tools may be used in combination. There are ongoing discussions about how mechanical removal, DASH, and chemical treatment might be used together in the same areas to achieve higher levels of control of the algae. In order to help the process move forward, pre and post management monitoring of these sites is critical for the work this year. In all likelihood, before a combined approach is pursued, it will be vital to determine how effective each technique is on its own.

Containment is another key piece of this management puzzle. After all, starry stonewort likely only made its way to the lake by hitching a ride from somewhere else on a boat or a trailer. Local watercraft stewards, such as those deployed by the Chautauqua Lake Association, will work with boaters at launches to help keep invasive species from spreading, and educate the public on how they can help. The CWC will also engage the public on its volunteer invasive species kayak paddles to both manage known infestations but also keep an eye out for any new areas of growth – or new invasives threatening the lake. Many different organizations, funders, and members of the public will play important roles in addressing not only starry stonewort this year, but also all of our invasive species on land and in the water. Thanks to everyone for their vigilance.

The DASH grants are part of the NYS Department of Environmental Conservation’s Invasive Species Grant Program with funding from the State’s Environmental Projection Fund.