The channel is roughly 460 kilometres across at its narrowest point between the Mozambique city of Angoche and the town of Tambohorano, Madagascar. The channel achieves a maximum depth of 3290 metres.
The prevailing current is a warm water flow toward the southwest. There is ongoing significant siltation water pollution discharging from the west central Madagascar rivers, resulting from widespread slash-and-burn deforestation in the Central Highlands.
Circulation and Hydrography
This channel manifests a southwesterly flowing current which exits into the Agulhas Current at the southern mouth. The entire marine channel is approximately 1600 kilometres in length. At its northern end is the Cape Amber (which is essentially the northern tip of Madagascar) , south of which the northern branch of the East Madagascar Current flows past the Comores into the northern mouth of the Mozambique Channel.
Coastlines and Islands
Beach at Nosy Be, Madagascar. @C.Michael Hogan
The Madagascar coastline consists of sandy beaches, abrupt termination of tsingy limestone landforms and coastal mangrove swamps. Massive deforestation of the Madagascar central highlands beginning after French colonial rule has led to corresponding extensive erosion and loss of topsoil, most of which has accrued to siltation of rivers that discharge to the Mozambique Channel. These reddened rivers are clearly visible from low flying aircraft today, and are creating deleterious discharges to the Mozambique Channel that provide ongoing habitat destruction of coral reefs and other aquatic communities.
On the Mozambique side the north coastal end of the channel has an extensive reef and island system, which forms a shallow inner channel, which is suitable for small boats, but treacherous and generally unpassable for larger vessels. south of Mozambique Island however, the mainland turns swampy and heavily silted by mainland river and stream discharge.
In the northern part of the channel there are several significant islands including the Comoros as well as a number of islands belonging to Madagascar, including Nosy Be and Nosy Komba.
The deeper ocean portions of the Mozambique Channel contain rich quantities of tuna and other pelagic fishes. The hard bottoms of the continental slopes manifest considerable lobster resources, particularly in the northern third and southern third of the Channel. Soft bottom continental shelves between Angoche and Ponta d'Oura exhibit deep-water shrimp, crayfish and crab. Correspondingly the soft bottoms between Angoche and Chiloane are exploited for small demersal fish and shrimp.
Marine mammals of the Mozambique Channel include the Indo-Pacific bottlenose dolphin, Striped dolphin, Humpback whale and Short-finned pilot whale. Cetacean biodiversity is particularly great in the vicinity of Mayotte.
In terms of continental coastal habitats, the estuaries and lagoons have important finfish and crustacean resources. Areas with sandy beaches provide harvests of small demersal fish, bivalves, as well as both penaeide and non-penaeide shrimp. Mangrove swamp areas are key locations for the mangrove crab, but these forests are being overharvested. Since much of the fishing is conducted by local artisanal fishermen, the coastal areas tend to suffer from overfishing. Other coastal waters issues along Mozambique are water pollution impacts due to runoff from agricultural use of phosphorus and nitrogen based fertilisers as well as pesticides and herbicides.
The dinoflagellate Brachydinium taylorii was earlier thought to occur only in the Mozambique Channel, but was found in the 1970s to occur off of Walvis Bay in the Benguela Current. The Mozambique Channel is home to one of the two extant species of coelacanth, Latimeria chalumnae, a bony fish that was thought to be extinct until the first specimen was found in 1938. This species is sparsely distributed in the Mozambique Channel and southerly to the South African Coast. Coastal waters, northwest Madagascar. @ C.Michael Hogan
See main article: Madagascar dry deciduous forests ecoregion
Along the northeast of the Mozambique Channel the dry deciduous forests of western Madagascar are some of the world’s richest and most distinctive tropical dry forests. They are characterized by very high local plant and animal endemism at the species, genera and family levels. A significant portion of these forests have already been cleared, and the remaining forests are fragmented and critically threatened by uncontrolled burning and clearing for grazing and agriculture. Since human settlement of this region, an estimated 97 percent of the island’s dry deciduous western forests have been destroyed, and those remaining are extremely localized and isolated. This ecoregion also contains spectacular limestone karst formations, known as tsingy, and their associated forests, including the World Heritage Site of Bemaraha. The river systems and wetlands of this ecoregion are also critically endangered habitats, home to several endemic animal species.
There is little written history of the coastal areas of the Mozambique Channel until the Portuguese colonial era of the early sixteenth century. However, it is generally clear that the Mozambique side of the channel was settled by indigenous African peoples for considerable time; it is also clear that Muslim seafaring traders from the north had arrived along both sides of the channel in the period 800 to 1000 AD. The Mozambique coastline was settled much earlier than the Madagascar side, and also embraced much higher population densities.
- Margaret Barnes, Harold Barnes. 1986. Oceanography And Marine Biology , Volume 24 (Google eBook) Routledge. 650 pages
- Bernardo Ferraz, Barry Munslow. 2000. Sustainable development in Mozambique. Africa World Press. 242 pages
- Alexander G.Findlay. 1866. A directory for the navigation of the Indian Ocean. 1062 pages
- Nick Garbutt, Hilton Hastings, Wendy Pollecutt, C. Michael Hogan, Tahiana Andriaharimalala. 2006. Anjajavy, the village and the forest. Lumina Technologies Press. Santa Rosa, Ca.
- George Karleskint, Richard Turner, James Small. 2009. Introduction to Marine Biology. Cengage Learning. 581 pages
- M.D.D.Newitt. 1995. A history of Mozambique. Indiana University Press. 679 pages
- J.J.Guillaumet. 1984. The vegetation: an extraordinary diversity. pp. 27 – 54 in A. Jolly, P. Oberlé, R. Albignac (eds.) Key Environments: Madagascar. IUCN, Pergamon Press, New York. ISBN: 0080280021
- John H. Steele, Steve A. Thorpe, Karl K. Turekian. 2009. Ocean Currents: A Derivative of the Encyclopedia of Ocean Sciences. Academic Press. 612 pages