Reminder of blue-green algae risks

Joint news release NHS Highland - The Highland Council

The Highland Council and NHS Highland are issuing a reminder to people to be on the lookout for blooms of potentially hazardous blue-green algae (also known as Cyanobacteria) in the region’s lochs and rivers.

Blue-green algae occur naturally in lochs, ponds, reservoirs, rivers and in the sea. Sometimes the blue green algae can form blooms which can release toxins into the water. They are a common seasonal occurrence and blooms occur across the Highlands fairly regularly each year. However, during this current period of prolonged warm weather, the chance of blue-green algae affecting water courses increases significantly.

In still waters, the algae can multiply during the summer to such an extent that they discolour the water making it appear green, blue-green or greenish brown.  Shoreline mats of blue-green algae may appear and are usually coloured brown to black. Sometimes a scum may form on the surface of the water. This scum can appear in different places at different times, but is most commonly found near the shoreline.

Contact with blue-green algae can have health effects for humans and animals. The health effects on people coming into contact with toxic scums include skin rashes, eye irritation, vomiting and diarrhoea, fever and pains in muscles and joints. The toxins, which may be produced by the algae, are also poisonous to animals and can cause severe illness and death of livestock, dogs, waterbirds and fish.

The Highland Council and NHS Highland are advising the public, especially dog owners, to be alert to the blooms as temperatures rise. It is advised that people avoid contact with the algal scum and the water close to it. The risk posed by blue-green algae to small animals like dogs is significant over the summer months as they tend to drink more water in the heat and may eat shoreline algal crusts. Dog owners should prevent their pets from coming into contact with water which could be affected.

Fish caught in waters affected by blue-green algae should not be eaten and should not be fed to pets.

The Council’s Environmental Health team and the Health Protection team at NHS Highland will respond to incidents of illness related to Blue Green algae working with colleagues in SEPA and Scottish Water.

You can also download the Bloomin’ Algae app and help monitor blooms across Scotland and the UK.

Background information

22 Jun 2020