Four estuarine researchers have set the lions among the wildebeest by calling for a resumption of artificial river breaching, dredging and other actions that they believe are needed to delay the 'premature' transformation of South Africa's largest estuary into a permanent freshwater lake or a muddy swamp.

Debates have raged for decades over the best way to "save" Lake St Lucia, a vast and complex estuary system whose ecological health is shaped by the joint influence of fresh water and salt water.

The 70km-long lake, home to a rich variety of animals, birds and water life, is the centrepiece of the iSimangaliso Wetland Park, South Africa's first World Heritage Site and second-largest protected area after Kruger National Park.

It is also the largest estuarine lake system in Africa, serving a vital and nationally important role as a nursery ground for sea fish, prawns and other marine creatures.

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Depending on the year, the season and other factors, the shallow waters of Lake St Lucia can be completely fresh on one hand, or many times saltier than seawater.

Yet, despite its size and protected status, the lake and its abundant wildlife have been in trouble for decades, sparking heated debates over what should be done to protect them.

Now, more than a decade after a multimillion-rand rehabilitation project to reconnect the lake to its single biggest lifeline of fresh water (the Mfolozi River) - and a decision to ensure "minimum human interference" in natural processes - a group of...