Ulenge Island officially, Ulenge Island Marine Reserve (''Kisiwa cha Hifadhi Akiba cha Ulenge'', in

Swahili Swahili may refer to: * Swahili language, a Bantu language official in Kenya, Tanzania and Uganda and widely spoken in the African Great Lakes * Swahili people, an ethnic group in East Africa * Swahili culture Swahili culture is the culture of ...

) is a protected, seasonally habited island in the

Tanga Bay Tanga Bay (''Ghuba la Tanga'', in Swahili) is a bay in Mkinga District of Tanga Region of Tanzania. The bay is home to Tanga Island and is surrounded in the north by Chongoleani ward, west by Mabokweni and Mzizima wards. To the south is Centr ...

of Pemba Channel under the Tanga Marine Reserves (TMRS) with the IUCN category II located within Tanga City Council of Tanga Region in

Tanzania Tanzania (; ), officially the United Republic of Tanzania ( sw, Jamhuri ya Muungano wa Tanzania), is a country in East Africa within the African Great Lakes region. It borders Uganda to the north; Kenya to the northeast; Comoro Islands and ...

Kwale Island Kwale is a small town in and the capital of Kwale County, Kenya. It is located at around ; 30 km southwest of Mombasa and 15 km inland. The town has an urban population of 10,063 (2019 census). It is next to the Shimba Hills National ...

and Ulenge Island are the only islands in the marine reserve that are seasonally inhabited. Of Tanga's whole marine reserves system, Ulenge Island is the most degraded. Ulenge's

reef A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock out ...

s had the lowest fish numbers and the lowest

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...

cover and species diversity (5-7%, 16 coral genera). This is mostly because

and Tanga City Council are nearby, which has a greater negative human impact. Ulenge Island is nicknamed by English speakers as ''Bird Island'' due to its importance as a seabird sanctuary.

History

The

people from the north, led by Chief Mwinyi Ulenge, are said to have been the initial inhabitants of Ulenge Island. They were compelled to travel to the mainland due to a water deficit on the island. The majority of them relocated to

Chongoleani Chongoleani(''Kata ya Chongoleani '', in Swahili) is an administrative ward in Tanga City Council of Tanga Region in Tanzania. The Mtimbwani and Kwale wards of Mkinga border the ward to the north. Tanga Bay of Pemba Channel is to the east. T ...

ward of Tanga city. The island is also the location of two of Tanga's most famous lighthouses; the Ulenge Island Front Range Lighthouse and the Ulenge Island Rear Range Lighthouse.

Geography and ecology

The primary

biotope A biotope is an area of uniform environmental conditions providing a living place for a specific assemblage of plants and animals. ''Biotope'' is almost synonymous with the term "habitat", which is more commonly used in English-speaking countrie ...

at Ulenge Island Marine Reserve is mangrove vegetation. Despite the presence of all mangrove species, species with robust root systems, such as

Rhizophora mucronata ''Rhizophora mucronata'' (loop-root mangrove, red mangrove or Asiatic mangrove) is a species of mangrove found on coasts and river banks in East Africa and the Indo-Pacific region. Description ''Rhizophora mucronata'' is a small to medium si ...

and

Sonneratia alba ''Sonneratia alba'' is a mangrove tree in the family Lythraceae. The specific epithet ' is from the Latin meaning "white", referring to the flowers. Description ''S. alba'' grows up to tall with a trunk diameter up to . The cracked to fissured ...

, predominate. Numerous plant (trees and grass) and animal (unstudied) populations can be found on Ulenge Island. Daily tidal wash through in the mangrove ecosystem on Ulenge results in a relatively thin layer of silt buildup. According to

Birdlife International BirdLife International is a global partnership of non-governmental organizations that strives to conserve birds and their habitats. BirdLife International's priorities include preventing extinction of bird species, identifying and safeguarding ...

, the Ulenge and Kwale Island Marine Reserves are located in IBM 35, an important bird region. This bird area contains a diverse range of bird species, including Greater Sand Plover, Curlew Sandpiper, Crab Plover, migrating waders, and many more. Despite being threatened by human activity and climate change-related reasons, mangroves and coral reefs are not actually in danger. On the west and south of Ulenge Island, the intertidal zone is longer (up to 800 m), while it is shorter (50–350 m) on the seaward side. North of Ulenge Island, the intertidal is rock, with large algae mats in the lower intertidal zones. On the lower intertidal zone on the seaward side, algae mats were also discovered. Along the Ulenge-Kwale channel, beyond the algal mats, to the south and south-west of Ulenge (in Tanga Bay), and in the lower intertidal zones of Kwale Bay, one can see

seagrass Seagrasses are the only flowering plants which grow in marine environments. There are about 60 species of fully marine seagrasses which belong to four families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and Cymodoceaceae), all in the orde ...

beds. Turbidity and bottom sediment type, which are regulated by rainfall/river discharge patterns and oceanic conditions, determine the amount and distribution of seagrass. On the seaward side,

coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. Co ...

s are few. The results of the manta tow and swimming

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

cover surveys showed a relatively small area of patchy coral reefs that were stressed by sediments from Tanga Bay and nearby

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

s. In most of the Ulenge Island waters, there was less than 10% coral cover.Muhando, C. A. "Biophysical Features in the Northern Tanga Marine Reserves, Tanzania." Marine Parks and Reserves Unit, Dar es Salaam, Tanzania. vi (2011).

References

{{Authority control Tanga District Islands of Tanzania Coastal islands of Tanzania Uninhabited islands of Tanzania Islands of Tanga Region