Mat-like phenomenon on Dunnet beach is ‘free-floating algal species’
Highland Council has given an assurance that there are no health concerns over a strange mat-like substance spreading across a large expanse of Dunnet beach.
The phenomenon – which at first glance looks like saturated rolls of carpet stretching into the distance – has been identified as a floating or stranded algae which is a natural feature of the environment.
Walkers were puzzled when they encountered the algae on the beach on Sunday.
It had the consistency of saturated cardboard or thin matting, some of which was starting to disintegrate. Small sections could be picked up by hand.
After seeing a series of photos, a spokesperson for Highland Council explained: “These large mats are caused by a particular filamentous red algae known as Spermothamnion repens.
“This is often found much further south in the UK. It is a naturally forming, free-floating algal species and not caused by any pollution problems, as many people think.
“The natural gyre [circulating sea current] in Dunnet Bay allows this free-floating species to easily photosynthesize as it tumbles around in the shallow water, causing huge rafts of red algae to be produced.
“After some weather events lots of these algae can wash up on the sand and dry into the mats, as shown in the photographs. It can be a little unpleasant to walk through when still wet on the beach, or swim through when in the water.
“There are no health concerns associated with this floating or stranded algae and it is a natural feature of the Dunnet Bay environment.”
Dorcas Sinclair, from the voluntary group Caithness Beach Cleans, said: “This seems to be a natural phenomenon that we have observed over the last 30 years – it has probably been there forever.
“There has never, to our knowledge, been a problem with it apart from being a nuisance when litter-picking. It is easily avoided as it tends to be in certain parts of the beach.”
A spokesperson for the Scottish Environment Protection Agency said: “Our team have been out to investigate and they’re satisfied this is naturally occurring seaweed/algae.
“We’re not aware of any environmental impacts at the beach.”