The Hawaiian Islands are made up of a chain of ancient volcanic islands that have formed at irregular intervals over the last ten million years. There are over 100 islands in the chain, eight of which are considered major. Of the eight major islands, Kauai is the oldest, and the island of Hawaii is the youngest, having formed within the past million years. This vast discrepancy in age has contributed to the tremendous biodiversity that has evolved there. The other factor responsible for Hawaii's great species diversity is the island chain's remoteness. The nearest continent is 2,400 mi (3,862 km) away, thus limiting the total colonization that could, or has, taken place. The niches available to these colonizing species are very diverse due to geophysical events. For example, on the island of Kauai, the average annual rainfall on the windward side of Mount Waialeale is 460 in (1,169 cm), whereas on its leeward side, it is only 19 in (48 cm). The temperature on the islands ranges from 75–90°F (24–32°C) for 300 days each year. The lowest temperature ever recorded in Hawaii was 54°F (12°C). Thus with its tropical climate and unique biotic communities, it is easy to understand why Hawaii has been considered a paradise. But now this paradise is threatened by serious environmental problems caused by humans.
The impact of humans has been felt in the Hawaiian Islands since their first arrival, but perhaps never more so than today. In the last quarter century tourism has replaced sugar cane and pineapple as the islands' main revenue source. Over six million tourists visit Hawaii each year spend $11 million a day. With tourism comes development that often destroys natural habitats and strains existing natural resources . Hawaii has more than 60 golf courses , with plans to develop at least 100 more. This would destroy thousands of acres of natural vegetation, require the use of millions of gallons of freshwater for irrigation , and necessitate the use of tons of chemical fertilizers and pesticides in their maintenance. The increased number of tourists, many of whom visit the islands to enjoy its natural beauty, are often destroying the very thing they are there to see. Along the shore of Hanauma Bay, just south of Honolulu, over 90% of the coral reef is dead, primarily because people have trampled it in their desire to see and experience this unique piece of nature .
Much of Hawaii's fauna and flora are unique. Over 10,000 species are native to the Hawaiian Islands, having evolved and filled specialized niches there through the process of adaptive radiation from the relatively few original colonizing species. Examples are found in virtually every group of plants and animals in Hawaii. The avian adaptive radiation in the Hawaiian Islands surpasses even the best-known example, Darwin's finches of the Galapagos Islands. From as few as 15 colonizing species evolved 90 native species of birds in the Hawaiian archipelago. Included in this number are the Hawaiian honeycreepers of the family Drepanididae. This endemic family of birds arose from a single ancestral species, which gave rise to 23 species, including 24 subspecies, of honeycreepers spread throughout the main islands. Niche availability and reproductive isolation contributed greatly to the spectacular diversity of forms that evolved. These birds developed adaptations such as finch-like bills for crushing seeds, parrot-like bills for foraging on larvae in wood, long decurved bills for taking nectar and insects from specialized flowers, and small forcep-like bills for capturing insects.
Introductions of vast numbers of alien species is taking its toll on native Hawaiian species, a process that began when the first humans settled the islands over 1,500 years ago. Many native species of birds had experienced drastic population declines by the time Europeans first encountered the islands over 200 years ago. Since then at least 23 species of Hawaii's native birdlife have become extinct, and currently over 30 additional avian species are threatened with extinction . Through the process of primary ecological succession , one new species became established in the Hawaiian Islands every 70,000 years. Introductions of alien species are taking place a million times faster, and are thus eliminating native species at an unprecedented rate. Recent estimates indicate that there are over 8,000 introduced species of plants and animals throughout the Hawaiian Island chain. The original Polynesian settlers brought with them pigs, dogs, chickens, and rats, along with a variety of plants they had cultivated for fiber, food, and medicine. With the Europeans came cattle, horses, sheep, cats, and additional rodents. The mongoose was introduced purposefully to control the rat populations; however, they presented more of a threat to ground-nesting birds. The introduction of rabbits caused the loss of vast quantities of vegetation and ultimately the extinction of three bird species on Laysan Island. Over 150 species of birds, including escaped cage birds, have been introduced to the islands. However, most of these have not established breeding populations.
Although Hawaii represents only 0.2% of the United States's land base, almost 75% of the total extinctions of birds and plants of the nation have occurred in this state. Hawaii's endemic flora are disappearing rapidly. Introduced mammalian browsers are decimating the native plantlife, which never needed to evolve defense mechanisms against such predators, and other introduced animals are destroying populations of native pollinators. Habitat destruction and opportunistic non-native vegetation are also working against the endemic Hawaiian plant species. Organizations such as the Hawaii Plant Conservation Center are working to preserve the state's floral diversity by collecting and propagating as many of the rare and endangered species as possible. Their greenhouses now contain over 2,000 plants representing almost two thirds of Hawaii's native species, and their goal is to propagate 400 of the state's most endangered plants.
Introduced plant and animal species and their assault on native species are by no means the only environmental problems facing the Hawaiian Islands. Because Hawaii's population is growing at a higher rate than the national average, and in part due to its isolation, it is facing many environmental problems on a grander scale and at a more rapid rate than its sister states on the mainland. Energy is one of the primary problems. Much of Hawaii's electricity is produced by burning imported oil, which is extremely expensive. Because of limited reserve capabilities with regard to electrical generation, Hawaii faces the potential for blackouts.
Planners have been, over the past several decades, looking at the feasibility of tapping into Hawaii's seemingly vast geothermal energy resources. Hawaii has the most active volcano in the world, Kilauea, whose underground network of geothermal reserves is the largest in the state. The proposed Hawaii Geothermal Deep Water Cable project would supply the energy for a 500-megawatt power plant, the electrical power of which would be transmitted from the island of Hawaii to Oahu by three undersea cables. This would, of, course, be of economic and environmental benefit by reducing dependence on oil reserves. Opponents of this geothermal power plant point to several problems. They are concerned with the potential for the release of toxic substances, such as hydrogen sulfide, lead , mercury , and chromium, into the environment from well-heads. They also have voiced negative opinions concerning construction of a geothermal plant so near the lava flows and fissures of Hawaii's two active volcanoes. An alternately proposed site would have the facility located in Hawaii's last major inholding of lowland tropical rain forest . To avoid economic disaster from escalating prices for imported oil and the problem of frequent blackouts, Hawaii must reach some compromise on geothermal energy and/or research the potential for getting its electricity from one or more of wind, wave, or solar energy .
Hawaii is also faced with environmental problems of another sort–natural disasters. Volcanoes not only provide the potential for geothermal energy, they also have the potential for massive destruction. Over the past 200 years, Hawaii's two active volcanoes, Kilauea and Mauna Loa, have covered nearly 200,000 acres (81,000 ha) of land with lava, and geologists expect them to remain active for centuries to come. Severe hurricanes and tidal waves also hold the potential for vast destruction, not only of human property and lives, but of natural areas and the wildlife it holds. Many of the endemic species of Hawaii are threatened or endangered, and their populations are often so low that a single storm could wipe out most or all of its numbers.
There are efforts to reverse the environmental destruction in the Hawaiian Islands. Several organizations comprised of native Hawaiians are working to stem the destruction and loss of the wilderness paradise discovered by their ancestors.
[Eugene C. Beckham ]
Pratt, D., P. Brunner, and D. Berret. The Birds of Hawaii and the Tropical Pacific. Princeton, NJ: Princeton University Press, 1987.
Shallenberger, R., ed. Hawaii's Birds. 3rd ed. Honolulu: Hawaii Audubon Society, 1981.
Stewart, F., ed. A World Between Waves: Writings on Hawaii's Rich Natural History. Washington, DC: Island Press, 1992.
White, D. "Plants in a Precarious State." National Wildlife 31 (May 1993): 30–35.