The cause of a massive fish kill in Amanzimtoti River and Lagoon on Monday, 23 March is still unclear and results of additional tests done are still awaited from eThekwini Municipality.
The municipality’s department of water and sanitation was informed of the fish kill by the National Department of Environmental Affairs’ Lungiswa Mgxwati on Wednesday, 25 March at around noon.
Neo Leburu of Water Quality Management sent the following observations to chairman of Toti Conservancy, Laura Taylor:
- Dead fish were observed in the Toti River in the vicinity of the civic centre towards the lagoon area. The dead fish were mostly tilapia.
- A sheen on the water surface was also observed around the civic centre area, but this was not visible beyond the N2 bridge on Civic Road. It was not oily to touch.
- The water appeared to have a discolouration that is darkly stained, almost like ‘black tea’.
DWS took samples for water quality, including chemical and microbiological samples, for emergency analysis and the results are still pending.
“On 26 March we took a sample for soap, oil and grease (SOG) profiling for emergency analysis and we are awaiting the results,” he said via email.
“Speaking to community members around the area, it was reported that the fish were observed jumping and tossing on the surface. Based on the observations thus far, it is unlikely that the cause of the fish kill is sewage or temperature-related.
The colour in the water could also be indicative of low pH, which can also result in tilapia mortalities.”
eThekwini head of communications, Tozi Mthethwa responded to the Sun’s queries. “eThekwini Municipality has conducted tests and the latest analysis showed that there is no sewage in the water, however the samples taken have shown high levels of oxygen.
While the fish kill cause has still not been established, it is suspected that the fish died due to algal bloom (rapid increase or accumulation in the population of algae). Investigations are ongoing.”
The conservancy was outraged it had heard nothing further regarding the cause of the fish kill.
“We have heard nothing of the outcome of various tests that have been done to determine the cause of the fish kill in the Toti Lagoon,” said Laura. “At this stage we know the following:
- It was not sewage;
- It has caused high dissolved oxygen levels;
- There was an oily sheen covering the river;
- Fish have died horrible deaths, doing back flips, but seemingly not gasping for breath;
- The numbers of fish dead were probably close to 1,000 through the lagoon system.
Other than taking samples no-one seems to be doing anything about it.”
