Biscayne Bay provides a study in contrasts. North Biscayne Bay has undergone substantial changes during the twentieth century resulting from the development of the metropolis of Miami around it while south Biscayne Bay has been relatively little affected by the dramatic human population
increase in South Florida. The phytoplankton at 24 stations throughout Biscayne Bay were examined monthly for 1 year. Phytoplankton were found to be 5 to 10 times higher in abundance in the north bay compared to the south and even more abundant near canal mouths. Eutrophication from freshwater
runoff is the likely cause of the higher abundance of phytoplankton in the north bay as well as the higher fluorescence response indices and chlorophyll to phaeopigment ratios in the phytoplankton in the north. Phytoplankton are most abundant in the north bay right after the first major rains
of the rainy season, thought to be the result of the large amounts of nutrients flushed into the bay at that time. Phytoplankton are least abundant at the end of the dry season after a long period of little runoff. Phytoplankton abundance shows virtually no seasonality in the south bay where
land runoffis relatively insignificant. The south Biscayne Bay ecosystem remains dominated by benthic macrophytes while the north bay has shifted to an ecosystem dominated by a relatively dense plankton community with few macrophytes remaining.
The Bulletin of Marine Science is dedicated to the dissemination of high quality research from the world's oceans. All aspects of marine science are treated by the Bulletin of Marine Science, including papers in marine biology, biological oceanography, fisheries, marine affairs, applied marine physics, marine geology and geophysics, marine and atmospheric chemistry, and meteorology and physical oceanography.