An ecological disaster has been averted at the Seekoei estuary in Jeffreys Bay.
The Kouga Municipality’s decision to open the Seekoei’s mouth in an attempt to save fish that were trapped and dying in the salty waters of the lagoon has met with success.
“The salinity of the estuary shot up to twice that of sea water over the summer months, resulting in large numbers of fish dying,” said Kouga Community Services Portfolio Councillor Daniel Benson.
“Since the breach in June, the estuary’s salt level has almost halved, once again making it possible for estuarine life to survive.”
Benson said the municipality had submitted an application to the provincial Department of Economic Development, Environmental Affairs and Tourism (DEDEAT) in April, requesting authorisation for the breach in terms of section 30(a) of the National Environmental Management Act (NEMA).
“At that stage the situation was becoming dire. Due to increased evaporation and the lack of fresh water flowing into the estuary, the salinity had shot up and dead fish began surfacing in the shallows,” he explained.
“The water level of the estuary had also dropped to more than a metre below the causeway buttress, with only isolated pools remaining in the middle and lower lagoon.
“The Seekoei Estuary Management Committee, therefore, resolved to submit an emergency application to DEDEAT for the artificial breaching of the mouth to allow sea water to enter the lagoon and reduce the salinity, while also enabling fish to escape to the ocean.”
The breach took place over a three-week period and sea water was able to enter the lagoon over six high tides.
“The result was a dramatic drop in the salinity of the estuary, from 74 in extreme cases to 40, which is only five units more than sea water,” Benson said.
“This would suggest that good mixing of the different water masses had occurred, due to the combined effects of tidal action and gale-force south-westerly winds.”
He said that while the municipality had been able to avert disaster, sand prawns and other invertebrates had all but disappeared from the lagoon.
“We were, however, grateful to find that some sand prawns had survived near areas where there was some fresh-water seepage.”
He cautioned that the risk of re-occurrence further remained high.
“Preventing a salinity spike is one of the matters we will be addressing through the implementation of the Seekoei Estuary Management Plan, which was recently officially signed off by East Cape Environmental Affairs MEC, Gerald Mvoko.”
A report on the breach was tabled to Council at a meeting on Tuesday, July 30.