Nitrogen in Estuarine and Coastal Marine Ecosystems

Nixon, Scott W.; Pilson, Michael E. Q.

doi:10.1016/b978-0-12-160280-2.50024-9

Cited by 208 publications

(118 citation statements)

References 67 publications

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“…Since the estuarine benthos is often primarily aphotic (Nixon & Pilson 1983), many studies have considered material cycling only from the standpoint of heterotrophic metabolism (Nixon et al 1976, Boynton et al 1980, Fisher et al 1982, Boynton & Kemp 1985. However, in 2 large East Coast estuaries, the York River estuary (Rizzo 1990) and the Neuse River estuary, 30 to 40 % of the benthos supports some benthic microalgal metabolism.…”

Section: Influence Of Light Attenuationmentioning

confidence: 99%

Significance of euphotic sediments to oxygen and nutrient cycling in a temperate estuary

Rizzo¹,

Lackey²,

Christian³

1992

Mar. Ecol. Prog. Ser.

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Sediment-water nutrient and oxygen exchanges were measured under light and dark conditions at 1 oligohaline (Stn D) and 1 mesohaline (Stn A) shallow (1 m) site in the Neuse River estuary, North Carolina. USA. Mean respiration rates were very similar between sites (11 to 12 mg 0 2 m-' h-'), but maximum net productivity at the mesohaline site (74 mg Oz m-' h-') was nearly twice that of the oligohaline site (40 mg O2 m-2 h-'). NH4 fluxes were also significantly different. On average, releases of NH, from sediments at both sites occurred in the dark (13 to 22 pm01 N h-' for Stns D and A, respectively) and, slightly, at the lowest irradiance (67 E m-' S-'. 0.3 to 5 pm01 N h-'). NH, was taken up at average rates between 3 and 12 pm01 N m-' h-' at 3 higher irradiances. Mean NO, (nitrate + nitnte) fluxes were very low ( < l 0 pm01 N m-2 h-'), nearly always directed out of the sediment, and not significantly different. Filterable reactive phosphorus fluxes also did not follow any consistent response to changes in irradiance. Flux vs irradiance curves were used in conjunction with estimates of in situ light availability to the benthos to compute ecosystem-level influence of autotrophy on material exchanges. The autotropic-heterotrophic transitions were 1 to 2 m (oligohaline) and 3 to 4 m (mesohaline). When integrated over depth and area the mesohaline sediments were always net NH, sources to the water column, net O2 sources in fall and winter and net O2 sinks in spring and summer. Oligohaline sediments were O2 sinks except during fall, and NH, sources only in winter and summer. Cultural eutrophication has the potential to alter the balance of benthic autotrophy and heterotrophy which in turn may foster phytoplanktonic productivity.

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Section: Influence Of Light Attenuationmentioning

confidence: 99%

Significance of euphotic sediments to oxygen and nutrient cycling in a temperate estuary

Rizzo¹,

Lackey²,

Christian³

1992

Mar. Ecol. Prog. Ser.

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“…Despite considerable effort it has not been possible to generalize about the relation between nutrient concentration and productivity (Boynton et al 1982, Nixon & Pilson 1983, Cole & Cloern 1984. Part of the problem is due to the general availability of nutrientsin estuanes.…”

Section: Introductionmentioning

confidence: 99%

“…More recently, researchers have shown that much of the variability in phytoplankton production is highly correlated with a composite factor, the product of phytoplankton biomass and light availability (Falkowslu 1981, Cole & Cloern 1984, Harding et al 1986, Pennock & Sharp 1986. Experimental work in largescale mesocosms at the Marine Ecosystem Research Laboratory (MERL) has concomittently established a strong linear relationship between nutrient loading level and phytoplankton biomass (Nixon & Pilson 1983, Nixon et al 1984, Keller 1987a. Given this relationship, the predictive ability of an empirical model including both light availability and biomass is not surprising.…”

Section: Introductionmentioning

confidence: 99%

Estimating phytoplankton productivity from light availability and biomass in the MERL mesocosms and Narragansett Bay

Keller¹

1988

Mar. Ecol. Prog. Ser.

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Recent research has suggested that primary productivity in estuanne waters can be predicted as a function of phytoplankton biomass (chlorophyll a concentration) multiplied by light avalability in the photic zone (photic depth times incident irradiance). The apphcability of this function was confirmed using data from 1010 I4C incubations (during 1978 to 1984) from 4 diverse mesocosm experiments and Narragansett Bay. For each experiment 70 to 80 % of the variation in productivity was explained by the composite function. A regression equation developed from all experiments explained 82 % of the variation in primary productivity and was not statistically different from a previously reported equation based on comparable data from 4 estuarine regions (North and South San Francisco Bay, Puget Sound, and New York Bight). Phytoplankton production was correlated with biomass alone on a seasonal basis (summer, r = 0.87; non-summer, r = 0.77), with chlorophyll-specific productivity higher during summer (June to September) than non-summer (October to May). The decline in the slope of the relation between production and biomass during non-summer periods corresponded to the seasonal switch from summer dominance by nanoplankton (primarily flagellates) to non-summer dominance by net plankton (primarily diatoms) and coincided with decreased light availability in the photic zone. Annual productivity was also highly correlated with the mean annual product of chlorophyll a, photic depth and incident light ( r = 0.96).

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“…In estuaries, early evaluation of eutrophication was made by Ketchum (1969) and was popularized by Jaworski in the Potomac River (Jaworski et al 1972). During the evolution of conceptual models of estuarine eutrophication, cautions about oversimplification of this problem have been made for a number of years (e.g., Schindler 1981;Nixon and Pilson 1983;Vollenweider et al 1992). However, there is still a tendency to think of eutrophication in estuarine waters in terms of a simple linear response to a single limiting nutrient: what Cloern (2001) has described as a Phase I model.…”

mentioning

confidence: 99%

Phytoplankton response to nutrient enrichment in an urbanized estuary: Apparent inhibition of primary production by overeutrophication

Yoshiyama

Sharp

2006

Limnology & Oceanography

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Phytoplankton response to nutrients was examined with a 26-yr database from the Delaware Estuary. Biomassnormalized primary production did not increase linearly with increasing nutrient concentrations and instead showed saturation at comparatively low nutrient concentrations and decreased at high concentrations. To separate the effects of light availability and temperature on primary production from those of other environmental variables, we developed an empirical model of areal primary production. The model equation was obtained for the entire dataset and the effect of the residual variables was expressed as correction factors of observed primary production to the model estimates. The model accounted for 67% of variability of observed primary production overall, indicating that production of the estuary was mainly controlled by light availability and temperature. In contrast, a similar model applied to a Chesapeake Bay database had shown a poorer fit, indicating consistent light limitation in the Delaware Estuary and varying strengths of light and nutrient limitation in the Chesapeake Bay. The relationships between nutrients and correction factors for the Delaware Estuary showed that the model underestimates primary production at low and mid nutrient concentrations and overestimates it at high concentrations. The model fit and correction factors for five regions of the estuary indicate a high-nutrient, low-growth situation in the Delaware Estuary because of varying influences of light limitation, proportions of nutrients, and probably toxic contaminants in areas with large anthropogenic inputs-including high nutrients.Much of the classical thinking about eutrophication has arisen from lake studies. In lake systems, a relatively simple model appeared to successfully describe phytoplankton response to the effect of a single limiting nutrient, phosphate (Hutchinson 1969). In estuaries, early evaluation of eutrophication was made by Ketchum (1969) and was popularized by Jaworski in the Potomac River (Jaworski et al. 1972). During the evolution of conceptual models of estuarine eutrophication, cautions about oversimplification of this problem have been made for a number of years (e.g., Schindler 1981;Nixon and Pilson 1983;Vollenweider et al. 1992). However, there is still a tendency to think of eutrophication in estuarine waters in terms of a simple linear response to a single limiting nutrient: what Cloern (2001) has described as a Phase I model. To construct more complex models, Cloern addresses system-specific responses; complex ge-1 Corresponding author (kyoshi@udel.edu). AcknowledgmentsNumerous graduate students, research associates, and postdoctoral researchers, as well as many undergraduate and high school student volunteers, have assisted over the years; we thank all of them for their contributions. We also thank James E. Cloern and two anonymous reviewers for their useful comments on the manuscript.

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Nitrogen in Estuarine and Coastal Marine Ecosystems

Cited by 208 publications

References 67 publications

Significance of euphotic sediments to oxygen and nutrient cycling in a temperate estuary

Significance of euphotic sediments to oxygen and nutrient cycling in a temperate estuary

Estimating phytoplankton productivity from light availability and biomass in the MERL mesocosms and Narragansett Bay

Phytoplankton response to nutrient enrichment in an urbanized estuary: Apparent inhibition of primary production by overeutrophication

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