Tag Archives: Invasive Species

Caspian Tern Population Growing on Lake Champlain

Caspian Tern

Caspian Tern and lake ChamplainHydroprogne caspia

.

The Caspian Tern, Hydroprogne caspia, is the largest tern inhabiting the Lake Champlain Basin, and is, in fact, the largest tern in the world. After Double-crested Cormorants denuded parts of Island C of Lake Champlain’s Four Brothers Islands in eight years ago, Caspian Terns found the bare ground appealing and began nesting there.

.

Newcomers to Lake Champlain

Caspian terns and Lake Champlain

Four Brothers Islands, Lake Champlain

Relative newcomers to Lake Champlain – the first recorded nesting was in 2001, when a pair was found on Young Island, off of North Hero and on Popasquash Island, off shore between St. Albans and Swanton. By 2004 Caspian terns began nesting on Four Brothers Island and as of 2007 that colony had 50 pairs of birds. The island now hosts over 100 nesting pairs – a ten-fold increase since they were first confirmed on Island C ten years ago.

Although the Caspian Tern is rare to Lake Champlain, it is not listed as threatened or endangered in either Vermont or New York. Much of the Caspian Tern’s core population is found in the Great Lakes region, but that population is suffering from avian botulism, which is killing thousands of terns. Lake Champlain hosts the only Caspian tern colonies in Vermont and the only other New York colony is on Little Galoo Island in Lake Ontario..

.

Caspian Tern Characteristics

caspian tern on lake champlainThe same size as gulls, and with similar white plumage, Caspian Terns has bright orange bills and swept-back black crests. They are one of three species of terns that can be found on Lake Champlain.  They can be found throughout much of the world, but rarely in large numbers. While hunting, terns dive down on prey, un-like most gulls. They also hunt with their heads lowered to the water, a posture quite different from soaring gulls. Their voice, a raspy ‘kowk’ also differs from that of gulls. While Caspian terns have increased in number, their cousins, common terns have faced troubles.  In the late 1960s, between 300 and 400 pairs of common terns nested on Lake Champlain, but by 1988 the population had fallen to just 50 pairs. The species is currently listed as ‘Endangered’ in Vermont and ‘Threatened’ in New York. The birds nest on small rocky islands in the lake. Work by Audubon Vermont, the Vermont Non-game and Natural Heritage Program, and the Lake Champlain Land Trust has increased the number of nesting terns since the late 1980s and now between 160 and 200 pairs nest on the lake.

.

.

Interesting Trivia About Caspian Terns:

Caspian Terns may begin to vocalize while still in the egg. When an adult gives a ‘Fish Call’ signaling their return to the nest with food, the soon-to-be chicks may respond with begging calls before they are even hatched.

.


.

How You Can Prevent Invasive Species Expansion

We’ve examined the vast variety of invasive species that are posing threats to Lake Champlain’s ecosystem. By now you’re wondering , “What can I do to prevent invasive species expansion?”

.

What Can You Do?

.

Boat Owners:

  • Inspect your boat for zebra mussels

    Inspect your boat

    If you are a boat owner, make sure whenever you move your boat from one body of water to the other that it is free of zebra mussels, one of the most dangerous and invasive of all the species. The larval stage of zebra mussels is microscopic in size so you cannot necessarily see them.

  • Clean your boat off when it has come in contact with infested bodies of water, and give it a good look over. Throw any zebra mussels you find in the trash.
  • Remove all mud, plants, or animals and dispose of on dry land.
  • Drain all bilge water, live wells, bait buckets, and all other water from your boat, engine and equipment.
  • Wash all parts of your fishing gear and boat that have been in contact with water. Do not allow wash water to flow into any body of water or storm sewer.

  • Drain all water from the boat, including the bilge, live well, and engine cooling system. Dry the boat and trailer in the sun for at least five days, or if you use your boat sooner, rinse off the boat, trailer, anchor, anchor line, bumpers, engine, etc. with hot water or at a car wash.

.

Anglers:

  • Don’t move fish from one body of water to another.
  • Never release unused bait fish, even in waters where using them is allowed.
  • Never move fish overland, unless they have been certified as being disease-free.
  • Make sure that your boat and equipment are clean and dried before using them in a different waterway.
  • Inspect all parts of your fishing gear, boat, and trailer that have been in contact with water.

.

Everyone:

  • Purchase non-invasive plants and fish for your landscapes and aquarium.
  • Don’t release unwanted plants or animals into the wild.
  • When swimming or boating in an area infested with Eurasian water milfoil, try not to break parts off the plant—this is how the plant spreads.

.

Additional Infomation:

Invasive Aquatic and Wetland Animals (Invasive Species) by Suellen May
Invasive Aquatic and Wetland Plants (Invasive Species) by Suellen May
Invasion Ecology by Julie Lockwood, Martha Hoopes and Michael Marchetti
Invasive Plants: Guide to Identification and the Impacts and Control of Common North American Species by Sylvan Ramsey Kaufman and Wallace Kaufman

.

Other Invasive Threats to Lake Champlain

Other Invasive Threats to Lake Champlain

We’ve looked at fish, mollusks, crayfish and plants that want to make Lake Champlain their home. Here are some other invasive threats to Lake Champlain:.

.

  • VHS infected - Hemorrhaged Walleye

    Hemorrhaged Walleye

    VHS: viral hemorrhagic septicemia: an often lethal fish disease affecting many species.  VHS in the Great Lakes drainage has led to significant restrictions on transporting fish between water bodies.  It is so significant that new outbreaks must be reported to the World Health Organization for Animal Health.  The disease transmits easily between fish (both individuals and species) and mortality rates seem to be highest in colder waters (37-54 F).  Because some fish can be carriers of the virus and show no external signs, the actual presence of the disease can only be determined by laboratory testing.

    .

    .

    .

     

.
  • Spiny water flea and fishhook water flea: 

Spiny water flea and fishhook water flea

These two plankton species could drastically disrupt Lake Champlain’s food web. Spiny water flea and fishhook water flea both came from Northeast Europe; they were first noticed in Lake Huron in 1984 and Lake Ontario in 1998. These two species  were most likely released with a ship’s ballast water. In 2008 spiny water flea were found in the Great Sacandaga Lake in New York, just upstream from the feeder for the Champlain Canal.

** Since this article was originally published (June 11, 2012), Spiny Water Fleas have been confirmed in the Champlain Canal  and in Lake George; both of these waterways are linked directly to Lake Champlain. It now (August3, 2012) seems inevitable that Spiny Water Fleas will become established in Lake Champlain, if they haven’t already.

Spiny Waterfleas collect in masses on fishing lines.

Spiny Waterfleas collect in masses on fishing lines.

In addition to competing with the native zoo-plankton, spiny water flea and fishhook water flea are much more difficult for small fish to ingest, and are therefore a poorer food source. The long spines of these species can hook them onto anglers’ lines by the hundreds, making fishing difficult. Eggs and adult water fleas can travel unseen in a boat’s bilge water, bait buckets, and live wells.

Learn to recognize these water-fleas on fishing gear.

Inspect and remove aquatic plants and animals, including gelatinous or cotton batting-like material from lines, especially where they meet a swivel, lure or down-rigger ball connection (plucking like a guitar string helps).

Drain lake or river water from live-well and bilge before leaving access.

Dispose of unwanted live bait and worms in the trash.

 .

  • Double-crested Cormorants

    Double-crested Cormorants

    Double-crested Cormorants: Cormorants are relative newcomers to Lake Champlain and have since become a concern to wildlife managers. They first nested on Young Island, Vermont, in 1981; then expanded to Four Brothers Islands, New York, by 1984, and peaked at over 20,000 birds by 1999. Population increases were associated with destruction of vegetation and displacement of other birds from nesting colonies of stick nests built high in trees on islands or in patches of flooded timber. .

Gangly Double-crested Cormorants are prehistoric-looking, black fishing birds with yellow-orange facial skin. Though they look like a combination of a goose and a loon, they are relatives of frigatebirds and boobies.

Double-crested Cormorants float low on the surface of water and dive to catch small fish. After fishing, they stand on docks, rocks, and tree limbs with wings spread open to dry. In flight, they often travel in V-shaped flocks that shift and reform as the birds alternate bursts of choppy flapping with short glides..

Obviously, Lake Champlain is a great lake; who could fault these newcomers for wanting to take up residence here? But these invasive species are threats to the health and survival of our native species, and will disrupt the health, recreation and aesthetic enjoyment of Lake Champlain’s human residents. We must protect our lake; so, what can we do…?.

Next: What Can You Do to Protect Lake Champlain? ( Next >> )

Previous: Invasive Invertebrates ( << Previous )

 

Invasive Plants

Plant Invaders

Invasive plants are non-native species that are capable of moving or, more likely, being moved into a habitat and then monopolizing resources such as light, nutrients, water, and space at the expense of and to the detriment of other species. They are more aggressive and successful than native species at dominating the available resources.

Invasive Plants in the Lake Champlain Basin

  • hydrilla

    Hydrilla

    Hydrilla (Hydrilla verticillata): is a highly aggressive plant. Hydrilla has clogged drainage canals in the southeast and it’s been reported as close as Massachusetts, Maine, and southern New York. Fragments falling from boats, trailers, and live wells can start new populations, which often begin near boat launches.Hydrilla was first introduced to the United States as a popular aquarium plant, which was then accidentally released into the wild in Florida. Hydrilla is capable of completely clogging waterways. Its vertical branches often out-compete native plants, affecting water quality and restricting flow. The widespread growth of this plant has dramatic impacts on recreational uses such as boating, fishing and swimming.Compared to other aquatic plants, Hydrilla grows well in deeper, darker waters and new infestations may establish a foothold there before spreading into shallower waters and out-competing other resident plants..

.

EURASIAN MILFOIL

Eurasian Milfoil

  • Eurasian Water milfoil (Myriophyllum spicatum), first discovered in the Basin in 1962, is found in many areas throughout the Lake and Basin. In some areas infestations are severe. Detailed watermilfoil studies have been conducted for many of Lake Champlain’s bays and for 35 other lakes within the Basin, but many areas have little or no study regarding the presence and extent of infestation. Because Eurasian water milfoil is spread by plant fragments transported by waves, wind, currents, people, and to some extent, animals, it is not easily controlled.

 

.

  • Variable-leaved Milfoil (Myriophyllum heterophyllum) : Related to Eurasian Water milfoil was found in 2009 in Missisquoi Bay; it too can become a nuisance. Because milfoil spreads by stem pieces, roots and seeds, plant parts can easily hitchhike on recreational equipment if not removed. Boaters are advised to avoid beds of watermilfoil to prevent spreading the plant further. Boaters, anglers and other recreational enthusiasts should take precautions to avoid transporting this and other invasive species to other waters or other parts of Lake Champlain.

.

  • Japanese Knotweed

    Japanese Knotweed

    Japanese knotweed (Polygonum cuspidatum) was first introduced to the United States as an ornamental plant in the late 1800’s for its appealing flowers. It was also used for erosion control because of its prolific growth. It has since spread into the wild across the United States, including the Lake Champlain Basin. It spreads by underground rhizomes that easily fragment and spread to other areas. This is a problem especially along stream banks where natural forces contribute to the spread of knotweed.

Japanese knotweed has already altered the natural characteristics of the Lake Champlain Basin. Since it grows early in the season and is very dense, it excludes the growth of native plant species. When dense stands are removed from river banks there can be increased erosion until native plants are able to reestablish themselves.

.

  • European Water Chestnut

    European Water Chestnut

    European water chestnut (Trapa natans), first documented in Lake Champlain in the 1940s, displaces other aquatic plant species, is of little food value to wildlife, and forms dense mats that change habitat and interfere with recreational activities. Water chestnut is a fierce competitor in shallow waters with soft, muddy bottoms. Uncontrolled, it creates nearly impenetrable mats across wide areas of water. In South Lake Champlain, many previously often fished bays are now inaccessible and floating mats of chestnut can create a hazard for boaters. This noxious plant also blocks light into the water, a critical element of a well-functioning aquatic ecosystem, reduces oxygen levels which may increase the potential for fish kills.

Submersed leaves are feather-like; each leaf is divided into segments that are whorled around the leaf stem. White flowers form in the axils of the surfacing leaves in July. Fruit are nut-like and “woody” with typically four sharp, barbed spines. Long cord-like rarely branching stems can attain lengths of up to 16 feet. Water chestnut grows in freshwater lakes and ponds and slow moving streams and rivers. It prefers calm, shallow, nutrient-rich waters.

  • Invasive Plants Didymo

    Didymo or ‘Rock Snot’

    Didymo: Didymosphenia geminata, commonly referred to as “didymo” or “rock snot” is a freshwater algae. Native distribution of the species includes cool temperate regions of Northern Europe and Northern North America. While not much of a threat to Lake Champlain itself, didymo may pose a threat to rivers and streams because it can form dense mats in stream beds. Scientific studies conducted around the world have yet to show that didymo has significant impacts to salmon and trout.

    Didymo attaches to the streambed by a stalk. It has a rough texture similar to wet wool and mimics strands of toilet paper, as opposed to other species of algae which feel slimier.

    Didymo can be accidentally spread by people using rivers, as its microscopic cells can cling to boats, waders, fishing gear, sandals, and anything else that comes in contact with water. Gear must be dried for a minimum of 48 hours or cleaned with a bleach solution to get rid of the algae.

 

What else poses a threat to Lake Champlain’s ecosystem?

Next: Are There Other Invasive Threats to Lake Champlain? ( Next >> )

Previous:  Invasive Invertebrates ( << Previous )

.