Invasive Pond Plants and Animals

Common Reed

While some people may argue that the Common Reed isn't an invasive species as it is native to North America, the past two hundered years or so have seen a huge increase of the area the Common Reed has taken over. This invasive species has been known to create monocultures in various areas, causing the habitat of wetlands to diminish, as well as effecting the nutrient cycle in areas. (Dead stems take a few years to decompose, keeping nutrients out of reach of other plants.)

Fanwort

Fanwort can be distinguished by its small yellow-centered white flower, its small floating leaves and the fan-shaped leaves that are submerged underwater. This fast-growing invasive species can be found in ponds, lakes, streams, even ditches, but needs good light and warm water to grow. Fanwort can have a large impact on native plants, and has the potential to eliminate these plants from their native environment.

Flowering Rush

Quite distinctive with its long, sword-like leaves and its pink flower with three petals and sepals, this invasive species can survive in almost any environment. This aggressive plant spreads quite easily, and displaces any native plants that may have previously been there.

Eurasian Watermilfoil

Native to Europe, Asia and North Africa, this is quite possibly the most widely distributed invasive species of plants due to the fact that it can thrive in almost any environment. It is a submerged plant, with slender stems that are up to 3m long. This plant can grow in various depths of water, ranging from 0.5m to around 10m deep.

This invasive species of plant grows very quickly, and creates a thick mat on the water surface, blocking sunlight that any other submerged plant may need. It also raises both the pH and temperature of the water, while decreasing oxygen levels.

European Frog-bit

European Frog-bit has become a dominant invasive species of plant in the northern USA as well as in central and eastern Canada. Resembling the waterlily, the plant has small white flowers, with small kidney-shaped leaves (approximately 1" wide). While the roots are submerged in the water, the roots never actually anchor at the bottom of the water garden or pond. As with the Eurasian Watermilfoil, the European Frog-bit formes a dense mass on the surface of the water, blocking sunlight for other plants.

Hydrilla

The invasive species Hydrilla is mostly apparant in the southern USA, but could spread anywhere quite easily due to the accidental release from aquariums and water gardens into the wild. It is one of the most serious invasive species due to the fact that it is so adaptive and can survive in almost any environment. The stems of this plant grow up to 2 meters long, with whorls of leaves around the stem. Infestations of this plant can restrict water flow, and even cause flooding in extreme cases.

Parrot Feather

This invasive species can be indentified by its small, white flowers and submergable leaves that are reddish, feather-like and present only in the winter. This species can form dense stands that take over any shallow lake, stream or other body of freshwater.

Purple Loosestrife

The Purple Loosestrife is distinguished by its flower stalk that is make up of many small five or six-petaled flowers. This invasive species has a rootstalk that can send out up to 50 shoots of flower stalks, resulting in this plant creating a monoculture in areas where it is abundant. This can make wetlands less biologically diverse, and less likely to shelter any fish or wildlife.

Water Caltrop

This floating invasive species can grow in water up to 5 meters deep, and are anchored to the ground by fine roots. The Water Caltrop has two types of leaves - fine feathery ones under water, and large floating leaves that float on top of the water. There are also white flowers and a fruit the shape of a bull head. When this plant is present in water, it creates a thick mat over the surface of the water that prevents sunlight from reaching submerged plants and reduces oxygen levels in water.

Yellow Floating Heart

This invasive species is similar to a waterlily, only with a yellow flower with fringed petals and heart-shaped leaves. Each flower less than 2" in diameter. When growing in the wild, it takes over slow-moving bodies of water, including lakes and wetlands, and reduces the growth of plants native to that area.

Yellow Iris

The yellow iris (1m-2m tall) has been used for many years as everything from a decorative flower to erosion control. Unfortunately, this invasive species can rival natural plants in the environment. Due to the ability to survive submersed in water, as well as in drier environments, this often results in this invasive species taking over the specific environment.

Goldfish

A very popular fish for aquariums and water gardens, goldfish can have a bad effect on natural environments when let loose, either by accidental escapes from a water garden, or an intentional release from an aquarium. Due to the fact that this invasive species can survive in almost any type and temperature of water, as well as the fact that goldfish like to eat live plants, goldfish threaten native fish species by competing for food.

Grass Carp

The Grass Carp is another invasive species of fish that can survive in a variety of water temperatures, and threatens native fish species by providing competition for food. These fish feed heavily on aquatic vegetation; it is recommended that they are not used for water gardens as the accidental release into any natural body of water could have an effect on the native fish.

Mosquito Fish

This invasive species can grow up to 3.5 cm in length. These fish, surprisingly, do not help control mosquito populations more than most native species of fish. They do, however, like to harass other fish, and compete for food and habitat.

Northern Snakehead

The Northern Snakehead is was introduced into waters by intentional release by people who purchased them live for consumption or aquariums. This invasive species has the potential to be a very large problem due to the fact that it can live out of water for days, and can thus travel from one body of water to another on its own. The Northern Snakehead also poses a problem as well as consuming vegetation, these fish eat other fish and small reptiles, mammals, birds, amphibians, and the like; they also have no natural enemies in North America.

Round Goby

This invasive species was introduced into North American waters from the ballast of boats coming from Europe. It's a small fish that lives near the water bottom, preferablly where it is rocky or sandy, where they feed on small organisms that can be found there. They also like to feed on zebra mussels, which, although helping to control the zebra mussel population, can pass on high contaminant levels from the zebra mussels higher up on the food chain. These small fish also eat the eggs and fry of various larger fish, and have their own defense mechanism from being eaten themselves - their gills can expand and protrude sharp, spiny gill plates, which can cause a fish to choke on the Round Goby.

Rudd

The Rudd is believed to have been introduced to North American waters through bait-bucket dumping. This invasive species is a large fish that can grow up to 35cm long. It inhabits quiet water and feeds on both vegetation and insects; however it does not process vegetation well and releases many nutrients in the water, which could cause an increase in algae and lower oxygen levels. The vegetation that they mostly consume comes from around the shoreline, disrupting spawning and nursery habitats for these fish.