Image: Sharyn Hodges via Twitter
Ecologists think they know why 11.5 million clams washed up on Robberg Beach in Plettenberg Bay in the Western Cape last week.
The dedicated marine team of Nature’s Valley Trust, a non-profit organisation focusing on marine conservation and research in Plettenberg Bay and surrounding areas, said the washouts had become an annual event.
In a statement the marine team said: “The most plausible reason is that strong easterly swells and winds cause a large disturbance in the sand banks in which these clams usually reside.
“The turbulent water movement may prevent the clams from being able to burrow back and thus become subject to wave action and consequently wash out on to the beach.
“What we don’t know is why there are so many clams in the area, and why these strong winds are now causing them to wash out.”
The Marine Tourism Sustainability Project team and SANParks have quantified the clams (Mactra glabrata) through surveys which looked at the extent of the washout.
According to their calculations the recent washout extended to 5,875m² with the average number of clams in the deepest section (more than a metre deep) at 35,300m³.
The washout has left tons of protein on the beach and scavenger activity is expected.
Courtesy of timeslive.co.za
Tim Dibble of the Department of Conservation and Recreation used a tractor while burying Atlantic surf clams on Revere Beach in Revere – Photo by Craig F. Walker/Globe Staff
Hundreds of thousands of Atlantic surf clams washed up on Revere Beach in recent days, creating a strange spectacle on the popular seashore Wednesday and a foul-smelling coda to the summer.
Authorities were trying to determine the cause of the mass die-off. Just before midday, as waves crashed nearby, bulldozers dispatched by the state Department of Conservation and Recreation dug large trenches in the sand to bury the juvenile shellfish in an “environmentally friendly manner.”
It was the third and largest event of its kind involving surf clams this summer, and similar events have occurred in the last 10 years at Nantasket Beach Reservation and Ipswich Bay, the DCR said.
The Division of Marine Fisheries is analyzing the clams and expects to have preliminary results in the coming days that might point to a cause.
“I’m puzzled by this,” said Bruce Berman, a spokesman for Save the Harbor/Save the Bay, an environmental advocacy group. “There have been shellfish kills, and they’re increasing in my opinion, as we deal with results of climate change.”
The changing water temperatures and fresh/saltwater mix of the ocean could have killed the “particularly sensitive” clams, said Berman, who was at Revere Beach on Wednesday morning. He also said a particular type of algae could have clogged the gills of the clams and caused them to suffocate.
“The extent and duration of this event are fairly unique in my experience, though that doesn’t mean they’re unique in the world,” Berman said. “But if they keep coming up on the beach every tide, it’s an uphill battle.”
Courtesy of bostonglobe.com