A LARGE area of brown marine algae left much of the sea on Bournemouth’s shoreline looking decidedly murky at the weekend.

Some suggested that it may have been linked to the recent £3.6million council project to replenish the town’s beaches by pumping in an extra 320,000 cubic metres of sand.

Concerned Daily Echo readers sent in pictures, fearing the material may have been toxic for swimmers after lifeguards failed to supply an explanation for the unusual sea colouring.

But the borough released a statement on Saturday confirming the matter posed no risk to the public.

“Following some recent reports of frothy, discoloured water on the south west coast shorelines, the Environment Agency have taken samples, which are found to be harmless and non-toxic to humans and dogs,” the statement said.

“This is a marine algae which onshore winds are forming into the froth being reported.”

John Hourston, of campaign group the Blue Planet Society, took a striking photograph of the water near Boscombe Pier showing the sharp contrast in colours.

“I am in no doubt that it is phytoplankton,” said Mr Hourston.

“Whether it has anything to do with the beach replenishment is pure speculation.

“But the fact that it has coincided with such a large amount of material coming in from another area is suggestive that it could have been caused by the beach replenishment.

“Tonnes and tonnes of sand were brought in. This type of phytoplankton can thrive because of anthropogenic causes, as well as sea temperature and various other things.”

Dorset naturalist and wildlife photographer, Steve Trewhella, said there has been a May bloom of algae stretching across the county’s coastline.

He said, however, that the recent sand replenishment scheme may have added to the problems.

“If you throw a handful of sand into a bucket of water, it doesn’t stay clear for very long, so you can imagine what it does on the seabed,” Mr Trewhella added.

“You notice it more when you are diving. The sea looks calm but you get underneath and it’s terrible – you can’t see your hands in front of your face sometimes it is so thick.

“I wouldn’t want to be diving within 10 miles of Bournemouth at the moment because of that.”