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Coastal zone management and conservation
Ocean Management 4 ( 1 9 7 8 ) 3 0 3 - - 3 1 7
Coastal Zone Management and Conservation A.E.F. Heydorn Oceanographic Research Institute, Durban (Republic of South Africa)
ABST RACT I m p r o v e d u n d e r s t a n d i n g o f t h e i n t e r - r e l a t i o n s h i p b e t w e e n p h y s i c a l a n d biological para m e t e r s in t h e f u n c t i o n i n g o f e c o s y s t e m s , r e s u l t e d in close i n t e r d i s c i p l i n a r y c o l l a b o r a t i o n in t h e p l a n n i n g a n d d e v e l o p m e n t o f R i c h a r d s Bay H a r b o u r o n t h e c o a s t o f Z u l u l a n d , s o u t h e r n east Africa. In its pristine s t a t e t h e l a g o o n utilized for this p u r p o s e h a d a n area o f c. 3 0 0 0 ha, a n average d e p t h o f 1 m , a n a r r o w c o n n e c t i o n w i t h t h e sea (resulting in c o n s i d e r a b l e lag in tidal w a t e r e x c h a n g e ) , river inflows t h r o u g h e x t e n s i v e filtering s w a m p s a n d m a r g i n a l v e g e t a t i o n fulfilling a vital stabilizing f u n c t i o n . Because o f t h e high biological p r o d u c t i v ity o f t h e s y s t e m every e f f o r t was m a d e t o r e t a i n its ecological viability in spite o f harbour development. C o l l a b o r a t i o n b e t w e e n engineers, ecologists a n d p l a n n e r s r e s u l t e d in a s c h e m e w h e r e b y t h e l a g o o n was divided i n t o a n o r t h e r n h a r b o u r area a n d a s o u t h e r n s a n c t u a r y area. T h e s a n c t u a r y receives a m a j o r p r o p o r t i o n o f river i n f l o w a n d h a s b e e n p r o v i d e d w i t h its o w n o p e n i n g to t h e sea. Water level a n d p o l l u t i o n c o n t r o l is aided b y t h e p r o v i s i o n o f tidal gates in t h e b e r m wall. A p a r t f r o m its biological f u n c t i o n , t h e a e s t h e t i c a n d recreat i o n a l asset o f t h e s a n c t u a r y area t o t h e growing city o f R i c h a r d s Bay is s u b s t a n t i a l . This p a p e r discusses t h e success a n d failure o f t h i s s c h e m e . T h e l a t t e r was caused b y c a n a l i z a t i o n o f a filtering s w a m p (i.e. f l o o d - p l a i n ) , b y p o o r agricultural p r a c t i c e s in t h e c a t c h m e n t a n d e x c e p t i o n a l f l o o d s in 1 9 7 6 / 1 9 7 7 r e s u l t i n g in massive silt d e p o s i t i o n in t h e s a n c t u a r y area. F u t u r e m a n a g e m e n t o f t h e area is again heavily d e p e n d e n t u p o n interdisciplinary c o l l a b o r a t i o n a n d t h e final o u t c o m e m a y y e t be a significant ecological a n d a e s t h e t i c asset.
INTRODUCTION As little as ten years ago agriculturists, industrialists and engineers had relatively little c o n t a c t with biologists in southern Africa. This was largely due to the fact that increased p r o d u c t i o n was the main criterion in these various fields o f hum a n activity. The Province of Natal and Zululand on the east
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coast of South Africa (between the latitudes of 26 ° and 31"S) provides a good example, tn agriculture increased production of sugar was the prime concern; in commerce consolidation of industries was the top priority, coupled with the search for improved marketing outlets; biologists were looking at the life cycles and population dynamics of exploitable marine organisms in terms of their potential for sport and recreational fisheries; planners were investigating future growth points and at ways and means of providing more job opportunities for expanding urban populations; the work of the ecologists was acknowledged but they operated mainly at academic levels. The concept of co-ordinated use of our overall environment, the sensitivities of which would set limits to all the above activities, was hardly t h o u g h t of and interdisciplinary channels of communication were to a large e x t e n t non-existent. Uneasiness about the unco-ordinated use of limited natural resources was however germinating in the minds of responsible people in most disciplines. Events such as mass mortalities of fish and other organisms in major estuarine systems due to pollution (e.g., in Durban Bay) or because of salinity imbalances and siltation (e.g., in the St. Lucia Lake System) then began to demonstrate the effects of ecological disruption and it was n o t long before public emotions were stirred by issues of this nature. Scientists began applying their minds to the inter-relationships between various levels of foodwebs and between ecosystems, e.g., between marine and estuarine ecosystems (Heydorn, 1973). A tremendous a m o u n t of t h o u g h t was triggered off by the a n n o u n c e m e n t by the S.A. Government in 1970, that Richards Bay was to be developed as a harbour to cater especially for the export of coal and the requirements of expanding industrial activity in Zululand. In August of the same year the S.A. Council for Scientific and Industrial Research (C.S.I.R.) organized the first of a series of interdisciplinary meetings to discuss the ecological effects of the proposed harbour development. The idea of dividing Richards Bay into a northern harbour area and a southern sanctuary area was born. This paper is to a large extent the story of Richards Bay Harbour with its idealistic planning, spectacular construction (within five years), its success as a harbour and its failure as an ecological exercise on enormous scale. The environment in which it is situated is briefly described, as is the refusal of the environment to yield totally to human manipulation. It is a story not w i t h o u t hope for the future and if its setting happens to be African and subtropical, its interests in terms of interdisciplinary communication, planning and action stretch well beyond the southern African sub-continent.
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THE COASTAL
ENVIRONMENT
OF NATAL
To be able to discuss the implications of harbour development at Richards Bay a brief description of the coastal environment of Natal is necessary:
Terrestrial features
The major features of the Natal coastline are the reasonably straight configuration of the shore, the large number of rivers flowing into the sea south of St. Lucia, the absence of rivers to the north of St. Lucia and the major estuarine systems of Durban Bay, Richards Bay, St. Lucia and the Kosi Lake System {Fig. 1). The edge of the continental shelf lies fairly close to the present shoreline, except between Richards Bay and Durban where it moves up to 35 km from the coast. High dunes covered in vegetation border most of this coastline. Between the dunes and the Lebombo mountain range lies the low coastal plain of
THE
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305
Zululand which continues southwards as far as Richards Bay and northwards through the greater part of Moqambique. During the Pliocene this plain was submerged and formed part of the continental shelf. King (1967} estimates that the Drakensberg plateau reached an uplifted level of about 2 000 m during the Quarternary Era (1 million years ago) and nearly 1 000 m only 80 km inland. The descent of the land from here to the sea is therefore steep and the major rivers flowing from west to east have carved spectacular gorges, all of which deepen rapidly inland. These rivers are therefore still in the process of cutting actively and transporting terrestrial sediment to the sea, particularly during the summer months when they are subject to heavy flooding. Where the final approach of rivers to the sea is through flat or slightly shelving land, alluvium is deposited and swamps or floodplains are formed. These plains are covered by dense vegetation of which phragmites reed and papyrus are typical and rivers meander through them towards the sea. During floods the water overtops the riverbanks and spreads out over the floodplains depositing much of its silt load in the process. During heavy floods the course of a river may alter within a floodplain, but the plain as a whole is a stable coastal feature. Because of this efficient filtering action, Natal's estuaries in their pristine condition contained clear water, had stable banks and carried rich animal and plant life. Where large rivers such as the Tugela flow directly into the sea, a vast a m o u n t of alluvium is deposited on the seabed, accumulating to form banks. The Tugela Bank which is one of Natal's best prawn trawling grounds, was to a large extent formed in this manner. In recent years overgrazing in catchment areas and poor agricultural practices closer to the sea have vastly increased the a m o u n t of silt carried by the rivers. At the same time floodplains were drained, either for planting sugar cane or to establish industries on reasonably flat ground. Understandably this has led to severe ecological problems (Heydorn, 1977) and some of these will be discussed further in the present paper.
Water movements and currents
The water washing the Natal coastline originates largely from the tropical Indian Ocean South Equatorial Current deflected southward by the coast of the African mainland (Fig. 2). This water mass flows southwards between Africa and Madagascar and is known as the Moqambique Current. Off the northern Natal coast the current is strenghtened by the addition of water, also of south-equatorial origin, which has rounded the southern tip of Madagascar as the East Madagascar Current. The combined current, now known as
306
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the Agulhas Current, flows close to the coast as far south as approximately Port Elizabeth (Bang and Pearce, 1978) after which the major portion of the water is deflected southeastwards by the Agulhas Bank. Off Natal the Agulhas Current always flows some distance from the shore and seldom comes closer than about 5 km. It is separated from the shore by a body of water of different hydrological character (Bang and Pearce, 1978). A typical transect through the current is illustrated in Fig. 3 but it should be borne in mind that the distance of the Agulhas Current from the shore and the temperature and salinity regimes vary from day to day and seasonally.
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Inshore of the Agulhas Current cooler water frequently moves in a northerly direction, particularly during the winter months (Bang and Pearce, ~978). For purposes of the present paper it is not necessary to ~o into greater detail. A further factor contributing ~o the geomorphology of the Natal coast is ocean swell which strikes the coast without any buffering action of kelp beds (as on the west coast), coral reefs or the presence of offshore islands (as in Mozambique). Generally the swell reaches the coast at an angle from the southeast. This generates considerable nearshore sediment movement which, together with seasonal river flow-rate patterns, plays a major role in the seasonal opening and closing of river and estuary mouths.
Estuaries As indicated above, the heavy terrestrial runoff has a further striking effect upon the geomorphology of Natal and the ecology of its littoral waters -- the formation of numerous estuaries, a total of 72 of which enter the sea over a distance of less than 400 km. These range from widened river mouths (regularly closed during dry periods), to major bays or estuarine systems. They contain an extremely rich fauna ranging from bacteria and plankton to crocodiles and hippopotami and furthermore provide shelter and food for m a n y fish, prawns and other forms of marine life during the juvenile stages of their life cycle. Adult marine fish also enter estuaries for feeding purposes and provide excellent angling opportunities. It is therefore difficult to over-emphasize the importance of the estuaries through their significance in the life-cycle of numerous marine organisms, their role in human food production, their recreational potential and sheer scenic beauty. It is inevitable that the role of estuaries in these respects should come into conflict with other pursuits of m o d e m society, for example harbour development, agricultural activities in the catchment areas and, unfortunately, waste disposal. Consequently few of Natal's estuaries are free from man-induced modifications and many are severely degraded. The relative areas occupied by the four major systems are as follows:
Durban Bay 1 060 Richards Bay 2 990 St. Lucia 30 520 Kosi Lake System 3 600
ha ha ha ha
Total 38 170 ha
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RICHARDSBAY Richards Bay lies about 190 km to the north of Durban and has featured prominently in the news over the past eight years because of its developm e n t as an industrial harbour. In its original state it consisted of a wide bay, approximately three times the size of Durban Bay and connected with the sea via a narrow channel (Fig. 4). The depth of the bay varied from 0.25 to 1.25 m, with a deeper channel around the margin. Several rivers and streams enter the bay, the most important of which are the Umhlatuzi and Qupu flowing from the southwest and the Umzingazi (draining Lake Umzingazi) from the north. The largest freshwater volume is discharged from the Umhlatuzi and Enseleni catchments. Richards Bay in its original state was a true estuary with a salinity gradient ranging from freshwater in the west to seawater at the mouth. The margins of Richards Bay had a substratum consisting of deep, soft mud, with occasional patches of sand. The banks were mostly low-lying and marshy, overgrown with swamp vegetation along the northern and western margin and mangroves along the southern and eastern edges. Extensive and important Zostera beds occurred in the entrance channel. The fauna and flora of Richards Bay was described fairly comprehensively by Millard and Harrison (1951} and has also been studied by the National Institute for Water Research of the CSIR, the Oceanographic Research Institute, Durban and the Port Elizabeth Museum, between 1970 and 1972. The results of these latter studies are important because they provide baseline values against which subsequent changes can be measured. Millard and Harri-
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Fig. 4. Richards Bay (after Millard and Harrison, 1951).
309
son listed a total of 183 species from the whole estuary. They pointed out that the majority of the species were young and juvenile forms and emphasized the importance of the Zostera beds to many of these organisms, it is clear that Richards Bay in its original form represented an almost classical nursery and feeding ground. The a n n o u n c e m e n t in 1969 by the Government that Richards Bay was to be developed as a harbour was therefore received with mixed feelings by m a n y people. On the one hand, the new port was an obvious necessity in terms of the economic growth of the country as a whole and also the need to provide a stimulus and work opportunities for the emerging State of KwaZulu. On the other hand the growing population of the region needed the recreational outlet provided by the bay, the protein source it represented and it was recognised as a vital attraction in Natal's dynamic tourist industry. The latter aspect was to be highlighted subsequently due to political upheaval in Moqambique and the closure of that beautiful coastline to tourists from South Africa and other parts of the world. In an a t t e m p t to find a compromise between these conflicting needs, the CSIR called a meeting in August 1970 at which the following organizations were represented: S.A. Council for Scientific and Industrial Research Town and Regional Planning Commission of Natal Zoology Department, University of Cape Town S.A. Railways and Harbours Richards Bay Town Board Oceanographic Research Institute, Durban The main topics discussed at the meeting were how pollution in the new harbour could be controlled and what could be done to preserve the ecology of the area. It was agreed that the latter could best be achieved by retaining a salinity gradient through the system similar to that in the original situation and by altering the tidal rise and fall in the bay as little as possible. Amongst other matters the possibility of dividing the bay by means of a berm with a northern harbour area and a southern sanctuary area with a new and separate m o u t h was raised for the first time (Fig. 5). The necessity for canalizing the Umhlatuzi River in order to facilitate construction of rail and road services was also mentioned. Clearly this would mean that the filtering function of the Umhlatuzi floodplain would be removed and the ecologists stated in direct terms how serious the environmental implications of this would be. In spite of differences in opinion between various parties, the meeting represented a first step towards multidisciplinary communication and was generally hailed as such. From the harbour construction and management point of view the berm dividing the bay would have the advantages of: (a)
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Fig. 5. Richards Bay development plan (after Environment R.S.A., 2(3), 1975).
reducing silting (because the Umhlatuzi River would be entering the sanctuary) and therefore the necessity for dredging in the harbour channels would be minimized; (b) facilitate more comfortable berthing of ships because of reduced wave action and water movement; (c) road and rail access would be provided to the southern side of the harbour, including the coal loading area. From the ecological point of view, this arrangement would have the advantages of: (a) protecting the sanctuary against pollution stemming from the harbour; (b) facilitate maintenance of normal salinity gradients in the sanctuary area. However, as already mentioned, it was clear that a smaller area receiving unfiltered waters from the Umhlatuzi would be prone to rapid siltation and
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that changes in the tidal rise and fall patterns were likely to affect the perxpheral vegetation of the sanctuary (e.g., the mangroves which are sensitiv(~ to water levels). Bank stability and biological productivity were therefore likely to suffer. A further point of concern was that the Zostera beds would be destroyed and that this would reduce biological productivity even furthe~~ The S.A. Railways and Harbours engineers who were responsible for construction of the harbour on a very tight time schedule, were extremely cooperative in attempting to cut ecological disruption to a minimum. It was agreed to incorporate tidal gates in the berm wall to assist with water level control in the sanctuary and every effort was made to meet environmental criteria stipulated by ecologists. There was one exception -- no alternative could be found to the canalizing of the Umhlatuzi River. A committee was established to ensure adequate liaison between the various parties involved during the period of harbour construction. It was decided to place responsibility for managing the sanctuary area in the hands of Natal's major conservation agency, the Natal Parks, Game and Fish Preservation Board, and hydrological, physical and biological survey work was sponsored to monitor environmental and biological changes during and subsequent to harbour construction. The press and voluntary conservation bodies were full of praise for this "enlightened planning". The harbour was completed and officially opened in 1976. The economic benefits of the new port were immediately apparent. The new city of Richards Bay is growing with leaps and bounds, peripheral industries are mushrooming and job opportunities were created for thousands of people, black and white. The pollution problems emanating from the intensive human activity seemed reasonably under control and the aesthetic, recreational and food producing potential of the sanctuary area to the growing industrial complex was described in glowing terms. Then, in the 1976/77 summer, unscheduled floods made their appearance. The harbour remained reasonably unaffected because the Umhlatuzi did not open into it. This river, now unbridled because of the canalization, tore down its artificial course with greater velocity than ever before. Its banks, no longer protected by natural vegetation were undercut and collapsed, and hectares of valuable sugarcane lands established on the former floodplain were washed away. The same applied to the major road bridge over the Umhlatuzi linking Richards Bay and Durban and, according to recent calculations by the CSIR, 3.2 million tons of silt were deposited in the sanctuary forming a huge new delta. Everyone seemed surprised except for those who had foreseen this situation at the meeting held in August 1970.
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THE ECOLOGICAL IMPLICATIONS OF THE NEW SITUATION AT RICHARDS BAY In modern economic planning benefits and disadvantages must be constantly weighed up against each other. In former years, relatively little t h o u g h t was given to the ecological implications of coastal development in Natal, because of the tremendous regenerating power of vegetation and apparent environmental resilience in this sub-tropical region and also because the Province has so many estuaries and river m o u t h s t h a t degradation of one or other system did n o t seem to matter all t h a t much. However, three bodies became increasingly concerned with the progressive and cumulative degradation of the coastal environment, in particular of estuaries, and began voicing their concern ever more intensively over the past five years. These were the Town and Regional Planning Commission of Natal, the Natal Parks, Game and Fish Preservation Board and the Oceanographic Research Institute, Durban. The two former bodies have statutory status and carry responsibility for co-ordinated planning, land usage and conservation in the Province. The Oceanographic Research Institute is particularly interested in environm e n t ] f o o d w e b interaction and, with the financial support of the two former bodies and the CSIR, carries o u t intensive research in the estuarine and nearshore marine environments in Natal. This is an on-going task and is conducted in close collaboration with a number of universities and other research institutions. An overriding realization emanating from the joint work of these organizations is that it is erroneous to consider estuaries as individual entities and that they must be seen in the c o n t e x t of Natal's overall estuarine environment. It is only through the latter concept that a meaningful picture of the optimal utilization potential of this environment can be obtained and also of the overall degree of degradation which can be tolerated. This latter aspect gives reason for grave concern and it is in this light that the situation in Richards Bay will now be discussed. (a) Champion (1970) described the life history of the prawn P e n a e u s indic u s and associated species pointing o u t t h a t the juveniles move into estuaries, find shelter and food amongst the roots of marginal vegetation and amongst benthic macrophytes, grow to sexual maturity and then move out to sea again to spawn. Wallace and Van der Elst (1975) describe a similar situation for teleost fishes emphasizing how the reproductive cycles are adapted to coincide with the seasonal opening and closing of estuaries and river mouths. In section 2 of their paper mention was made of the pronounced longshore water movements along the Natal coast as well as of the exposed conditions with regard to ocean swell. It stands to reason t h a t delicate juvenile forms of life would either be carried away by currents or destroyed if t h e y c a n n o t
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find suitable estuarine conditions at the right stage in their life cycle. ~e~ydorn {1973) has described the situation of estuarine and marine interdependence in Natal in greater detail. It is clear that estuarine degradation must have deleterious effects on marine life which, in adult form, are not associated with estuaries. Although quantitive data are not yet available it is highly probable that declining trends in Natal's game and reef fish populations (Van der Elst, in preparation) can be attributed in part to reduced availability and accessibility of estuarine nursery areas. As Durban Bay has lost much of its biological viability due to pollution and loss of vegetation, and the harbour section of Richards Bay is likely to go the same way, the incredibly rapid siltation of the Richards Bay sanctuary area is viewed with much concern. (b) Siltation from the Umhlatuzi River is, however, n o t the only source for concern regarding the sanctuary area of Richards Bay. The new m o u t h scoured far more rapidly than anticipated by the hydrologists and engineers who designed it due, to a large extent, to the unscheduled floods of summer 1976/77. Consequently the tidal regime has changed drastically to the detrim e n t of mangroves and swamp forests bordering the sanctuary. Furthermore, sanding up in the sanctuary is also taking place as a result of marine sand being transported in through the new mouth. In due course it is expected that the m o u t h itself will sand up and approach a configuration closer to that of the original m o u t h of the bay. In the meantime, optimistic forecasts that the new sanctuary would retain the characteristics of the original Richards Bay, but on smaller scale are not materializing. '(c) Pollution monitoring is being carried out by the CSIR in the harbour section and at this stage is n o t excessive. Effluents from a large aluminium and a large fertilizer factory on the periphery of the harbour are carefully treated and checked. Coaldust is a problem but also under control at this stage. However, as industry expands around the new harbour city, pollution will increase and the biological productivity of the harbour section will decrease accordingly. The tidal gates in the berm wall are of obvious benefit during extreme water level conditions but t h e y do also represent a means whereby pollution from the harbour can reach the sanctuary. (d) The sugar industry established on the Umhlatuzi floodplain is also deeply concerned about the ecological changes taking place in the sanctuary area. On the one hand the straightened river flows at much greater velocity through a course unprotected by natural vegetation. Much of the silt in the new delta shown {Fig. 6), represented valuable sugar cane land before the floods. The belated realization t h a t the sugar cane fields should never have been established on the floodplain, that river courses should not have been changed when the swamps were drained and that ecologists had warned against the dangers of further canalization do not help the farmers of the
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Fig. 6. Aerial photograph of Umhlatuzi floodplain and Richards Bay sanctuary area, April 1977.
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region at this stage. One really does not know where the answer lies because the Umhlatuzi will continue to try and meander through its original floodplain -- endangering the sugar fields and road bridges. Farmers are also concerned because saltwater from the sanctuary can "back u p " into their lands during spring tide conditions. Dams in the catchment to control river flow are only a partial answer because of the magnitude of floods occurring m Natal. Canalizing the river in concrete would be excessively expensive and upset seepage patterns basic to the type of soil found in swamps or floodplains. A solution other than allowing the sugar cane fields to revert to their original swamp condition is n o t in sight at present and quite apart from practical problems this will hardly be acceptable to the sugar industry. (e) What is happening is that the new delta is being rapidly covered by swamp vegetation and in part by mangroves. Given time to develop, it will take on a filtering action and in due course the whole sanctuary area will presumably become a swamp through which the Umhlatuzi River will again meander towards the sea. It is already attracting m a n y birds including flamingoes, pelicans, herons and numerous species of waders. It will become biologically productive as a swamp but n o t as an estuary. Nevertheless inlets in the swamp should provide at least some shelter to juvenile marine organisms. In other words, nature is reshaping itself according to the new situation created by man. If this process is allowed to continue the future of the sanctuary area of Richards Bay in terms of natural food production and aesthetic value will not be w i t h o u t hope. It will not, however, be what it was designed to be -- an estuarine sanctuary to make good, at least in part, the disruption to marine and estuarine life brought about by harbour construction.
CONCLUSION The story of Richards Bay will probably go down in history as a classical example of severe problems created through human manipulation of an envir o n m e n t w i t h o u t due consideration for its sensitivities. The harbour itself is an u n d o u b t e d success but it must be admitted that the concept of an associated water area as an estuarine sanctuary is a failure. The sugar farmers of the Umhlatuzi floodplain have been left with an enormous problem -- partly created by themselves but vastly accelerated by the river canalization. The already heavily degraded estuarine environment of Natal has suffered m~other severe setback and the same applies to the food producing potential of the coastal waters of the Province. The loss of the sanctuary as an import a n t recreational outlet for a rapidly growing population cannot be shrugged aside. That the loss of the sanctuary area is a further blow to the tourist
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i n d u s t r y w h i c h is o f such vital i m p o r t a n c e t o t h e coastal regions o f Natal can also n o t be d i s p u t e d . F r o m the big plus o f the success o f R i c h a r d s Bay h a r b o u r a w h o l e string of minusses m u s t be s u b t r a c t e d if t h e u l t i m a t e b e n e f i t is to be calculated. As m a n y o f the minusses are intangible an empirical c a l c u l a t i o n is n o t possible at this stage In t h e s h o r t t e r m , t h e benefits p r o b a b l y o u t w e i g h the disadvantages b u t in the long t e r m the picture m a y well be d i f f e r e n t because o f the serious implications o f progressively declining f o o d resources f o r a r o c k e t i n g h u m a n p o p u l a t i o n . A t t h a t stage t h e f a c t t h a t a s o u n d e c o n o m y c a n n o t be built o n a d a m a g e d e n v i r o n m e n t will finally be b r o u g h t h o m e . In this cont e x t the s t o r y o f R i c h a r d s Bay is relevant t o all h u m a n e n d e a v o u r .
REFERENCES Bang, N.D. and Pearce, A.F., 1978. Physical oceanography. In: A.E.F. Heydorn et al. Ecology of the Agulhas Current region: An assessment of biological responses to environmental parameters in the southwest Indian Ocean. Trans. R. Soc. S. Afr., 43 (2): 151--190. Carter, R.A., 1977. The distribution of Calanoid Copepoda in the Agulhas Current system off Natal, South Africa. Unpublished M. Sci. thesis, University of Natal, Durban, 165 pp. Champion, H.F.B., 1970. Aspects of the biology of Penaeus indicus (Milne Edward) with notes on associated Penaeidae occurring off Natal on the east coast of South Africa. Oceanography in South Africa -- 1970, Durban, 4--6 Aug. 1970, (G1): 1--17. Heydorn, A.E.F., 1973. The interdependence of marine and estuarine ecosystems in South Africa. S. Afr. J. Sci., 69(1): 18--24. Heydorn, A.E.F., 1977. Agriculture and earthworks -- Death knell of Natal's estuaries. Afr. Wild Life, 31(6): 27--30. King, L.C., 1967. South African scenery: A textbook of geomorphology. Oliver and Boyd, London, 308 pp. Millard, N.A.H. and Harrison, A.D., 1951. The ecology of South African estuaries, 5. Richards Bay. Trans. R. Soc. S. Afr., 34(1): 157--179. Wallace, J.H. and Van der Elst, R.P., 1975. The estuarine fishes of the east coast of South Africa, 4. Occurrence of juveniles in estuaries; 5: Biology, estuarine dependence and status. Invest. Rep. oceanogr. Res. Inst., (42): 1--63.
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Coastal Zone Management and Conservation A.E.F. Heydorn Oceanographic Research Institute, Durban (Republic of South Africa)
ABST RACT I m p r o v e d u n d e r s t a n d i n g o f t h e i n t e r - r e l a t i o n s h i p b e t w e e n p h y s i c a l a n d biological para m e t e r s in t h e f u n c t i o n i n g o f e c o s y s t e m s , r e s u l t e d in close i n t e r d i s c i p l i n a r y c o l l a b o r a t i o n in t h e p l a n n i n g a n d d e v e l o p m e n t o f R i c h a r d s Bay H a r b o u r o n t h e c o a s t o f Z u l u l a n d , s o u t h e r n east Africa. In its pristine s t a t e t h e l a g o o n utilized for this p u r p o s e h a d a n area o f c. 3 0 0 0 ha, a n average d e p t h o f 1 m , a n a r r o w c o n n e c t i o n w i t h t h e sea (resulting in c o n s i d e r a b l e lag in tidal w a t e r e x c h a n g e ) , river inflows t h r o u g h e x t e n s i v e filtering s w a m p s a n d m a r g i n a l v e g e t a t i o n fulfilling a vital stabilizing f u n c t i o n . Because o f t h e high biological p r o d u c t i v ity o f t h e s y s t e m every e f f o r t was m a d e t o r e t a i n its ecological viability in spite o f harbour development. C o l l a b o r a t i o n b e t w e e n engineers, ecologists a n d p l a n n e r s r e s u l t e d in a s c h e m e w h e r e b y t h e l a g o o n was divided i n t o a n o r t h e r n h a r b o u r area a n d a s o u t h e r n s a n c t u a r y area. T h e s a n c t u a r y receives a m a j o r p r o p o r t i o n o f river i n f l o w a n d h a s b e e n p r o v i d e d w i t h its o w n o p e n i n g to t h e sea. Water level a n d p o l l u t i o n c o n t r o l is aided b y t h e p r o v i s i o n o f tidal gates in t h e b e r m wall. A p a r t f r o m its biological f u n c t i o n , t h e a e s t h e t i c a n d recreat i o n a l asset o f t h e s a n c t u a r y area t o t h e growing city o f R i c h a r d s Bay is s u b s t a n t i a l . This p a p e r discusses t h e success a n d failure o f t h i s s c h e m e . T h e l a t t e r was caused b y c a n a l i z a t i o n o f a filtering s w a m p (i.e. f l o o d - p l a i n ) , b y p o o r agricultural p r a c t i c e s in t h e c a t c h m e n t a n d e x c e p t i o n a l f l o o d s in 1 9 7 6 / 1 9 7 7 r e s u l t i n g in massive silt d e p o s i t i o n in t h e s a n c t u a r y area. F u t u r e m a n a g e m e n t o f t h e area is again heavily d e p e n d e n t u p o n interdisciplinary c o l l a b o r a t i o n a n d t h e final o u t c o m e m a y y e t be a significant ecological a n d a e s t h e t i c asset.
INTRODUCTION As little as ten years ago agriculturists, industrialists and engineers had relatively little c o n t a c t with biologists in southern Africa. This was largely due to the fact that increased p r o d u c t i o n was the main criterion in these various fields o f hum a n activity. The Province of Natal and Zululand on the east
303
coast of South Africa (between the latitudes of 26 ° and 31"S) provides a good example, tn agriculture increased production of sugar was the prime concern; in commerce consolidation of industries was the top priority, coupled with the search for improved marketing outlets; biologists were looking at the life cycles and population dynamics of exploitable marine organisms in terms of their potential for sport and recreational fisheries; planners were investigating future growth points and at ways and means of providing more job opportunities for expanding urban populations; the work of the ecologists was acknowledged but they operated mainly at academic levels. The concept of co-ordinated use of our overall environment, the sensitivities of which would set limits to all the above activities, was hardly t h o u g h t of and interdisciplinary channels of communication were to a large e x t e n t non-existent. Uneasiness about the unco-ordinated use of limited natural resources was however germinating in the minds of responsible people in most disciplines. Events such as mass mortalities of fish and other organisms in major estuarine systems due to pollution (e.g., in Durban Bay) or because of salinity imbalances and siltation (e.g., in the St. Lucia Lake System) then began to demonstrate the effects of ecological disruption and it was n o t long before public emotions were stirred by issues of this nature. Scientists began applying their minds to the inter-relationships between various levels of foodwebs and between ecosystems, e.g., between marine and estuarine ecosystems (Heydorn, 1973). A tremendous a m o u n t of t h o u g h t was triggered off by the a n n o u n c e m e n t by the S.A. Government in 1970, that Richards Bay was to be developed as a harbour to cater especially for the export of coal and the requirements of expanding industrial activity in Zululand. In August of the same year the S.A. Council for Scientific and Industrial Research (C.S.I.R.) organized the first of a series of interdisciplinary meetings to discuss the ecological effects of the proposed harbour development. The idea of dividing Richards Bay into a northern harbour area and a southern sanctuary area was born. This paper is to a large extent the story of Richards Bay Harbour with its idealistic planning, spectacular construction (within five years), its success as a harbour and its failure as an ecological exercise on enormous scale. The environment in which it is situated is briefly described, as is the refusal of the environment to yield totally to human manipulation. It is a story not w i t h o u t hope for the future and if its setting happens to be African and subtropical, its interests in terms of interdisciplinary communication, planning and action stretch well beyond the southern African sub-continent.
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THE COASTAL
ENVIRONMENT
OF NATAL
To be able to discuss the implications of harbour development at Richards Bay a brief description of the coastal environment of Natal is necessary:
Terrestrial features
The major features of the Natal coastline are the reasonably straight configuration of the shore, the large number of rivers flowing into the sea south of St. Lucia, the absence of rivers to the north of St. Lucia and the major estuarine systems of Durban Bay, Richards Bay, St. Lucia and the Kosi Lake System {Fig. 1). The edge of the continental shelf lies fairly close to the present shoreline, except between Richards Bay and Durban where it moves up to 35 km from the coast. High dunes covered in vegetation border most of this coastline. Between the dunes and the Lebombo mountain range lies the low coastal plain of
THE
NATAL
COAST
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Fig. 1. The Natal coastline (after King, 1967).
305
Zululand which continues southwards as far as Richards Bay and northwards through the greater part of Moqambique. During the Pliocene this plain was submerged and formed part of the continental shelf. King (1967} estimates that the Drakensberg plateau reached an uplifted level of about 2 000 m during the Quarternary Era (1 million years ago) and nearly 1 000 m only 80 km inland. The descent of the land from here to the sea is therefore steep and the major rivers flowing from west to east have carved spectacular gorges, all of which deepen rapidly inland. These rivers are therefore still in the process of cutting actively and transporting terrestrial sediment to the sea, particularly during the summer months when they are subject to heavy flooding. Where the final approach of rivers to the sea is through flat or slightly shelving land, alluvium is deposited and swamps or floodplains are formed. These plains are covered by dense vegetation of which phragmites reed and papyrus are typical and rivers meander through them towards the sea. During floods the water overtops the riverbanks and spreads out over the floodplains depositing much of its silt load in the process. During heavy floods the course of a river may alter within a floodplain, but the plain as a whole is a stable coastal feature. Because of this efficient filtering action, Natal's estuaries in their pristine condition contained clear water, had stable banks and carried rich animal and plant life. Where large rivers such as the Tugela flow directly into the sea, a vast a m o u n t of alluvium is deposited on the seabed, accumulating to form banks. The Tugela Bank which is one of Natal's best prawn trawling grounds, was to a large extent formed in this manner. In recent years overgrazing in catchment areas and poor agricultural practices closer to the sea have vastly increased the a m o u n t of silt carried by the rivers. At the same time floodplains were drained, either for planting sugar cane or to establish industries on reasonably flat ground. Understandably this has led to severe ecological problems (Heydorn, 1977) and some of these will be discussed further in the present paper.
Water movements and currents
The water washing the Natal coastline originates largely from the tropical Indian Ocean South Equatorial Current deflected southward by the coast of the African mainland (Fig. 2). This water mass flows southwards between Africa and Madagascar and is known as the Moqambique Current. Off the northern Natal coast the current is strenghtened by the addition of water, also of south-equatorial origin, which has rounded the southern tip of Madagascar as the East Madagascar Current. The combined current, now known as
306
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Fig. 2. Major water movements in the S.W. Indian Ocean (after Heydorn, 1973).
the Agulhas Current, flows close to the coast as far south as approximately Port Elizabeth (Bang and Pearce, 1978) after which the major portion of the water is deflected southeastwards by the Agulhas Bank. Off Natal the Agulhas Current always flows some distance from the shore and seldom comes closer than about 5 km. It is separated from the shore by a body of water of different hydrological character (Bang and Pearce, 1978). A typical transect through the current is illustrated in Fig. 3 but it should be borne in mind that the distance of the Agulhas Current from the shore and the temperature and salinity regimes vary from day to day and seasonally.
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Fig. 3. Transect through the Agulhas Current (after Carter, 1977).
307
Inshore of the Agulhas Current cooler water frequently moves in a northerly direction, particularly during the winter months (Bang and Pearce, ~978). For purposes of the present paper it is not necessary to ~o into greater detail. A further factor contributing ~o the geomorphology of the Natal coast is ocean swell which strikes the coast without any buffering action of kelp beds (as on the west coast), coral reefs or the presence of offshore islands (as in Mozambique). Generally the swell reaches the coast at an angle from the southeast. This generates considerable nearshore sediment movement which, together with seasonal river flow-rate patterns, plays a major role in the seasonal opening and closing of river and estuary mouths.
Estuaries As indicated above, the heavy terrestrial runoff has a further striking effect upon the geomorphology of Natal and the ecology of its littoral waters -- the formation of numerous estuaries, a total of 72 of which enter the sea over a distance of less than 400 km. These range from widened river mouths (regularly closed during dry periods), to major bays or estuarine systems. They contain an extremely rich fauna ranging from bacteria and plankton to crocodiles and hippopotami and furthermore provide shelter and food for m a n y fish, prawns and other forms of marine life during the juvenile stages of their life cycle. Adult marine fish also enter estuaries for feeding purposes and provide excellent angling opportunities. It is therefore difficult to over-emphasize the importance of the estuaries through their significance in the life-cycle of numerous marine organisms, their role in human food production, their recreational potential and sheer scenic beauty. It is inevitable that the role of estuaries in these respects should come into conflict with other pursuits of m o d e m society, for example harbour development, agricultural activities in the catchment areas and, unfortunately, waste disposal. Consequently few of Natal's estuaries are free from man-induced modifications and many are severely degraded. The relative areas occupied by the four major systems are as follows:
Durban Bay 1 060 Richards Bay 2 990 St. Lucia 30 520 Kosi Lake System 3 600
ha ha ha ha
Total 38 170 ha
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RICHARDSBAY Richards Bay lies about 190 km to the north of Durban and has featured prominently in the news over the past eight years because of its developm e n t as an industrial harbour. In its original state it consisted of a wide bay, approximately three times the size of Durban Bay and connected with the sea via a narrow channel (Fig. 4). The depth of the bay varied from 0.25 to 1.25 m, with a deeper channel around the margin. Several rivers and streams enter the bay, the most important of which are the Umhlatuzi and Qupu flowing from the southwest and the Umzingazi (draining Lake Umzingazi) from the north. The largest freshwater volume is discharged from the Umhlatuzi and Enseleni catchments. Richards Bay in its original state was a true estuary with a salinity gradient ranging from freshwater in the west to seawater at the mouth. The margins of Richards Bay had a substratum consisting of deep, soft mud, with occasional patches of sand. The banks were mostly low-lying and marshy, overgrown with swamp vegetation along the northern and western margin and mangroves along the southern and eastern edges. Extensive and important Zostera beds occurred in the entrance channel. The fauna and flora of Richards Bay was described fairly comprehensively by Millard and Harrison (1951} and has also been studied by the National Institute for Water Research of the CSIR, the Oceanographic Research Institute, Durban and the Port Elizabeth Museum, between 1970 and 1972. The results of these latter studies are important because they provide baseline values against which subsequent changes can be measured. Millard and Harri-
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Fig. 4. Richards Bay (after Millard and Harrison, 1951).
309
son listed a total of 183 species from the whole estuary. They pointed out that the majority of the species were young and juvenile forms and emphasized the importance of the Zostera beds to many of these organisms, it is clear that Richards Bay in its original form represented an almost classical nursery and feeding ground. The a n n o u n c e m e n t in 1969 by the Government that Richards Bay was to be developed as a harbour was therefore received with mixed feelings by m a n y people. On the one hand, the new port was an obvious necessity in terms of the economic growth of the country as a whole and also the need to provide a stimulus and work opportunities for the emerging State of KwaZulu. On the other hand the growing population of the region needed the recreational outlet provided by the bay, the protein source it represented and it was recognised as a vital attraction in Natal's dynamic tourist industry. The latter aspect was to be highlighted subsequently due to political upheaval in Moqambique and the closure of that beautiful coastline to tourists from South Africa and other parts of the world. In an a t t e m p t to find a compromise between these conflicting needs, the CSIR called a meeting in August 1970 at which the following organizations were represented: S.A. Council for Scientific and Industrial Research Town and Regional Planning Commission of Natal Zoology Department, University of Cape Town S.A. Railways and Harbours Richards Bay Town Board Oceanographic Research Institute, Durban The main topics discussed at the meeting were how pollution in the new harbour could be controlled and what could be done to preserve the ecology of the area. It was agreed that the latter could best be achieved by retaining a salinity gradient through the system similar to that in the original situation and by altering the tidal rise and fall in the bay as little as possible. Amongst other matters the possibility of dividing the bay by means of a berm with a northern harbour area and a southern sanctuary area with a new and separate m o u t h was raised for the first time (Fig. 5). The necessity for canalizing the Umhlatuzi River in order to facilitate construction of rail and road services was also mentioned. Clearly this would mean that the filtering function of the Umhlatuzi floodplain would be removed and the ecologists stated in direct terms how serious the environmental implications of this would be. In spite of differences in opinion between various parties, the meeting represented a first step towards multidisciplinary communication and was generally hailed as such. From the harbour construction and management point of view the berm dividing the bay would have the advantages of: (a)
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"CAL~
Fig. 5. Richards Bay development plan (after Environment R.S.A., 2(3), 1975).
reducing silting (because the Umhlatuzi River would be entering the sanctuary) and therefore the necessity for dredging in the harbour channels would be minimized; (b) facilitate more comfortable berthing of ships because of reduced wave action and water movement; (c) road and rail access would be provided to the southern side of the harbour, including the coal loading area. From the ecological point of view, this arrangement would have the advantages of: (a) protecting the sanctuary against pollution stemming from the harbour; (b) facilitate maintenance of normal salinity gradients in the sanctuary area. However, as already mentioned, it was clear that a smaller area receiving unfiltered waters from the Umhlatuzi would be prone to rapid siltation and
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that changes in the tidal rise and fall patterns were likely to affect the perxpheral vegetation of the sanctuary (e.g., the mangroves which are sensitiv(~ to water levels). Bank stability and biological productivity were therefore likely to suffer. A further point of concern was that the Zostera beds would be destroyed and that this would reduce biological productivity even furthe~~ The S.A. Railways and Harbours engineers who were responsible for construction of the harbour on a very tight time schedule, were extremely cooperative in attempting to cut ecological disruption to a minimum. It was agreed to incorporate tidal gates in the berm wall to assist with water level control in the sanctuary and every effort was made to meet environmental criteria stipulated by ecologists. There was one exception -- no alternative could be found to the canalizing of the Umhlatuzi River. A committee was established to ensure adequate liaison between the various parties involved during the period of harbour construction. It was decided to place responsibility for managing the sanctuary area in the hands of Natal's major conservation agency, the Natal Parks, Game and Fish Preservation Board, and hydrological, physical and biological survey work was sponsored to monitor environmental and biological changes during and subsequent to harbour construction. The press and voluntary conservation bodies were full of praise for this "enlightened planning". The harbour was completed and officially opened in 1976. The economic benefits of the new port were immediately apparent. The new city of Richards Bay is growing with leaps and bounds, peripheral industries are mushrooming and job opportunities were created for thousands of people, black and white. The pollution problems emanating from the intensive human activity seemed reasonably under control and the aesthetic, recreational and food producing potential of the sanctuary area to the growing industrial complex was described in glowing terms. Then, in the 1976/77 summer, unscheduled floods made their appearance. The harbour remained reasonably unaffected because the Umhlatuzi did not open into it. This river, now unbridled because of the canalization, tore down its artificial course with greater velocity than ever before. Its banks, no longer protected by natural vegetation were undercut and collapsed, and hectares of valuable sugarcane lands established on the former floodplain were washed away. The same applied to the major road bridge over the Umhlatuzi linking Richards Bay and Durban and, according to recent calculations by the CSIR, 3.2 million tons of silt were deposited in the sanctuary forming a huge new delta. Everyone seemed surprised except for those who had foreseen this situation at the meeting held in August 1970.
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THE ECOLOGICAL IMPLICATIONS OF THE NEW SITUATION AT RICHARDS BAY In modern economic planning benefits and disadvantages must be constantly weighed up against each other. In former years, relatively little t h o u g h t was given to the ecological implications of coastal development in Natal, because of the tremendous regenerating power of vegetation and apparent environmental resilience in this sub-tropical region and also because the Province has so many estuaries and river m o u t h s t h a t degradation of one or other system did n o t seem to matter all t h a t much. However, three bodies became increasingly concerned with the progressive and cumulative degradation of the coastal environment, in particular of estuaries, and began voicing their concern ever more intensively over the past five years. These were the Town and Regional Planning Commission of Natal, the Natal Parks, Game and Fish Preservation Board and the Oceanographic Research Institute, Durban. The two former bodies have statutory status and carry responsibility for co-ordinated planning, land usage and conservation in the Province. The Oceanographic Research Institute is particularly interested in environm e n t ] f o o d w e b interaction and, with the financial support of the two former bodies and the CSIR, carries o u t intensive research in the estuarine and nearshore marine environments in Natal. This is an on-going task and is conducted in close collaboration with a number of universities and other research institutions. An overriding realization emanating from the joint work of these organizations is that it is erroneous to consider estuaries as individual entities and that they must be seen in the c o n t e x t of Natal's overall estuarine environment. It is only through the latter concept that a meaningful picture of the optimal utilization potential of this environment can be obtained and also of the overall degree of degradation which can be tolerated. This latter aspect gives reason for grave concern and it is in this light that the situation in Richards Bay will now be discussed. (a) Champion (1970) described the life history of the prawn P e n a e u s indic u s and associated species pointing o u t t h a t the juveniles move into estuaries, find shelter and food amongst the roots of marginal vegetation and amongst benthic macrophytes, grow to sexual maturity and then move out to sea again to spawn. Wallace and Van der Elst (1975) describe a similar situation for teleost fishes emphasizing how the reproductive cycles are adapted to coincide with the seasonal opening and closing of estuaries and river mouths. In section 2 of their paper mention was made of the pronounced longshore water movements along the Natal coast as well as of the exposed conditions with regard to ocean swell. It stands to reason t h a t delicate juvenile forms of life would either be carried away by currents or destroyed if t h e y c a n n o t
313
find suitable estuarine conditions at the right stage in their life cycle. ~e~ydorn {1973) has described the situation of estuarine and marine interdependence in Natal in greater detail. It is clear that estuarine degradation must have deleterious effects on marine life which, in adult form, are not associated with estuaries. Although quantitive data are not yet available it is highly probable that declining trends in Natal's game and reef fish populations (Van der Elst, in preparation) can be attributed in part to reduced availability and accessibility of estuarine nursery areas. As Durban Bay has lost much of its biological viability due to pollution and loss of vegetation, and the harbour section of Richards Bay is likely to go the same way, the incredibly rapid siltation of the Richards Bay sanctuary area is viewed with much concern. (b) Siltation from the Umhlatuzi River is, however, n o t the only source for concern regarding the sanctuary area of Richards Bay. The new m o u t h scoured far more rapidly than anticipated by the hydrologists and engineers who designed it due, to a large extent, to the unscheduled floods of summer 1976/77. Consequently the tidal regime has changed drastically to the detrim e n t of mangroves and swamp forests bordering the sanctuary. Furthermore, sanding up in the sanctuary is also taking place as a result of marine sand being transported in through the new mouth. In due course it is expected that the m o u t h itself will sand up and approach a configuration closer to that of the original m o u t h of the bay. In the meantime, optimistic forecasts that the new sanctuary would retain the characteristics of the original Richards Bay, but on smaller scale are not materializing. '(c) Pollution monitoring is being carried out by the CSIR in the harbour section and at this stage is n o t excessive. Effluents from a large aluminium and a large fertilizer factory on the periphery of the harbour are carefully treated and checked. Coaldust is a problem but also under control at this stage. However, as industry expands around the new harbour city, pollution will increase and the biological productivity of the harbour section will decrease accordingly. The tidal gates in the berm wall are of obvious benefit during extreme water level conditions but t h e y do also represent a means whereby pollution from the harbour can reach the sanctuary. (d) The sugar industry established on the Umhlatuzi floodplain is also deeply concerned about the ecological changes taking place in the sanctuary area. On the one hand the straightened river flows at much greater velocity through a course unprotected by natural vegetation. Much of the silt in the new delta shown {Fig. 6), represented valuable sugar cane land before the floods. The belated realization t h a t the sugar cane fields should never have been established on the floodplain, that river courses should not have been changed when the swamps were drained and that ecologists had warned against the dangers of further canalization do not help the farmers of the
314
Fig. 6. Aerial photograph of Umhlatuzi floodplain and Richards Bay sanctuary area, April 1977.
315
region at this stage. One really does not know where the answer lies because the Umhlatuzi will continue to try and meander through its original floodplain -- endangering the sugar fields and road bridges. Farmers are also concerned because saltwater from the sanctuary can "back u p " into their lands during spring tide conditions. Dams in the catchment to control river flow are only a partial answer because of the magnitude of floods occurring m Natal. Canalizing the river in concrete would be excessively expensive and upset seepage patterns basic to the type of soil found in swamps or floodplains. A solution other than allowing the sugar cane fields to revert to their original swamp condition is n o t in sight at present and quite apart from practical problems this will hardly be acceptable to the sugar industry. (e) What is happening is that the new delta is being rapidly covered by swamp vegetation and in part by mangroves. Given time to develop, it will take on a filtering action and in due course the whole sanctuary area will presumably become a swamp through which the Umhlatuzi River will again meander towards the sea. It is already attracting m a n y birds including flamingoes, pelicans, herons and numerous species of waders. It will become biologically productive as a swamp but n o t as an estuary. Nevertheless inlets in the swamp should provide at least some shelter to juvenile marine organisms. In other words, nature is reshaping itself according to the new situation created by man. If this process is allowed to continue the future of the sanctuary area of Richards Bay in terms of natural food production and aesthetic value will not be w i t h o u t hope. It will not, however, be what it was designed to be -- an estuarine sanctuary to make good, at least in part, the disruption to marine and estuarine life brought about by harbour construction.
CONCLUSION The story of Richards Bay will probably go down in history as a classical example of severe problems created through human manipulation of an envir o n m e n t w i t h o u t due consideration for its sensitivities. The harbour itself is an u n d o u b t e d success but it must be admitted that the concept of an associated water area as an estuarine sanctuary is a failure. The sugar farmers of the Umhlatuzi floodplain have been left with an enormous problem -- partly created by themselves but vastly accelerated by the river canalization. The already heavily degraded estuarine environment of Natal has suffered m~other severe setback and the same applies to the food producing potential of the coastal waters of the Province. The loss of the sanctuary as an import a n t recreational outlet for a rapidly growing population cannot be shrugged aside. That the loss of the sanctuary area is a further blow to the tourist
316
i n d u s t r y w h i c h is o f such vital i m p o r t a n c e t o t h e coastal regions o f Natal can also n o t be d i s p u t e d . F r o m the big plus o f the success o f R i c h a r d s Bay h a r b o u r a w h o l e string of minusses m u s t be s u b t r a c t e d if t h e u l t i m a t e b e n e f i t is to be calculated. As m a n y o f the minusses are intangible an empirical c a l c u l a t i o n is n o t possible at this stage In t h e s h o r t t e r m , t h e benefits p r o b a b l y o u t w e i g h the disadvantages b u t in the long t e r m the picture m a y well be d i f f e r e n t because o f the serious implications o f progressively declining f o o d resources f o r a r o c k e t i n g h u m a n p o p u l a t i o n . A t t h a t stage t h e f a c t t h a t a s o u n d e c o n o m y c a n n o t be built o n a d a m a g e d e n v i r o n m e n t will finally be b r o u g h t h o m e . In this cont e x t the s t o r y o f R i c h a r d s Bay is relevant t o all h u m a n e n d e a v o u r .
REFERENCES Bang, N.D. and Pearce, A.F., 1978. Physical oceanography. In: A.E.F. Heydorn et al. Ecology of the Agulhas Current region: An assessment of biological responses to environmental parameters in the southwest Indian Ocean. Trans. R. Soc. S. Afr., 43 (2): 151--190. Carter, R.A., 1977. The distribution of Calanoid Copepoda in the Agulhas Current system off Natal, South Africa. Unpublished M. Sci. thesis, University of Natal, Durban, 165 pp. Champion, H.F.B., 1970. Aspects of the biology of Penaeus indicus (Milne Edward) with notes on associated Penaeidae occurring off Natal on the east coast of South Africa. Oceanography in South Africa -- 1970, Durban, 4--6 Aug. 1970, (G1): 1--17. Heydorn, A.E.F., 1973. The interdependence of marine and estuarine ecosystems in South Africa. S. Afr. J. Sci., 69(1): 18--24. Heydorn, A.E.F., 1977. Agriculture and earthworks -- Death knell of Natal's estuaries. Afr. Wild Life, 31(6): 27--30. King, L.C., 1967. South African scenery: A textbook of geomorphology. Oliver and Boyd, London, 308 pp. Millard, N.A.H. and Harrison, A.D., 1951. The ecology of South African estuaries, 5. Richards Bay. Trans. R. Soc. S. Afr., 34(1): 157--179. Wallace, J.H. and Van der Elst, R.P., 1975. The estuarine fishes of the east coast of South Africa, 4. Occurrence of juveniles in estuaries; 5: Biology, estuarine dependence and status. Invest. Rep. oceanogr. Res. Inst., (42): 1--63.
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