Microbial mediation of 'reactive' nitrogen transformations in a temperate lagoon

Anderson, Iris C.; McGlathery, Karen J.; Tyler, Anna Christina

doi:10.3354/meps246073

Cited by 72 publications

(45 citation statements)

References 39 publications

(50 reference statements)

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“…DON accounted for a large portion (Ն50%) of the daily TDN flux (Fig. 5), which agrees with previous observations in shallow-water sediments (Lomstein et al 1998;Anderson et al 2003). Large fluxes of DON are considered to reflect hydrolysis of freshly produced organic material at the surface of the sediment (Blackburn and Blackburn 1993), a situation that can be very likely in the presence of microalgal mats, such as those existing in Gullmar Fjord.…”

Section: Autotrophy and Heterotrophy Along The Depth Gradient-supporting

confidence: 90%

“…That the sediment at 1 m is a sink for DIN is in agreement with a number of studies from shallow-water sediments (e.g., Cerco and Seitzinger 1997;Sundbäck and Miles 2000;Anderson et al 2003). The fact that the autotrophic state of the sediment is due to MPB photosynthesis makes MPB a key controlling factor in N flux at the sediment-water interface (see further discussion below).…”

Section: Autotrophy and Heterotrophy Along The Depth Gradient-supporting

confidence: 86%

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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

131

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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: Autotrophy and Heterotrophy Along The Depth Gradient-supporting

confidence: 90%

Section: Autotrophy and Heterotrophy Along The Depth Gradient-supporting

confidence: 86%

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

131

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“…6) is consistent with there being little or no microphytobenthos nutrient uptake in the dark. This seems contrary to the recent findings of Anderson et al (2003), who suggest that dark uptake by microphytobenthos is likely to be an important sink for mineralised N. Our results do not deny this possibility but imply that the true N mineralisation rate in Mahurangi Harbour sediments is much higher than the dark uptake rate, and the NH 4 -N efflux observed is a net excess. Our net NH 4 -N and NO 3 -N efflux results are comparable with the efflux rates measured in light and dark at the shallower depths in Gullmar Fjord in spring but are higher than those measured in late summer (Sundbäck et al 2004).…”

Section: Discussioncontrasting

confidence: 56%

“…While the reduction in microphytobenthos nutrient uptake in the dark would account for the outer harbour results, the inner harbour results may indicate some changes in biogeochemical processes within the sediments (e.g. Anderson et al 2003). The presence of a NO 3 -N efflux in the chambers indicates that some of the NH 4 -N released from the sediments was being nitrified.…”

Section: Nutrientsmentioning

confidence: 99%

Benthic nutrient fluxes along an estuarine gradient: influence of the pinnid bivalve Atrina zelandica in summer

Gibbs¹,

Funnell²,

Pickmere³

et al. 2005

Mar. Ecol. Prog. Ser.

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Benthic nutrient fluxes (BNF) can supply 30 to 100% of the nutrient requirements of benthic and pelagic algae in an estuary, and can, thus, potentially sustain benthic and pelagic primary production within the estuarine food web. While BNF can be influenced by microbial processes, epibenthic suspension-feeding bivalves have the potential to alter fluxes by their influence on the community composition of surrounding macrofauna and benthic boundary conditions, and their feeding activities. In Mahurangi Harbour, New Zealand, the large suspension feeding pinnid Atrina zelandica (hereafter referred to as Atrina) occupies large areas of the harbour floor. Consequently, Atrina have the potential to substantially influence the BNF and, thus, primary production, and the food supply to the filter feeding community within the harbour, including the rack-farmed Pacific oyster aquaculture industry. Mahurangi Harbour is almost always isohaline, but exhibits a strong gradient in suspended sediment concentration, which declines from head to mouth. As Atrina increase their rate of pseudofaeces production with increases in suspended sediment concentration, we conducted in situ light and dark paired benthic chamber experiments with and without Atrina at 4 stations along this turbidity gradient, to determine their effect on BNF. Our results showed substantially greater BNF from Atrina beds than bare sediments. We also found greater net BNF (difference between Atrina beds and bare sediment) in the less turbid water under dark conditions, but enhanced water column nutrient supply in the more turbid water in light, due to Atrina excretion of ammoniacal nitrogen . On an areal basis, we estimate that BNF from Atrina beds may account for up to 80% of the nutrient supply for pelagic primary production and, thus, they are of major importance to the sustainability of aquaculture in this harbour. KEY WORDS: Benthic nutrient flux · Benthic chambers · Estuarine turbidity gradient · Atrina zelandica · Microphytobenthos Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 288: [151][152][153][154][155][156][157][158][159][160][161][162][163][164] 2005 important part of the nutrient dynamics of an estuary (e.g. Newell et al. 2002).Bioturbation and grazing pressure by macrofauna can destabilise the sediments (de Deckere et al. 2001), stimulating microbial activity and enhancing denitrification (Gilbert et al. 1998). However, the presence of large benthic animals may also stabilise the sediments, and affect the composition and functioning of macrofaunal communities (Cummings et al. 1998, Ellis et al. 2000, Norkko et al. 2001, Reise 2002. Abundant suspension-feeders may build loose hummocks, multi-species epibenthic thickets or solid reefs, accommodating diverse epibenthic assemblages. Their raised and rough surfaces alter benthic boundary conditions (Green et al. 1998) and, hence, turbulence (Reise 2002), while their biodeposits may enrich the sediments and smother the microphytobenthos. Bel...

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“…Moreover, anoxia may limit DFAA mineralization within organic-rich sediments and foster an efflux , but DO production was generally high in Hog Island Bay, except at Shoal and Creek in the summer, and aerobic mineralization at the sediment surface may have decreased the DFAA flux to the water column. The high gross mineralization rate at our sites (0.9-6.5 mmol m Ϫ2 d Ϫ1 N; Anderson et al 2003) further indicates that DFAA could have been consumed within the sediments by bacteria (Lomstein et al 1998) or microalgae, which are capable of both light and dark DFAA uptake (Jorgensen 1982;Admiraal et al 1984;Nilsson and Sundback 1996). Dark uptake of DFAA may provide a competitive advantage to buried microalgae (Nilsson and Sundback 1996).…”

Section: Sediment Fluxes and The Influence Of Benthic Microalgaethe Dmentioning

confidence: 99%

Benthic algae control sediment—water column fluxes of organic and inorganic nitrogen compounds in a temperate lagoon

Tyler

McGlathery

Anderson

2003

Limnology & Oceanography

143

101

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Coastal lagoons are a common land-margin feature worldwide and function as an important filter for nutrients entering from the watershed. The shallow nature of lagoons leads to dominance by benthic autotrophs, which can regulate benthic-pelagic coupling. Here we demonstrate that both microalgae and macroalgae are important in controlling dissolved inorganic as well as organic nitrogen (DIN and DON) fluxes between the sediments and the water column. Fluxes of nitrogen (NH , NO , DON, urea, and dissolved free and combined amino acids [DFAA,DCAA]) and O 2 were measured from October 1998 through August 1999 in sediment cores collected from Hog Island Bay, Virginia. Cores were collected from four sites representing the range of environmental conditions across this shallow lagoon: muddy, high-nutrient and sandy, low-nutrient sites that were both dominated by benthic microalgae, and a mid-lagoon site with fine sands covered by dense macroalgal mats. Sediment-water column DON fluxes were highly variable and comparable in magnitude to DIN fluxes; fluxes of individual compounds (urea, DFAA, DCAA) often proceeded simultaneously in different directions. Where sediment metabolism was net autotrophic because of microalgal activity, TDN (total dissolved nitrogen) fluxes, mostly comprised of DIN, urea, and DFAA, were directed into the sediments. Heterotrophic sediments, including those underlying macroalgal mats, were a net source of TDN, mostly as DIN. Macroalgae intercepted sediment-water column fluxes of DIN, urea, and DFAA, which accounted for 27-75% of calculated N demand. DON uptake was important in satisfying macroalgal N demand seasonally and where DIN concentrations were low. Up to 22% of total N uptake was released to the water column as DCAA. Overall, macroalgae assimilated, transformed, and rereleased to the water column both organic and inorganic N on short (minutes-hours) and long (months) time scales. Microalgae and macroalgae clearly regulate benthic-pelagic coupling and thereby influence transformations and retention of N moving across the land-sea interface.

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Microbial mediation of 'reactive' nitrogen transformations in a temperate lagoon

Cited by 72 publications

References 39 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

Benthic nutrient fluxes along an estuarine gradient: influence of the pinnid bivalve Atrina zelandica in summer

Benthic algae control sediment—water column fluxes of organic and inorganic nitrogen compounds in a temperate lagoon

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