Number: 462
Mnemonic: Florida

• IDENTIFICATION
• LEGAL CLUSTERS
• GEOGRAPHIC CLUSTERS
• TRADE CLUSTERS
• ENVIRONMENT CLUSTERS
• OTHER FACTORS

I. Identification

1. The Issue

2. Description

The cost to taxpayers of introduced species in Florida was estimated in a 1993 report of the Congressional Office of Technology Assesment, to range from hundreds of millions through billions of dollars over the past few decades. These estimates do not include effects on native ecosystems, such as extinction of native species that are of no immediate economic concern.
The best documentation related to this subject relates to costs to agriculture. About a fourth of this country's gross national product is lost each year to foreign plant pests and the costs of controlling them. In the case of cotton. The total accumulated cost of the boll weevil, originally from Mexico, in the 1890's now exceeds 50 billion dollars.
The costs of introduced pathogens and parasites to human health and the health of economically important species have never been comprehensively estimated, but must be enormous. A recent example is the tiger mosquito , now commonplace in Florida, introduced to the U.S. from Japan in the mid-1980's and now spreading in many regions, breeding largely in water that collects in disgarded tires. The species attacks more hosts than any other mosquito in the world, including many mammals, birds and reptiles. It can thus carry disease organisms from one species to another, including into humans.
Costs to natural systems, although not easily translated into dollars, are staggering. Perhaps the greatest impacts are caused by plant species that come to dominate entire ecosystems. The Melaleuca plant, which is increasing its range in south Florida by some 35 acres each day, replaces cypress and other native plants and provides poorer habitat for numerous animals. In many regions and near the everglades, it forms vast, dense monocultures where no other plant can grow.
Introduced species can drastically affect specific plants or animals even when the invaders do not modify the entire ecosystem; for example, feeding upon a native species to the point of its extinction. The semaphore cactus, found until recently in the lower Florida Keys, is such a victim. The South American cactus moth most likely arrived in Florida through the transport in cut flowers. The moth reached the Florida Keys by 1990, and soon eliminated most of the semaphore cactus in the region. Any that remain today must be protected by cages. Meanwhile the moth has adapted to eat other plants in the Keys, and has continued to grow in number.

1. The first is its geographic insularity. The Florida penninsula is a "habitat island" bounded on three sides by water, and on the fourth side by forest.
2. Second, in Florida land cover is dominated by human-produce d habitats, such as agriculture and residential tracts. Heavy agriculture and residential use is often unfavorable to native plant and animal species, but seems to be suitable for a variety of non-indigenous species.
   
3. Third, Florida has large tropical or subtropical areas, particularly, in the southern part of the state, and the abscence of freezing temperatures allows many species to survive. It is no accident that the northern limits of the ranges of many of Florida's introduced species are precisely where overnight freezes occur. Moreover, the climate of the state has encouraged the introduction and dissemination of an immense number of non-native species that are sold as ornamental plants or pets. The accidental escape of the exotic ornamentals such as the banana poka (pictured below) the Brazilian pepper, or of pets like bulbuls(related to finches), and tropical fish would be innocuous in most regions of the U.S., because of the local climate. In Florida, these animals have thrived and spread, suffocating local species.
4. The fourth distinguishing feature of Florida, is that it is a hub for transportation and popular destinations for tourists. Most visitors from Latin America enter through Miami, and many planes and ships from other regions land there as well. Fully 85 percent of all plant shipments into the U.S. pass through Miami; in 1990 the total was estimated at 333 million plants.(Dahlsten, 1989)
   
5. Finally, Florida is a center for the trade in exotic pets. Many U.S. pet store chains have their headquarters in Florida, and rely on the international traffic to supply them with newer and more exotic pets all the time. Many people do not have any idea how to keep these animals, and even tually end up releasing them into the Florida habitat. This is common with tropical fish and birds such as the African grey parrot, common to pet stores, who destroys palm trees, and consumes the food supply of native birds. Popular tropical fish such as the Zebra Danio and other tetras thrive in Florida marsh waters that are extremely similar in temperature and food supply to their native homes in the Caribbean. Exotic reptiles released into the wild, quickly find thier way to water sources, and compete for the food supply of Floridian species such as the Alligator snapping turtle In fact, one of the most common turtle species today in the Everglades, the Red eared slider was originally imported from Europe and sold as a durable pet.

Obviously the likelihood of inadvertant introduction of alien species is enormous.
[The banana poka or Passifloraceae is a light-loving vine, which smothers the forest canopy, cutting off light to native plants on the forest floor].(photo taken from University of Hawaii Botany Department)

the U.S. Fish and Wildlife Service is ordered to restrict the entry of fish or wildlife that threaten humans, agriculture, horticulture, forestry, or wildlife. At present, however, the Service views very few species as posing such threats, and in any event, a certain number of prohibited species are smuggled in. The Animal and Plant Health Inspection Service of the U.S. Department of Agriculture prohibits the introduction of several other species that may carry disease that affect poultry and livestock, and the U.S. Public Health Service prohibits importation of species that may threaten human health.
The Non-Indigenous Aquatic Nuisance Prevention and Control Act of 1990 authorizes the regulation of introductions of aquatic nuisance species such as the zebra mussel The act has not been well implemented. Neither has the Federal Noxious Weed Act of 1974, which has been slow to exercise the authority of the act. Such documented problems such as the Brazilian Pepper, which suffocates fish and other aquatic animals by its quick root growth, is not yet banned.

The troubles with introduced species do not always originate at the international borders of Florida: major problems often ensue when a species from a state in which it is native, moves to another in which it is not naturally found. The Florida Wildlife Service has no authority to regulate interstate transport, beyond the laws that ban entry of specific species.
very Generally, federal and most state agencies have adopted a policy of assuming that a species will pose no problems unless proven otherwise and, therefore, have not demanded that individuals wishing to import a plant or animal species demonstrate that its introduction will prove innocuous. This was the case with the Spade Toad: a colorful toad from South America, marketed as a pet. As the toad matures, it grows to the size of a football or larger, and is often disgarded by pet owners. The adult spade toad digs several large burrows, much like gophers, and has become a nuisance to yard owners. Worse, many agencies actively promote the import and spread of new species for political reasons, without any serious consideration of their potential consequences. The Florida state Wildlife Commission has funded extensive programs to implement new game species with little consideration of the damage they might inflict. In general, interstate movement of species, including fish and game animal s, is viewed with even less concern than importation from outside the country. By accident or design, funding for the enforcement of the meager regulations that now govern the movement of exotics is woefully inadequate.

It is far more difficult to deal with introduced species once they are established than it is to keep them out. Yet current state and federal laws are only invoked after a species is already in the U.S.. A recent paper by a team of biologists from the University of Washington proposes far more stringent regulations on what importation should be allowed, pointing to a policy of "guilty until proven innocent" rather than assuming that a species will be harmless.(McKnight, 1993) They further recommend that interstate transport should be more carefully regulated. Whether any of these laws or recommend ations become a reality requires a public will to do so.

Eradicating Them Trying to eradicate every single individual of a harmful introduced species in Florida is a seductive but controversial goal. A failed attempt may prove very costly, both in terms of money, and what it could do to non-target species.
For example, the attempt to eradicate the introduced fire ant from Florida proved disastrous. In 1957 Congress authorized $2.4 million for the project, which included the use of a poison called heptachlor. The poison killed significant numbers of wildlife and cattle, and the residue could be found in the systems of many non-target organisms, especially birds. The poison had very little effect on fire ants , in fact, their range expanded dramatically during the campaign. It is estimated that today, a total eradication of the ants would cost well over $200 million for Florida alone.
Eradication campaigns in Florida against the Asian citrus blackfly was an attempt to control a species in a limited area. The insect found in Key West, was sprayed with an oil-based mixture, at a cost of over $200,000. The species simply migrated up the Florida Keys to attack other areas. Thegiant African snail was a serious agricultural pest that was eradicated in Florida, but at the cost of extinguishing many native snail species and 1 million dollars.
Controlling Them
If eradication is impossible, the population of an introduced species can of ten be controlled in order to contain the level of economic and /or ecological damage. This is known as "nuisance control".
Pesticides
Chemicals, both insecticides and herbicides, are widely used for this purpose, although they must be carefully chosen. Some of the newer pesticides have far fewer side effects. Glyphosate-based pesticides have been used with some success to control plants such as the malaleuca and brazillian pepper in south Florida. The major drawbacks are their higher cost, the necessity of repeated application, and the fact that they affect other plants than just the species for which they are intended.

Insecticides are now available that, when used properly, pose no hazards to human health. One potential problem with both herbicides and insecticides lies in the ability of targeted species to develop resistance against them.

Mechanical methods
Introduced pests can often be controlled with machinery. The common Water hyacinth(pictured in the background of this page), introduced from South America to Florida at the end of the 19th Century, spread to cover more than 120,000 acres of public waters by 1960, smothering beds of submersed native vegitation and producing other detrimental effects . Coverage today is maintained at around 3,000 acres by a combination of mechanical harvesting and herbicide. Another form of maintenance regarding foreign plants, is simply the use of "hand power" to remove them. "Brazilian pepper hunts', are common conservation tasks in Florida, also known as"bush-bashes."
Biological Control
Perhaps the major method that Florida has used to maintain acceptable levels of introduced pest species is biological control, in which a natural enemy, particularly from the intruder's native region is introduced to keep the pest under control. Roughly one in five of all recent biological control projects have led to significant control of the target pest. Still the method has its dangers. An imported predator, herbivore or parasite could attack a non-target species and several instances are known in which biological control agents caused major damage. The mosquito fish used to control mosquito populations, has hybridized with native species and threatened their genetic integrity. Further, an introduced biological control cannot simply be recalled if it is found to have an unintended impact as one can simply stop using a pesticide.

Concluding Thoughts