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Orconectes rusticus
Rusty crayfish
Rusty crayfish O. rusticusare spread by anglers who use
them as bait. They are prolific and have serious impacts like
severely reducing lake and stream vegetation and depriving
native fish and their prey of cover and food. They also
reduce native crayfish populations
Geographical range
Native range: Indiana, Ohio, Kentucky, and Michigan in the
United States.
Known introduced range: Has invaded many areas
surrounding it's native range. It has moved as far west as
North and South Dakota, north as Canada and Maine, and
south as Tennessee.
Description
According to Bowen (1999), “O. rusticus can be identified by it’s more robust claws and by the dark, rusty spots on each side of their
carapace. The spots are located on the carapace as though you picked up the crayfish with paint on your forefinger and thumb. The
spots may not always be present or well developed on rusty crayfish from some waters. In the spring, males will molt into a sexually
inactive form (called Form II) and then molt back into the reproductively competent form (Form I) in summer. Form I males are
characterized by large claws, a hook on one pair of their legs, and hardened gonapods. The hook and the larger claws are used for
grasping females during mating. Males are usually larger than females of the same age.”
Habitat description
According to Bowen (2003), “O. rusticus inhabit lakes, ponds, and streams. They prefer areas that offer rocks, logs, or other debris
as cover. Bottom types may be clay, silt, sand, gravel, or rock. Rusty crayfish inhabit both pools and fast water areas of streams.
They generally do not dig burrows other than small pockets under rocks and other debris, although there have been reports of more
substantial burrows. O. rusticus need permanent lakes or streams that provide suitable water quality year-round.”
General impacts
According to Bowen (2003), “invading O. rusticus frequently displace native crayfish, reduce the amount and kinds of aquatic plants
and invertebrates, and reduce some fish populations
Carcinus maenas
Green Crab
This crab is native to Europe and northern Africa. It has been introduced to the
USA, Australia and South Africa. It is a voracious a euryhaline food generalist.
The voracious predator in some locations of its introduced range, has caused the
decline of other crab and bivalve species.
Description
Maximum carapace length is 60 mm and slightly wider. It has 5 antero-lateral
teeth on each side of the carapace and 3 lobes between the eyes. Colour highly
variable, mostly greenish, green-brown and green-grey.
Habitat description
Salinity tolerance enables distribution in estuaries
General impacts
Voracious predator. The crab is able to crush mussels and shows a clear
potential to negatively threaten mussel farms.
Management information
Preventative : Biological control agents such as the parasitic cirriped Sacculina
carcinus have been discussed, but have not been tested in the wild yet.
Invasion pathways to new locations
Aquaculture
Live food trade
Pet/aquarium trade
Ship ballast water
Ship/boat hull fouling
This species has been nominated as among 100 of the "World's Worst" invaders
Axis axis
Indian Spotted Deer
Axis axis is an introduced species of deer from India. It has historically
been introduced to various locations because of its desirable qualities
as a game species. When herd populations become too large they
impact local vegetation and increase erosion. They also forage on a
variety of vegetation removing food sources for many native species
and domestic cattle. They also carry transmissible diseases and pose
an increased threat to human safety in and around highway corridors.
Geographical range
Native range: India, Nepal, and Sri Lanka (Anderson, 1999).
Known introduced range: Australasia-Pacific. Europe, North America,
and South America (Fox Free Task Force, UNDATED; Council of
Europe, 2002; National Park Service, 2004; and Jaksic et al. 2002)
Description
A. axis is a moderately large deer standing 88-97 cm at the shoulders. It has a rufous brown coat that is covered with white spots on
the abdomen, rump, throat, insides of legs and ears, and underside of tail that persist throughout the life of the animal. A dark stripe
runs down the back from the nape to the tip of the tail. A gland-bearing cleft is present on the front of the pastern of the hind foot.
Weights can top 30-75 kg in males and 25-45 kg in females (Anderson, 1999; and Davis and Schmidly, 1997). Antlers are present
only on bucks.
Occurs in:
agricultural areas, coastland, natural forests, planted forests, range/grasslands, scrub/shrublands, urban areas
Management information
The most successful control strategies currently for A. axis to date has been a combination of fencing and hunting. Fencing is not
100% effective though, and deer eventually escape (downed trees, human poaching). A. axis can also jump over 6 foot tall fencing
and studies show that 10 foot or higher fencing is required to adequately keep A. axis out of or in an area. Reproductive control using
such techniques as contraception and sterilization are also possibilities but are expensive and time consuming requiring many man
hours of labor intensive field work. New Zealand controls its exotic deer populations through recreational and commercial hunting and
these have been very effective techniques. Once A. axis become established in urban and suburban areas hunting does not remain a
practical method of control, therefore it is best to gain control of A. axis populations before they become established in suburban
areas (Anderson, 1999; and the University of Hawai‘i, UNDATED).
Eleutherodactylus
coqui
Caribbean tree frog
Geographical range
Native range: South America: Puerto Rico (Beard et al. 2003).
Known introduced range: Australasia-Pacific, North America (USGS-NAS, 2004). Galapagos Islands (Snell
and Rea, 1999)
Management information
Preventative measures: Intentional transport of frogs has been banned in Hawai‘i (Kraus and Campbell,
2002).
Physical: Hand-capture is a successful method when dealing with small numbers (Kraus and Campbell,
2002).
Chemical: Field trials are being conducted to evaluate the efficacy of a direct spray application of a
concentrated caffeine and water solution for control on 0.1 - 0.5 ha infested plots. If these trials are
successful, it is hoped that management agencies in the State of Hawai‘i will be able to reduce the spread
and potential impact of these pest species on a landscape scale. (Campbell et al. 2002). Spraying of citric
acid on infested plants to kill coqui frog eggs, juveniles, and adults, is recommended (CTAHR, Undated) but
evidence of efficacy has not been demonstrated.
Occurs in:
agricultural areas, natural forests, planted forests, riparian zones, urban areas, wetlands
This species has been nominated as among 100 of the "World's Worst" invaders
Eleutherodactylus
coqui is a relatively
small tree frog native
to Puerto Rico. The
frogs are quite
adaptable to different
ecological zones and
elevations. Their loud
call is the main
reason they are
considered pests. E.
coqui's mating call is
its namesake, a highpitched, two-note "coqui" (ko-kee') which
attains nearly 100
decibels at 0.5
meters. E. coqui have
a voracious appetite.
There is concern in
Hawai‘i, where it has
been introduced, that
E. coqui may put
Hawai‘i’s endemic
insect and spider
species at risk and
compete with
endemic birds and
other native fauna
which rely on insects
for food.
Lygodium
microphyllum
small leaf
climbing fern
Occurs in:
natural forests, riparian zones, wetlands
Geographical range
Native range: Africa, Asia, Australasia-Pacific,
Europe-Asia (USDA-GRIN, 2005).
Known introduced range: North America
(University of Florida, 2001).
Description
"L. microphyllum is a fern with dark brown, wiry rhizomes and climbing, twining fronds of indeterminate growth, to 30 m (90 ft) long; main rachis
(leaf stalk above petiole) wiry, stemlike. Leafy branches off main rachis (constituting the pinnae) once compound, oblongish in overall outline, 512 cm (2-5 in) long. Leaflets (pinnules) usually unlobed, stalked, articulate (leaving wiry stalks when detached); leaf-blade tissue usually glabrous
below; fertile leaflets of similar size, fringed with tiny lobes of enrolled leaf tissue covering the sporangia along the leaf margin." (University of
Florida, 2001).
General impacts
Pemberton et al. (2003) refers to L. microphyllum as, "An aggressive invasive weed of moist habitats in Florida. This rapidly spreading weed
colonizes new areas without the need of habitat disturbance and frequently completely dominates native vegetation. Herbicidal and mechanical
controls are expensive, temporary solutions, and are damaging to non-target plants."
Once L. microphyllum has established, "It climbs and blankets other vegetation, ultimately causing mortality to mature canopy and subcanopy
trees Sometimes, L. microphyllum covers other vegetation so completely, it is not possible to see other plants beneath it Near the ground
surface, a thick mat of old and new fronds also forms, ultimately smothering and stifling native plants including herbs and tree seedlings that
would ordinarily maintain the forest canopy if allowed to mature.“ similarly report that, "L. microphyllum forms dense mats of rachis plant
material. These thick, spongy mats are slow to decompose, exclude native understory plants, and can act as a site for additional fern
colonization. It is difficult for other plant species to grow through the dense mat made by this fern, thereby reducing plant diversity. Large
expanses of fern material also may alter drainage and water movement."
Mus musculus Linnaeus
house mouse
The house mouse probably has a world distribution more extensive than any
mammal apart from humans. Its geographic spread has been facilitated by its
commensal relationship with humans which extends back at least 8,000 years.
They do considerable damage by destroying crops and consuming and/or
contaminating food supplies intended for human consumption. They are prolific
breeders, sometimes errupting and reaching plague proportions. They have also
been implicated in the extinction of indigenous species in ecosytems they have
invaded and colonised which are outside their natural range. An important factor
in the success of the house mouse is their behavioural plasticity brought about
by the decoupling of genetics and behaviour. This enables the house mouse to
adapt quickly and to survive and prosper in new environments.
Occurs in:
agricultural areas, coastland, disturbed areas, natural forests, planted forests,
range/grasslands, riparian zones, scrub/shrublands, urban areas
Description
A long tail (60-105 mm - approximately equal to its head and body length of 65-95 mm), large prominent black eyes, round ears and a
pointed muzzle with long whiskers. Adults 12-30 g. Wild mice are commonly light brown to black; belly fur white, brown, or grey.
Colour of tail also lighter below than above.
Geographical range
Native range: Native to the Indian subcontinent, the house mouse has accompanied humans to, and colonised, tropical, temperate,
semi-desert, desert, and subantarctic regions throughout the world.
General impacts
House mice are major economic pests, consuming and despoiling crops and human foodstuffs, and have also been implicated in
extirpations and/or extinctions of indigenous species in ecosytems they have invaded and colonised which are outside their natural
range. They are host to a range of diseases and parasites infectious to humans, the most serious being bubonic plague (Yersinia
pestis) and salmonella (Salmonella spp.). However, mice are considered relatively unimportant as vectors for their transmission to
humans.
This species has been nominated as among 100 of the "World's Worst" invaders
Norops sagrei can be identified by its extensible
throat fan that is often coloured yellow or
reddish-orange and has a white line down the
centre of its backside. This species is a habitat
generalist that prefers open vegetation of
disturbed sites. N. sagrei is a ground dweller but
will venture up several feet into trees and
shrubs. This species competes with Anolis
carolinensis and other introduced congeners. N.
sagrei also prey on the hatchlings of A.
carolinensis.
Occurs in:
disturbed areas, urban areas
Geographical range
Native range: The brown anole is native to
Cuba, the Bahamas, and their satellite islands
(Campbell, 2002).
Known introduced range: North America,
Hawai‘i, Jamaica (Campbell, 2002). They have
also been introduced into Granada (Kolbe et al
2004).
Description
N. sagrei or brown anole is a “trunk ground ecomorph” sensu. It is described as having an extensible throat fan that can be yellow to
red-orange. This species can be between 13 and 21.3 cm. It also has enlarged toe pads and a short snout. N. sagrei can erect a
dorsonuchal crest when exposed to certain stimuli. The tail may have a crest-like ridge, but this is highly variable between individuals
and should not be confused with the dorsonuchal crest. Also, the tail is laterally compressed. Females have a light line down the
middle of their backs, but males do not. They tend to have a lighter mid-dorsal stripe that is distinct and often boldly patterned in
females and often indistinct in males. Individuals change their colors and patterns throughout this range. Male color is highly variable,
ranging from light gray to nearly jet-black, and plain colored to covered dorsally with irregular dark patches or chevrons and a network
of light lines. Females exhibit a large range of color, but nearly always have some type of obvious wavy dorsal pattern along the
midline of their back.
Management information
Campbell (2002) observes that, no control or eradication measures have been implemented for the brown anole, in Florida (North
America) where it has established. He further adds that this species would be very difficult if not impossible to completely eradicate
due to its high density, high reproductive potential, and habitat generality.
The North American bullfrog Rana catesbeiana has been
widely distributed via aquaculture and the aquarium trade. It is
one of the most frequently cultivated edible frogs, world-wide.
Primary concerns are competition with and predation upon
native herpetofauna.
Description
Large size: adults 10-20 cm snout-to-vent length and 60-900
g. Dorsal color is light green to olive to brownish-green, often
with a mottled pattern of greens and browns. A fold of skin
runs from the eye around conspicuous eardrums. The mostly
white ventral surface may be mottled with gray.
Occurs in:
lakes, water courses, wetlands
General impacts
Competes with native anurans. Larvae can have a significant impact upon benthic algae, and thus perturb aquatic community
structure. Adults may be responsible for significant levels of predation on native anurans and other aquatic herpetofauna, such as
snakes and turtles. These impacts have been documented for bullfrogs on the west coast of the United States and they are the likely
ones for the species globally.
Geographical range
Native range: The bullfrog is native to central and eastern USA and southeastern Canada.
Known introduced range: It has been introduced to Hawaiii'i, parts of western USA and southwestern Canada, Mexico and the
Caribbean, South America, Europe and Asia.
This species has been nominated as among 100 of the "World's Worst" invaders