Healthy ecosystems provide habitat for native species, retain nutrients and sediment, and store floodwaters. Efforts to protect critical habitat in the Lake Champlain Basin, such as riparian and wetland areas, include improving habitat connectivity and wildlife passage, reducing nutrient runoff into rivers and streams, supporting restoration measures for species of concern, and reducing the risk of new invasions of non-native species.
AQUATIC INVASIVE SPECIES
A number of aquatic invasive species have arrived in Lake Champlain, but no new species have been detected since the discovery of spiny waterflea in 2014.
Non-native species are plants, animals, and pathogens that are introduced to the Lake Champlain Basin from outside the watershed. The list of non-natives currently present in the Basin includes those whose impact has been difficult to quantify, including well-liked species such as rainbow trout, brown trout, and largemouth bass as well as the lesser known faucet snail or European fingernail clam. Some of these non-native species are designated as invasive species, meaning they are known to cause economic or environmental harm or have an adverse effect on human health.Of the 50 known aquatic non-native species in Lake Champlain, just over a dozen are invasive (Figure 11). Commonly known aquatic invasive species (AIS) include plants such as Eurasian watermilfoil, purple loosestrife, and water chestnut; crustaceans and mollusks such as spiny waterflea, rusty crayfish, and zebra mussel; and harmful pathogens such as largemouth bass virus.
The spiny waterflea is the most recent aquatic invasive species to be detected in Lake Champlain and poses the greatest risk of spread to other water bodies. This crustacean, which is native to northern Europe and Asia, likely was introduced with released ballast water into the Great Lakes, after which it spread rapidly to the inland lakes of the Adirondacks and then to Lake Champlain. The Lake Champlain Long-Term Water Quality and Biological Monitoring Program first detected spiny waterflea in the Lake in 2014. In addition to its negative impact on the Lake’s plankton communities, the species’ long, barbed tail fouls the lines and downriggers of anglers. That fishing equipment, along with bilge water, provides a key means for the spiny waterflea to further its spread in the Basin.
Treatment of high-risk boats with a hot-water high-pressure wash can help to prevent the spread of aquatic invasive species. Photo: LCBP.
Asian clams have been present in the Champlain Canal and Lake George for several years, but it was not until 2016 that they were found by an angler in Lake Bomoseen. Asian clams are small bivalves that can clog water intake pipes and irrigation systems and can carpet sandy areas on a lake bottom. They are hermaphrodites, meaning each individual can reproduce without a mate, a trait that allows them to spread rapidly. The Lake Champlain AIS Rapid Response Task Force evaluated the detection of Asian clam in Lake Bomoseen for potential management action. Because the population was spread over a large area (making in-lake control of the species nearly impossible), the task force suggested increased boat launch stewardship and installation of a decontamination station.
The Basin’s ecosystem likely is affected by some non-native species that have not yet been documented to cause harm in water bodies. Local watershed organizations actively manage species such as European frogbit and yellow flag iris. Species on the doorstep of Lake Champlain that present the greatest threat from outside the Basin include round goby, quagga mussel, hydrilla, and starry stonewort.
The Basin is also threatened by a number of terrestrial invasive species and forest pests and pathogens that can cause significant economic damage. Emerald ash borer, a devastating invasive forest pest species, was detected for the first time in Vermont in February 2018, and hemlock woolly adelgid, another forest pest, was discovered in the Lake George region in 2017.
Some of the most significant impacts to Lake Champlain ecology are caused by aquatic invasive species, which have altered the plankton community at the base of the food web.
Zooplankton are the food source that drives the fishery of Lake Champlain, supporting Atlantic salmon, lake trout, and other key species. Scientists at SUNY Plattsburgh documented declines in native plankton called rotifers after the invasive zebra mussel was first detected in southern Lake Champlain in 1993. Zebra mussels established themselves throughout the Lake in less than a decade. Their impact on plankton is just one of this invasive species’s far-reaching effects. Zebra mussels also smother and displace native mussels, clog water intake pipes, cut the feet of swimmers, and encrust submerged historic shipwrecks.
After the detection of invasive alewives, populations of native water fleas known as copepods and cladocera shifted, suggesting that alewives not only out-compete native rainbow smelt but also may impact the native group of water fleas, which serve as part of the base of the Lake Champlain food chain. The invasive spiny waterflea, which arrived in 2014, may also affect the Lake’s ecosystem. Samples collected in summer 2014 showed a sharp spike in densities of spiny waterflea during the initial invasion of this species. Spiny waterflea densities declined in the following years, but a decline in the abundance of several planktonic species of rotifers and some common crustaceans has been attributed to spiny waterflea predation.
While some invasive species migrate, human activity is the most common cause of aquatic invasive species spread.The primary source of new aquatic species in the Northeast is ballast water taken in by ships at sea and released into the Great Lakes. Once in the Great Lakes, a species can spread through the canals that connect Northeast water bodies and that provide a leading pathway for introduction to Lake Champlain (Figure 12). The Champlain Canal, which connects the Lake to the Hudson River, has been the most significant pathway for AIS spread. A feasibility study has recently begun to examine options for a barrier on the Champlain Canal to prevent the movement of aquatic non-native and invasive species.
Aquatic invasive species can hitch a ride on recreational vessels passing through canals that connect Lake Champlain to other water bodies in the region. Photo: LCBP.
Other pathways of introduction and spread include baitfish release, aquarium and pet dumping, water garden escapes, and overland transport on watercraft, trailers, and recreational equipment. The LCBP and many partners support boat launch steward and greeter programs on Lake Champlain and other water bodies throughout the Basin. The stewards inspect boats as they launch and depart from lakes to intercept invasive species before they are spread. Watercraft decontamination stations have been strategically placed across the Adirondack region, on the shorelines of Lake George and Lake Champlain, and at various locations throughout Vermont. Stewards treat high-risk boats with high-pressure hot water to flush any potential non-native and invasive species from boat exteriors, engines, and other compartments. Vermont and New York have recently strengthened rules and regulations requiring boaters to clean and drain their boats and trailers when moving between waterways to help prevent the spread of AIS. In another prevention step, Québec has implemented new baitfish regulations.Steward programs also collect important information about the overland transport of boats. Surveys show that vessels entering Lake Champlain come from as far away as Texas and Colorado and that certain water bodies in the Northeast are commonly visited in a short period of time immediately before arriving on Lake Champlain or after departing (Figure 13). An understanding of boat movement helps to prioritize AIS-infested water bodies for boat inspections and decontamination stations. Partners in the Basin take a regional approach to risk assessment and spread prevention by sharing techniques and data from their programs.
The LCBP boat launch steward program expanded to Quebec for the first time in 2017. Photo: OBVBM.
Early detection and rapid response are key elements of spread prevention efforts. Containing and managing new introductions of species before they become established helps to lower the potential long-term management burden that falls on the states and non-profit organizations, all of which have limited resources and funding. Trained volunteers serve a critical role as early detectors of new species and the spread of existing invasive species in the Basin.
Invasive water chestnut continues to require intensive control measures each year, but coordinated management efforts have greatly reduced the extent of infestations.
The water chestnut is an invasive plant that forms dense leafy mats that float on the water surface. In the southern end of Lake Champlain, water chestnut limits boat traffic and recreational use, crowds out native plants, and creates oxygen-depleted zones uninhabitable for fish and other organisms. It was first documented in southern Lake Champlain in the 1940s and was likely introduced through the Champlain Canal from a water garden escape. The Hudson River also contains significant populations of water chestnut.
Lake Champlain’s water chestnut control program is a long-standing success story. Nearly a dozen U.S. federal, state, provincial, and non-government organizations provide support to harvest water chestnut mechanically and by hand in Lake Champlain and other inland waters in the Basin. Since 1999, these efforts have pushed areas of dense population from Crown Point southward to the Dresden Narrows. Substantial progress by hand harvesting has been made at a few satellite populations in the Richelieu River, Pike River, and Missisquoi National Wildlife Refuge (Figure 14).
Mechanical and hand harvesting efforts to control water chestnut over the past few years have been challenging due to fluctuating water levels in the Lake. Low water levels in 2016 limited management staff and volunteers in their ability to access shallow areas for harvesting plants; fortunately, higher water in 2017 allowed teams to make up for the lost progress. In 2017, after water levels recovered, teams harvested more than 2,000 rosettes in Black Creek Marsh in St. Albans Bay that were discovered the previous year.
The effort to control this invasive plant could soon be augmented by a new technological tool. The Lake Champlain Committee and Vermont Department of Environmental Conservation are evaluating the possibility of using drones to increase the efficiency of water chestnut management in the Lake. Drones are being evaluated for use in detection, surveying, documentation, and monitoring water chestnut beginning in 2018.
Dive In: What You Can Do
Become a volunteer citizen scientist. Contact your local watershed organization or state agency and learn how to look for and identify invasive species.
Clean, drain, and dry. Take steps to stop aquatic hitchhikers.
Dispose of bait properly. Don’t dump in water bodies.
Use only native species. Don’t plant invasives in lawns or gardens.
Use local firewood. Never move firewood between locations.