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Lake research is priority for science team

From boaters and shoreline residents to municipal and regional agencies seeking to protect one of Connecticut’s largest fresh-water resources, the wide community of stakeholders with an interest in preserving the ecological balance of Candlewood Lake will benefit greatly from scientific research conducted this summer by WCSU students and faculty.

Under the faculty supervision of WCSU Professor of Biological and Environmental Sciences Dr. Mitch Wagener, Western biology students are participating in two research projects designed to explore the environmental impact of invasive plant and mollusk species that have spread to lakes in western Connecticut. The studies have been conducted in collaboration with the Candlewood Lake Authority (CLA), an agency representing the five municipalities bordering the lake. The CLA has provided a paid internship for Western senior Catrina Morgan to participate in the research work, and a $6,000 grant from the Connecticut Department of Environmental Protection has financed purchase of equipment and supplies for the studies.

A team of four Western biology students coordinated by Morgan this summer continued a research project initiated in 2008 to evaluate the effectiveness of a promising biological tool to control the growth of the pest weed Eurasian milfoil in the shallows near the shoreline of Candlewood Lake.  Pursuing an innovative strategy to implant a species of weevils known to damage milfoil stems, the Ohio-based ecological consulting firm EnviroScience has continued annual stocking to implant weevil eggs on milfoil stems at several test sites in an effort to build weevil populations to a level sufficiently large to control or reverse milfoil proliferation.

Morgan has worked with seniors Bruna Oliveira and Heather Shepard and junior Emma Canfield to conduct field and laboratory studies that have focused on a single test location in a sheltered cove along the northern shoreline of Candlewood Lake. Field work requires periodic visits to the cove for snorkel dives to collect stem samples from milfoil at the weevil implantation site, as well as milfoil from a designated control site where no eggs were stocked. The student researchers bring these samples to the Science Building biology lab for investigation to check for damage to the milfoil and to identify weevil populations found on the stems.

Wagener observed that research sampling this year has been conducted at a sheltered cove location because it offers “a better nursery environment for the weevils and they are less likely to scatter in the lake.”  Studies to date have provided no clear answer as to whether the weevil implantations will contain milfoil spread, he added. “In order for weevils to have an impact, they need to be present in larger numbers, and we’re not there yet.”

In the wake of the discovery last year of the zebra mussel species in the waters of Lake Zoar and Lake Lillinonah — a short distance downstream in the Housatonic River watershed from Candlewood Lake — the CLA convened a Zebra Mussel Task Force comprised of representatives drawn from the area community and a wide range of municipal, regional and state agencies, as well as WCSU and  FirstLight Power Resources, owner of the Candlewood Lake reservoir and its power generating facilities.

As a task force member, Wagener participated in the group’s discussions that produced an interim report in March offering background on the zebra mussel threat and recommendations for prevention and control of the spread of the invasive mollusk in Candlewood Lake and the surrounding area. An important recommendation of the task force was to establish a program for early detection and monitoring of zebra mussel presence in Candlewood Lake, as well as Lake Lillinonah and Lake Zoar.

To implement this recommendation, Wagener has overseen a research project this spring and summer to collect plankton in water samples at Candlewood, Lillinonah, Zoar and Houstanic River test sites on a biweekly basis. Biology seniors Morgan and Oliveira have joined the research team to provide support in the field work, using long funnel-shaped nets of fine mesh to draw up plankton samples for placement in collection jars returned to the Science Building lab for analysis to determine the presence or absence of zebra mussel veligers, or larvae.   

Wagener has supervised microscopic investigation of the samples to search for evidence of zebra mussel larvae. Associate Professor of Biological and Environmental Sciences Dr. Ed Wong has provided additional support by applying a molecular genetics technique known as polymerase chain reaction, or PCR, to reproduce and analyze sections of DNA from the plankton samples. Wong’s search for DNA sequence matches provides an important tool to confirm whether zebra mussel larvae are present.

CLA Executive Director Larry Marsicano has noted that the early detection effort will provide useful documentation and baseline information concerning the presence or absence of zebra mussel veligers at various locations in the Housatonic watershed, as well as early warning of any contamination found in Candlewood Lake.    

Wagener credited the CLA, the Friends of Lillinonah and the Lake Zoar Authority for important contributions to the zebra mussel research through their assistance in making boating and other logistical arrangements to support sample collection in the field.

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