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Michael W. Lomas - One of the best experts on this subject based on the ideXlab platform.
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C : N : P stoichiometry at the Bermuda Atlantic Time-series Study station in the North Atlantic Ocean
Biogeosciences, 2015Co-Authors: Arvind Singh, Adam C. Martiny, Ulf Riebesell, S. E. Baer, Michael W. LomasAbstract:Abstract. Nitrogen (N) and phosphorus (P) availability, in addition to other macro- and micronutrients, determine the strength of the ocean's carbon (C) uptake, and variation in the N : P Ratio of inorganic nutrient pools is key to phytoplankton growth. A similarity between C : N : P Ratios in the plankton biomass and deep-water nutrients was observed by Alfred C. Redfield around 80 years ago and suggested that biological processes in the surface ocean controlled deep-ocean chemistry. Recent studies have emphasized the role of inorganic N : P Ratios in governing biogeochemical processes, particularly the C : N : P Ratio in suspended particulate organic matter (POM), with somewhat less attention given to exported POM and dissolved organic matter (DOM). Herein, we extend the discussion on ecosystem C : N : P stoichiometry but also examine temporal variation in stoichiometric relationships. We have analyzed elemental stoichiometry in the suspended POM and total (POM + DOM) organic-matter (TOM) pools in the upper 100 m and in the exported POM and subeuphotic zone (100–500 m) inorganic nutrient pools from the monthly data collected at the Bermuda Atlantic Time-series Study (BATS) site located in the western part of the North Atlantic Ocean. C : N and N : P Ratios in TOM were at least twice those in the POM, while C : P Ratios were up to 5 times higher in TOM compared to those in the POM. Observed C : N Ratios in suspended POM were approximately equal to the canonical Redfield Ratio (C : N : P = 106 : 16 : 1), while N : P and C : P Ratios in the same pool were more than twice the Redfield Ratio. Average N : P Ratios in the subsurface inorganic nutrient pool were ~ 26 : 1, squarely between the suspended POM Ratio and the Redfield Ratio. We have further linked variation in elemental stoichiometry to that of phytoplankton cell abundance observed at the BATS site. Findings from this study suggest that elemental Ratios vary with depth in the euphotic zone, mainly due to different growth rates of cyanobacterial cells. We have also examined the role of the Arctic Oscillation on temporal patterns in C : N : P stoichiometry. This study strengthens our understanding of the variability in elemental stoichiometry in different organic-matter pools and should improve biogeochemical models by constraining the range of non-Redfield stoichiometry and the net relative flow of elements between pools.
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Regional variation in the particulate organic carbon to nitrogen Ratio in the surface ocean
Global Biogeochemical Cycles, 2013Co-Authors: Adam C. Martiny, Jasper A. Vrugt, François Primeau, Michael W. LomasAbstract:The concept of constant elemental Ratios in plankton communities—the Redfield Ratio—is of central importance to ocean biogeochemistry. Recently, several studies have demonstrated regional differences in the plankton C:P and N:P Ratio. However, less is known about potential systematic variations in the C:N Ratio. Here we present an analysis of the particulate organic carbon to nitrogen Ratio of 40,482 globally distributed samples from the upper 200 m of the ocean water column. Particulate organic carbon and nitrogen concentRations are highly correlated (R 2 = 0.86) with a median value of 6.5. Using an artificial neural network analysis, we find regional variations in the C:N Ratio linked to differences in environmental conditions. The Ratio is lower in upper latitude cold water as well as upwelling regions in comparison to the warm oligotrophic gyres. We find substantial differences between ocean gyres that might be associated with differences in the nutrient supply Ratio. Using cell sorting, we also quantified the C:N Ratio of Prochlorococcus,Synechococcus, and picoeukaryotic field populations. The analysis demonstrates that picophytoplankton lineages exhibit a significantly higher Ratio than the bulk particulate material but are only marginally significantly different from each other. Thus, the dominance of picophytoplankton in ocean gyres may contribute to the elevated Ratios observed in these regions. Overall, the median C:N Ratio derived from 40,482 samples is close to the canonical Redfield Ratio, but significant regional deviations from this value are observed. These differences could be important for marine biogeochemistry and the regional coupling between the ocean's carbon and nitrogen cycles.
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strong latitudinal patterns in the elemental Ratios of marine plankton and organic matter
Nature Geoscience, 2013Co-Authors: Adam C. Martiny, Michael W. Lomas, Jasper A. Vrugt, François Primeau, Chau T A Pham, Keith J Moore, Simon A LevinAbstract:Nearly 75 years ago, Alfred C. Redfield observed a similarity between the elemental composition of marine plankton in the surface ocean and dissolved nutrients in the ocean interior 1 . This stoichiometry, referred to as the Redfield Ratio, continues to be a central tenet in ocean biogeochemistry, and is used to infer a variety of ecosystem processes, such as phytoplankton productivity and rates of nitrogen fixation and loss 2‐4 . Model, field and laboratory studies have shown that different mechanisms can explain both constant and variable Ratios of carbon to nitrogen and phosphorus among ocean plankton communities. The range of C/N/P Ratios in the ocean, and their predictability, are the subject of much active research 5‐12 . Here we assess global patterns in the elemental composition of phytoplankton and particulate organic matter in the upper ocean, using published and unpublished observations of particulate phosphorus, nitrogen and carbon from a broad latitudinal range, supplemented with elemental data for surface plankton populations. We show that the elemental Ratios of marine organic matter exhibit large spatial variations, with a global average that differs substantially from the canonical Redfield Ratio. However, elemental Ratios exhibit a clear latitudinal trend. Specifically, we observed a Ratio of 195:28:1 in the warm nutrient-depleted low-latitude gyres, 137:18:1 in warm, nutrient-rich upwelling zones, and 78:13:1 in cold, nutrient-rich high-latitude regions. We suggest that the coupling between oceanic carbon, nitrogen and phosphorus cycles may vary systematically by ecosystem. A. C. Redfield first noted the similarity between the particulate nutrient Ratios of plankton living in the surface ocean and that of dissolved nutrients in the deep ocean 1 . He predicted that deep-ocean nutrient Ratios were controlled by the uniform nutrient requirements of sinking, and subsequently remineralized, surface plankton. This concept remains a central tenet in our understanding of ocean biogeochemistry. However, model, field and laboratory studies have shown that different mechanisms can explain both constant and variable C/N/P Ratios among ocean plankton communities, but the range of Ratios in the ocean and the relative importance of each mechanism are subject to much research 510,13,14 . Despite this continued lack of understanding of global patterns, the N/P Ratio is routinely used to draw conclusions about ocean ecosystem processes, particularly related to nutrient limitation of phytoplankton production and the net magnitude of N2 fixation and denitrification. 2,3 . Alas, these Ratios are of critical importance to study, model and predict ocean biogeochemical cycles. Equally important is the C/P Ratio of ocean plankton
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Revisiting N2 fixation in the North Atlantic Ocean: Significance of deviations from the Redfield Ratio, atmospheric deposition and climate variability
Deep Sea Research Part II: Topical Studies in Oceanography, 2013Co-Authors: Arvind Singh, Michael W. Lomas, Nicholas R. BatesAbstract:The average oceanic nitrate-to-phosphate molar Ratio (NO3?:PO43??16:1, referred to as the Redfield Ratio) in subsurface waters, which is similar to the average Ratio of particulate nitrogen (N)-to-phosphorus (P) in phytoplankton, is the cornerstone in calculating geochemical estimates of N2 fixation and denitrification rates. Any deviations from this canonical Redfield Ratio in intermediate ocean waters, expressed as N* (a measure of NO3? in excess or deficit of 16×PO43?), provides an integrated estimate of net N fluxes into and out of the ocean. In well-oxygenated ocean basins such as the North Atlantic Ocean, N* estimates are usually positive and can be used to infer that rates of N2 fixation exceed rates of denitrification. We use this approach to estimate N2 fixation over the last two decades (1988–2009) based on data collected at the Bermuda Atlantic Time-series Study (BATS) site in the North Atlantic Ocean near Bermuda. Our results indicate that interpretation of the N* tracer as an estimate of N2 fixation should be undertaken with caution, as N2 fixation is not the only process that results in a positive N* estimate. The impacts of a locally variable nitrogen-to-phosphorus Ratio, relative to the fixed Redfield Ratio, in the suspended particulate matter as well as in the subsurface water nutrients and atmospheric N deposition on N* variability were examined. Furthermore, we explored the role of climate modes (i.e., North Atlantic Oscillation and Arctic Oscillation) on N* variability. We found that N* in the subsurface waters was significantly affected by these factors and hence previous estimates of N2 fixation using this technique might have been substantially overestimated. Our revised estimate of N2 fixation in the North Atlantic Ocean (0°N–50°N, 20°W–80°W) is 12.2±0.9×1011 mol N yr?1, and based on long-term BATS data provides better constraints than both earlier indirect and direct estimates N2 fixation.
Daniel Liptzin - One of the best experts on this subject based on the ideXlab platform.
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C:N:P stoichiometry in soil: is there a “Redfield Ratio” for the microbial biomass?
Biogeochemistry, 2007Co-Authors: Cory C Cleveland, Daniel LiptzinAbstract:Well-constrained carbon:nitrogen:phosphorus (C:N:P) Ratios in planktonic biomass, and their importance in advancing our understanding of biological processes and nutrient cycling in marine ecosystems, has motivated ecologists to search for similar patterns in terrestrial ecosystems. Recent analyses indicate the existence of “Redfield-like” Ratios in plants, and such data may provide insight into the nature of nutrient limitation in terrestrial ecosystems. We searched for analogous patterns in the soil and the soil microbial biomass by conducting a review of the literature. Although soil is characterized by high biological diversity, structural complexity and spatial heterogeneity, we found remarkably consistent C:N:P Ratios in both total soil pools and the soil microbial biomass. Our analysis indicates that, similar to marine phytoplankton, element concentRations of individual phylogenetic groups within the soil microbial community may vary, but on average, atomic C:N:P Ratios in both the soil (186:13:1) and the soil microbial biomass (60:7:1) are well-constrained at the global scale. We did see significant variation in soil and microbial element Ratios between vegetation types (i.e., forest versus grassland), but in most cases, the similarities in soil and microbial element Ratios among sites and across large scales were more apparent than the differences. Consistent microbial biomass element Ratios, combined with data linking specific patterns of microbial element stoichiometry with direct evidence of microbial nutrient limitation, suggest that measuring the proportions of C, N and P in the microbial biomass may represent another useful tool for assessing nutrient limitation of ecosystem processes in terrestrial ecosystems.
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C:N:P stoichiometry in soil: Is there a "Redfield Ratio" for the microbial biomass?
Biogeochemistry, 2007Co-Authors: Cory C Cleveland, Daniel LiptzinAbstract:Well-constrained carbon:nitrogen:phosphorus (C:N:P) Ratios in planktonic biomass, and their importance in advancing our understanding of biological processes and nutrient cycling in marine ecosystems, has motivated ecologists to search for similar patterns in terrestrial ecosystems. Recent analyses indicate the existence of "Redfield-like" Ratios in plants, and such data may provide insight into the nature of nutrient limitation in terrestrial ecosystems. We searched for analogous patterns in the soil and the soil microbial biomass by conducting a review of the literature. Although soil is characterized by high biological diversity, structural complexity and spatial heterogeneity, we found remarkably consistent C:N:P Ratios in both total soil pools and the soil microbial biomass. Our analysis indicates that, similar to marine phytoplankton, element concentRations of individual phylogenetic groups within the soil microbial community may vary, but on average, atomic C:N:P Ratios in both the soil (186:13:1) and the soil microbial biomass (60:7:1) are well-constrained at the global scale. We did see significant variation in soil and microbial element Ratios between vegetation types (i.e., forest versus grassland), but in most cases, the similarities in soil and microbial element Ratios among sites and across large scales were more apparent than the differences. Consistent microbial biomass element Ratios, combined with data linking specific patterns of microbial element stoichiometry with direct evidence of microbial nutrient limitation, suggest that measuring the proportions of C, N and P in the microbial biomass may represent another useful tool for assessing nutrient limitation of ecosystem processes in terrestrial ecosystems.
S. Skinner - One of the best experts on this subject based on the ideXlab platform.
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does the Redfield Ratio infer nutrient limitation in the macroalga spirogyra fluviatilis
Freshwater Biology, 2008Co-Authors: Simon A. Townsend, Julia Schult, Michael M. Douglas, S. SkinnerAbstract:Summary 1. The cellular nutrient contents of microalgae, when growing at or approaching maximum rates, approximate the Redfield C : N : P (molar) Ratio of 106 : 16 : 1. Deviations from this optimal Ratio can be used to infer nutrient limitation of microalgal growth. However, this Ratio may not be applicable to macroalgae, which are distinguished from microalgae by forming a thallus that is a discrete structure visible to the naked eye. The utility of the Redfield Ratio to infer nutrient limitation of the growth of macroalgae was tested for Spirogyra fluviatilis in a field experiment conducted in tropical Australia. 2. The optimal cellular C : N : P Ratio for S. fluvialitis was estimated by means of in situ nutrient addition. This was compared with S. fluvialitis cellular Ratios determined from eight sites with a wide range of soluble N concentRations (<1–90 μg L−1), a smaller range of soluble P concentRations (5–12 μg L−1), and soluble molar N : P Ratios of 0.11– 27. 3. Spirogyra fluviatilis had an optimal molar C : N : P Ratio of 1800 : 87 : 1 which differs substantially from the Redfield Ratio, and suggests that the latter Ratio is not applicable to this macroalga. ConcentRations of N and P in the river deviated from the optimal N : P Ratio of 87 : 1, inferring nutrient limitation of growth. 4. C : P and C : N Ratios of S. fluviatilis varied in accordance with general stoichiometric relationships for autotrophs under nutrient limitation of growth. Ratios of C : P and C : N increased, respectively, with increased severity of P- and N-limitation. Additionally, C : P Ratios increased with increased N : P Ratios, whilst the C : N Ratio increased with decreased N : P Ratios. The C : N molar Ratio however was an insensitive indicator of nutrient depletion compared with the C : P Ratio. Under N-limitation of growth, luxury amounts of P were stored by S. fluviatilis. 5. In aquatic environments where macroalgae are sufficiently abundant to be sampled, their cellular carbon, nitrogen and phosphorus stoichiometry can be used to infer nutrient limitation of growth when their optimal C : N : P Ratio is known.
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Does the Redfield Ratio infer nutrient limitation in the macroalga Spirogyra fluviatilis
Freshwater Biology, 2008Co-Authors: Simon A. Townsend, Julia Schult, Michael M. Douglas, S. SkinnerAbstract:Summary 1. The cellular nutrient contents of microalgae, when growing at or approaching maximum rates, approximate the Redfield C : N : P (molar) Ratio of 106 : 16 : 1. Deviations from this optimal Ratio can be used to infer nutrient limitation of microalgal growth. However, this Ratio may not be applicable to macroalgae, which are distinguished from microalgae by forming a thallus that is a discrete structure visible to the naked eye. The utility of the Redfield Ratio to infer nutrient limitation of the growth of macroalgae was tested for Spirogyra fluviatilis in a field experiment conducted in tropical Australia. 2. The optimal cellular C : N : P Ratio for S. fluvialitis was estimated by means of in situ nutrient addition. This was compared with S. fluvialitis cellular Ratios determined from eight sites with a wide range of soluble N concentRations (
Cory C Cleveland - One of the best experts on this subject based on the ideXlab platform.
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C:N:P stoichiometry in soil: is there a “Redfield Ratio” for the microbial biomass?
Biogeochemistry, 2007Co-Authors: Cory C Cleveland, Daniel LiptzinAbstract:Well-constrained carbon:nitrogen:phosphorus (C:N:P) Ratios in planktonic biomass, and their importance in advancing our understanding of biological processes and nutrient cycling in marine ecosystems, has motivated ecologists to search for similar patterns in terrestrial ecosystems. Recent analyses indicate the existence of “Redfield-like” Ratios in plants, and such data may provide insight into the nature of nutrient limitation in terrestrial ecosystems. We searched for analogous patterns in the soil and the soil microbial biomass by conducting a review of the literature. Although soil is characterized by high biological diversity, structural complexity and spatial heterogeneity, we found remarkably consistent C:N:P Ratios in both total soil pools and the soil microbial biomass. Our analysis indicates that, similar to marine phytoplankton, element concentRations of individual phylogenetic groups within the soil microbial community may vary, but on average, atomic C:N:P Ratios in both the soil (186:13:1) and the soil microbial biomass (60:7:1) are well-constrained at the global scale. We did see significant variation in soil and microbial element Ratios between vegetation types (i.e., forest versus grassland), but in most cases, the similarities in soil and microbial element Ratios among sites and across large scales were more apparent than the differences. Consistent microbial biomass element Ratios, combined with data linking specific patterns of microbial element stoichiometry with direct evidence of microbial nutrient limitation, suggest that measuring the proportions of C, N and P in the microbial biomass may represent another useful tool for assessing nutrient limitation of ecosystem processes in terrestrial ecosystems.
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C:N:P stoichiometry in soil: Is there a "Redfield Ratio" for the microbial biomass?
Biogeochemistry, 2007Co-Authors: Cory C Cleveland, Daniel LiptzinAbstract:Well-constrained carbon:nitrogen:phosphorus (C:N:P) Ratios in planktonic biomass, and their importance in advancing our understanding of biological processes and nutrient cycling in marine ecosystems, has motivated ecologists to search for similar patterns in terrestrial ecosystems. Recent analyses indicate the existence of "Redfield-like" Ratios in plants, and such data may provide insight into the nature of nutrient limitation in terrestrial ecosystems. We searched for analogous patterns in the soil and the soil microbial biomass by conducting a review of the literature. Although soil is characterized by high biological diversity, structural complexity and spatial heterogeneity, we found remarkably consistent C:N:P Ratios in both total soil pools and the soil microbial biomass. Our analysis indicates that, similar to marine phytoplankton, element concentRations of individual phylogenetic groups within the soil microbial community may vary, but on average, atomic C:N:P Ratios in both the soil (186:13:1) and the soil microbial biomass (60:7:1) are well-constrained at the global scale. We did see significant variation in soil and microbial element Ratios between vegetation types (i.e., forest versus grassland), but in most cases, the similarities in soil and microbial element Ratios among sites and across large scales were more apparent than the differences. Consistent microbial biomass element Ratios, combined with data linking specific patterns of microbial element stoichiometry with direct evidence of microbial nutrient limitation, suggest that measuring the proportions of C, N and P in the microbial biomass may represent another useful tool for assessing nutrient limitation of ecosystem processes in terrestrial ecosystems.
Simon A. Townsend - One of the best experts on this subject based on the ideXlab platform.
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does the Redfield Ratio infer nutrient limitation in the macroalga spirogyra fluviatilis
Freshwater Biology, 2008Co-Authors: Simon A. Townsend, Julia Schult, Michael M. Douglas, S. SkinnerAbstract:Summary 1. The cellular nutrient contents of microalgae, when growing at or approaching maximum rates, approximate the Redfield C : N : P (molar) Ratio of 106 : 16 : 1. Deviations from this optimal Ratio can be used to infer nutrient limitation of microalgal growth. However, this Ratio may not be applicable to macroalgae, which are distinguished from microalgae by forming a thallus that is a discrete structure visible to the naked eye. The utility of the Redfield Ratio to infer nutrient limitation of the growth of macroalgae was tested for Spirogyra fluviatilis in a field experiment conducted in tropical Australia. 2. The optimal cellular C : N : P Ratio for S. fluvialitis was estimated by means of in situ nutrient addition. This was compared with S. fluvialitis cellular Ratios determined from eight sites with a wide range of soluble N concentRations (<1–90 μg L−1), a smaller range of soluble P concentRations (5–12 μg L−1), and soluble molar N : P Ratios of 0.11– 27. 3. Spirogyra fluviatilis had an optimal molar C : N : P Ratio of 1800 : 87 : 1 which differs substantially from the Redfield Ratio, and suggests that the latter Ratio is not applicable to this macroalga. ConcentRations of N and P in the river deviated from the optimal N : P Ratio of 87 : 1, inferring nutrient limitation of growth. 4. C : P and C : N Ratios of S. fluviatilis varied in accordance with general stoichiometric relationships for autotrophs under nutrient limitation of growth. Ratios of C : P and C : N increased, respectively, with increased severity of P- and N-limitation. Additionally, C : P Ratios increased with increased N : P Ratios, whilst the C : N Ratio increased with decreased N : P Ratios. The C : N molar Ratio however was an insensitive indicator of nutrient depletion compared with the C : P Ratio. Under N-limitation of growth, luxury amounts of P were stored by S. fluviatilis. 5. In aquatic environments where macroalgae are sufficiently abundant to be sampled, their cellular carbon, nitrogen and phosphorus stoichiometry can be used to infer nutrient limitation of growth when their optimal C : N : P Ratio is known.
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Does the Redfield Ratio infer nutrient limitation in the macroalga Spirogyra fluviatilis
Freshwater Biology, 2008Co-Authors: Simon A. Townsend, Julia Schult, Michael M. Douglas, S. SkinnerAbstract:Summary 1. The cellular nutrient contents of microalgae, when growing at or approaching maximum rates, approximate the Redfield C : N : P (molar) Ratio of 106 : 16 : 1. Deviations from this optimal Ratio can be used to infer nutrient limitation of microalgal growth. However, this Ratio may not be applicable to macroalgae, which are distinguished from microalgae by forming a thallus that is a discrete structure visible to the naked eye. The utility of the Redfield Ratio to infer nutrient limitation of the growth of macroalgae was tested for Spirogyra fluviatilis in a field experiment conducted in tropical Australia. 2. The optimal cellular C : N : P Ratio for S. fluvialitis was estimated by means of in situ nutrient addition. This was compared with S. fluvialitis cellular Ratios determined from eight sites with a wide range of soluble N concentRations (
