Poor recovery of fungal denitrification limits nitrogen removal capacity in a constructed Gulf Coast marsh

Starr, Sommer F.; Mortazavi, Behzad; Tatariw, Corianne; Kuehn, Kevin A.; Cherry, Julia A.; Smyth, E.; Wood, Abigail Griffin; Sebren, Saysha E.

doi:10.1016/j.soilbio.2022.108692

Cited by 10 publications

(2 citation statements)

References 72 publications

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“…3 ) removal, thus demonstrating the role denitrifying fungi play in salt marsh sediment biogeochemistry (Starr et al, 2022). These studies provide a basis to rethink salt marsh N 2 O dynamics and study salt marsh fungi to determine the significance of fungi in acting as an N 2 O source.…”

Section: Introductionmentioning

confidence: 76%

Nitrous oxide production and isotopomer composition by fungi isolated from salt marsh sediments

et al. 2022

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The emissions of nitrous oxide (N2O), a potent greenhouse gas and ozone-depleting agent, have been steadily increasing from coastal environments, such as salt marsh sediments, as a result of anthropogenic nutrient loading. Biotic processes, including nitrification and denitrification, are the largest sources of N2O from salt marsh sediments. While it is assumed that the bulk of N2O from salt marsh sediment is produced by nitrification and bacterial denitrification, recent reports suggest fungal denitrification may contribute significantly. In this study, four fungi capable of growth under sulfidic conditions were isolated from salt marsh sediments in North Inlet, South Carolina, USA. Fungal species included Purpureocillium lilacinum, Trichoderma harzianum, Trichoderma virens, and Rhodotorula glutinis, as determined by sequencing the18S and 28S rRNA genes. The isotopomer signatures of N2O produced by these fungi were measured using isotope ratio mass spectrometry, which can be used to estimate the contribution of different sources of N2O. Up to 22.8% of nitrite provided in growth media was converted to N2O by fungal strains isolated from salt marsh sediments. The site preference (SP) of N2O produced by salt marsh sediment fungi ranged from 7.5 ± 1.6‰ to 33.4 ± 1.2‰. These values are lower than the SP of N2O from the model fungal denitrifier Fusarium oxysporum (37.1 ± 2.5‰), which is the SP typically used as an endmember in isotope mass balance considerations. The N2O SP values we measured expand the range of N2O SP used for isotope mass balances calculations to determine the relative contribution of fungi to N2O production in salt marsh sediments.

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Section: Introductionmentioning

confidence: 76%

Nitrous oxide production and isotopomer composition by fungi isolated from salt marsh sediments

et al. 2022

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“…We conducted our study at a natural brackish tidal marsh (hereafter, NAT) and a nearby (~ 0.5 km) constructed tidal marshes (hereafter, CON-1) along the West Fowl River in Mobile County, Alabama, U.S.A (Figure 1a). Tides at both marshes are diurnal but strongly meteorologically driven, with a range of 0.52 m, mean low water of -0.45 m, and mean high water of 1.66 m (Starr et al 2022). NAT is located directly adjacent to the West Fowl River, dominated primarily by a mixture of Juncus roemerianus (black needlerush) and Spartina patens (saltmeadow cordgrass), and characterized by a series of naturally occurring tidal creeks (Figure 1b).…”

Section: Site Descriptionmentioning

confidence: 99%

Seasonal sediment dynamics in a constructed and natural tidal marsh in the northern Gulf of Mexico

Dybiec

Rinehart

Cherry

2023

Preprint

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Declines in sediment loading, combined with sea-level rise, are a major driver of recent tidal marsh loss. As such, evaluations of sediment dynamics are necessary for assessments of current and future marsh resilience to sea-level rise. While tidal marsh creation is used to offset these losses, few studies have assessed sediment dynamics in these systems; those that have were focused on accumulation at a single time and/or place, without considering the composition of accumulated sediment (i.e., organic vs. inorganic). We compared seasonal sediment dynamics between a natural and nearby 34-year-old constructed tidal marsh in the northern Gulf of Mexico. In July 2021, we set up a series of permanent sampling points along one tidal creek in each marsh and made monthly measurements of sedimentation, surface organic matter accumulation, and surface scour for one year. We found that sedimentation and organic matter accumulation were lower in the constructed marsh, while surface scour did not differ. Additionally, we found that the relationship between distance from the mouth of each tidal creek and sedimentation differed between marshes (positive in natural, negative in constructed), as did organic matter accumulation (no relationship in natural, positive in constructed). Despite this, we found that both marshes followed similar seasonal trends in sediment accumulation (highest in summer, lowest in winter). Our results suggest that considering local sedimentation rates is critical to insuring that adequate sedimentary dynamics develop in restored and created marshes, underscoring the importance of evaluating spatial and temporal variation in sedimentary dynamics to assess restoration outcomes.

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Labile organic matter promotes nitrogen retention in natural and constructed gulf coast marshes

Starr,

Mortazavi,

Tatariw

et al. 2024

Biogeochemistry

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Coastal marshes mitigate allochthonous nitrogen (N) inputs to adjacent marine habitat; however, their extent is declining rapidly. As a result, marsh restoration and construction have become a major foci of wetland management. Constructed marshes can quickly reach similar plant biomass to natural marshes, but biogeochemical functions like N removal and retention can take decades to reach functional equivalency, often due to lags in organic matter (OM) pools development in newly constructed marshes. We compared denitrification and dissimilatory nitrate reduction to ammonium (DNRA) rates in a 32 year-old constructed marsh and adjacent reference marsh in the Northern Gulf of Mexico. Marsh sediments packed into 3 mm “thin discs” were subjected to three OM quality treatments (no OM addition, labile OM, or recalcitrant OM) and two N treatments (ambient nitrate or elevated nitrate) during a 13 day incubation. We found that OM addition, rather than marsh type or nitrate treatment, was the most important driver of nitrate reduction, increasing both denitrification and DNRA and promoting DNRA over denitrification in both marshes. Fungal and bacterial biomass were higher in the natural marsh across treatments, but recalcitrant OM increased fungal biomass in the constructed marsh, suggesting OM-limitation of fungal growth. We found that constructed marshes are capable of similar denitrification and DNRA as natural marshes after 30 years, and that labile OM addition promotes N retention in both natural and constructed marshes. Graphical Abstract Conceptual figure highlighting the findings of this experiment. Under control treatment with no C addition (bottom panel), constructed and natural marshes have similar rates of both DNRA and denitrification. The natural marsh has higher fungal and bacterial biomass, while fungal biomass is not detectable in the constructed marsh. Under labile OM additions (upper left panel), rates of both DNRA and denitrification are increased and DNRA becomes favored over denitrification in both marshes. Recalcitrant OM additions (upper right) increase denitrification, but do not affect DNRA or % denitrification. The addition of recalcitrant OM also increases the detectability of fungal biomass in the constructed marsh.

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Poor recovery of fungal denitrification limits nitrogen removal capacity in a constructed Gulf Coast marsh

Cited by 10 publications

References 72 publications

Nitrous oxide production and isotopomer composition by fungi isolated from salt marsh sediments

Nitrous oxide production and isotopomer composition by fungi isolated from salt marsh sediments

Seasonal sediment dynamics in a constructed and natural tidal marsh in the northern Gulf of Mexico

Labile organic matter promotes nitrogen retention in natural and constructed gulf coast marshes

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