A spokesperson from the Scottish Environment Protection Agency (SEPA) said:
“Every day SEPA works to protect and enhance Scotland’s environment. SEPA has received a number of reports of scum washing up on beaches in the Firth of Forth.
“SEPA Officers have carried out an investigation in response to these complaints and have taken samples which confirm that this is the result of two different kinds of natural phenomenon.
“Our samples show that the substance at Silver Sands Aberdour is pollen and that the substance at Portobello is phytoplankton. This week conditions have been perfect for the phytoplankton to grow and the breeze has been in an onshore direction. Whilst these scums may be unpleasant to look at and may smell bad, they are not a health hazard to swimmers or dogs.
“If you’re not sure what you’re seeing, or are at all concerned, please do contact our 24 hour pollution line on 0800 807060 so we can investigate.”