Bioturbation has a limited effect on phosphorus burial in salt marsh sediments

Abstract. It has been hypothesized that the evolution of animals during the Ediacaran–Cambrian transition stimulated the burial of phosphorus in marine sediments. This assumption is centrally based on data compilations from marine sediments deposited under oxic and anoxic bottom waters. Since anoxia excludes the presence of infauna and sediment reworking, the observed differences in P burial are assumed to be driven by the presence of bioturbators. This reasoning however ignores the potentially confounding impact of bottom-water oxygenation on phosphorus burial. Here, our goal is to test the idea that bioturbation increases the burial of organic and inorganic phosphorus (Porg and Pinorg, respectively) while accounting for bottom-water oxygenation. We present solid-phase phosphorus speciation data from salt marsh ponds with and without bioturbation (Blakeney salt marsh, Norfolk, UK). In both cases, the pond sediments are exposed to oxygenated bottom waters, and so the only difference is the presence or absence of bioturbating macrofauna. Our data reveal that the rate of Porg and Pinorg burial are indistinguishable between bioturbated and non-bioturbated sediments. A large terrestrial fraction of organic matter and higher sedimentation velocity than generally found in marine sediments (0.3 ± 0.1 cm yr−1) may partially impact these results. However, the absence of a clear effect of bioturbation on total P burial puts into question the presumed importance of bioturbation for phosphorus burial.

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Bioturbation has a limited effect on phosphorus burial in salt marsh sediments

10.5194/bg-2020-340 ◽

2020 ◽

Author(s):

Sebastiaan J. van de Velde ◽

Rebecca K. James ◽

Ine Callebaut ◽

Silvia Hidalgo-Martinez ◽

Filip J. R. Meysman

Keyword(s):

Salt Marsh ◽

Bottom Water ◽

Solid Phase ◽

Organic Phosphorus ◽

Inorganic Phosphorus ◽

Sediment Reworking ◽

Co2 Concentrations ◽

Bottom Waters ◽

Salt Marsh Sediments ◽

The Impact

Abstract. It has been hypothesised that the evolution of animals during the Ediacaran-Cambrian transition had a major impact on atmospheric O2 and CO2 concentrations. The models upon which this hypothesis rests, critically assume that bioturbation by the newly evolved fauna increased the burial of organic phosphorus (Porg) within the seafloor, relative to organic carbon (Corg) and that inorganic phosphorus (Pinorg) burial was not affected by bioturbation. This assumption is centrally based on data compilations from marine sediments deposited under oxic and anoxic bottom waters. Since anoxia excludes the presence of infauna and sediment reworking, the observed differences in P burial are assumed to be solely driven by the presence of bioturbators. This reasoning however ignores the potentially confounding impact of bottom water oxygenation on phosphorus burial. Here, our goal is to provide a field verification for the idea that bioturbation increases the relative burial of organic phosphorus, while accounting for bottom water oxygenation. We present solid-phase phosphorus speciation data from salt marsh ponds with and without bioturbation (Blakeney salt marsh, Norfolk, UK). In both cases, the pond sediments are exposed to oxygenated bottom waters and so the only difference is the presence/absence of bioturbating macrofauna. Our data reveal that both the Corg : Porg ratio of buried organic matter and the rate of Pinorg burial are indistinguishable between bioturbated and non-bioturbated sediments. The absence of a clear effect of bioturbation on total P burial implies that previous studies may have overestimated the impact of the rise of bioturbation on atmospheric O2 and CO2 concentrations in the early Cambrian.

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Coupled benthic cycling of iron, phosphorus and sulfur in the Benguela upwelling system

10.5194/egusphere-egu2020-19291 ◽

2020 ◽

Author(s):

Kristin Anna Ungerhofer ◽

Gert-Jan Reichart ◽

Peter Kraal

Keyword(s):

Water Column ◽

Bottom Water ◽

Solid Phase ◽

Oxygen Depletion ◽

Biogeochemical Cycles ◽

Sediment Surface ◽

Upwelling System ◽

Benguela Upwelling ◽

Bottom Waters ◽

The Impact

The Benguela upwelling system (BUS) offshore Namibia is among the most productive ocean regions worldwide and is a globally important reservoir of biodiversity and biomass. The forcing of cold, nutrient-rich deep waters up the coastal shelf leads to high rates of primary productivity in surface waters, intense carbon remineralization and consequently to (bottom water) oxygen depletion on the shelf that varies temporally and spatially with the intensity of the upwelling. Recurring events of deoxygenation have a severe impact on marine ecosystems, for instance increased mortality and altered biogeochemical cycles of key elements such as carbon (C), iron (Fe), phosphorus (P) and sulfur (S). Therefore, it is crucial that we establish a clear mechanistic framework of the impact of oxygen depletion on (global) biogeochemical cycles, not only to allow for the reconstruction of climate-ocean feedbacks in upwelling regions in the past, but to enable predictions of future behavior. During an expedition with RV Pelagia in February of 2019, we collected water column and sediment samples from the shelf and slope off Namibia (100 to 1517 m water depth, bottom water O2 between 0.5 and 175 &#181;mol L-1) and measured nutrient fluxes in on-board sediment incubations to understand the early diagenetic behavior of those key elements and trace metals underlying the (periodically) oxygen-depleted waters of the BUS. We analyzed dissolved concentrations as well as solid-phase speciation of key elements such as iron (Fe), manganese (Mn), phosphorus (P) and sulfur (S) to understand the chemical and physical processes controlling their distribution along the depth/redox-transect. Our results show intense P cycling on the shelf, as evidenced by very high pore-water P concentrations, an enhanced efflux of PO4 to suboxic bottom waters and indications of phosphorite formation at depth in the sediment. N/P ratios well below Redfield indicate N depletion and (relative) P accumulation in the water column, a shift in nutrient stoichiometry that can impact the composition of microbial communities in such waters. Meanwhile, the slope sediments are overlain by oxic bottom waters, retain P more efficiently and exhibit N/P ratios close to Redfield stoichiometry. The capacity of the sediment to buffer toxic sulfide and prevent its release to the water column was dependent on the abundance of sulfide oxidizers at the sediment surface. Furthermore, the variable accumulation of sulfide affected Fe speciation and sedimentary P retention. Overall, we show an intimate coupling between sedimentary cycles of essential elements in the Benguela upwelling system, a stark contrast between shelf and slope environments that is further enhanced by local variation of oxygen depletion and a very strong role of microbes in driving the cycles.

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Energy Harvesting, Electrode Processes and the Partitioning and Speciation of Solid Phase Iron and Sulfur in Marine Sediments

10.21236/ada416521 ◽

2003 ◽

Author(s):

Clare E. Reimers

Keyword(s):

Energy Harvesting ◽

Marine Sediments ◽

Solid Phase ◽

Electrode Processes

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Salt Marsh Sediments as Recorders of Holocene Relative Sea-Level Change

Salt Marshes ◽

10.1017/9781316888933.011 ◽

2021 ◽

pp. 225-256

Author(s):

W. Roland Gehrels ◽

Andrew C. Kemp

Keyword(s):

Salt Marsh ◽

Sea Level ◽

Sea Level Change ◽

Relative Sea Level ◽

Level Change ◽

Marsh Sediments ◽

Salt Marsh Sediments

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Effects of Macrofaunal Recolonization on Biogeochemical Processes and Microbiota—A Mesocosm Study

Water ◽

10.3390/w13111599 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1599

Author(s):

Annika Fiskal ◽

Aixala Gaillard ◽

Sebastien Giroud ◽

Dejan Malcic ◽

Prachi Joshi ◽

...

Keyword(s):

Microbial Communities ◽

Bottom Water ◽

Surface Sediments ◽

Sediment Cores ◽

Lake Basin ◽

Sediment Properties ◽

Chironomid Larvae ◽

Sediment Reworking ◽

Mesocosm Experiments ◽

Tubificid Worms

Macroinvertebrates are widespread in lake sediments and alter sedimentary properties through their activity (bioturbation). Understanding the interactions between bioturbation and sediment properties is important given that lakes are important sinks and sources of carbon and nutrients. We studied the biogeochemical impact of macrofauna on surface sediments in 3-month-long mesocosm experiments conducted using sediment cores from a hypoxic, macrofauna-free lake basin. Experimental units consisted of hypoxic controls, oxic treatments, and oxic treatments that were experimentally colonized with chironomid larvae or tubificid worms. Overall, the presence of O2 in bottom water had the strongest geochemical effect and led to oxidation of sediments down to 2 cm depth. Relative to macrofauna-free oxic treatments, chironomid larvae increased sediment pore water concentrations of nitrate and sulfate and lowered porewater concentrations of reduced metals (Fe2+, Mn2+), presumably by burrow ventilation, whereas tubificid worms increased the redox potential, possibly through sediment reworking. Microbial communities were very similar across oxic treatments; however, the fractions of α-, β-, and γ-Proteobacteria and Sphingobacteriia increased, whereas those of Actinobacteria, Planctomycetes, and Omnitrophica decreased compared to hypoxic controls. Sediment microbial communities were, moreover, distinct from those of macrofaunal tubes or feces. We suggest that, under the conditions studied, bottom water oxygenation has a stronger biogeochemical impact on lacustrine surface sediments than macrofaunal bioturbation.

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Long-Term Fertilization Alters Nitrous Oxide Cycling Dynamics in Salt Marsh Sediments

Environmental Science & Technology ◽

10.1021/acs.est.1c01542 ◽

2021 ◽

Author(s):

Xuefeng Peng ◽

Qixing Ji ◽

John H. Angell ◽

Patrick J. Kearns ◽

Jennifer L. Bowen ◽

...

Keyword(s):

Nitrous Oxide ◽

Salt Marsh ◽

Marsh Sediments ◽

Salt Marsh Sediments

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Estimation of Phosphorus and Nitrogen Waste in Rainbow Trout (Oncorhynchus mykiss, Walbaum, 1792) Diets Including Different Inorganic Phosphorus Sources

Animals ◽

10.3390/ani11061700 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1700

Author(s):

Maria Consolación Milián-Sorribes ◽

Ana Tomás-Vidal ◽

David S. Peñaranda ◽

Laura Carpintero ◽

Juan S. Mesa ◽

...

Keyword(s):

Rainbow Trout ◽

Oncorhynchus Mykiss ◽

Inorganic Phosphorus ◽

Point Of View ◽

Inorganic P ◽

Monocalcium Phosphate ◽

Rainbow Trout Oncorhynchus Mykiss ◽

Phosphorus Sources ◽

Total P ◽

P Sources

This study was conducted to evaluate the apparent availability and P and N excretion in rainbow trout (Oncorhynchus mykiss) using different inorganic phosphorus sources. With this goal, fish (153 ± 14.1 g) fed four inorganic P sources were assayed: monoammonium phosphate (MAP, NH4H2PO4), monosodium/monocalcium phosphate (SCP-2%, AQphos+, NaH2PO4/Ca(H2PO4)2·H2O in proportion 12/88), monosodium/monocalcium phosphate (SCP-5%, NaH2PO4/Ca(H2PO4)2·H2O in proportion 30/70) and monocalcium phosphate (MCP, Ca(H2PO4)2·H2O). Phosphorus (P) digestibility, in diets that included MAP and SCP-2% as inorganic phosphorus sources, were significantly higher than for SCP-5% and MCP sources. In relation to the P excretion pattern, independent of the diet, a peak at 6 h after feeding was registered, but at different levels depending on inorganic P sources. Fish fed an MAP diet excreted a higher amount of dissolved P in comparison with the rest of the inorganic P sources, although the total P losses were lower in MAP and SCP-2% (33.02% and 28.13, respectively) than in SCP-5% and MCP sources (43.35% and 47.83, respectively). Nitrogen (N) excretion was also studied, and the fish fed an SCP-5% diet provided lower values (15.8%) than MAP (28.0%). When N total wastes were calculated, SCP-2% and SCP-5% showed the lowest values (31.54 and 28.25%, respectively). In conclusion, based on P and N digestibility and excretion, the SCP-2% diet showed the best results from a nutritional and environmental point of view.

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