Abstract
Louisiana estuaries are important habitats in the northern Gulf of Mexico, a region undergoing significant and sustained human- and climate-driven changes. This paper synthesizes data collected over multiple years from four Louisiana estuaries – Breton Sound, Terrebonne Bay, the Atchafalaya River Delta Estuary, and Vermilion Bay – to characterize trends in phytoplankton biomass, community composition, and the environmental factors influencing them. Results highlight similarities in timing and composition of maximum chlorophyll, with salinity variability often explaining biomass trends. Distinct drivers for biomass versus community structure were observed in all four estuarine systems. Systems shared a lack of significant correlation between river discharge and overall phytoplankton biomass, while discharge was important for understanding community composition. Temperature was a significant explanatory variable for both biomass and community composition in only one system. These results provide a regional view of phytoplankton dynamics in Louisiana estuaries critical to understanding and predicting the effects of ongoing change.
•Resolution of environmental drivers for both biomass and community composition•Generally, biomass was tied to salinity, while assemblage structure was linked to discharge.•No system exhibited identical drivers for both biomass and community.•One system showed a unique relationship with temperature for biomass and community structure.•Results help set a baseline against which effects of ongoing estuarine change can be compared.
