Fresh water danger for Lake St Lucia

Lake St Lucia is drying up and under pressure. That's the view of local ecologist and tour operator Kian Barker who has spoken out about his and others' growing concern over the continued closure of the estuary mouth, which is preventing sea water from entering the system.

The long-term closure of the mouth - since June 2002 - was resulting in the lake becoming a fresh water system.

A Greater St Lucia Wetland Park spokesperson said bird and animal life remained healthy despite the very low water level.

There was no shortage of grazing or fresh water for hippos, according to the park authority's Joseph Fataar, and there were many fish-feeders, especially pelicans and ducks and, during summer, huge numbers of waders, all exploiting the rich feeding.

Because of the continued low level of the huge lake, fish were concentrated in a smaller water volume, and a survey last December showed some 30 species, dominated by tilapia, which were "breeding prolifically", Fataar said.

Some estuarine fish that should move out to sea to spawn and return to the lake system were unable to do so because of the closed mouth.

Park ecologist Ricky Taylor said salinity levels fluctuated depending on evaporation and increased fresh water inflow or rainfall, and salt levels were higher in the northern reaches of the lake.

Barker said his concerns over the continued closure of the estuary mouth were shared by other experts.

St Lucia was turning into a fresh water lake and fresh water species were starting to invade a traditional estuarine area.

He said ncema grass was growing near the mouth and fresh water weeds were beginning to colonise in the lower section of the estuary.

Barker believed the lake level had been allowed to drop too far. If water was allowed to enter slowly, this would avoid a sudden blast bringing a lot of silt into the system.

Source: www.iol.co.za