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PLETTENBERG BAY NEWS - Millions of clams washed up on a stretch of Plettenberg Bay's coastline over the past week following what experts have described as the "perfect storm".
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The washout of these clams on especially the Robberg stretch of beach has become somewhat of an annual event in recent years, leaving scientists seeking answers.
Local marine biologist Gwen Penry said they have noticed that the clams usually wash up following strong easterly winds. "We believe this causes some upwelling below the surface resulting in the clams dislodging from their homes – where they live between 20 and 30cm below the sand – and subsequently washing out," Penry said.
Plettenberg Bay experienced strong easterly winds for three days before the clams started to wash up.
She added that the winds also brought about a sudden change in water temperature leaving the clams unable to function properly, which added to the occurrence.
The turbulent water movement may also prevent the clams from being able to burrow back and thus become subject to wave action and consequently washing out on the beach.
'Severe circumstances'
According to Penry, SA National Parks' Kyle Smith has taken the lead in establishing the reasons for these occurrences. Samples have been sent to a laboratory for testing to rule out any other causes.
"This doesn't happen every time we experience easterly winds. We believe it is a combination of severe circumstances which leads to the clams washing up."
Nature's Valley Trust (NVT) director Dr Mark Brown said what they do not know is why there are so many clams in the area and why the strong winds have now been causing them to wash out. On Wednesday 13 March, the NVT marine team assisted Smith in undertaking a survey and data collection in an attempt to quantify the biomass of the washout along Robberg Beach. These results revealed that the extent of the washout was 5 875sq m.
The average number of clams in the deepest section – more than a metre deep – was 35 300 per cubic metre, and the number of clams in the entire washout was about 11.5-million. This created an enormous amount of protein for scavengers to feed on and left a stench across some parts of Plett.
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