Ministerial Conference on
Environment and Development
in Asia and the Pacific 2000
Kitakyushu, Japan 31 August - 5 September 2000
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Biological disasters in the Pacific IslandsImported plants and animals - often associated with agriculture - cause far greater long-term environmental damage than a physical disaster. Cyclones can last for days, droughts for months, but biological disasters are open-ended, causing irreversible changes to ecosystems. Most introductions of exotic organisms into the Pacific were deliberate, although associated diseases and pests were unexpectedly imported with desired species. New Zealand immigrants arrived from England with more than 1,305 species of animals. In Australia, imported animals now make up more than 10% of the population of land mammals. Imported cattle, possums, rabbits, goats, pigs, deer, horses, donkeys, and sheep graze on native plants, prevent other animals from using waterholes, compete with native fauna for shelter, and carry diseases that harm wildlife and other domestic stock. Cats, dogs, fox, rats, stoat, and other carnivores, prey on a wide range of native species. Widespread use of poisons to try and control some of the introduced species (such as rabbits in Australia and possums in New Zealand) has killed native wildlife as well. Other animals, including a wide variety of rats, snakes, snails, and insects were accidental introductions. Rats accompanied the first humans into the islands and had a devastating impact on smaller species of birds. The most dramatic recent biological disaster was the accidental introduction of the brown snake into Guam following World War II. The brown snake feeds on birds. Guam birds had no experience with snakes and today biologists are struggling to restore native bird populations on Guam. The massive decline of Guam's bird populations has had a series of impacts, including a massive infestation of spiders and other insects in bush areas of Guam.
Coastal marine areas have also had a series of accidental introductions. For example, the introduction of Japanese starfish, a predator on oysters, into the coastal areas of Tasmania, resulted in major problems for a valuable the shellfish industry. Red tides in New Zealand may have been stimulated by the introduction of toxic dinoflagellates from Japan, carried in the ballast water of ore carrier ships. Epics of red tides killed a multitude of inshore marine life and contaminated shellfish. Health dangers resulted in closure of many of New Zealand’s oyster farms.
Undesirable plants and plant diseases were often imported along with the desirable plants. Some of these diseases and pests were highly dangerous and have infected wildlife areas, displacing or killing native species. For example, the Merremia vine was introduced to Vanuatu from the United States during World War II (possibly to camouflage military installations). Today, the vine smothers whole forests when logging opens clearings in the rainforest canopy. Biological disasters are often linked to physical disasters and to pollution. Cyclones, droughts or pollution can destabilise delicate ecological balances leading to a rapid proliferation of a pest or disease. Agricultural experts believe disruption of the environment by severe cyclones in 1992 and 1993 facilitated the pervasive taro leaf blight in Samoa in 1995. Pollution from fertilisers and sewage is thought to provide nutrients fuelling red tides and die-backs of sea grass beds and kelp in Australia and New Zealand.
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Imported
plants, especially agricultural grasses for grazing, displace native habitats
through human cultivation and by subsequent seed dispersion. Some species
aggressively invade wildlife areas, killing native plants and thus destroying
important ecological links between indigenous animals and associated plants. New
Zealanders, during their acclimatisation programme, imported more than 1,893
species of plants (New Zealand UNCED report 1992) while Australia imported about
2000 species of plants (Year Book Australia 1994).