Effects of water source and mixing on phytoplankton dynamics within a tidally influenced system

Abstract

Phytoplankters are primary producers and an important energy source within pelagic nearshore habitats. The growth of these organisms is affected by riverine-oceanic interactions. A measurable interaction over 24 hours is the density difference between these water sources, where less-dense riverine water is warmer and has lower salinity. Ebb currents enhance the advection of riverine output, placing it on top of the oceanic water and creating stratification. Primary production increased during stratification periods, but reduced when transitioning between a flood and ebb current. Visual analysis of phytoplankton community composition also highlighted increases in the population during high ebb and flood current rates. The large increase in Skeletonema population during this study suggested that the movement or growth of certain phytoplankton genera are affected by these water source interactions. This study concludes that since changes happen within the water column over a short period of time, an entire tidal exchange must be monitored before any conclusions can be made about the water column or its occupants.