Riparian zone denitrification affects nitrogen flux through a tidal freshwater river

Ensign, Scott H.; Piehler, Michael F.; Doyle, Martin W.

doi:10.1007/s10533-008-9265-9

Cited by 66 publications

(64 citation statements)

References 37 publications

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“…Salt marsh DNF has been studied for decades, with early work identifying the importance of landscape heterogeneity on rates of DNF (Kaplan et al 1979). Rates of salt marsh DNF have been linked to organic matter levels (Seitzinger 1994, Starr andGillham 1993), substrate availability (Seitzinger 1988, Tobias et al 2001, Hamersley and Howes 2005 and frequency and duration of inundation (Morris 1991, Ensign et al 2008). Rates of DNF in SAV beds have been found to vary widely.…”

Section: Habitat-specific Dnfmentioning

confidence: 99%

Habitat-specific distinctions in estuarine denitrification affect both ecosystem function and services

2011

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Abstract. Resource limitation controls the base of food webs in many aquatic ecosystems. In coastal ecosystems, nitrogen (N) has been found to be the predominant limiting factor for primary producers. Due to the important role nitrogen plays in determining ecosystem function, understanding the processes that modulate its availability is critical. Shallow-water estuarine systems are highly heterogeneous. In temperate estuaries, multiple habitat types can exist in close proximity to one another, their distribution controlled primarily by physical energy, tidal elevation and geomorphology. Distinctions between these habitats such as rates of primary productivity and sediment characteristics likely affect material processing. We used membrane inlet mass spectrometry to measure changes in N 2 flux (referred to here as denitrification) in multiple shallow-water estuarine habitats through an annual cycle. We found significantly higher rates of denitrification (DNF) in structured habitats such as submerged aquatic vegetation, salt marshes and oyster reefs than in intertidal and subtidal flats. Seasonal patterns were also observed, with higher DNF rates occurring in the warmer seasons. Additionally, there was an interaction between habitat type and season that we attributed to the seasonal patterns of enhanced productivity in individual habitat types. There was a strong correlation between denitrification and sediment oxygen demand (SOD) in all habitats and all seasons, suggesting the potential to utilize SOD to predict DNF. Denitrification efficiency was also higher in the structured habitats than in the flats. Nitrogen removal by these habitats was found to be an important contributor to estuarine ecosystem function. The ecosystem service of DNF in each habitat was evaluated in US dollars using rates from a regional nutrient-offset market to determine the cost to replace N through management efforts. Habitat-specific values of N removal ranged from approximately three thousand U.S. dollars per acre per year in the submerged aquatic vegetation to approximately four hundred U.S. dollars per acre per year in the subtidal flat. Because of the link between habitat type and processes such as DNF, changes in habitat area and distribution will have consequences for both ecosystem function and the delivery of ecosystem services.

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Section: Habitat-specific Dnfmentioning

confidence: 99%

Habitat-specific distinctions in estuarine denitrification affect both ecosystem function and services

2011

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“…Ratios of N 2 :Ar, and O 2 :Ar in water samples were used to determine the concentration of N 2 and O 2 in each sample (Kana et al 1994, Ensign et al 2008. After 24 h, 50 ml water samples were collected for nutrient analysis from the reservoir water line in each core.…”

Section: Sediment Biodeposit and Pore Water Analysesmentioning

confidence: 99%

“…Water was filtered through Whatman GF/F filters (25 mm diameter, 0.7 µm nominal pore size), and the filtrate was analyzed with a Lachat Quick-Chem 8000 automated ion analyzer for NO 3 and NH 4 . Benthic fluxes were reported as mmol N m −2 d −1 and were calculated using the equation (C out − C in ) × F/A, where C represents the concentration of any analyte, C out and C in are the outflow and inflow concentrations (µM), respectively, F is the peristaltic pump flow rate (l h −1 ), and A is the surface area of the core (m 2 ) (Miller-Way & Twilley 1996, Ensign et al 2008. Although some previous studies have conducted light/dark experiments and analyzed the samples using MIMS (Ferguson & Eyre 2007), we chose to not use light incubations because this approach often results in the formation of gas bubbles, which significantly and selectively affect gas concentrations in water (Reeburgh 1969), an effect reflected by our experience.…”

Section: Sediment Biodeposit and Pore Water Analysesmentioning

confidence: 99%

Effect of aquacultured oyster biodeposition on sediment N<sub>2 production in Chesapeake Bay

Higgins¹,

Tobias²,

Piehler³

et al. 2013

Mar. Ecol. Prog. Ser.

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Suspension feeding bivalves have the potential to mitigate estuarine and coastal marine eutrophication by permanently removing nitrogen (N) from the system. We conducted an integrated field and laboratory examination of the effect of eastern oyster biodeposition on sediment denitrification (DNF) and anammox (AMX) rates to quantify the N removal potential of oyster aquaculture using 2 commercial-scale sites in Chesapeake Bay, USA. Sediment N 2 production rates were measured using 2 techniques, 15 N isotope tracer (n = 51) and N 2 :Ar (n = 30). Oyster biodeposit N-load rates explained 21% of variation in sediment N 2 production (DNF and AMX). Oyster sediment N 2 production rates ranged from 0.00 to 1.56 mmol N m −2 d −1 and were almost always lower than reference sediments. From laboratory-based biodeposit addition and fieldbased forced biodeposit accumulation experiments, we found ~2.50 mmol N m −2 d −1 to be the maximum sediment N 2 production capacity of these sediments, regardless of increasing organic N or labile organic carbon delivery rates. We found no evidence to support the contention that biodeposition associated with oyster aquaculture significantly impacts annual N removal via sediment N 2 production, i.e. stimulation or inhibition, above reference rates, but there was evidence that sediment NH 4 + efflux rates were increased. We estimate the N removal rate via sediment N 2 production at similar oyster cultivation sites (1750 m 2 ) with 5 × 10 5 oysters ranges from 0.49 to 12.60 kg N yr −1 , compared to 2.27 to 16.72 kg N yr −1 at reference sites. Thus, aqua cultured oyster biodeposition did not have a ubiquitously enhancing effect on N removal rates via N 2 production and is therefore unlikely to be effective as a policy initiative for eutrophication mitigation.

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“…Inflow water (measured from a bypass line that flowed directly into sample vials) and outflow water leaving the microcosms were analyzed for N 2 , O 2 and Ar dissolved gases in water using a Balzers Prisma QME 200 quadruple mass spectrometer (membrane inlet mass spectrometer (MIMS); Pfeiffer Vacuum; Kana et al 1994). Concentrations of O 2 and N 2 were determined using the ratio with Ar (Kana et al 1994;Ensign et al 2008). We used the gas ratios with Ar rather than the gas concentrations alone in order to partition physical and biological effects on samples.…”

Section: Continuous-flow Incubationmentioning

confidence: 99%

“…Estuaries are dynamic environments where tidal fluctuations can create oxygenated conditions for nitrification at low tide, facilitating nitrate loss through denitrification after the sediments are inundated and reduced at high tide (Ensign et al 2008). However, To date, the evidence for an effect of macroalgal mats on denitrification is equivocal.…”

Section: Introductionmentioning

confidence: 99%

Gracilaria vermiculophylla in the Virginia Coastal Bays: Documenting the Distributionand Effects of a Non-Native Species

Gulbransen¹

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Non-native species are of worldwide concern in both terrestrial and aquatic systems. Macroalgal introductions in coastal environments can have varied and often harmful effects, especially when surrounding habitats are altered by the invasion. Gracilaria vermiculophylla is a red macroalga that is native to East Asia and has been introduced to temperate estuaries around the world. It cannot be easily identified based on morphology alone, and is frequently mistaken for native congeners if genetic testing is not used. Mats of the macroalga can accumulate on subtidal and intertidal substrate within the Virginia coastal bays, USA and are held in place by tube decorating polychaetes on the order of months to years.The broad goals of this dissertation were to determine how widespread the G. vermiculophylla invasion was in the Virginia coastal bays and to document potential effects of G. vermiculophylla mats on biogeochemistry, trophic cascades, and on public health in the region. I found that the introduction was widespread in both subtidal and intertidal habitats, with higher intraspecific genetic richness and diversity than currently documented in other invasions. In addition, I found that intertidal sediment, marsh cordgrass, and mudflat invertebrates all incorporated nitrogen of G. vermiculophylla origin, which indicates that the macroalga is an important mediator of nutrient transfers in the system. Work on intertidal mudflats showed that the presence of G.ii vermiculophylla in this system, at moderate densities, could increase oxic-anoxic heterogeneity in the sediment and thus increase coupled nitrificationdenitrification. In addition, although G. vermiculophylla was associated with an overall increase in invertebrate biomass, shorebirds chose to forage on bare mudflats. Lastly, I found that G. vermiculophylla was a reservoir for the pathogenic bacteria, Vibrio parahaemolyticus and V. vulnificus which can cause gastroenteritis, severe wound infections, septicemia, and death in humans. In addition, oysters, sediment, and water collected in close proximity to mats of G. vermiculophylla had higher concentrations of both bacterial species when compared to samples collected on bare mudflats. Taken together, data collected within the Virginia coastal bays indicate that this widespread habitat modifier can have important effects on nitrogen availability, food web interactions, and shellfish sanitation.iii

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Riparian zone denitrification affects nitrogen flux through a tidal freshwater river

Cited by 66 publications

References 37 publications

Habitat-specific distinctions in estuarine denitrification affect both ecosystem function and services

Habitat-specific distinctions in estuarine denitrification affect both ecosystem function and services

Effect of aquacultured oyster biodeposition on sediment N<sub>2 production in Chesapeake Bay

Gracilaria vermiculophylla in the Virginia Coastal Bays: Documenting the Distributionand Effects of a Non-Native Species

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