Differential supply of autochthonous organic carbon and nitrogen to the microbial loop in the Delaware Estuary

Parker, Alexander E.

doi:10.1007/bf02696015

Cited by 16 publications

(9 citation statements)

References 28 publications

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“…Regarding other estuarine systems, bacterial ammonium uptake rates found in the North LW treatment are similar to those found in the Delaware Estuary using the same experimental approach (Parker, 2005) and those reported in a Mediterranean coastal lagoon using eukaryotic inhibitors (Trottet et al, 2011). It has been described that when substrate enrichments are below 50 % of the nutrient in situ concentration, uptake rates must be regarded as real.…”

Section: Discussionsupporting

confidence: 78%

“…The positive and significant correlations found between bacterioplankton and phytoplankton NH 4 + uptake rates support this finding, suggesting that this process was coupled between these communities in the North of Laguna de Rocha. Coupling in the ammonium uptake by phytoplankton and bacterioplankton has also been reported in other estuarine environments as the Delaware estuary (Parker, 2005) or coastal waters (Bradley et al, 2010).…”

Section: Discussionsupporting

confidence: 53%

“…In contrast, in estuaries and coastal lagoons the plankton system might have a net heterotrophic metabolism or show seasonal shifts from net autotrophy to net heterotrophy, which may be due to turbidity, changes in nutrient availability or to inputs of allochthonous organic matter (Revilla et al, 2002;Hopkinson and Smith, 2005). As a consequence, in transitional ecosystems bacteria can meet their organic matter requirements not only via primary production but also through plants leachates, macrophytes exudates or allochthonous sources (i.e., runoff, riverine inputs), which lead to a loose coupling between bacteria and phytoplankton (Parker, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Incidence of phytoplankton and environmental conditions on the bacterial ammonium uptake in a subtropical coastal lagoon

et al. 2014

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Section: Discussionsupporting

confidence: 78%

Section: Discussionsupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

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Incidence of phytoplankton and environmental conditions on the bacterial ammonium uptake in a subtropical coastal lagoon

et al. 2014

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“…Phytoplankton carbon productivity and nitrogen (NO 3 and NH 4 ) uptake rates were estimated using dual-labeled 13 C/ 15 N tracer incubations (Legendre and Gosselin, 1996;Parker, 2005 …”

Section: Detailed Methodsmentioning

confidence: 99%

Elevated ammonium concentrations from wastewater discharge depress primary productivity in the Sacramento River and the Northern San Francisco Estuary

Parker

Dugdale

Wilkerson

2012

Marine Pollution Bulletin

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a b s t r a c tPrimary production in the Northern San Francisco Estuary (SFE) has been declining despite heavy loading of anthropogenic nutrients. The inorganic nitrogen (N) loading comes primarily from municipal wastewater treatment plant (WTP) discharge as ammonium (NH 4 ). This study investigated the consequences for river and estuarine phytoplankton of the daily discharge of 15 metric tons NH 4 -N into the Sacramento River that feeds the SFE. Consistent patterns of nutrients and phytoplankton responses were observed during two 150-km transects made in spring 2009. Phytoplankton N productivity shifted from NO 3 use upstream of the WTP to productivity based entirely upon NH 4 downstream. Phytoplankton NH 4 uptake declined downstream of the WTP as NH 4 concentrations increased, suggesting NH 4 inhibition. The reduced total N uptake downstream of the WTP was accompanied by a 60% decline in primary production. These findings indicate that increased anthropogenic NH 4 may decrease estuarine primary production and increase export of NH 4 to the coastal ocean.

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“…Dugdale and Wilkerson (1986). Carbon uptake was calculated in the same manner, using measured DIC concentrations to calculate substrate enrichment (Legendre and Gosselin, 1996;Parker, 2005). We report both V and r because while the two rates are related (r is derived from V), V provides an indication of phytoplankton physiology, while r provides information on C and N flux and cycling.…”

Section: Carbon and Nitrogen Assimilationmentioning

confidence: 99%

The effect of inorganic nitrogen speciation on primary production in the San Francisco Estuary

Parker

Hogue

Wilkerson

et al. 2012

Estuarine, Coastal and Shelf Science

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Keywords:San Francisco Estuary primary production phytoplankton carbon ammonium nitrate a b s t r a c tWe describe the results of a series of 96-h enclosure experiments conducted using water from stations in the northern San Francisco Estuary (SFE) along a gradient in ammonium (NH 4 ) and nitrate (NO 3 ) concentrations. Using dual-labeled 13 C/ 15 N tracers, we followed the timing and sequence of primary (carbon, C) production and phytoplankton nitrogen (N) use during experimental phytoplankton blooms. Our results show that diatoms consistently drive the phytoplankton blooms in the enclosures. By tracing both C and N uptake we provide clear evidence that high rates of C uptake are linked to phytoplankton NO 3 , and not NH 4 , use. Results from kinetics experiments demonstrated higher specific uptake rates (V MAx ) for NO 3 compared to NH 4 in the SFE. Finally, dissolved inorganic carbon and nutrient drawdown ratios in the enclosures from the chronically high NH 4 regions of the SFE were substantially lower than predicted from the Redfield ratio, suggesting suppressed C uptake, in relation to other elemental uptake. Our conceptual model of the DIN interactions that lead to higher primary production and phytoplankton blooms in the SFE suggests that higher rates of primary production that accompany phytoplankton NO 3 uptake are sufficient to outpace phytoplankton losses, leading to blooms, compared to the lower rates associated with NH 4 uptake (only 20% of that based upon NO 3 ). Historical changes in wastewater practices have increased the proportion of NH 4 to the DIN pool in the SFE leading to reduced access to NO 3 by phytoplankton. This may help to explain some of the reduced primary production and phytoplankton biomass observed there since the 1970s.

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Differential supply of autochthonous organic carbon and nitrogen to the microbial loop in the Delaware Estuary

Cited by 16 publications

References 28 publications

Incidence of phytoplankton and environmental conditions on the bacterial ammonium uptake in a subtropical coastal lagoon

Incidence of phytoplankton and environmental conditions on the bacterial ammonium uptake in a subtropical coastal lagoon

Elevated ammonium concentrations from wastewater discharge depress primary productivity in the Sacramento River and the Northern San Francisco Estuary

The effect of inorganic nitrogen speciation on primary production in the San Francisco Estuary

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