CHEMICAL AND BIOLOGICAL EVIDENCE LINKS MICROCYSTINS TO SALMON NETPEN LIVER-DISEASE

Evidence is presented that links microcystins to a severe liver diseas e that occurs in Atlantic salmon that are netpen-reared in coastal Bri tish Columbia. Liquid chromatography-linked protein phosphatase bioass ay analysis of extracts of liver tissue taken from Atlantic salmon aff licted with netpen liver disease showed the presence of an inhibitor o f protein phosphatase that was chromatographically indistinguishable f rom microcystin-LR. Analysis of liver tissue from healthy control fish showed a complete absence of microcystin-LR. Intraperitoneal injectio n of microcystin-LR into healthy Atlantic salmon re-created the pathol ogic changes of netpen liver disease, including diffuse necrosis and h epatic megalocytosis.