May 10, 2013, 12:18 PM
Hello and a warm welcome to yet another edition of the environment, your weekly column that brings issues of environment to limelight.
In our edition today, we bring you a national report on biodiversity; habitat and water quality prepared and presented by Madam Anna Mbenga-Cham, Principal Fisheries officer at the Ministry of Fisheries during a sub regional forum on the protection of the Canary Current Large Marine Ecosystem: a challenge of a large marine ecosystem held in The Gambia recently.
According to her report, The Gambia is located between 13oN and 14oW latitude on the west coast of Africa with a length of 480km, 51km wide at its widest westerly end facing the Atlantic Ocean, 80 km long coastline and a continental shelf area of about 4000Km and a total land area of about 11,000 Km² with about one fifth of the surface area occupied by the River Gambia.
The river runs almost 1600 km from the Futa Djallon highlands in the Republic of Guinea to the Atlantic Ocean dividing the country into the North and South bank and the country is bordered on three sides by the Republic of Senegal and on the west by the Atlantic Ocean.
The country’s climate is Sudano-Sahelian characterized by a long dry season from November to May and a short rainy season from June to October, with a total population of 1,360,681 and a growth rate of 2.7% (2003 census); the country is located in the highly productive up-welling zone of the Atlantic Ocean and Canary Current Large Marine Ecosystem region and further enhanced by the huge annual influxes of nutrients from the river.
Habitats: Marine and Coastal Ecosystems, the coastline is from the mouth of the Allahein River in the South to Buniadu point in the north, consist of different types of coastal and marine habitats of higher ecological value such as wetland habitats, coastal scrub/grassland, lagoon complexes, river/ estuary and mangrove fringe
She stated in her report that protected/reserved areas and estuarine ecosystem are key habitat areas for terrestrial such as Mangrove forest, Coastal wetlands, Sea grass beds, Sediments and Soft bottom habitats. In this habitat littoral species are common: meiofauna, which includes high amount of microorganisms like bacteria, nematodes, annelids, larvae of oligochaetes, dense patches of copepods, coelenterates and different species of shellfish.
Wetlands habitats of The Gambia
Ms. Mbenga Cham said wetlands are the most productive of the ecosystems and have a vital role in the maintenance of bio-diversity; it also provides habitat for fish and wildlife, and maintaining natural hydrological regimes. These ecosystems are important for spawning as well as a nursery ground of fish and fisheries species. They also serve as a source of food and migratory paths (juvenile, fish, shrimps, oysters etc.) hence marine and coastal - shallow marine waters, sub tidal beds, rocky shores, sandy beaches, estuarine waters, intertidal mud flats, salt marshes, brackish lagoons and fresh water lagoons.
Estuarine flora are mainly mangroves, in some areas close to the mangroves are other mixed vegetations such as Avicenna Africana, languncularia racemosa, conocarpus erectus, Rhizophora mangle, Rhizophora racemosa and Rhizophora harisonii. Avicenna species is the most salt tolerant thus found along the Atlantic coastline (Banjul and kombo Saint Mary areas as well as in lagoon areas close to the sea).
There are five (5) species of dolphins found in The Gambia: namely Atlantic Humpback Dolphin (Sausa teuszin), Common Battlenose Dolphin (Torsops truncates), Clymene Dolphin (Stenelle Clymene), Long Snoated Common Dolphin (Capensis Dolpinus) and Short Finned Pilot Whale (Globicephala macrorchynchus).
Dolphin habitats can be found in groups ranging from 2-15, especially in coastal waters to hundreds of individuals in offshore areas up to 2 – 2.5 m
Turtle species in the Gambia are four species types that have been recorded so far and these are Green turtle (Chelonia Mydas), Olive Ridely (lepidochelys Olivacea), Hawaksbill Eretmochelys Imbicata, Leader Back (Dermochelys Coriacea) and Longger Head Turtle (Carreta Caretta); where 75% of the Gambia’s Coastline approximately 60km is considered for nesting of number of turtles.
The West African Manatee
This, according to the report belongs to the order of sirenian, they live in wetland, in costal and marine ecosystems to inland floodplains, lakes and rivers. In the Gambia, manatees occur in both fresh and salty water areas and are said to be abundant in the estuaries.
The Gambian coastal and marine biodiversity is threatened by coastal erosion, sand mining and pollution, the report said, adding that the rate of erosion of The Gambian coastline has been estimated to be 1-2 metres per year amounting to a land loss averaging 2.5 -3.0 ha of land per year or (Delft hydraulics, 1992).
The report further revealed that the ecosystems are being threatened by anthropogenic factors and this include conversion of land uses, sand mining, overharvesting wetland products, as well as natural factors such as mangrove die-back, Coastal Erosion, Saline Content, among others, over fishing particularly the demersal species and mangroves forests need special adaptations to be able to grow on a stable soil that the tide will not be able to wash away and to be able to survive the constant changes in water level and salinity.
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