Invasive Water Chestnuts Plague Rabbit Pond

Along with the Canadian geese settling in Rabbit Pond this summer, invasive water chestnut plants, a more threatening wildlife species, have seized Rabbit Pond’s muddy waters. The Office of the Physical Plant (OPP) discovered an infestation of water chestnuts, a green aquatic plant with floating leaves and white flowers, while clearing the edges of Rabbit Pond in late August. Uncontrolled populations of the plant could seriously damage Rabbit Pond’s aquatic ecosystem. On the surface of the pond, the plant forms large mats of foliage that limit the amount of sunlight that can reach the native aquatic plants below. Water chestnuts also compete with the native plants for nutrients in the pond, according to the United States Geological Survey (USGS) website’s catalogue of Non- Indigenous Aquatic Species. A prevalence of water chestnuts also lowers the oxygen level of pond water, potentially killing large populations of fish and other aquatic animals. In most ponds, the large mass of plants impedes fishing and boating, and the sharp spines on the chestnuts present safety issues for swimmers. Ronald Johnson, Manager of Grounds and Capital Projects, said, “Water chestnuts are still a relatively new occurrence in Rabbit Pond, and OPP thinks that they were probably introduced by the large population of Canadian geese inhabiting the area this spring and summer.” In late August, Patricia Russell, Campus Sustainability Coordinator alerted Johnson of the water chestnut problem. Ms. Russell heard of the invasive plants from the environmental group Friends of Andover Community Trees (FACT), which monitors invasive plants in Andover. The volunteer group initially identified the water chestnuts in Rabbit Pond. “The water chestnut issue should not be ongoing. The cold winter weather will kill the plants,” said Johnson. OPP plans to organize a student volunteer project in mid-October to remove the patches of water chestnuts from on and around Rabbit Pond, according to Johnson. Local photographer Kristina Trott also submitted a photo of the ducks and water chestnuts on Rabbit Pond to The Andover Patch, an online newsletter that publishes photos from the town of Andover. The water chestnut was first introduced to North America in the 1870’s, when it was grown in a botanical garden. It escaped cultivation and was found in the Charles River by 1879, according to the USGS website. The plant continued to spread through more than 300 acres throughout 55 miles of Lake Champlain and is now present in all states in New England, New York, and Pennsylvania.