Influences of river flow on the dynamics of phytoplankton production in a partially stratified estuary

Abstract

The mesohaline reach of Chesapeake Bay (USA) recelves most of its allochthonous nutnent input from a single source, the Susquehanna h v e r Seaward of the turb~dity maximum, concentrahons of dissolved inorganic nutrients decrease rapidly as phytoplankton b~o m a s s Increases along the s a l i~t y gradient The annual cycle of nverine nutrlent input is In phase with phytoplankton biomass but out of phase with phytoplankton productivity In tfus region kverlne nutnent Input and phytoplankton blomass peak dunng spring but phytoplankton produchvlty peaks dunng summer Seasonal variahons in biomass are correlated \mth rivenne rutrate input whlle seasonal vanations in produchvlty are correlated w t h light and temperature Evldence 1s presented w h~c h suggests that the spnng flux of nitrogen from the watershed and the summer productivlty maxlmum are coupled via the accumulahon and sedlmentahon of phytoplankton blomass dunng sprlng and subsequent recycling of regenerated n~trogen Into the euphotic zone during summer We conclude that the occurrence of maxlmum productivity dunng summer in the mesohahne reach of the Bay is a consequence of the recycling of nitrogen dehvered to the system durlng the previous spnng Inter-annual variations In the magmtude of the summer productivlty maximum appear to be related to variahons in vertical stratdicahon which influences the vertical flux of regenerated ammonium from the benthos to the euphotlc zone In this context the extent of seasonal oxygen depletion dunng summer appears to be determined by nverlne mtrate input durlng the spring freshet and the strength and variabihty of vertlcal stratification dunng summer

Source, biogeochemical cycling, and fluorescence characteristics of dissolved organic matter in an agro‐urban estuary

“…The seasonal movement of the salt wedge and associated density stratification in microtidal estuaries has been identified as an important factor regulating phytoplankton production, and regeneration of NH 4 and inorganic P (Hayward et al 1982;Malone et al 1988;Sellner et al 2001). In our study, peaks in NH 4 and TP concentrations also coincided with the advance of the salt wedge into the middle and upper estuary.…”

Modeling the seasonal autochthonous sources of dissolved organic carbon and nitrogen in the upper Chesapeake Bay

“…Moreover, they were set a priori and so were not used for any major tuning of the model. Mortality rates for phytoplankton were increased in the spring and fall to account for sinking and sedimentation following the spring bloom (Malone et al, 1996(Malone et al, , 1988 and mixing of the water column associated with the fall overturn (Boicourt, 1992). Mortality rates for zooplankton were increased during the summer and early fall to reflect high seasonal predation by ctenophores (Stoecker et al, 1987) and the jellyfish Chrysaora quinquecirrah (Baird and Ulanowicz, 1989;Purcell, 1992).…”

The Effects of System-Level Nutrient Enrichment on Bacterioplankton Production in a Tidally-Influenced Estuary**

“…Based on the primacy of temperature and salinity in driving the variability of environmental conditions in SWMP data and the important role of these parameters in regulating the composition, abundance, and activity of planktonic microbes (APPLE, DEL GIORGIO, and KEMP, 2006;COTTRELL and KIRCHMAN, 2003;LOMAS et al, 2002;MALONE et al, 1988;SMITH and KEMP, 1995), we explored their effect on biological processes using BP : CHLA ratios as a response variable. Our analyses of literature data showed that both temperature and salinity are important factors influencing the covariation of BP and algal biomass, with no evidence that dissolved nutrient concentrations influenced this relationship (analyses not shown).…”