Causes and Effects of Coastal Degradation

Destruction of the coastal resources continues to worsen

The rapid growth of the coastal urban centres in Kenya, Tanzania, Mozambique and South Africa, and the fast development of the coastal tourism sector, produce vast quantities of pollution from untreated domestic sewage, posing a threat to the near-shore habitats such as coral reefs.
Pollution from industrial waste is generally not a problem since the level of this development is localised at present, though measures need to be in place to prevent potential harm.

Pollution from shipping and oil terminals is also minimal at present, despite a large proportion of oil exports from the Gulf region passing through the coastal seas of eastern Africa. Serious oil spills have already occurred around Mombasa and Maputo, damaging nearby mangrove forests and beaches. The threat of further spills is likely to increase as economies develop and industries expand - demanding greater supplies of oil.

Coastal tourism and Industrial development
Coastal tourism contributes significantly to local economies of the region, particularly Kenya, where it accounts for a large and increasing proportion of foreign currency earnings. In Tanzania and Mozambique the potential for growth of this sector is huge. Tourism relies heavily on the coastal zone, not just for beach sites for development, but for food and as a leisure area for tourists.

Though an important source of income, coastal tourism often raises a number of environmental concerns. The activities of tourists can affect the marine ecosystem directly, through boat and anchor damage to coral reefs, and indirectly by increasing demands for cleared land for development, collection of shells for souvenirs, seafood, and mangrove poles and coral lime for construction. The extraction of living corals , baked in kilns to produce lime, has also contributed to coastal habitat degradation especially in Tanzania.

Excess amount of sediments
The many large rivers along the coast of the ecoregion carry vital nutrients and sediments that are important to plankton, mangroves and seagrass beds. These rivers connect the shoreline with the interior of the continent of Africa; thus activities hundreds of kilometres upstream can influence the coastal zone. During periods of severe floods the tremendous loads of sediment washed out to sea can overwhelm nearby coral reefs that require clean waters for their existence.

Climate change and its serious impacts

Changes to the coastlines caused by human activity have exacerbated the effects of climate change . Sea level is rising at about 1 millimetre per year, which, under normal circumstances, habitats can adapt to, but the loss of inshore coral reefs and coastal mangrove forests adds to the potential damage caused by sea level rise and coastal erosion. The result can be catastrophic. Already the loss of coastal land due to erosion is an ever-growing concern to developers and farmers.

Threats to marine animals
Marine mammals were hunted to the edge of extinction in the Indian Ocean before anyone realised that they were declining to such low numbers that their very existence was threatened. The more recent intensive collection of certain animals (e.g. sea-cucumbers) has caused local extinction along some areas of the coast.

Sharks and rays are extremely slow breeders, producing only a few juveniles each year. They too are being fished beyond their natural recovery rates, with the result that these days in the shallow waters of most of the region, sharks are very rarely observed. A few larger species, known to have been abundant one hundred years ago, are currently so rare that there is a very real possibility that they may completely vanish from the region.

Possible disappearance of key species
Trends indicate that in the next 50 years Dugongs and marine turtles may no longer be part of the marine diversity of eastern Africa. Dugongs used to be common around estuarine areas where they fed on seagrasses. Nowadays, perhaps only a few hundred are believed to exist in the entire region.

In many areas marine turtles continue to be caught and killed for meat. Five of the world's seven marine turtle species (Green, Hawksbill, Olive Ridley, Loggerhead and Leatherback), all of which are recognised as being in danger of extinction, nest on the beaches of the region. In many places their eggs are taken from their nesting sites which are also vulnerable to destruction from the construction of beach hotels, sand-mining and beach erosion.

Overexploitation of local fisheries
F isheries are a vital employment activity to hundreds of thousands of families on the coast. At least as many again are involved in the post-harvest activities of marketing and processing. The products of the industry (fish, molluscs, shrimps and crabs) provide the main protein component of the diet of the majority of the coastal people and many more people inland (where dried or salted products are sold).

In Tanzania, for example, the estimated average consumption of seafood per person (9.4 kg/year) is greater than the combined consumption of meat and poultry. For the entire region at least 500 species of fish constitute the bulk of catches, yielding an estimated 200,000 tonnes each year.

Most of the catch is from fishers equipped with simple, artisanal gears such as hook and line, hand spears, woven fish traps and various types of nets. Total catches from Mozambique are about 115,000 tonnes, with between 90-95% being caught by about 80,000 artisanal fishers.

Other more industrialized fishing methods also exist, including motorised vessels equipped with trawl nets hauled by power winches. In Mozambique alone the industrial and semi-industrial fishing fleet exceeds 150 vessels, earning the economy over US$ 100 million per year, mostly through the export of shrimps. These trawlers are also active in Tanzania and Kenya, though not to the same scale as in Mozambique which has far greater areas around river mouths suitable for shrimps.

Destructive fishing practices

Over the last few decades destructive fishing methods, such as the use of dynamite and small-meshed nets, have destroyed seagrass beds and coral reefs. These practices still continue in many places despite being illegal in all countries. Preliminary research along the coast of Kenya and Tanzania indicates that human activities such as these have reduced fish catches from coral reefs by 30-40%.

Large proportions of the by-catch (e.g. non-commercial or unwanted species) of shrimp trawlers are juvenile fish. The loss of these immature individuals threatens future fishery resources. Offshore fishing grounds, some of the only areas on earth from where fish catches are increasing, are also open to plundering, often by industrial foreign fleets.

Demand for timber
Mangrove wood is extremely hard and insect-resistant. The harvesting of mangroves for timber and fuel, like basic fishing techniques, has been practised for thousands of years, with poles continuing to be exported from the region.

Reckless cutting of mangroves has cleared large areas of previously productive forest. Mangrove forests are also the first to be cleared for the construction of saltpans from where most of the region's much needed sea salt is produced. Additional pressure from tourism developers, coastal construction, farmers and the ever-growing need for fuel wood, further encourages large swathes of primary mangrove forest to be cut indiscriminately with little or none re-planted.

Pressure on other marine species
Seaweeds have recently become an important economic resource in Tanzania where they are farmed for export and processing into food additives. The seaweed is grown on lines attached to wooden stakes across the seabed of shallow lagoons. Other methods of farming marine organisms, known as mariculture, include the culture of shrimps and fish in coastal ponds, usually in mangrove areas. There are not many mariculture farms in the region at present.

However, investors and developers have started to persuade governments of the region of the financial benefits of such practices, which, if not sensibly developed, can adversely affect not only the forests, but also the many fisheries and people who depend on the productivity of the habitat.

Use in medical research
Recently medical research into fighting the various forms of cancer and other diseases which affect humans has begun focusing on the sea for possible cures derived from animals such as sponges, soft corals and tunicates. This kind of research, known as bio-prospecting, has started to explore the rich coral reefs of eastern Africa where these animals are found in abundance.

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