Abstract
Environmental mechanisms that drive changes in phytoplankton community structure remain a remarkably understudied topic in phytoplankton ecology. For this study, two seasons and four sampling sites in the Florida Keys (FK) were selected for phytoplankton analyses to test if environmental constraints select for driving taxonomic diversity. One hundred and twenty-six taxa belonging to 10 classes and 6 phyla were identified, where significant differences in taxonomic composition and biovolume characterized the FK on spatial and temporal scales, with Bacillariophyta being the most representative phylum. A small number of taxa were limited to specific sites or seasons, whereas the majority were present at all sites and in both seasons, albeit in different densities. Canonical correspondence analysis results demonstrated that taxa are distributed along seasonal and spatial gradients defined by temperature, light and waves. The resultant variability in species composition indicates that the phytoplankton community structure is related to changing hydrodynamic conditions, temperature and light availability, which define the temporal and spatial filters for the most important phytoplankton functional groups observed in this study.
