Black mussels cover a South African beach

Black mussels

Black mussels wash ashore on a South African beach. Photo is a screen grab from the video

A stretch of Rodderg Beach in South Africa turned into "mussel beach" recently when hundreds of thousands of black mussels washed ashore in a mystery that has local officials searching for the reason why.

The beach in Plettenberg Bay was covered with the black mussels over a 325-yard section. Some believed it was caused by a red tide, a harmful algal bloom, but marine experts dismissed that possibility.

Dr. Mark Brown of Nature's Valley Trust told The Herald of Port Elizabeth, South Africa, that the massive beaching is not linked "to red tide or anything sinister at this stage."

Instead, Brown believes the black mussels were dislodged by heavy seas.

"A similar event happened in November last year in the same spot," Brown told The Herald. "Essentially large swells and currents break beds of mussels off the reef and they wash up."

Earth Touch has a video report showing the massive black mussel beaching:

Marine ecologist Kyle Smith of SA National Parks told The Herald that along with heavy swells, a large amount of sand movement might also have been a contributing factor.

"Most of the mussels were still alive when they washed up, which lowers the possibility that it is related to some form of toxin from either a red algal bloom or other source," Smith said.

As a precautionary measure, officials warned people not to eat the black mussels, tempting as it might be.

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