BIOLOGICAL RECOVERY OF AN ACID LAKE AFTER REDUCTIONS IN INDUSTRIAL EMISSIONS OF SULFUR

THERE is now considerable evidence from Canada1-4, Norway5, Sweden6 and Scotland7 that lake and stream acidification is chemically reversible. Water quality improvements have been shown to occur rapidly when inputs of sulphur are reduced8. However, there is little evidence that biological systems recover after emission reductions9. We report here on changes in the biological community of an acid-stressed lake near the metal smelters at Sudbury, Canada, during a 10-year period (1978-1988) after smelter emissions of sulphur were reduced by more than 50%. Our studies of the fish, benthic invertebrates, and zooplankton in this lake show that rapid recovery and reinvasion occurs among some acid-sensitive species. © 1990 Nature Publishing Group.