A BIOCHEMICAL PROFILE FOR PREDICTING THE CHRONIC EXPOSURE OF SHEEP TOMICROCYSTIS-AERUGINOSA, AN HEPATOTOXIC SPECIES OF BLUE-GREEN-ALGA

Sheep which grazed on the shoreline of a freshwater lake which had a t oxic bloom of Microcystis aeruginosa were studied for evidence of chro nic poisoning, and a serum biochemical profile was developed to indica te sub-lethal, chronic poisoning in the sheep which had been exposed t o microcystins. The profile included measurements of glutamate dehydro genase (GLDH), gamma-glutamyl transferase (gamma GT), bile acids, bili rubin and albumin. Of 18 sheep which were exposed to M aeruginosa for more than three months, 100 per cent had high serum concentrations of bile acids, 94 per cent had high activities of GLDH and gamma GT, 83 p er cent had high bilirubin and 72 per cent had low albumin concentrati ons compared with the median values of unexposed animals. Other sheep which were exposed for shorter periods, showed evidence of hepatic inj ury after one week of exposure. The majority of the sheep showed no pr eference for an alternative, uncontaminated source of water.