Ascension

About

Ascension lies south of the equator, in the middle of the Atlantic. It is some 100 km west of the mid-Atlantic Ridge, 1,504 km south-southwest of Liberia (Cape Palmas), and 2,232 km from Brazil (Recife).

Ascension is a geologically young mid-ocean volcanic island with primarily a desertic climate. However, there are also important wetland ecosystems in the coastal waters, the shores and Green Mountain top, which is often in cloud (caused by the moist SE trade winds being forced up by the mountain) and has some characteristics of cloud forest. As a result of its remoteness, it one of the most remarkable island floras and faunas in the world. It is of world significance for its 11 species of breeding seabirds. It has also one of the most important breeding sea turtle populations in the world. There are 6 unique species of land plants, 9 of marine fish and shellfish, and over 20 of land invertebrates.

One of its unique habitats is anchialine pools (i.e. without surface connection with the sea but salt or brackish and influenced by the tide) located at Shelly Beach where two endemic shrimps Typhlaty rogersii and Procaris ascensionis are found. This system is important as a rare example of early colonization and speciation on a remote, young volcanic island.

Until very recently, most seabirds, including the world population of the critically endangered Ascension frigate-bird Fregata aquila, bred only on the outer rocky stack, Boatswainbird Island. Before humans introduced invasive species, Ascension itself had been a hugely important colony providing the only nesting location for seabirds over large tracts of the Atlantic Ocean. Following the successful efforts of conservationists to remove feral cats from the island, in 2014, the first frigatebird chick hatched on the mainland in over a century. Other seabird species also are re-colonising the main island.

Several endemic plants are restricted to Green Mountain, and its slopes; these include the ferns Xiphopteris ascensionense, Marattia purpurascens, Asplenium ascensionis and Pteris adscensionis. In 2009, a once-thought extinct parsley fern Anogramma ascensionis was rediscovered here and efforts are being deployed to ensure its survival. The endangered tiny tussock-grass Sporobolus caespitosus also occurs here as well as in a few places on the northern and eastern slopes of coastal hills. The flowering endemic plant, Ascension spurge Euphorbia origanoides, also occurs here.

Endemic invertebrates include pseudoscorpions: Apocheiridium cavicola, Allowithius ascensionis, Garypus titanius, Neocheiridium sp. and Stenowithius duffeyi and the two endemic shrimps mentioned above.

The beaches are one of the world’s most important breeding grounds for endangered green turtles Chelonia mydas, and their second most important Atlantic nesting area. Critically Endangered hawksbill turtles Eretmochelys imbricate also occur commonly, but nesting has not been demonstrated.

In the marine environment, approximately 70 fish species are found. 11 species are endemic and a further 12 are known only from Ascension and St Helena. In addition to the inshore endemic fish noted, the blackfish Melichthys niger is extraordinarily abundant. Although a widespread tropical species, elsewhere it is not recorded as playing such a dominant role. It is an omnivore, grazing algae off rocks and rapidly cleaning the hulls of anchored boats. The shoreline rock surfaces are dominated by encrusting calcareous algae and sponges.

Offshore around the island, many cetacean species including the porpoise Steno bredanensis, bottlenose dolphins Tursiops truncatus, pan-tropical spotted dolphins Stenella attenuata, humpback whales Megaptera novaeangliae, sperm whales Physeter macrocephalus and Gervais’ beaked whales Mesoplodon europaeus are seen.

Read more about the wildlife, history and cultural heritage of all of the UK Overseas Territories in the 704 page Britain’s Treasure Islands book (CLICK HERE).

Watch 42 ‘mini-documentaries’ that explore the wildlife, cultures and history of all of the UK Overseas Territories (CLICK HERE). 

Map

Video

Ascension Island – wildlife and heritage

 

Ascension Island – natives and aliens

 

Ascension Island – supplying the garrison

 

Read more about the wildlife, history and cultural heritage of all of the UK Overseas Territories in the 704 page Britain’s Treasure Islands book (CLICK HERE).

Watch 42 ‘mini-documentaries’ that explore the wildlife, cultures and history of all of the UK Overseas Territories (CLICK HERE).