Africa Environment Outlook

POLLUTION OF SOUTHERN AFRICA'S COASTAL AND MARINE ENVIRONMENT

In South Africa, there are some 63 ocean outfalls along the coast discharging approximately 800 000 m³ of sewage and industrial effluent into the sea every day

Marine and coastal ecosystems are being degraded rapidly in Southern Africa by pollution from land-based activities and dumping at sea. Land-based pollution sources include discharge of sewage, industrial effluents, stormwater run-off, wind-blown litter, suspended sediments, and agro-chemicals. The increase in these types of pollution is largely a result of the rapid growth in population and in tourism in coastal centres, and of unsustainable land management practices inland. For example, in South Africa, the populations of Cape Town and Port Elizabeth, two major coastal cities, grew by 22 per cent and 24 per cent respectively during the 1990s (Macy 1999). Raw sewage is discharged in these cities because the large and rapidly growing population requiring sanitation facilities exceeds the capacity of municipal treatment plants. In South Africa, there are some 63 ocean outfalls along the coast discharging approximately 800 000 m³ of sewage and industrial effluent into the sea every day. Most of the large pipelines discharge into deeper waters, but 27 older pipelines discharge above the high water mark (DEA&T 1999). This is dangerous to human health because bathing waters are contaminated and popular seafood species such as mussels may become contaminated.

South African fur seal, Namibia

Klein/Hubert/Still Pictures

Industrial effluents in the sub-region come mainly from large fish processing plants, abattoirs, and chemical and manufacturing industries. In the case of Mozambique, for example, 126 factories in and around Maputo do not have waste treatment plants and their drains discharge toxic wastes, poisons, non-degradable substances and organic matter into their neighbourhoods (Chenje & Johnson 1996). Most of Tanzania's textile mills release dyes, bleaching agents, alkalis and starch directly into Msimbazi Creek in Dar es Salaam, from where they can easily flow into the Indian Ocean (Chenje & Johnson 1996). Agricultural run-off containing fertilizer residues and soil sediments contributes to silting of estuaries and to smothering of habitats, and has also been suspected of contributing to the occurrence of toxic algal blooms (such as red tides). Pollution of coastal and marine environments poses a threat to human health, through direct contact or through consumption of contaminated fish or seafood. It also degrades marine environments, resulting in declines in economic returns from fisheries and tourism.

Solid waste also enters the marine environment through stormwater run-off or is blown out to sea. Plastics constitute an increasing proportion of marine and coastal litter and present a particular hazard because of their endurance in the environment. Litter, especially plastics, kills many marine animals through ingestion and entanglement. It is also unsightly and a hazardous deterrent to beach users (Ballance, Ryan & Turpie 2000, Ryan 1996). Efforts have been made to reduce the volume of plastics entering the marine environment in South Africa, including regulations on the thickness of plastics used in the packaging industry and incentives for re-use of plastic bags or use of alternative materials (Ministry for Environmental Affairs & Tourism 2000).

Sources of pollution at sea include accidental and deliberate discharges of oil and dumping of garbage such as plastics. Dredge spoils-often rich in heavy metals such as lead, copper, zinc, mercury, and cadmium-are dumped at designated sites. There have been several recent incidences of oil spills off the South African coast that have had serious adverse effects on the Africa penguin populations in the area and on other marine life, particularly large numbers of sea birds, seals, as illustrated in Box 2c.4.

Box 2c.4 Oil spills and emergency responses in South Africa

In June 1994, the iron ore carrier the Apollo Sea broke up and sank in Table Bay. The resulting pollution caused oiling of 10 000 penguins, of which 5 000 died. The clean-up costs of this disaster were estimated at around US$1.5 million, including costs of beach cleaning, penguin rehabilitation, and interruption of port activities. Six years later, another vessel, the Treasure, spilled more than 1 500 tonnes of fuel oil and 20 000 penguins were oiled. In the world's largest and most successful seabird rescue operation (involving members of the public from all over South Africa) almost 20 000 birds were translocated to avoid further oiling, and oiled birds were rehabilitated and released.

Source:University of Cape Town 2001,Minister of Transport's declaration to Senate, 30 August,1994