Corals of the Cape Verde Islands
Sources:
- Wells, Susan M. (Ed.), (1964), Coral Reefs Of The World, Vol. 1: Atlantic And Eastern Pacific. United Nations Environmental Program (UNEP). IUCN Cambridge, U.K. Pp.369-371
- Fofbet, J. (1964), Campagne De La Calypso Aux Iles Du Cap Verd (1959), Rebult Scientific, Camp, Calypso Pp. 631-41.(Page 4 & 5) Introduction
- Photographs of Favia fragum, Nudibranch, and Porites astreoides - courtesy of Dr. Peter Wirtz, Centro De CiÍncias BiolÛgicas (CCBG), Universidade Da Madeira
- NMITA - Neogene Marine Biota of Tropical America
General Description:
No true reefs exist along the West African coast or in the archipelagos of the Gulf of Guinea and Cape Verde but there are a number of sites with rich coral communities. These generally form in very shallow, protected coves, the number and size of colonies decreasing abruptly outside such areas. In open waters, hermatypic species are limited to depths of less than 20 m although there are some exceptions in the archipelagos.
Studies on West African corals include those of Thiel (1928, 1940 and 1941) and Chevalier (1966 a, b and 1970) which are based exclusively on museum material. Other papers include Koch (1886), Gravier (1910), Gardiner (1939), Buchanan (1954), Monod (1954), Allan and Wells (1962) and Forest (1959 and 1964). Laborel (1974) provides an overview and synthesis of these works and discusses the results of field visits to Senegal, the Cape Verde Islands, Sierra Leone, Cape Palmas on the western coast of the Ivory Coast, Accra and Cape Three Points on Ghana, West Cameroon, Gabon and the islands of Principe and Annobon.
A description of the coastal and marine environments of West Africa as given in UNDIESA/UNEP (1984) and Laborel (1974) briefly summarizes the hydrology of the region. High precipitation and numerous rivers result in large masses of warm (above 24 degrees C) and low salinity (less than 35ppt) water, known as Guinean waters, circulating in the Gulf of Guinea. These are invariable shallow and rest on colder water, their extent varying greatly throughout the year.
Favia fragum |
They are permanent off the Grain Coast (Sierra Leone and Liberia) and in the Bight of Biafra (Nigeria, Cameroon and Gabon). They are found seasonally from Mauritania to Angola, where they may be replaced by older and more saline waters from other currents or upwellings, and they are also seasonal around the islands of the Gulf of Guinea and the Cape Verde Archipelago. A list of West African corals and a detailed analysis of the oculinid corals of the region are given in Laborel (1974).
Tubastrea coral polyps |
Two oculind corals, Schizoculina africana and S. fissipara, are endemic to the region and are adapted to Guinean waters and very low salinities. They are absent outside these waters, for example at Annobon or the eastern Cape Verde Islands. Colonial shallow water dendrophyllids are among the most abundant corals in West Africa, covering vertical rocky surfaces with brilliantly coloured populations. Their taxonomy is still confused and it not clear how many species are restricted to the area. The genus Astrangia is well represented. Millepora and hermatypic corals are found mainly around the islands where some of them are endemic, and the more tolerant
species also occur in low salinity mainland littoral waters. Madracis pharensis seems to be abundant everywhere in the tropical and subtropical Atlantic and other species of this genus are found in the two archipelagos. The taxonomy of Siderastrea still needs clarification. S. Sidera, a form similar to S. Stellato, and S. Radians are found in the islands of the Gulf of Guinea; the latter is also found along the mainland and is the only species of the genus found the Cape Verde Islands.
Porites astreoides
|
There are three species of Porites: P. Astreoides, P. Porites and P. Bernardi. P. Bernardi is endemic to West Africa and is found from Liberia to Gabon and in the islands of the Gulf of Guinea, but is absent from Sierra Leone and the islands of Cape Verde. The two other species are found in the Cape Verde Islands. Two faviid populations have been found, one in the Cape Verde Islands and one on the coast of Gabon and in the islands of the Gulf of Guinea. No Diploria species appear to be extant on the West Coast; subfossil specimens have been reported from the Cape Verde Islands, but these records are considered dubious (Laborel in litt., 1985). Montastrea cavernosa is found only in the islands of the Gulf of Guinea and Acropora is absent from the region.
The following areas have a noticeable amount of reef construction:
Cape Verde Islands: The coral fauna, of one hydrocoral and five hermatypic species, consists of little or unmodified West Indian forms including one Guinean species (Schizoculina africana) and two species (P. Porites and Favia fragum) which are found neither in the Gulf of Guinea nor in Brazil. P. Porities is abundant in tide pools but rare in open waters, and F. Fraguant is common in shallow waters throughout the islands. P. Astreoides is very abundant, mainly in sheltered areas. At Bahia das Gatas (north coast of Sao Vicente Island) - Bahia de Sal-Rei (Boa Vista) and Pedra Lume (Sal) slabs of living Siderastre radans up to 10 m wide and small pinnacles of Millepora are present. Branching forms of Madracis are found in deep waters.
Selected Links
www.umassd.edu/specialprograms/caboverde/corals.html
compiled by raymond almeida, richard leary
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