A Metabolism-Based Trophic Index for Comparing the Ecological Values of Shallow-Water Sediment Habitats

Rizzo, W. M.; Dailey, Susan K.; Lackey, GL; Christian, Robert R.; Berry, B. E.; Wetzel, Richard L.

doi:10.2307/1352230

Cited by 52 publications

(45 citation statements)

References 40 publications

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“…Daily CR was calculated by multiplying hourly values by 24. The trophic status (balance between autotrophy and heterotrophy) of the sediment at each depth was assessed by applying the Trophic Oxygen Status Index (TOSI) (Viaroli and Christian 2004), derived from the four-scale Benthic Trophic Status Index (BTSI) (Rizzo et al 1996, see also Risgaard-Petersen 2003), where a score of 3 is fully autotrophic, 2 is net autotrophic, 1 is net heterotrophic, and 0 is fully heterotrophic. In practice, TOSI is derived graphically by plotting individual core values of NPP against CR (Viaroli and Christian 2004).…”

Section: Methodsmentioning

confidence: 99%

“…The fact that in situ 14 C-uptake by MPB can be higher at 4 m in depth than at 0.5 m (Sundbäck et al 1996) also indicates that sediments can be autotrophic at depths of Ͼ1 m in similar waters. In the microtidal Neuse River estuary (North Carolina), the autotrophic-heterotrophic transition depth varied between 1 and 4 m (Rizzo et al 1992).…”

Section: Autotrophy and Heterotrophy Along The Depth Gradient-mentioning

confidence: 99%

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Benthic nitrogen fluxes along a depth gradient in a microtidal fjord: The role of denitrification and microphytobenthos

Sundbäck

Linares

Larson

et al. 2004

Limnology & Oceanography

128

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In littoral sediments, microphytobenthic (MPB) nitrogen assimilation often exceeds nitrogen removal by denitrification, partly because MPB activity suppresses denitrification. Little is known about the balance between these two processes at sublittoral depths. Benthic pigment composition, light and dark oxygen, and nutrient fluxes (NO 3 Ϫ , NH 4 ϩ , dissolved organic nitrogen (DON), PO , Si(OH) 4 ), as well as denitrification were measured between 1 and 3Ϫ 4 15 m in depth in Gullmar Fjord (Skagerrak) in spring and autumn. The hypothesis was that the assimilation/ denitrification ratio would decrease with depth, along with decreasing MPB activity caused by light limitation. MPB photosynthesis occurred along the entire depth gradient, although sediments were net autotrophic only above 5 m. Inorganic nitrogen (DIN) (and silica) flux changed along the depth gradient, the general pattern being sediment uptake at Յ5 m and efflux at Ն10 m depth. DON flux (ϳ50% of total dissolved nitrogen flux) showed a less clear pattern. Two trends regarding DIN fluxes and denitrification-significant light effects and negative correlations with gross primary productivity-showed that MPB activity influenced nitrogen (N) turnover. Although denitrification increased with depth, rates remained low (Ͻ0.4 mmol N m Ϫ2 d Ϫ1 ), and MPB assimilation (0.2-3.6 mmol N m Ϫ2 d Ϫ1 ) exceeded or equaled denitrification. MPB incorporated ϳ35% of the remineralized N along the depth gradient, whereas denitrification removed ϳ20%. Thus, the influence of MPB on benthic nitrogen turnover, denitrification included, extends to sublittoral depths. Further, denitrification does not necessarily remove more N in the deeper, heterotrophic part of the photic zone, compared to the littoral, autotrophic zone.

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Section: Methodsmentioning

confidence: 99%

Section: Autotrophy and Heterotrophy Along The Depth Gradient-mentioning

confidence: 99%

Benthic nitrogen fluxes along a depth gradient in a microtidal fjord: The role of denitrification and microphytobenthos

Sundbäck

Linares

Larson

et al. 2004

Limnology & Oceanography

128

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“…In order to establish whether the relationship between the activity of benthic microalgae and coupled nitrification-denitrification was significant and at the same time facilitate an analysis of covariance, data were grouped according to the classification scheme for shallow sediments proposed by Rizzo et al (1996). This scheme-the benthic trophic state index (BTSI)-operates with four different sediment types: (0) fully heterotrophic, (1) net heterotrophic, (2) net autotrophic, and (3) highly autotrophic.…”

Section: Methodsmentioning

confidence: 99%

“…This scheme-the benthic trophic state index (BTSI)-operates with four different sediment types: (0) fully heterotrophic, (1) net heterotrophic, (2) net autotrophic, and (3) highly autotrophic. In the given context, BTSI Rizzo et al (1996) and distribution of samples within the different categories. The criteria are based on mean O 2 fluxes in light and dark for each sampling event.…”

Section: Methodsmentioning

confidence: 99%

Coupled nitrification‐denitrification in autotrophic and heterotrophic estuarine sediments: On the influence of benthic microalgae

Risgaard‐Petersen¹

2003

Limnology & Oceanography

194

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Field data obtained from 18 European estuaries using the isotope pairing technique were analyzed for trends in relationship between activity of benthic microalgae and coupled nitrification-denitrification. Kruskal-Wallis tests and analyses of covariance performed on the field dataset showed strong statistical evidence for the hypothesis that sediments colonized by microalgae whose activity exceeds community respiration display lower rates of coupled nitrification-denitrification than do heterotrophic sediments. In fully heterotrophic sediments, 90% of the measurements fell within the range 0-92 mol N m Ϫ2 h Ϫ1 with a median of 20.3 mol N m Ϫ2 h Ϫ1. In highly autotrophic sediments, 90% of the measurements fell within the range 0-34 mol N m Ϫ2 h Ϫ1 , and the median was 4.2 mol N m Ϫ2 h Ϫ1 . The hypothesis was tested experimentally using 15 N and microsensor (NO ) techniques in prepared Ϫ 3 microcosms with and without algal activity. The results of the experimental studies were consistent with the hypothesis derived from the field data analysis. For the 15 N study, coupled nitrification-denitrification in alga-colonized sediments was between 4 and 51% of the activity in sediments without algae activity, depending on the N load. For the microsensor study, there was no indication of net NO production in alga-colonized sediments before furthermore showed that compared to heterotrophic sediment, the presence of active microalgae might reduce the population of nitrifying bacteria capable of having an active metabolism. These bacterial populations could display diurnal variations in activity correlated with the diurnal variations in O 2 penetration depth, however. The results showed that induction of nitrogen limitation of the nitrifying bacteria population is a major controlling mechanism of coupled nitrification-denitrification in alga-colonized sediments.

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“…2). Applying the 2 trophic indices Trophic Oxygen State Index (TOSI; Viaroli et al 1996) and the Benthic Trophic State Index (BTSI; Rizzo et al 1996), based on net oxygen production and community respiration, shows that both sites can be categorised as net autotrophic to highly autotrophic (BTSI 2-3) (Fig. 4).…”

Section: Oxygenmentioning

confidence: 99%

Nitrogen fluxes, denitrification and the role of microphytobenthos in microtidal shallow-water sediments:an annual study

Sundbäck¹,

Miles²,

Göransson³

2000

Mar. Ecol. Prog. Ser.

216

135

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The annual cycle of oxygen and nitrogen flux, denitrification and microphytobenthic variables (primary production, biomass, composition and calculated N demand) were studied for 2 shallow-water microtidal sediment sites in NE Kattegat, 1 sandy and 1 silty, by incubating undisturbed sediment in the laboratory in light and darkness. Both sites (2 stations within each) were characterised by low concentrations of inorganic nitrogen (IN), in the overlying water during summer (NO3 generally < l pM), with winter concentrations of 5 and 30 pM for the sandy and silty site, respectively. Through the activity of microphytobenthos, the sediment systems appeared to be net autotrophic during most of the year. Net oxygen production varied between -400 and 6600 pm01 m-? h-', being highest during the warmest season. Although the composition of the microphytobenthos depended on the sediment type, it did not have a crucial effect on the magnitude of the microphytobenthic biomass or function. The .temporal pattern of the function of the microalgal community, on the other hand, was significantly influenced by the sediment type; sandy sediment exhibited a smooth seasonality, controlled mainly by temperature and light, while the silty microtidal sediment was also controlled by stochastic events, such as sediment resuspension. Microphytobenthos had a significant effect on the IN flux, the clearest effect being found for NH4. Total denitrification (isotope-pairing technique) generally varied between < l and 40 pm01 m-2 h-', being dominated by nitrification-coupled denitrification (D,,), and being 1 order of magnitude higher at the silty site. Microphytobenthic activity generally inhibited denitrification in the low-N areas in this study. The results suggest that the microphytobenthos functions as a major control throughout the annual cycle, by forming communities that are net photoautotrophic throughout the year, and by significantly influencing both the IN flux and denitrification rates. Sandy sediment appeared to function as an IN sink during winter and early spring, while no clear seasonal pattern was found for silty sediment. Calculated N demand of the microphytobenthos far exceeded the measured sediment net uptake of N, supporting the idea that sandy systems in low-nitrogen areas can be highly productive through a closed recycling of N. The ratio between calculated microphytobenthic N demand and measured denitrification rates suggests that denitrification has a minor role as a N sink, particularly in sandy, cold-climate microtidal sediments. MARINE ECOLOGY PROGRESS SERIES Mar Ecol Prog Ser

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A Metabolism-Based Trophic Index for Comparing the Ecological Values of Shallow-Water Sediment Habitats

Cited by 52 publications

References 40 publications

Benthic nitrogen fluxes along a depth gradient in a microtidal fjord: The role of denitrification and microphytobenthos

Benthic nitrogen fluxes along a depth gradient in a microtidal fjord: The role of denitrification and microphytobenthos

Coupled nitrification‐denitrification in autotrophic and heterotrophic estuarine sediments: On the influence of benthic microalgae

Nitrogen fluxes, denitrification and the role of microphytobenthos in microtidal shallow-water sediments:an annual study

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