The Dynamics of Nitrogen and Phosphorus Cycling in the Open Waters of the Chesapeake Bay

McCarthy, James J.; Taylor, W. Rowland; Taft, Jay L.

doi:10.1021/bk-1975-0018.ch040

Cited by 61 publications

(34 citation statements)

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“…We estimated the potential influence of this process by comparing calculated phytoplankton demand for NH: to that supplied by sediment regeneration (Table 1). We have limited discussion to NH: because this appears to be the preferred form of nitrogen in most areas of the bay (McCarthy et al 1975). Since we did not have direct measurements of phytoplankton nitrogen demand, this was estimated by combining Redfield composition ratios with phytoplankton productivity data.…”

Section: Influence Of Sediment Processes On Estuarine Watersmentioning

confidence: 99%

Nutrient regeneration and oxygen consumption by sediments along an estuarine salinity gradient

Boynton¹,

Kemp²

1985

Mar. Ecol. Prog. Ser.

292

125

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Nutrient fluxes and oxygen consumption (SOD) across the sediment-water interface were measured in situ along with vertical profiles of dissolved and particulate-phase nutrients in sediments and overlying water at 8 locations along the salinity gradient of Chesapeake Bay during spring and summer. Strong spatial and temporal patterns were evident. Highest rates of sediment NH: regeneration and SOD occurred in summer at mid-salinity (12 to 17 %a) stations. Sediment fluxes of dissolved inorganic phosphorous (DIP) were always low, possibly due to relatively oxidized conditions in surficial sediments. Nitrate (NO;) fluxes generally were directed into the sedirnents in spring and from the sediments during summer, and in both seasons fluxes were proportional to NO3 concentrations in overlying waters. Seasonal shifts in sediment 0:N flux ratios suggest that denitrification may have been important in spring but not summer. Significant relations were inferred between C:N:P composition of suspended materials and surficial sediments and the magnitude and direction of sediment-water fluxes. Although accretion of particulate nitrogen in sediments was less than 6 % of NH: regeneration in the lower bay, it was similar to rates of NH: flux in the low salinity region, suggesting that burial represents a significant sink for N in some estuarine zones. SOD constituted an important term in water column O2 budgets at all stations (1G50 % of total respiration), and sediment regeneration of NH: was capable of supplying 13 to 40 % of calculated phytoplankton N requirement, being more important during the summer period of higher productivity.

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Section: Influence Of Sediment Processes On Estuarine Watersmentioning

confidence: 99%

Nutrient regeneration and oxygen consumption by sediments along an estuarine salinity gradient

Boynton¹,

Kemp²

1985

Mar. Ecol. Prog. Ser.

292

125

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“…The nitrogen cycle in the Chesapeake Bay, USA, has been studied by a number of workers in recent years, and the gross spatial and temporal patterns of variation in the major reservoirs of nitrogen in the Bay have been described by Carpenter et al (1969), McCarthy et al (1975McCarthy et al ( , 1977, and Taft et al (1978). The high levels of biomass and dissolved inorganic nitrogen which characterize the Bay facilitate experimental studies of the transformation of nitrogen in the water column, and simplify the task of collecting material for isotopic analysis.…”

Section: Introductionmentioning

confidence: 99%

Natural abundance of 15N in particulate nitrogen and zooplankton in the Chesapeake Bay

Montoya¹,

Horrigan²,

McCarthy³

1990

Mar. Ecol. Prog. Ser.

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Samples of dissolved inorganic nitrogen (DIN), particulate nitrogen (PN), and several species of zooplankton were collected at a series of stations in the main channel of the Chesapeake Bay, USA, during cruises in spring and fall 1984. The spatial and temporal variation in the natural abundance of I5N (Sl5N) in each of these pools, in combination with measurements of the concentrahons of DIN, PN. plant pigments, and the rates of biologically-mediated transformations of nitrogen, provide a number of insights into the dynamics of the nitrogen cycle in the Chesapeake Bay. During both spring and fall. SL5N of surface layer PN showed no consistent Bay-wide pattern of distribution. Instead, the overall gradient of DIN concentrations along the axis of the Bay appears to be less important than local processes in determining the distribution of I5N in PN. The relationship between 6 1 5~ of PN and 615N of dissolved pools indicated that phytoplankton uptake was the dominant process acting on DIN in spring, but that microbially-mediated transformations of nitrogen dominated in fall. During both seasons. 615N of particulate and dissolved pools suggested that phytoplankton consume both NOS and NH: roughly in proportion to concentration. The 6l5N of the zooplankton species sampled generally increased with trophic level. The S 1 5~ of the copepod Acartia tonsa was higher than that of PN by 4.2 ? 2.3 Om (X 2 SD) in spring and 3.3 f 1.0 9m (X f SD) in fall. Similarly. 615N of the ctenophore Mnemiopsis leidyi was higher than that of A. tonsa by 2.0 f 2.6% ((R f SD) in spring and 3.3 f 1.0% (X f SD) in fall. A reversal of the usual relationship between A. tonsa and M. leidyi occurred near the southern end of the Bay during spring, where 6 1 5~ of the copepod was greater than that of the ctenophore by as much as 4.9Ym. In general, spatial variability of S'=N of all 3 of these trophic levels (PN, copepods, and ctenophores) was greater in spring than in all, suggesting that phyto-and zooplankton have a greater direct influence on the estuarine nitrogen cycle during spring. A comparison of the 2 transects conducted on each cruise demonstrates that 6 1 5~ of the PN and A. tonsa, but not that of M. leidyi, can change markedly on a time scale of roughly a week. Such changes clearly indicate that repeated sampling may be essential in studies of the natural abundance of I5N in dynamic planktonic systems such as that in the Chesapeake Bay.

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“…The concept of the coupling of water column nutrient cycling and primary production has been discussed by Corner and Davies (1971) p Eppley et al (1973)·, Ketchum (1962 , Martin (1968), Dugdale (1967) and Dugdale and Goering-(1967). In the Chesapeake Bay where there is a high phytoplankton biomass and productivity in the presence of low ambient nutrient concentrations, McCarthy et al (1975McCarthy et al ( , 1977 have demonstrated that phytoplankton will preferentially utilize NH4 even in the presence of high ambient concentrations of NO -.…”

Section: Statusmentioning

confidence: 99%

“…92 are low. Phytoplankton productivity is, however, relatively high during these low nutrient conditions, and it is obvious that the required nutrients --..-must be supplied by recycling processes (McCarthy et al, 1975;Taft et al, 1975;Taft and Taylor, 1976;Taylor, unpublished data in Progress Report to Energy Research and Development Administration, 1975). Benthic regeneration is one phase of a recycling process and could possibly influence phytoplankton growth and, therefore, the productivity of the food chain.…”

Section: Introductionmentioning

confidence: 99%

Effects of energy related activities on the plankton of the Chesapeake Bay. Section 1. Progress report, 1 August 1976--30 September 1977

Taft¹

1977

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The Dynamics of Nitrogen and Phosphorus Cycling in the Open Waters of the Chesapeake Bay

Cited by 61 publications

References 0 publications

Nutrient regeneration and oxygen consumption by sediments along an estuarine salinity gradient

Nutrient regeneration and oxygen consumption by sediments along an estuarine salinity gradient

Natural abundance of 15N in particulate nitrogen and zooplankton in the Chesapeake Bay

Effects of energy related activities on the plankton of the Chesapeake Bay. Section 1. Progress report, 1 August 1976--30 September 1977

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