Ecogeochemistry and Denitrification in Non-eutrophic Coastal Sediments

Vieillard, Amanda M.; Thrush, Simon F.

doi:10.1007/s12237-021-00912-7

Cited by 12 publications

(4 citation statements)

References 82 publications

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“…Although N 2 production in MP-treatments decreased by a small percentage owing to increased aerobic mineralization in worm and combined groups; a weakened nitrogen cycling is likely a result of a chains-reaction when macrofauna loses its functional role in transporting labile OM and regulating microbial activities. This study has not included multiple limiting factors (e.g., OM quality, NO 3 - concentration) in N-cycling, as well as the complexity of pathways of denitrification, including directly denitrifying NO 3 - in overlying water and coupling of nitrification and denitrification processes at an oxic-anoxic sediment interface 74 . MP as synthetic polymers potentially participates in OM degradation 75 , and some materials (PLA) can serve as carbon sources which stimulate both nitrification and denitrification rates 72 .…”

Section: Discussionmentioning

confidence: 99%

“…MP as synthetic polymers potentially participates in OM degradation 75 , and some materials (PLA) can serve as carbon sources which stimulate both nitrification and denitrification rates 72 . In a eutrophic system, OM (quality and quantity) constrains denitrification when overlying water provides sufficient NO 3 − ; in a low-nutrient system, the NO 3 - supply from nitrification is the limiting factor for denitrification in the sediment 74 . In this case, we predicted that when the bioturbation rate decreased because of MP, O 2 demands increased because of OM accumulation.…”

Section: Discussionmentioning

confidence: 99%

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Modelled broad-scale shifts on seafloor ecosystem functioning due to microplastic impacts on bioturbation

You,

Della Penna,

Thrush

2023

Sci Rep

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Bioturbating species play an essential role in regulating nutrient cycling in marine sediments, but their interaction with microplastics (MP) remains poorly understood. Here we investigated the linkage between MP and ecosystem functioning using experimental observations of luminophore distribution in the sediment to parametrize bioturbation coefficients (Db). this information as fed into a simplified transport-reaction model, allowing us to upscale our experimental results. We found that the composition of bioturbators modulated shifts in the ecosystem functioning under microplastic stress. Maldanid worms (Macroclymenella stewartensis), functionally deep burrowing and upward-conveyor belt feeders, became less active. The Db of M. stewartensis reduced by 25% with the addition of 0.002 g MP cm−2 at surface sediment, causing accumulation of organic matter in the oxic sediment zone and stimulating aerobic respiration by 18%. In contract, the tellinid bivalve Macomona liliana, functionally a surface -deposit feeder that excretes at depth, maintained particle mixing behaviour in MP-contaminated systems. This study provides a mechanistic insight into the impacts of MP and indicates that the functional role of bioturbating species should be involved in assessing the global impact of MP. The model allowed us to understand the broad-scale impact of MP on seafloor habitat.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Modelled broad-scale shifts on seafloor ecosystem functioning due to microplastic impacts on bioturbation

You,

Della Penna,

Thrush

2023

Sci Rep

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“…For example, the effect of denitrifying bacteria on denitrification rates that convert reactive nitrogen into N 2 gas, effectively removing N from the system (Vieillard et al., 2020). Macrofaunal organisms through their biological activity such as structure building and sediment particle movement introduce organic carbon and oxygen to deeper layers of sediment where denitrifiers reside (Siwicka & Thrush, 2020), and therefore, their role, although indirect, is critical in mediating denitrification rates (Vieillard & Thrush, 2021). Low explanatory power of variables should not discourage us from studying the range of drivers that regulate multifunctionality.…”

Section: Discussionmentioning

confidence: 99%

Beyond the single index: Investigating ecological mechanisms underpinning ecosystem multifunctionality with network analysis

Siwicka

Gladstone‐Gallagher

Hewitt

et al. 2021

Ecology and Evolution

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Ecosystems simultaneously deliver multiple functions that relate to both the activities of resident species and environmental conditions. One of the biggest challenges in multifunctionality assessment is balancing analytical simplicity with ecosystem complexity. As an alternative to index‐based approaches, we introduce a multivariate network analysis that uses network theory to assess multifunctionality in terms of the relationships between species' functional traits, environmental characteristics, and functions. We tested our approach in a complex and heterogeneous ecosystem, marine intertidal sandflats. We considered eight ecosystem function, five macrofaunal functional trait groups derived from 36 species, and four environmental characteristics. The indicators of ecosystem functions included the standing stock of primary producers, oxygen production, benthic oxygen consumption, DIN (ammonium and NOx efflux) and phosphate release from the sediments, denitrification, and organic matter degradation at the sediment surface. Trait clusters included functional groups of species that shared combinations of biological traits that affect ecosystem function: small mobile top 2 cm dwellers, suspension feeders, deep‐dwelling worms, hard‐bodied surface dwellers, and tube‐forming worms. Environmental characteristics included sediment organic matter, %mud, %shell hash, and %sediment water content. Our results visualize and quantify how multiple ecosystem elements are connected and contribute to the provision of functions. Small mobile top 2 cm dwellers (among trait clusters) and %mud (among environmental characteristics) were the best predictor for multiple functions. Detailed knowledge of multifunctionality relationships can significantly increase our understanding of the real‐world complexity of natural ecosystems. Multivariate network analysis, as a standalone method or applied alongside already existing single index multifunctionality methods, provides means to advance our understanding of how environmental change and biodiversity loss can influence ecosystem performance across multiple dimensions of functionality. Embedding such a detailed yet holistic multifunctionality assessment in environmental decision‐making will support the assessment of multiple ecosystem services and social‐ecological values.

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“…We did not have access to instrumentation for analysis of ammonium (NH 4 + ), and expected that concentrations would be negligible in the aerated, unpolluted Falkland estuaries. It is possible that NH 4 + was present in estuarine sediment porewaters (e.g., Vieillard and Thrush 2021) but any leached to the water column was assumed to be rapidly oxidized to NO x , and therefore captured by our measurements.…”

Section: Methodsmentioning

confidence: 99%

Marine nutrient subsidies promote biogeochemical hotspots in undisturbed, highly humic estuaries

Evans

Felgate

Carter

et al. 2023

Limnology & Oceanography

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The land‐ocean dissolved organic carbon (DOC) flux represents a significant term within the global carbon budget, with peatland‐dominated regions representing the most intense sources of terrestrial DOC export. As the interface between freshwater and marine systems, estuaries have the potential to act as a filter of the land‐ocean carbon flux, removing terrestrially derived DOC, which is present at low concentrations in the oceans, via a combination of physicochemical and biological processes. However, the fate of peat‐derived DOC within estuaries remains poorly quantified, partly due to the complicating influences of heterogeneous soils, land‐use, point sources, and upstream modification of organic matter. To minimize these modifying factors, we studied DOC and inorganic nutrients in four small, peat‐dominated, minimally disturbed, and oligotrophic Falkland Island estuaries. Contrary to expectations, we found limited evidence of physicochemical estuarine DOC removal, and instead observed apparent “hot zones” of biogeochemical activity, where terrestrially‐derived silicate mixed with inorganic nitrogen and phosphorus entering the estuaries from the nutrient‐rich marine ecosystem. In two estuaries, this coincided with apparent in situ DOC production. We suggest that the observed phenomena of marine nutrient subsidy of estuarine productivity, and flexible utilization of multiple nutrients within the oligotrophic system, may once have been widespread in temperate estuaries. However, this function has been lost in many ecosystems due to catchment eutrophication by agricultural and urban development. We conclude that the estuaries of the Falkland Islands provide a valuable pre‐disturbance analogue for natural biogeochemical functioning in temperate estuaries receiving high organic matter inputs.

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Ecogeochemistry and Denitrification in Non-eutrophic Coastal Sediments

Cited by 12 publications

References 82 publications

Modelled broad-scale shifts on seafloor ecosystem functioning due to microplastic impacts on bioturbation

Modelled broad-scale shifts on seafloor ecosystem functioning due to microplastic impacts on bioturbation

Beyond the single index: Investigating ecological mechanisms underpinning ecosystem multifunctionality with network analysis

Marine nutrient subsidies promote biogeochemical hotspots in undisturbed, highly humic estuaries

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