Niue Island ecosystem
Niue Island, located in the South Pacific Ocean, is a large uplifted coral atoll known for its unique geological and ecological features. The island, often referred to as the Rock of Polynesia, encompasses an area of 77 square miles and is surrounded by steep limestone cliffs, a coastal strip of coral, and numerous caves. The coral reefs surrounding Niue play a vital role in its marine ecosystem, but they face significant threats due to global warming, overfishing, and the impacts of tropical cyclones, which occur approximately every four years.
The island's tropical climate supports a diverse flora, including endemic species such as the screwpine, as well as various orchids and hibiscus. Niue is also home to unique fauna, including several endemic birds and marine species, reflecting its rich biodiversity. In response to environmental challenges, Niue has established conservation efforts, including the creation of marine protected areas to safeguard its ecosystems for future generations.
Despite its low greenhouse gas emissions, Niue remains vulnerable to climate change, which affects its food and freshwater supplies. The local community is actively engaged in sustainable practices, emphasizing the importance of preserving their natural resources while adapting to the changing environment. Overall, Niue Island's coral ecosystem is a critical aspect of its identity, geography, and cultural heritage, warranting continued attention and preservation efforts.
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Subject Terms
Niue Island ecosystem
- Category: Marine and Oceanic Biomes.
- Geographic Location: Pacific Ocean.
- Summary: This large coral atoll and island nation in the South Pacific faces challenges because of global warming.
Niue is a large tropical, uplifted coral atoll in the South Pacific Ocean, located 1,500 miles (2,414 kilometers) northeast of New Zealand in the middle of a triangle formed by the Samoas to the northwest, the Tonga Archipelago to the southwest, and the Cook Islands to the southeast.
Formed out of a volcano and comprised primarily of coral and limestone, the oval-shaped Niue is commonly known as the Rock of Polynesia. It has an area of 77 square miles (199 square kilometers) and a coastline of around 40 miles (64 kilometers). Its lowest point is at sea level, and it rises to a maximum height of about 230 feet (70 meters) above sea level at a point near the village of Mutalau on the northeastern coast.
The terrain of Niue is characterized by a rocky shore, isolated beaches in protected shoreline coves, a series of steep coastal limestone cliffs formed in the Pleistocene epoch, numerous coastal limestone caves, and a central plateau that rises to around 200 feet (61 meters) above sea level. The thin layer of volcanic ash over the exposed coral limestone terraces indicates that volcanic activity uplifted the island.
The island is almost encircled by a coral reef platform with a single substantial breach near the capital, Alofi, along the central western coast. These reef flats feature submerged caves below and rock pools on top. The western coast of Niue is marked by two large bays, Alofi Bay in the center and Avatele Bay in the south, which are separated by a promontory, Halagigie Point. The southwest coast is marked by Blowhole Point, a small peninsula near the village of Avatele. Niue also includes three outlying nonterrestrial coral reefs: Beveridge Reef, 150 miles (241 kilometers) southeast; Antiope Reef, 110 miles (177 kilometers) southeast; and Haran Reef, 182 miles (293 kilometers) southeast.
The Niue Island Coral ecosystem experiences a tropical climate that is affected by southeast trade winds, the South Pacific Convergence Zone, and the tropical cyclone belt. Cyclones hit the island quadrennially. In 2004, Cyclone Heta, the largest recorded tropical cyclone, caused widespread destruction to the island. Rain falls primarily during the wet season, from November or December to April. The average annual precipitation is 82 inches (208 centimeters). The mean temperature is 83 Fahrenheit (28 Celsius).
Vegetation
Niue is designated as part of the Tongan Tropical Moist Forests ecoregion by the World Wildlife Fund, with about one-third of the island covered by tropical forests. The rest of the vegetation is primarily low-lying, saline-resistant plants. The flora of Niue include orchid (Orchidaceae), hibiscus (Malvaceae), frangipani (Plumeria), bougainvillea (Bougainvillea), rhododendron (Rhododendron), poinsettia (Euphorbia pulcherrima), and stands of ancient ebony (Diospyros). The screwpine Pandanus niueensis is endemic to Niue, that is, found nowhere else.
Following Cyclone Heta, the destruction of much of the forest cover led to the growth of a host of opportunistic and invasive heliophilous (sun-loving) plants, such as rattlepod (Crotalaria), white leadtree (Leucaena leucocephala), white shrimp plant (Justicia betonica), bitter vine (Mikania micrantha), blue porter weed (Stachytarpheta cayennensis), light-blue snakeweed (Stachytarpheta jamaicensis), and marigold tree (Tithonia diversifolia), as well as the indigenous morning glory vine (Merremia peltata).
Fauna
Niue supports several endemic birds, including the Polynesian triller (Lalage maculosa whitmeei), Polynesian starling (Aplonis tabuensis brunnescens), and purple-capped fruit-dove (Ptilinopus porphyraceus whitmeei). Two extinct bird species, the Niue night heron (Nycticorax kalavikai) and the Niue rail (Gallirallus huiatua), were also endemic to Niue. The combtooth blenny (Ecsenius niue) is one of Niue’s endemic marine fish.
Other endemic animal species include a land snail (Vatusila niueana); a crab (Orcovita gracilipes); a seed shrimp (Dantya ferox); a sea snail (Tectarius niuensis); and several insects, including a leafhopper (Empoasca clodia), a weevil (Elytrurus niuei), and a scale (Paracoccus niuensis). The Niuean flat-tailed sea snake (Laticauda schistorhyncha) may be endemic.
Conservation and Threats
As a small island nation, Niue’s food supply, freshwater supply, infrastructure, and ecosystem are exceptionally vulnerable to climate change. In 2001, the Niue government established the National Biodiversity Strategy and Action Plan to preserve the island’s unique plant and animal life. It established the Niue Nukutuluea Multiple-Use Marine Park in 2022 to preserve all of Niue's exclusive economic zone, including the Niue Moana Mahu Marine Protected Area and Beveridge Reef Nukutulueatama Special Management Area. The Niue Moana Mahu, or protected area, covers 40 percent of the island’s surrounding waters, where commercial fishing is restricted. Though the country’s greenhouse gas emissions are among the lowest in the world, the effects of climate change, overfishing, and the destruction of coral reefs pose a continuing threat to the island. These concerns escalated in the second decade of the twenty-first century, and the people of Niue began taking steps to preserve their country for future generations. They only take what they need from the ocean to survive, and they have taken steps to limit pollution from runoff.
The beaches of Niue are relatively young and dynamic, eroding and growing in response to specific storm conditions, particularly cyclones. The high level of foraminifera, a protozoan, in its northwestern beaches indicates that coral growth can be reestablished relatively quickly following cyclone devastation, but it also indicates that anthropogenic climate change most likely affects the state of these sites.
Agriculture, and in particular subsistence agriculture, is important to Niue, which has some 80 square miles (207 square kilometers) of land available for agricultural use. Though the majority of Niue’s volcanic-ash-based soil is rich in potassium and phosphorous, some areas lack essential plant nutrients like nitrogen and thus impede the growth of agriculture. Cows were introduced in the 1960s, and goats arrived in the late 1980s. There is a growing concern that the practice of slash-and-burn agriculture is affecting soil fertility. The effects of global warming pose a continuing threat.
Bibliography
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Forbes, D. L. Coastal Geology and Hazards of Niue. Pacific Islands Applied GeoScience Commission (SOPAC), 1996.
Gardner, Rhys Owen. Trees and Shrubs of Niue: An Identification Guide to the Island’s Indigenous and Naturalised Woody Plants. Katsura, 2010.
Hekau, Maihetoe, et al. Niue: A History of the Island. Suva, Fiji: Institute of Pacific Studies and Government of Niue, 1982.
Kreft, C. S. The Climate and Weather of Niue. New Zealand Meteorological Service, 1986.
Nunn, Patrick D. “Myths and the Formation of Niue Island, Central South Pacific.” Journal of Pacific History, vol. 39, no. 1, 2004, pp. 99–108, doi:10.1080/00223340410001684877. Accessed 2 Dec. 2024.
Parks, Clint. "Niue's Fight to Sustain Itself." National Geographic, 9 Oct. 2024, education.nationalgeographic.org/resource/niues-fight-sustain-itself. Accessed 2 Dec. 2024.