Invasive species in Hawaii
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As with a number of other geographically isolated islands,
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...
has problems with invasive species negatively affecting the natural
biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...
of the islands.


Historical examples

Hawaii is the most isolated major land mass in the world and that isolation has led to very high rates of
endemism Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...
. Uniquely adapted endemic species are often sensitive to competition from invasive species and Hawaii has had numerous extinctions (
List of extinct animals of the Hawaiian Islands This is a list of Hawaiian species extinct in the Holocene that covers extinctions from the Holocene epoch, a geologic epoch that began about 11,650 years before present (about 9700 BCE) and continues to the present day. The Hawaiian Island ...
). While not the only cause, introduction of invasive species can be a major cause of population decline and extinction. There are several routes for introduction of non-native species. Some species were accidentally introduced to Hawaii like the rat, fire ants, coqui frog, mosquitos, and asiatic rhinoceros beetle. Some are species brought in for cultivation that spread to wild areas like
miconia ''Miconia'' is a genus of flowering plants in the glory bush family, Melastomataceae, native to warm temperate to tropical regions of the Americas. The species are mostly shrubs and small to medium-sized trees up to 15 m tall. The generic name ...
, pigs, and goats. Some species were intentionally introduced for sport like
axis deer The chital or cheetal (''Axis axis''; ), also known as the spotted deer, chital deer, and axis deer, is a deer species native to the Indian subcontinent. It was first described and given a binomial name by German naturalist Johann Christian Po ...
and some for pest control like mongoose or
cane toad The cane toad (''Rhinella marina''), also known as the giant neotropical toad or marine toad, is a large, terrestrial true toad native to South and mainland Central America, but which has been introduced to various islands throughout Oceania ...
. The
mongoose A mongoose is a small terrestrial carnivorous mammal belonging to the family Herpestidae. This family is currently split into two subfamilies, the Herpestinae and the Mungotinae. The Herpestinae comprises 23 living species that are native to so ...
was introduced to Hawaii in the late-19th century in an attempt to control the large rat population in the sugar cane fields. However, since then, the mongoose population has grown to large numbers without controlling the rat population and has greatly diminished the population of native ground nesting birds, snails, and palms. Another example of an invasive species introduced in the 19th century is the fire tree, which is a small shrub that was brought from the Azores, Madeira, and the Canary Islands as an ornamental plant or for firewood. However, now it poses a serious threat to native plants on young volcanic sites, lowland forests, and shrublands, where it forms dense monocultural stands Another plant, the strawberry guava, was introduced in the early 19th century as an edible fruit. However, it now poses a major threat to Hawaii's rare endemic flora and fauna by forming shade-casting thickets with dense mats of surface feeder roots.


Potential harm from invasive species

Invasive species threaten biodiversity by causing disease, acting as predators or parasites, acting as competitors, altering habitat, or hybridizing with local species.


Disease

Invasive species often carry new diseases for native species. For example, the biting fly in Hawaii are small, even tiny, and include many species, some of which are vectors of diseases while others bite and cause considerable nuisance and health-related problems. The introduction of mosquitoes to Hawaii has resulted in the spread of
avian malaria Avian malaria is a parasitic disease of birds, caused by parasite species belonging to the genera '' Plasmodium'' and '' Hemoproteus'' (phylum Apicomplexa, class Haemosporidia, family Plasmoiidae). The disease is transmitted by a dipteran vecto ...
, and increases the risk of
dengue Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Symptoms typically begin three to fourteen days after infection. These may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic ...
and
west Nile virus West Nile virus (WNV) is a single-stranded RNA virus that causes West Nile fever. It is a member of the family '' Flaviviridae'', from the genus '' Flavivirus'', which also contains the Zika virus, dengue virus, and yellow fever virus. The v ...
(not known to be in Hawaii yet). Other native species can be affected by invasive species diseases as well, such as the once-dominant koa tree being killed by
koa wilt Koa wilt is a relatively new disease to Hawaii, discovered in 1980. Koa wilt is caused by a forma specialis of the fungus ''Fusarium oxysporum'', which is now abundant in Hawaiian soils and infects the native Acacia koa tree, a once-dominant spec ...
, which is believed to have been brought into Hawaii on an ornamental acacia plant, and the 'ohi'a tree, now being affected by Rapid Ohia Death.


Predators

Invasive predators can severely reduce the population sizes of native species, or even drive them extinct, because native prey species may not have evolved defenses against the novel predators.


Competition

Oftentimes the introduced species is better equipped to survive and competes with the native species for food or other resources. For example, the strawberry guava tree is one of Hawaii's worst invasive species. It is dangerous because it crowds out native plant species, breaks up natural areas, disrupts native animal communities, alters native ecosystem processes like water production, and provides refuge for alien fruit flies that are a major pest of Hawaiian agriculture.


Habitat alteration

Invasive species can change the state of an environment in many ways based on how they feed and interact with their new surroundings. These interactions along with competition can limit the amount and type of resources for native species.


Hybridization

Hybrid Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two dif ...
ization occurs when members of two different species mate with one another and produce viable offspring that carry genes from both parents. When an invasive species is much more abundant than a native relative, they may hybridize so often that the invaders genes "flood" the native species, such that no individuals contain the entire genotype of the native species, thus effectively driving the native species to extinction. For example, hybridization between Introduced mallards and the native
Hawaiian duck The Hawaiian duck (''Anas wyvilliana'') or koloa is a species of bird in the family Anatidae that is endemic to the large islands of Hawaii. Taxonomically, the koloa is closely allied with the mallard (''A. platyrhynchos''). It differs in that i ...
(''koloa maoli'') and between the rarest European duck (the white-headed duck) and the invasive North American ruddy duck may result in the extinction of the native species.


Cultural Practice Impacts

In Hawaii, the Hawaiian culture is closely connected to its environment and native species. Chants, ceremonies, hula, and other practices involve the use of plants (both native and Polynesian-introduced), traditional access to places of importance, and other activities that can be directly affected by invasive species. For example,
taro Taro () (''Colocasia esculenta)'' is a root vegetable. It is the most widely cultivated species of several plants in the family Araceae that are used as vegetables for their corms, leaves, and petioles. Taro corms are a food staple in Afri ...
(kalo, in Hawaiian) is defined in the Hawaiian Creation Chant as the plant from which Hawaiians were formed and is considered a sacred plant. The introduction of the
golden apple snail ''Pomacea canaliculata'', commonly known as the golden apple snail or the channeled apple snail, is a species of large freshwater snail with gills and an operculum, an aquatic gastropod mollusc in the family Ampullariidae, the apple snails ...
, which attacks taro, threatens the very existence of Hawaiian ancestors.


Threats to Hawaii's ecosystems

Hawaii has a growing invasive species crisis affecting the islands' endangered plants and animals, overall environmental and human health, and the viability of its tourism and agriculture-based economy. Invasive species occur globally, but Hawaii is more susceptible to invasive species because they are islands. The entire island chain of Hawaii has been devastated by invasive insects, plants, hoofed animals such as deer, goats, pigs and other pests. Feral pigs eat endangered birds' eggs and trample fragile native plants, rosy wolfsnails from Florida gorge themselves on the islands' native snails, weeds such as Australian tree fern and ''
Miconia calvescens ''Miconia calvescens'', the velvet tree, miconia, or bush currant, is a species of flowering plant in the family Melastomataceae. It is native to Mexico and Central and South America and it has become one of the world's most invasive species. M ...
'' plants shade out native plants, and coqui tree frogs aggravate tourists, eat native insects and decrease home values with their piercing calls.


Invasive aquatic species

The threat of invasive species to Hawaii's coral reefs is very concerning. Hawaii's economy relies on their coral reefs for an estimate $10 million tourism business. Freshwater invasive species also threaten Hawaii's ecosystems. In 2003 Lake Wilson was invaded with the floating water fern
Salvinia ''Salvinia'', a genus in the family Salviniaceae, is a floating fern named in honor of Anton Maria Salvini, a 17th-century Italian scientist. Watermoss is a common name for ''Salvinia''. The genus was published in 1754 by Jean-François Ségui ...
. The invasive fern competed with native species and fish. It has cost the state over $1 million to clean up the lake. Freshwater fish have also spread. Due to sport fishermen, species like
trout Trout are species of freshwater fish belonging to the genera '' Oncorhynchus'', '' Salmo'' and '' Salvelinus'', all of the subfamily Salmoninae of the family Salmonidae. The word ''trout'' is also used as part of the name of some non-salm ...
, bass, and other fish have been introduced to lakes and streams in Hawaii . Also, people released pet fish like
guppies The guppy (), also known as millionfish and rainbow fish, is one of the world's most widely distributed tropical fish and one of the most popular freshwater aquarium fish species. It is a member of the family Poeciliidae and, like almost all ...
, suckermouth catfish, and
swordtails ''Xiphophorus'' is a genus of euryhaline and freshwater fishes in the family Poeciliidae of order Cyprinodontiformes, native to Mexico and northern Central America. The many ''Xiphophorus'' species are all known as platyfish (or platies) and ...
in local bodies of water. The suckermouth catfish burrow into the ground, thus harming the local wildlife. Even seemingly harmless guppies can spread disease to native
gobies Gobiidae or gobies is a family of bony fish in the order Gobiiformes, one of the largest fish families comprising more than 2,000 species in more than 200 genera. Most of gobiid fish are relatively small, typically less than in length, and the ...
.


Invasive insects & arachnids

Insects can have major impacts on Hawaii's ecology, crops, and human health. Populations of introduced little fire ants in Hawaii can have major negative impacts on animals, crops, and humans. These small ants can provide a painful sting and are known to attack in swarms. Little fire ants are native to Central and South America, they were introduced to Hawaii on imported plants.
A major threat to Hawaiian crops is the coffee berry borer. It has been known to destroy entire crops of coffee, but some farmers have been able to fight off these pests with pesticides and other measures, while others are finding that the borer is developing resistance to pesticides. It is not known at this time exactly how the pest was introduced to Hawaii but Hawaii's Department of Agriculture in cooperation with the University of Hawaii are investigating how the species arrived to Hawaii and how it can be eradicated. The coconut rhinoceros beetle or Asiatic rhinoceros beetle was first detected in Hawaii on the golf course at Joint Base Pearl Harbor in December 2013. This large beetle feeds on the growing shoots at the tops of coconut trees damaging the emerging leaves and providing opportunities for infection with plant pathogens. The Hawaii Department of Agriculture, USDA, and University of Hawaii are actively working on eradicating the beetle. Another insect that is threatening Hawaii's economy is the small hive beetle, which has been destroying bee hives and honey production throughout the islands. The infestation does not only harm commercial honey production but also wild bee populations and their ability to pollinate plants. This could lead to major ecological problems if current trends are not reverted. In Hawaii, the
brown widow spider ''Latrodectus geometricus'', commonly known as the brown widow, brown button spider, grey widow, brown black widow, house button spider or geometric button spider, is one of the widow spiders in the genus ''Latrodectus''. As such, it is a 'cousi ...
has also been established, along with the
brown violin spider The Mediterranean recluse spider (''Loxosceles rufescens'') is a species of spider that originated in the Mediterranean region as its name implies, but can now be found in many parts of the world and is listed as one of the most invasive spiders w ...
, Asian spinyback spider, and the pale leaf spider. The spiders snuck on
bananas A banana is an elongated, edible fruit – botanically a berry – produced by several kinds of large herbaceous flowering plants in the genus ''Musa''. In some countries, bananas used for cooking may be called "plantains", distinguis ...
from tropical regions to get to Hawaii.


Invasive terrestrial chordates

Terrestrially, invasive species are proving to be a major difficulty in Hawaii because the islands lack many natural predators of invasive animals. Invasive predators often move to the top of the food chain and disrupt prey populations, particularly small mammals, birds, insects, and plants. The
veiled chameleon The veiled chameleon (''Chamaeleo calyptratus'') is a species of chameleon (family Chamaeleonidae) native to the Arabian Peninsula in Yemen and Saudi Arabia. Other common names include cone-head chameleon and Yemen chameleon. They are born pas ...
and the
Jackson's chameleon Jackson's chameleon (''Trioceros jacksonii''), also known as Jackson's horned chameleon, three-horned chameleon or Kikuyu three-horned chameleon, is a species of chameleon (family Chamaeleonidae) native to East Africa, but also introduced to Haw ...
have also been found in Hawaii. They originally came to Hawaii through the pet trade in the 1970s despite Hawaii's laws against the importing or transporting of chameleons, lizards or snakes. Jackson's and veiled chameleons eat mostly insects but also leaves, flowers, small mammals and birds. Hawaii's ecosystems are especially damaged by chameleons hunting and eating patterns, lack of natural predators, and ability to adapt to the various conditions throughout Hawaii. They have a great impact on the ecology of Hawaii. Another threat to Hawaii's ecosystems is a frog called the coqui frog. It makes loud noises, eats native bugs, and is a potential food source for the
brown tree snake The brown tree snake (''Boiga irregularis''), also known as the brown catsnake, is an arboreal rear-fanged colubrid snake native to eastern and northern coastal Australia, eastern Indonesia (Sulawesi to Papua), Papua New Guinea, and many islands ...
. Hawaii is also aggressively fighting to prevent the invasion of the
brown tree snake The brown tree snake (''Boiga irregularis''), also known as the brown catsnake, is an arboreal rear-fanged colubrid snake native to eastern and northern coastal Australia, eastern Indonesia (Sulawesi to Papua), Papua New Guinea, and many islands ...
. The snake has caused major economic and ecological problems in
Guam Guam (; ch, Guåhan ) is an organized, unincorporated territory of the United States in the Micronesia subregion of the western Pacific Ocean. It is the westernmost point and territory of the United States (reckoned from the geographic cent ...
. The snake has destroyed bird, bat, and lizard populations and caused several human disruptions including large numbers of snake bites and power outages from climbing electrical wires. It is estimated that if the species gets into Hawaii it could cost Hawaii up to $123 million. There is a great fear that the species will be transported over to Hawaii from Guam ships and will have the same impact there. Isolated numbers of brown snakes have already been recorded on or around cargo ships into Hawaii. The
feral pig The feral pig is a domestic pig which has gone feral, meaning it lives in the wild. They are found mostly in the Americas and Australia. Razorback and wild hog are Americanisms applied to feral pigs or boar-pig hybrids. Definition A feral ...
is also a major threat to Hawaii's natural ecology. Feral pigs that were originally released or escaped from farms have been breeding in the wild and creating a large population of wild pigs in Hawaii. They have major impacts on the ecology because they are very destructive of plants and habitat and lack predators. Their burrowing patterns also destroy bird nesting grounds and lead to erosion. In remote, mountainous areas, they destroy the nests of seabirds including Newell's shearwater (''Puffinus newelli'') and Hawaiian petrel (''Pterodroma sandwichensis''). These burrows also create standing pools of feces infested water that serve as ideal breeding grounds for mosquitoes. Many native Hawaiian birds are dying because of diseases transmitted by increasing numbers of mosquitoes.


Economic impact

The economic impact of allowing Invasive species to continue to propagate and spread throughout Hawaii poses severe risks for various Hawaiian industries central to the state's economy. According to a Legislative State Reference Bureau study from 2002, snails, insects and viruses that are nonnative have threatened the resurgence of the
taro root Taro () (''Colocasia esculenta)'' is a root vegetable. It is the most widely cultivated species of several plants in the family Araceae that are used as vegetables for their corms, leaves, and petioles. Taro corms are a food staple in Africa ...
crops which is an estimated 2 million dollar industry in the state. The taro aphid, which attacks plants in dry land taro crops, causes a 90% crop loss rate, devastating local farmers. The only way to effectively combat an infestation of invasive pest species is to remove all taro root from the area for one year further exacerbating the economic impact of the pest. The papaya industry, which comprises the 5th largest commodity in the state and takes in 16 million dollars annually, has also been affected by invasive species. The
Papaya ringspot virus ''Papaya ringspot virus'' (PRSV) is a pathogenic plant virus in the genus ''Potyvirus'' and the virus family ''Potyviridae'' which primarily infects the papaya tree. The virus is a non-enveloped, flexuous rod-shaped particle that is between 760& ...
has killed trees and ruins marketable fruit. Furthermore, with the introduction of fruit flies to Hawaii, fruit fly-free markets like Japan and California have restricted trade thus cutting off an estimated 300 million dollars of potential markets. Since 1985, four varieties of insect pests have attacked the sugar cane industry and cost farmers more than 9 million dollars. Rats and rodents have also attacked sugar cane crops throughout the islands causing between 6 and 10 million dollars in damages annually in the 1990s. In addition, invasive rats and rodents consume approximately 5-10% of the lucrative macadamia nut crop causing "1.8 – 3.6 million dollars of direct agricultural damages" to the industry. Mongooses were introduced to the island in the late 19th century as a way to control rodent populations. Since then, the mongoose has failed to effectively control rat populations while driving native birds and insects to extinction and preying on local poultry. This is an example of the difficulty of combating invasive species as seemingly quick and cost effective solutions have complicated effects on the local ecosystem. Another example was the introduction of the Indian myna, an animal meant to combat the spread of sugar cane eating worms. An unforeseen consequence of this introduction has been the introduction and rapid spread of seeds of an invasive weed, the ''
Lantana camara ''Lantana camara'' (common lantana) is a species of flowering plant within the verbena family ( Verbenaceae), native to the American tropics. It is a very adaptable species, which can inhabit a wide variety of ecosystems; once it has been introdu ...
''. Thus, considering the potential economic harm illustrated in the examples above, the problem of combating invasive species is a "recurring legislative concern." In order to eradicate the threats of current invasive species and to understand the risks of new invasive species, the legislature would need approximately 50 million dollars in funding annually. Currently, funding to battle invasive species is only 10-15% of needed levels with an additional 6% being contributed by federal sources. Considering the elevated costs, particularly in the depressed economy, government should focus on ongoing funding from dedicated sources as well as concentrating on prevention.


The Hawaii Invasive Species Council

In response to the 2002 state legislature reference bureau report, which identified the gaps in invasive species action funding and the risks posed by invasive species, the Hawaii Invasive Species Council (HISC) was formed. Th
HISC
is co-chaired by the Department of Land and Natural Resources and the Department of Agriculture and also includes the membership of the University of Hawaii, the Hawaiian Department of Business and Economic Development and Tourism, the Hawaii Department of Health and the Hawaii Department of Transportation. The HISC is composed of five working groups chaired by member agencies dealing with prevention, established pest management, public awareness, research and technology and natural resources. The HISC provides "policy level direction, coordination and planning among state departments, federal agencies and international and local initiatives for the control and eradication of invasive species." The HISC seeks to "maintain a comprehensive overview of issues and supports state wide invasive species prevention, early detection and control programs" in the effort to provide a testing ground for innovation in methods and capacity to address invasive species which can be adopted permanently by other funded agencies. HISC partners and major funding recipients include the Island Invasive Species Committees (ISCs). These grant-funded Committees leverage HISC funding with Federal, other state, county, and private funding to address priority invasive species that threaten their county (island). The ISCs are partnerships between government agencies (Federal, State, and County), nongovernment agencies, private business, and local landowners. Each committee
KISCOISCMISCMoMISC
an
BIISC
focuses on protecting their island from invasive pests by utilizing prevention, early detection, rapid response, and control methodology supported by a paid staff and field crew. The goal of the ISCs is to protect agriculture, valuable watersheds, human health and quality of life, Hawaiian cultural practices, and Hawaii's unique biodiversity. Currently, funding for the HISC is under 4 million dollars following a 50% state funding reduction due to tightening budget from poor economic conditions. The promised 2 million dollars for the program in the current state budget is also subject to reduction pending budget shortfalls in the state treasury which could further affect the effort to combat invasive species in the state.


See also

* Invasive species in the United States *
Japanese white-eye in Hawaii Along with a number of other organisms, the Japanese white-eye (''Zosterops japonicus'') has become an invasive species in Hawaii. Its native range includes much of East Asia, including Japan, China, Vietnam, Taiwan, and the Philippines. Introdu ...


References


External links


National Invasive Species Information Center
at the USDA National Agricultural Library
Hawaii Invasive Species CouncilHawaii Early Detection NetworkKauai Invasive Species CommitteeOahu Invasive Species CommitteeMaui Invasive Species CommitteeMoloka'i/Maui Invasive Species CommitteeBig Island Invasive Species Committee
{{United States topic, prefix= Invasive species in Invasive 01
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...
Invasive