Effects of Changes in pH on Transparency and Thermal Regimes of Lohi Lake, near Sudbury, Ontario

Abstract

Changes in Secchi transparency (depth) and thermal regimes accompanying experimental neutralization and subsequent re-acidification of Lohi Lake, near Sudbury, Ontario are described. Secchi depth was not correlated with chlorophyll concentrations, phytoplankton biomass or total phosphorus, but it was negatively correlated with pH. Secchi depth was positively correlated with thermocline depth, epilimnetic thickness, and hypolimnetic heating rates suggesting that acidification should result in deeper mixing zones and warmer hypolimnia in lakes. Several possible implications of changes in transparency and thermal regimes produced by acidification are presented.