Like most major rivers in populous regions the Connecticut has been impacted by invasive species. These transplants crowd out native species and degrade the habitats of plants and creatures that have not had time to evolve adequate natural defenses. Some of these are shoreline invaders like Japanese knotweed, purple loosestrife, and the ever-spreading phragmites. Others are introduced aquatic species and fish like large and smallmouth bass, brown and rainbow trout, carp, Asian clams, Eurasian milfoil, stream-choking didymo, a.k.a. “rock snot”, and now VHS.
Though we often focus our ire on the transplanted species themselves, at the bottom of almost every invasive introduction is some human activity that either: a) deliberately transplanted a species, or, b) brought it into a new habitat unawares.
Once invasive species get established, they are nearly impossible to dislodge. We end up either living with the consequences in diminished habitats, or taking severe measures in an attempt to reverse mistakes. Sometimes we even bring in one invasive species in an attempt control another. We can never know what all the possible long-range consequences might be, though it’s possible to anticipate a few. Still it’s no way to run a planet. The answer is to stop moving species around. It’s time to be responsible stewards.
For more perspective on the situation in the Connecticut River, read the River Currents article Our River Is Under Siege.
In 2005 CRWC awarded Laurie Callahan of Kennebunk, ME, a grant to support her project to map aquatic invasives on the river. It was entitled "The Connecticut River Outreach and Survey Project for Aquatic Invasive Plants". Read her report (PDF 300KB) and download the accompanying 2007 map of Invasive Aquatic Plants along the Connecticut River in VT & NH (PDF 1.7MB) shown at left. For detailed information about each site shown on the map, also download the accompanying table Combined Chart for 2006 & 2007 CT River Aquatic Invasive Plants Projects’ field site locations. The project covered only submersed- and floating-leaved invasive aquatic plant species in the main stem of the river, and does not show algal, wetland or riparian species.
Invasive Plant Atlas of New England The University of Connecticut's comprehensive web-accessible database of invasive and potentially invasive plants in New England continually updated by a network of professionals and trained volunteers.
What is it? Didymo (did-ih-mo), aka rock snot, is an invasive freshwater algae that has emerged across the globe as a threat to freshwater river and stream habitats. It prefers cold water river and stream habitats--spreading in massive mats across substrates. At its worst, didymo forms a smothering blanket on river and stream bottoms, choking aquatic plants, insects, fish, and their habitats. It will do great harm if it gets further established. It is spread, in part, via recreational boating and fishing.
Where is it? It’s recently invaded the Connecticut River watershed. Didymo has now been identified in sections of the upper Connecticut and the White River.
Description: Didymo forms mats on stream and river bottoms. Didymo can be tan, brown or yellow, and has a wet-cotton feel. It is not slimy. Didymo is often mistaken for discarded fiberglass or toilet tissue.
How it spreads: Didymo can invade any stream. One drop of contaminated water is sufficient to spread didymo. Its spread is helped by recreational boaters and fishermen who move it from place to place unknowingly when they don’t properly cleanse hulls and equipment. Boats, canoes, fishing waders, trailers, fishing equipment and anything that comes into contact with infected waters can spread didymo.
Prevention: To stop didymo it’s necessary to use proper procedures to clean and dry waders, equipment, boats and trailers promptly upon exiting the river, stream or lake. By implementing the most thorough cleansing techniques, we may still be able to stop its spread.
Didymo EPA site: http://www.epa.gov/region8/water/didymosphenia
What you can do: Download flyers and posters to distribute:
WARNING Check Clean Dry poster above. 11"x17" but can print smaller. (PDF 0.5MB)
Clean Boats = Healthy Rivers brochure (PDF 1.3MB)
Didymo Emergency poster (PDF 0.7MB)
CT DEP's brochure Didymo - Learn What You Can Do (PDF 1.2MB)
What is it? Eurasian watermilfoil is a hardy, submerged invasive aquatic plant that can form dense mats at the water’s surface.
Where is it? E. watermilfoil prefers the slow waters of lakes and ponds. It occurs throughout the continental United States across a wide range of aquatic conditions in both cold and warm water settings.
Description: Eurasian watermilfoil has feathery, olive green leaves arranged in whorls around the stem. Stems can reach 20 feet. Reddish flowers form at the surface during July and August.
It’s spread and impacts: E. watermilfoil reproduces through seeds and vegetative methods. Fragments and plant stems can readily reproduce. E. watermilfoil reproduces rapidly, displacing native species and biodiversity. It clogs lakes, ponds, and slow river habitats—blocking sunlight, reducing oxygen and impeding recreational uses.
Management methods and drawbacks: Mechanical removal, draw-downs, herbicides, and biological controls are employed. Mechanical harvesting helps, but leaves behind fragments that reproduce. Draw downs effect other habitats and species. Herbicides can be toxic to fish and other species. The native American Weevil—feeds on E. watermilfoil and has been used in some places to effect.
Eurasian watermilfoil government document:
What is it? Purple loosestrife is an introduced, woody, square-stemmed wetland plant native to Europe and Asia.
Where is it? Purple loosestrife was introduced as an ornamental plant in the 1800s and has now spread as a wetland invader across much of the northeast and north central United States. It is also found in the northwest U.S.
What does it look like? Purple loosestrife is perennial. It is from 4 – 10 feet high, and produces magenta-colored flower spikes. Mature plants can have from 30 – 50 stems arising from a single rootstock.
What it impacts and how it spreads: Purple loosestrife adapts readily to natural and disturbed wetlands, outcompeting native plants, sedges, and grasses. Purple loosestrife invades and spreads across a variety of wetlands including wet meadows, marshes, tidelands, river banks, stream sides, ponds, reservoirs, and ditches. It spreads in thick stands, driving out native species and reducing available habitat for native wildlife.
Purple loosestrife spreads from the production of abundant seed and also vegetatively, via stems attached to the rootstock. Purple loosestrife was once widely available as an ornamental and is still sold in some areas. This plant should not be purchased or distributed.
Treatments used: Hand pulling is used for small infestations. When attempting controls it is best to undertake them before the plant produces its abundant seed in summer. Herbicides and introduced biological controls have been used—including several introduced insect species.
Purple loosestrife government website:
Fight Purple Loosestrife -- become a beetle farmer! Download a PDF document of information on how you can fight this invasive plant by rearing and dispersing the leaf-feeding beetles that eat purple loosestrife.
What is it? VHS is an introduced infectious fish disease native to Europe, first identified in 2005 in Great Lakes fish populations.
Where is it? VHS has caused fish kills in the Great Lakes and St. Lawrence River, and is now present in inland lakes in Michigan, Wisconsin, and New York. (nearing Vermont and the CT Basin.)
What does it do? VHS kills fish. Species that have experienced fish kills from VHS include smallmouth bass, northern pike, gizzard shad, yellow perch, black crappie, bluegill, rock bass and walleye.
What does it look like? Symptoms in infected fish can include bulging eyes, tissue hemorrhaging and unusual behavior. The only way to confirm VHS is to test fish.
How is VHS spread? The VHS virus spreads to lake and river systems through the urine and reproductive fluids of infected fish. It is absorbed into the gills and also transfers to healthy fish when they consume VHS infected fish or infected baits. Natural fish movements increase its reach. Recreational boating, angling, and ballast water discharges spread VHS. VHS is also spread when fish are moved between water bodies in activities that include moving baitfish between waters, fish stocking, and importing fish. Transport of VHS infected water can spread it.
Practice prevention: Never transport fish from one body of water to another. Avoid commercial baits, and don’t transport them. Only release baitfish into the water body they were taken. Never dispose of fish parts or carcasses in any body of water. Remove all mud, aquatic plants and animals from gear, boats, motors, and trailers—and drain live wells, bilges, and bait tanks before leaving a body of water. All boats and gear used in known VHS-infected waters must be promptly and properly disinfected. Use proper techniques, including a bleach solution, in accordance with prescribed washing and drying guidelines.
VHS government website: http://www.dec.ny.gov/animals/25328.html
What is it? Water chestnut is an invasive, annual, rooted, floating-leaved plant that can form dense mats at the water’s surface crowding out native aquatic species.
Where is it? Water chestnut is a native of Eurasia and Africa that has spread into parts of the Northeast including New York, Vermont, Connecticut and Massachusetts—including, recently, a few coves and impoundments along the Connecticut River. Water chestnut is hardy, and can survive across a range of climates. It prefers quiet, nutrient rich water bodies, but it is sometimes found in slow moving water.
What does it look like? Water chestnut has floating, green triangular leaves that are shiny and waxy above, and coated with fine hairs on the underside. The feathery, submerged leaves are whorled around the stems. Stems can reach to 15 feet.
How does it spread? Water chestnut primarily reproduces by spreading its sharp, barbed nuts—each of which can produce 10 – 15 plants, and each of those plants may produce up to 20 seeds. The nuts float downstream and sink to the wet sediments, remaining viable for up to 12 years. Barbed water chestnut nuts can also spread by attaching to the feathers of waterfowl.
Water chestnut’s impacts and threats: Water chestnut is highly competitive. It spreads rapidly and displaces native species, reducing biodiversity. It can drive out native fish populations as it gathers in dense mats that block sunlight and reduce oxygen in the water. Mats of water chestnut can impede swimming, boating, and fishing. Various states have specifically outlawed the distribution of water chestnut.
Treatments/actions/preventions: Early detection is key to controlling and eliminating populations of this plant. Eradication methods include mechanical removal, drawdowns, and the use of herbicide. Hand pulling and mechanical harvesting work well. Plants should be removed before the nutlets are released in the fall.
Water chestnut government document: http://www.mass.gov/dcr/waterSupply/lakepond/factsheet/Water%20Chestnut.pdf
Photo credits: USFWS
Image Credits at Right - Illustrations: Bill Singleton; Photos: Elisabeth Cianciola, David Deen, ©Chris Hardie, ©Al Braden www.albradenphoto.com, River Music drawn by Tom Dudley - Greenfield Recorder, CRWC Staff.