Invasive Species: Understanding the Impacts and Sources of Harmful Alien Species in Hawaii, Study notes of Biology

Download Invasive Species: Understanding the Impacts and Sources of Harmful Alien Species in Hawaii and more Study notes Biology in PDF only on Docsity! Invasive Species Background Information Purpose The purpose of this activity is to introduce students to typical causes and impacts of invasive species, as well as sources of information on these species and appropriate remedial actions as it relates to Hawaii. Background Information What is an "invasive species?" — A species in an ecosystem is considered to be invasive when it is not native (alien) to the ecosystem and causes economic and/or environmental harm, or poses a threat to human health. All types of living organisms (plants, animals, bacteria, etc.) can be invasive. How do invasive species invade in the first place? — Human activities are the most common means through which alien species are introduced into ecosystems. Even when these species survive, they are not considered invasive unless they cause the type of harm described above. But if an ecosystem does not contain species that are able to control the population of an introduced species, the alien species may become invasive as it reproduces and disperses. Some alien species have been deliberately introduced through expanded global trade, harvesting exotic marine species for the aquarium industry, and use of non-native species in agriculture and pest control. Kudzu was originally imported from the Orient as an ornamental plant and was widely used for erosion control. But in the absence of natural controls, the alien plant became invasive as it spread and overgrew native plants. The Gypsy moth was imported in the late 1860's from France in an attempt to establish a silk industry in Massachusetts. The moths escaped and are now a major threat to U.S. forests. Other introductions are accidental. Fruit smugglers have inadvertently caused many outbreaks of the Mediterranean Fruit Fly (medfly), one of the world's most destructive fruit pests. Medfly larvae are able to develop and feed on fruits of many economically important trees and vegetables, including citrus, peach, pear, and apple. Larvae feed on the fruit pulp and eventually reduce the entire fruit to a juicy inedible mess. The zebra mussel is a well-known example of an invasive species introduced in the ballast water of ocean-going ships. Infestations of these mussels can clog water treatment and intake systems, interfering with many industrial activities, docks and boat engines. Wooden shipping containers may contain insects and plant diseases and were probably responsible for introduction of the wood-boring Asian Long-horned Beetle into the United States. Larvae of these beetles bore large tunnels that disrupt the flow of water and food materials within the tree. Eventually the tree literally falls apart and dies. There is a similar variety of pathways through which invasive species are spread from the site at which they are introduced. Natural pathways include water, wind, and other species. Wind is particularly significant in dispersing many plant Docsity.com diseases. Biological pathways are called vectors. For example, birds that eat the fruit of alien plants may carry the seeds over long distances before expelling the seeds in their feces. Similarly, cattle are vectors that disperse Tropical Soda Apple seeds. The weed spreads rapidly when cattle are sold from an infested region and transported to uninfested areas. Human beings may be vectors as well. Female Gypsy moths, for example, lay their egg masses on cars, recreational vehicles, and other surfaces. If humans carry an egg mass into an uninfested area, a new infestation is started. Since the moths cannot fly, human activity can greatly increase the rate at which the moths disperse. In fact, it is estimated that the Gypsy moth invades an additional 15,600 square miles each year (three times the area of Connecticut). Boats and boat trailers have played a large part in the rapid spread of Giant Salvina, a water fern from southeastern Brazil that crowds out native water plants, depletes dissolved oxygen in the water, interferes with migrating birds, and clogs water intakes of irrigation system and electrical generators. So, some new species come to visit; what's the big deal? — Invasive species can damage native species, change the native community structure, and can create serious economic problems. Invasive species threaten nearly half of the species currently protected under the Endangered Species Act. A single outbreak of medfly may cost millions of dollars to eradicate. Approximately 50,000 exotic species already are known to exist in the U.S., and this number is increasing. The costs of environmental damage, economic losses, and control measures for invasive species average $138 billion per year, more than all other natural disasters combined. What can be done about invasive species? — Prevention, early detection and eradication are key strategies for dealing with invasive species. If there had been a response when the Gypsy moth escape was first reported, the moth might never have become established. Port inspectors from the U.S. Department of Agriculture and Department of the Interior are responsible for detecting illegal importations of fruit, vegetables, animal products, fish and wildlife. Public education is also a vital part of prevention, and there are a variety of things that individuals can do to prevent inadvertent introductions. Homeowners can avoid purchasing invasive landscaping plants, and can replace invasive garden plants with non-invasive alternatives. Aquarium keepers can avoid introducing exotic fish and other aquatic species into local water bodies. Owners of exotic pets should remember that these pets may become invasive if they escape or are released. Boaters should clean boat and trailers thoroughly before transporting them to a different body of water. Hikers should clean their boots to get rid of weed seeds and pathogens which may have become attached. The National Centers for Coastal Ocean Science of the National Ocean Service is developing a pilot early warning system that is intended to provide a way to detect aquatic invasive species before they become well-established. This project is initially focused on Hawaii's marine and estuarine coastal areas. An Docsity.com