Scotsman: THEY have formed a succulent and nutritious part of the human diet for thousands of years. But a new report is warning that plentiful supplies of oysters and mussels could disappear over the next century because the oceans are becoming increasingly acidic. Dr John Baxter, the co-editor of an international report into the acidification of the world’s seas, said increasing levels of carbon dioxide being released into the atmosphere by industrialised countries was gradually changing the acid level…