A Historical Perspective on Eutrophication in the Pensacola Bay Estuary, FL, USA

In this chapter, we provide a brief description of the Pensacola Bay estuary, examining the available historical data for evidence of trends in eutrophication within the estuary. Common to many industrialized estuaries, Pensacola Bay has been subjected to unregulated point sources of nutrients and other contaminants, peaking during the 1950s and 1960s. Also, over the past 60 years, the region has experienced a fivefold increase in population in the watershed and a doubling of river nitrate concentrations. Today, the estuary exhibits classical symptoms of eutrophication, including extensive summer hypoxia, significant loss of sea grass habitat, and phytoplankton dynamics that respond strongly to seasonal and interannual variation in freshwater flow. Surprisingly, Pensacola Bay appears to have low nutrient concentrations, moderate productivity, and high water transparency, characteristics that appear to have persisted during a period of rapid human population growth. We find the lack of demonstrable changes in the distribution of phytoplankton biomass or distribution and severity of hypoxia during a period of increasing human population pressures enigmatic.