Nikumaroro

Category: Marine and Oceanic Biomes.

Geographic Location: Pacific Ocean.

Summary: This small atoll is uninhabited, rich in fauna and flora, and was made famous as being a possible crash site of American aviator Amelia Earhart’s final flight.

Marked by sharp coral, thick tropical foliage, and numerous coconut crabs, Nikumaroro Coral Atoll, formerly known as Gardner Island, is a small coral island, or atoll, located north of Western Samoa and the Tokelau Islands in the central South Pacific Ocean. Part of the Republic of Kiribati and the Phoenix Islands chain, Nikumaroro is a string of eight atolls and two submerged reefs that represents one of the last largely intact coral archipelago ecosystems in the world.

Approximately 4 miles (6 kilometers) long and 1 mile (2 kilometers) wide, Nikumaroro has three major sections: a central lagoon, a surrounding terrestrial rim, and an extensive ocean reef that has a steep drop. Nikumaroro is triangular and elongated in a northwest-southeast orientation.

The terrestrial rim, comprised of beach-rock ridges, rises through more than 16,000 feet (4,877 meters) of water. Nikumaroro forms part of a volcanic chain that includes a large seamount to the north and Carondelet Reef to the south. Other islands in the Phoenix group—including Kanton, McKean, Manra, and Orona—rest on parallel volcanic chains.

A low-lying atoll, Nikamaroro’s highest point is about 20 feet (6 meters) above sea level. The rim forms an elongated barrier that surrounds a narrow and shallow lagoon with coral heads. On the northeastern edge, the rim is continuous. On the southwestern edge, it is broken by two passages: the seminavigable west-facing Tatiman Passage, and the non-navigable south-facing Bauareke Passage, which acts as an overflow channel for the lagoon.

Outside the rim is a reef flat that is 650–820 feet (198–250 meters) wide and descends steeply into the ocean. On the northeast shore is a sandy beach about 65–130 feet (20–40 meters) wide.

Biodiversity

Just south of the Equator and west of the 180th meridian, Nikumaroro has a hot, equatorial climate with temperatures averaging 81 degrees F (27 degrees C) year round. Daily temperatures range from warm to hot, 77–90 degrees F (25–32 degrees C). Rainfall averages 40 inches (102 centimeters) annually. In the extreme north, rainfall totals as much as 120 inches per year (305 centimeters).

The local Kiribati climate is tempered by easterly trade winds, with high humidity during the November-to-April rainy season. The atoll does experience occasional gales and tornadoes. Severe droughts are a periodic condition.

The equatorial climate helps support a variety of wildlife and teeming vegetation, including palm trees, flowering plants, and low-lying brush. The tree flora consists mainly of grand devil’s claws (Pisonia grandis), also known as buka or mapou, and kou (Cordia subcordata), also called kanawa. Much of the kanawa has been cleared for its fine-grained wood, used to make furniture. These indigenous trees have been crowded out by plantations of coconut palm (Cocos nucifera), which have given rise to a population of feral coconuts.

The island’s dense underbrush consists primarily of the fan flower (Scaevola spp.), which has tough interwoven stalks, while the shores feature the low-growing, littoral-zone octopus bush (Tournefortia argentea).

Other recorded plant species include beach mulberry (Morinda citrifolia), a small tree common to volcanic terrain that bears the edible “cheese fruit,” named for its pungent odor; a Pacific hibiscus (Sida fallax) adapted to sandy soil; and purslane (Portulaca sp.), a tropical flowering plant also known as rose moss.

Though there have been reports of feral dogs and cats, the only mammal that assuredly lives on Nikumaroro is the rat. In the 1980s, dogs were systematically eradicated from the island. The other terrestrial vertebrates on the island are sea turtles (Chelonioidea and Dermochelyidae) and several seabirds, including boobies (Sula); gannets (Morus); and the rarest members of the Phaethontidae family, red-tailed tropicbirds (Phaethon rubricauda). Nikumaroro is part of the Phoenix Islands Protected Area and has been designated as an Important Bird Area by the Audubon Society.

Terrestrial invertebrate species are primarily crabs, such as hermit (Coenobitidae spp.) and fiddler (Ocypodidae), as well as a large population of coconut crabs (Birgus latro), the world’s largest terrestrial arthropods. Other invertebrates include insects such as spiders, ants, and bees.

The waters around the atoll support a diverse collection of fish species, including the gray reef shark (Carcharhinus amblyrhynchos), blacktip shark (Carcharhinus limbatus), whitetip reef shark (Triaenodon obesus), grouper (Serranidae), trevally (Carangidae), and barracuda (Sphyraenidae). One marine mammal species that has been reported around the atoll is the bottlenose dolphin (Tursiops).

Climate change is a factor in the future of all living things here. Warming sea temperatures are causing water levels to rise, which threatens the atoll with flooding and habitat disruption. Seawater temperature, too, has proven to be critical to coral species, as warmer waters have been correlated with coral bleaching events. The Kiribati government is looking into ways to protect the coral island and its species.

Human Settlement Efforts

First sighted by Europeans in 1824 and originally named Gardner Island, Nikumaroro has been the site of several colonization attempts, which have failed because it is so difficult to land vessels along its shores, and there is a lack of freshwater.

After the United Kingdom laid claim to the island in 1856, a coconut plantation was established, along with a small settlement of people from Micronesia, but the project was closed within a year.

During World War II, the United States Coast Guard established a long-range navigation (LORAN) station on the island with 25 crewmen. In the mid-1950s, the population reached a high of about 100 people, but drought and lack of freshwater led to the island’s evacuation in 1963. Two years later, the island was uninhabited and remains so.

The name was officially changed to Nikumaroro when the Republic of Kiribati gained independence from the United Kingdom in 1979. The island is perhaps most famous for being the possible crash site of American aviation pioneer Amelia Earhart, who disappeared, along with her navigator Fred Noonan, somewhere in the Pacific on July 2, 1937, en route to Howland Island during her final flight to circumnavigate the globe.

Bibliography

Allen, Gerald and Steven Bailey. “Reef Fishes of the Phoenix Islands, Central Pacific Ocean.” Atoll Research Bulletin 589 (2011).

Bryan, Edwin H., Jr. American Polynesia and the Hawaiian Chain. Honolulu, Hawaii: Tongg Publishing, 1942.

Fox, Michael D., et al. "Increasing Coral Reef Resilience Through Successive Marine Heatwaves. Geophysical Research Letters, vol. 48, no. 17, 2021. DOI: 10.1029/2021GL094128. Accessed 30 Aug. 2022.

Maude, Henry Evans. Of Islands and Men: Studies in Pacific History. Melbourne, Australia: Oxford University Press, 1968.

Stackpole, Edouard A. The Sea-Hunters, The New England Whalemen During Two Centuries: 1635–1835. Philadelphia: Lippincott, 1953.