Spiggie Loch. Shetland Islands Council’s environmental health team issued a warning yesterday (Wednesday) after blue-green algae was found in Spiggie Loch. Other affected areas are the Loch of Voe; the Loch of Cliff in Unst; Loch of the Ayre in Yell and the Loch of Aithsness. Blue-green algae at Spiggie Loch. Blue-green algae exist in fresh waters throughout the world, but are only noticed when their concentrations increase to form blooms or scums, which look like blue-green paint, or when they collect on the shoreline.