In Recovery – Lake St Lucia re-imagined      

The talk on the above subject   by Nicolette Forbes, had the full house of members riveted for the duration of her speech which was well supported by clear and informative maps of the changes to this endangered heritage site which makes up 63% of all estuary area in South Africa.

 Fortunately the established and recognized management practices were exposed in in the recent droughts, as unsustainable and scientifically wrong. Nicolette has played a major role in taking on the establishment   with strong scientific evidence and resorting to the courts to restrain the prevailing practices. 

 Essentially the farmers with the support of the previous environmental officers diverted the original course of the Umfolosi River by breaching the dunes and allowing the fresh water to escape into the sea and bypassing the La Lucia Lake system . The Umfolosi river catchment is bigger than the combined catchment of the other four main rivers feeding the lake, all of which have been compromised upstream. Excluding this water from the system proved disastrous in drought years and more recently the system all but dried up. Sea water has a salinity value of 35 whilst Lake St Lucia reached a salinity value of 300 in the drought. This was disastrous for fresh water fish of creatures able to only live in brackish water. Even the commercial fishermen along the coast saw fish stocks depleted due to the elimination of the natural estuarine nurseries. The alteration of the estuary by sugar farmers was started in the early 1900’s and one of the justifications was that the lakes would silt up without the diversion. In 1952 the Umfolosi was permanently diverted from the lake system, and it took four years for the lakes to create its own mouth. The concrete groynes were swept away by Demoina in 1984 which alleviated the situation.

 It was in 2012 that a decision was made to allow the Umfolosi to take its natural course. It was this decision that created the conflict with the farmers who claimed their cane would be flooded and resorted to the courts. who ruled in favour of Isimangaliso.

In order to do this earth moving equipment had to remove the 9 meter high spoil dumped there by 6 dredgers over the preceding years. This involved moving 2.6 million cubic meters of sand. This was a huge financial burden, however Andrew Zaloumis managed to raise 64 million rand to complete this work and the Lakes were at last reunited with the Umfolosi, its natural ally.

Fortunately the courts had supported Isimangaliso to rectify this humanitarian intervention, however she warns that vigilance is still required.   

 The rehabilitation of this World Heritage Site (1999), first started with the rehabilitation of the eastern shores and then the removal of plantations and alien trees in the direct proximity of the lake system, an area of 550 km 2.  Whilst estuary’s generally are not breeding grounds, they are the nurseries once the fish and crustaceans have entered the waters of the estuary             

SPEAKER: Nicolette Forbes

 

 A talk about the interesting past, tense present and exciting future of the Lake St Lucia estuary, in SA’s first World Heritage Site, the iSimangaliso Wetland Park, where I have led the restoration project since 2010.

The Lake St Lucia system is the largest estuary in the country.  The effects of a separate mouth policy, which removed the uMfolozi from the system in 1952, were exacerbated during the first decade of this century during a period of below average rainfall in which the lake dried up for the first time in recorded history.  More recently (2012) a decision was taken by the iSimangaliso Authority to reverse the separate mouth policy and re-link the two systems during a period when the uMfolozi mouth was closed resulting in a substantial input of fresh water into the system.  These actions have been coupled with dune management restoration and planning investigations to assist the development of a long-term policy to guide the future conservation of this World Heritage site.  To this end, LIDAR and bathymetric surveys of the system have been carried out to accurately delineate estuary boundaries and local contour lines.  The results of the physical investigations have been fed through an ecological response model to allow system health to be assessed and socio-economic consequences to be described allowing for an integrated management approach.

 

 

Nicolette Forbes 

Nicolette Forbes is an ecologist with Marine & Estuarine Research.  Having started her career in 1992 as a lecturer at the University of Natal, Durban now University of KwaZulu-Natal and working with mangroves in the estuaries of KZN, her perspective shifted to the broader environment in which the mangroves were growing and her work over the last 27 years has been focussed on the investigations of estuary function and restoration.  This work was recognised over a decade ago by the Wildlife and Environment Society of South Africa who selected her for the Conservationist of the Year Award in 2007 for her work in KZN.  Her experience has seen this accumulated research with KwaZulu-Natal coastal zone habitats, culminate in the restoration project within the iSimangaliso Wetland Park, South Africa’s first World Heritage Site.  This work, focussed on restoring key processes to this important coastal area to initiate changes in landscape level function.  The work has twice been presented internationally at the Society for Ecological Restoration Symposium in the Brazil and the Coastal and Estuarine Research Federation Conference in the USA.  More recently Nicolette and her colleague Bronwyn James of iSimangaliso were selected as the winners of the 2017 National Wetland Award in the Research and Science category which recognises “people who have made a significant contribution towards wetland scientific research providing a sound basis for informed management actions which strengthen water security”.

SA National Society Meeting 13 May 2019