5th UF Water Institute Symposium Abstract

Submitter's Name Mark Hoyer
Session Name Impacts of Climate Variability and Change on Water Availability and Quality
Author(s) Daniel Canfield,  UF
  Mark  Hoyer,  UF (Presenting Author)
  Long-term Changes in Water Quality at an Outstanding Florida Water System: Importance of Stochastic Events and Climate Change due to the Atlantic Multidecadal Oscillation
  Since 1986 citizen scientists from the Florida LAKEWATCH program have monitored nutrient concentrations (total phosphorus and total nitrogen), algal biomass (chlorophyll) and water clarity (Secchi transparency) at Little Lake Santa Fe, Lake Santa Fe and Melrose Bay, an Outstanding Florida Water system (OFW). Designating the Santa Fe Lake system as an OFW was to provide special protection to prevent impairment of water quality due to anthropogenic activities, but during 2007 measures of lake trophic state surged upward and water clarity decreased. The sudden increase in nutrient concentrations was linked to a catastrophic, 5,100-ha, forest fire (2007 Dairy Road Fire) that occurred in the adjacent Santa Fe Swamp. Further analyses of the data documented the impact of the hurricanes that struck Florida in 2004 and the impacts of droughts during the period of record. There was also an upward trend of the yearly measured minimal values for different water chemistries not only in the Santa Fe system, but also in other nearby lakes. Regional changes suggested in-lake changes were related not just to specific stochastic events or anthropogenic activities, but also to long-term climatic change. Changes within the 28-yr database at the Lake Santa Fe system were linked to the Atlantic Multidecadal Oscillation (AMO), causing Florida to enter a period of cumulative rainfall deficits since the 1980s. Trends in water quality at the Lake Santa Fe system could, therefore, reverse if Florida enters a period of increasing cumulative rainfall surpluses with a shift in the AMO.