People have been asked to be cautious when visiting lochs and burns around the isles as blue-green algae may be present.
Due to ongoing Covid-19 restrictions, the Scottish Environment Protectin Agency (SEPA) has not been able to carry out any regular water testing of any lochs suspected of containing the growth.
Shetland Islands Council, which regularly issues warnings over the algae, said it could be present in “lochs and other water bodies, especially in warmer weather”, and the public was asked to exercise caution where it may be seen.
Reports had been received to date of blooms in the Loch of Brindister, Kirkhouse Water near Bixter, and Clickimin Loch at Lerwick, the council said.
A statement read: “Dogs and livestock should be kept away from these lochs to prevent any potential health effects. The public are advised not to bathe in any affected waters and fishermen should also exercise caution.”
People are requested to make reports of sightings by contacting the local environmental health team on (01595) 745250, by email at email@example.com or via Facebook.
The environmental health service will take appropriate practical action and the list of affected lochs will be added to a webpage at www.shetland.gov.uk/environmental_health/publichealthalerts.asp
People can also report any sightings of blue-green algae using an app developed by the UK Centre for Ecology and Hydrology, available at www.ceh.ac.uk/algal-blooms/bloomin-algae where further information can be found.