Daniele Baker Master's Capstone November 15, 2013
Abstract: A 23-year record of limnological parameters for Onondaga Lake was used to evaluate changes during recovery from eutrophication. I (1) compared phytoplankton responses to total phosphorus (TP) in ecologically defined seasonal periods with those in a calendar date defined annual period, (2) ascertained whether chlorophyll-a (Chl-a) concentration was a good proxy for phytoplankton biomass, and (3) assessed whether the phytoplankton assemblage was altered in response to the environmental remediation. Seasonal variations in the relationships between Chl-a and biomass to TP were common. Irregular temporal patterns in Chl-a per unit biomass were due to a shift from Chl-a deficient to Chl-a rich phytoplankton, not changes in light regime. The phytoplankton assemblage varied mostly as a function of changes in total nitrogen (TN), TP, and TN:TP ratios. Phytoplankton diversity did not increase, but phytoplankton bloom frequencies and cellular biovolumes decreased. Synurophyceae and Chrysophyceae, absent since the onset of eutrophication, reappeared in 1998.