Impacts on marine and coastal systems and resources: # 1
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| Dumping on coast |
The main impact on the natural coastal environment is the loss of ecosystem integrity. This can be attributed to many factors; e.g. deterioration in marine water quality as a result of pollution, resource shrinkage due to over-exploitation of target organisms for food and bait, habitat elimination and fragmentation and reduced freshwater inflow into estuaries. This loss of ecosystem integrity also gives rise to impacts on the human environment which are compounded by population growth and largely uncontrolled expansion of the built environment within the coastal zone.
Overexploitation of resources and human activities which result in threats to biodiversity, disruption of ecosystem processes and habitat loss and fragmentation are mainly a consequence of human population growth, which is manifested by urban encroachment into the coastal zone.
One of the main Coastal Zone Management concerns is the lack of knowledge on and understanding of the impacts of rapid development of informal, sub-economic and low-, middle-, and upper- class housing along the coast. The concern has less to do with absolute numbers and rate of human population growth than the manifestation of the effects thereof; e.g. the consequent environmental impacts in terms of loss of natural habitat and biodiversity. This situation is aggravated by industrialisation at several coastal centres which gives rise to far-reaching environmental impacts linked mainly, but not only, to the adverse effects of pollution on ecosystem function.
 |  | | Polysteganus undulosus (Seventy-four) | Elf |
Depletion of certain fish stocks, such as the seventy-four (Polysteganus undulosus) and elf in KwaZulu-Natal, and many bait species demonstrate that resources are being harvested much more rapidly than they can regenerate, i.e. unsustainably. This is ultimately related to the increasing human population. In the southern and central Transkei region of the Eastern Cape Province harvesting of intertidal rocky shore organisms averages 550 kg (wet mass) per kilometre of shore per year (Hockey et al., 1988). Recent changes in rocky intertidal communities in Transkei suggest that the predator-prey balance, which may have been relatively stable when the human population was smaller, is now inherently unstable. The decreasing proportions of the brown mussel Perna perna in recent shellfish harvests, and its increasing scarcity on the shore indicate a situation of over exploitation (Siegfried et al., 1985; Hockey and Bosman, 1986).
Notable impacts on marine resources and other beneficial uses of the coast in recent years, as a result of coastal pollution, include:
- An extensive Ulva (green seaweed) growth which destroyed Gracilaria (red alga) beds in Saldanha Bay in 1994. Gracilaria is a source of agar used in the food and pharmaceutical industries. This event was attributed to nutrient enrichment from the fish factory effluents being discharged into the bay.
- an acid -iron effluent pipeline discharge on the KwaZulu Natal south coast which has resulted in a zone of depleted benthic communities on the seabed adjacent to the discharge.
- A major oil spill from the ore carrier Apollo Sea caused severe oil pollution along the south western Cape coast in June 1994.
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| Oil soaked penguins |
Besides chronic impacts on the marine environment, major incidents such as accidental oil spills give rise to significant environmental impacts of high intensity. For example, in 1998 a fractured marine bunkering pipeline in Table Bay docks resulted in a 200 tonne oil spill which fouled beaches and the rocky shoreline of Table Bay. It also resulted in the oiling of seabirds such as penguins and cormorants.
A reduction in fresh water supply to estuaries and urban encroachment on marine and coastal systems results in an increased rate of sedimentation within estuarine system and reduced intervals of estuary mouth openings, especially in KwaZulu Natal (see Freshwater Systems and Resources). Increased sedimentation is the result of the reduced scour potential of the river because there are fewer floods with less volume of water. This results in reduced volumes and rates of river flow and reduced water quality for industrial, domestic and ecosystem support.
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There is also information about Terrestrial Ecosystems in the following reports:
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Metropolitan reports:
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Affairs and Tourism. All Rights Reserved.
Site maintained by the Directorate Environmental Information and Reporting
Last update: October 1999
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