HUNDREDS of dead fish have been found in the waterways around Marina da Gama, and residents have raised the alarm.
Residents say they are unhappy with the lack of communication from authorities including CapeNature.
Marina da Gama, near Muizenberg, is surrounded by water channels of the Zandvlei Estuary Nature Reserve.
Rob MacLean, who has been living in the area for the past 27 years, said that although fish had died in the water before, this was the worst incident yet. “There were hundreds of dead fish in the water.”
The fish also attracted a lot of seagulls and the water had turned “reddish-brown”.
MacLean said he was in charge of ensuring the waterways in the area were properly looked after, and the lack of response did not help, while he was receiving calls and e-mails from residents to which he could not reply.
Another resident, Paul West, took pictures of some of the dead fish.
Belinda Walker, mayoral committee member for environmental, economic and spatial planning, said that on Thursday, March 22, they received reports of fish dying in the area.
An inspection by nature reserve staff revealed that, while there were some dead fish in the Marina da Gama channels, the fish in the main vlei seemed unaffected.
Fish samples taken to the Department of Agriculture, Forestry and Fisheries revealed oxygen depletion in the water was probably the cause.
“Cape Town’s wetlands are naturally low-nutrient systems, but now receive high levels of organic nutrients from urban run-off. This build-up of organic nutrients, combined with the weather conditions at Zandvlei over the previous week – including very hot days – could have caused an algae bloom leading to oxygen levels being very low.
“This would also account for the brown colour of the water and limited clarity,” Walker said.
The dead fish had been a very small percentage of the Zandvlei population. There was no evidence to suggest the situation was deteriorating, and the water body seemed to have corrected itself over the weekend. Contingency plans were put in place on Friday in case the situation reached a level warranting immediate intervention.
The city would continually monitor the situation and continue to remove dead fish.
Liesl Brink, spokeswoman for CapeNature, said they were assisting the City of Cape Town and stakeholders to set up an estuary management plan in Zandvlei. It would include investigating the various problems at the estuary and mapping out a sustainable way forward.