Iron and manganese colimitation in the Southern Ocean examined with a proteomic allocation model

2020 ◽  
Author(s):  
J. Scott P. McCain ◽  
Eric P. Achterberg ◽  
Alessandro Tagliabue ◽  
Erin M. Bertrand
Keyword(s):  
Southern Ocean ◽  
Primary Productivity ◽  
Coarse Grained ◽  
Biogeochemical Model ◽  
Cellular Mechanisms ◽  
Modeling Framework ◽  
Allocation Model ◽  
Fe And Mn ◽  
Geochemical Profiles ◽  
Iron And Manganese

<p>Iron (Fe) limits primary productivity in a large part of the ocean; but recent geochemical profiles and bottle incubation assays indicate that manganese (Mn) can also limit primary productivity in the Southern Ocean. Fe and Mn can interact to influence primary productivity, but the extent to which these elements colimit phytoplankton in the Southern Ocean is uncertain. In addition, current models are insufficient to assess colimitation as they assume a single, most scarce, resource. In order to examine Fe and Mn colimitation in phytoplankton, we developed a modeling framework to predict proteomic profiles under varying Fe, Mn, and light conditions. In our model, proteins are optimally allocated to various coarse-grained cellular pools, governed by environmental conditions. We predict that Fe controls cellular Mn quotas, largely because of paired stoichiometry within photosynthetic machinery. Our model suggests that the diffusion-limitation paradigm of Fe should be revisited, as diffusive flux of Fe does not appear to be limiting. We then use our model to explore various cellular mechanisms leading to phytoplankton Fe limitation. Lastly, using Fe and Mn biogeochemical model output, we predict regions in the Southern Ocean where Fe/Mn colimitation is most likely to occur.</p>

Quantifying the role of volcanic ash supply in the oceanic iron and manganese cycles

2020 ◽  
Author(s):  
Jack Longman ◽  
Martin Palmer ◽  
Thomas Gernon
Keyword(s):  
Primary Productivity ◽  
Volcanic Ash ◽  
Net Primary Productivity ◽  
Upper Ocean ◽  
Mean Values ◽  
Volcanic Material ◽  
Fe And Mn ◽  
Key Driver ◽  
Iron And Manganese

<p>Primary productivity in the upper ocean is a key driver of Earth’s carbon cycle. The supply of micronutrients such as iron (Fe) and manganese (Mn) to the ocean is now known to exert a controlling influence on net primary productivity. Fragmental volcanic material, or tephra, is enriched in such nutrients, highly reactive and regularly supplied to the upper ocean when eruptions occur. However, there are no existing estimates of the global magnitude of the volcanic supply of these (and associated) nutrients to the oceans. Here we present new data from ten volcanic provinces globally including the Aleutian Islands and Lesser Antilles to estimate depletion factors of both Fe and Mn in altered tephra. By comparing the concentration of altered tephra to unaltered protolithic compositions, we can estimate depletion factors, and thus the amount of each element supplied to the oceans via this method. Using a novel Monte Carlo approach, we estimate mean values of Fe and Mn to be on the order of 26.1 and 0.25 Gmol yr<sup>-1</sup>, respectively. These values are broadly comparable to riverine and atmospheric dust fluxes to the ocean, indicating that volcanism plays a major role in Fe and Mn ocean cycles.</p>

scholarly journals Southern Ocean carbon export efficiency in relation to temperature and primary productivity

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Gaojing Fan ◽  
Zhengbing Han ◽  
Wentao Ma ◽  
Shuangling Chen ◽  
Fei Chai ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Primary Productivity ◽  
Carbon Export ◽  
Ocean Carbon

scholarly journals On iron flagellates

1946 ◽  
Vol 232 (588) ◽  
pp. 311-342 ◽  
Keyword(s):  
Organic Substances ◽  
Habitat Conditions ◽  
Liquid Media ◽  
Brown Colour ◽  
Fe And Mn ◽  
Iron Deposits ◽  
Manganese Compounds ◽  
Small Content ◽  
Iron And Manganese

The physiology and morphology of iron- and manganese-depositing flagellates are investigated by means of cultural experiments, with special reference to Anthophysa vegetans Stein, Siderodendron manganiferum n.gen., n.sp., Siphomonas Fritschii n.gen., n.sp. and Bikosoeca ( Poteriodendron ) petiolata (Stein) n.comb. Anthophysa multiplies in various liquid media containing small amounts of organic substances, hay decoction being specially favourable. Still better results are achieved with soil-water cultures, which afford the only successful cultures of Siderodendron and Siphomonas , while Bikosoeca also grows well in hay infusions. Addition of Fe" and Mn" is essential. The brown colour of biological iron deposits is shown to be due to admixture of manganese compounds, while mere ferric precipitates are in microscopical amounts almost colourless. Anthophysa and Siderodendron deposit more manganese than iron, so that their stalks appear brown, while those of Siphomonas are generally light brown. The envelopes of Bikosoeca are almost entirely composed of ferric compounds and appear colourless or faintly yellowish. All four organisms exhibit various modifications according to the habitat conditions. The formation of stalks and envelopes respectively depends on the availability of the relevant metals in the form of lower oxides, but the organisms here described can also exist without producing these structures. The oxidation of ferrous and manganese compounds is catalysed by the cells of these flagellates, although the role of this process in the cellular metabolism is not known. Nutrition is holozoic, chiefly by ingestion of bacteria. Like other holozoic flagellates these organisms cannot exist in the presence of an abundant bacterial vegetation owing to the resulting lack of oxygen. They thrive in quiet, well-aerated waters, with a small content of organic substances, above zones in which Fe and Mn compounds are reduced and from which ferrous and manganous compounds diffuse to the overlying oxidation zone, where these flagellates deposit Fe"' and Mn'" in a morphologically defined form. ‘Iron’ flagellates generally live in association and competition with iron bacteria of the Leptothrix group, the removal of which produces much better growth. A description of the relevant flagellates and of their appearance under various conditions, as well as diagnoses of Siderodendron and Siphomonas , are given.

scholarly journals Seabed Resuspension in the Chesapeake Bay: Implications for Biogeochemical Cycling and Hypoxia

2020 ◽  
Vol 44 (1) ◽  
pp. 103-122
Author(s):  
Julia M. Moriarty ◽  
Marjorie A. M. Friedrichs ◽  
Courtney K. Harris
Keyword(s):  
Organic Matter ◽  
Chesapeake Bay ◽  
Water Column ◽  
Primary Productivity ◽  
Environmental Changes ◽  
Light Attenuation ◽  
Sediment Resuspension ◽  
Nitrogen Dynamics ◽  
Biogeochemical Model ◽  
Order Of Magnitude

AbstractSediment processes, including resuspension and transport, affect water quality in estuaries by altering light attenuation, primary productivity, and organic matter remineralization, which then influence oxygen and nitrogen dynamics. The relative importance of these processes on oxygen and nitrogen dynamics varies in space and time due to multiple factors and is difficult to measure, however, motivating a modeling approach to quantify how sediment resuspension and transport affect estuarine biogeochemistry. Results from a coupled hydrodynamic–sediment transport–biogeochemical model of the Chesapeake Bay for the summers of 2002 and 2003 showed that resuspension increased light attenuation, especially in the northernmost portion of the Bay, shifting primary production downstream. Resuspension also increased remineralization in the central Bay, which experienced larger organic matter concentrations due to the downstream shift in primary productivity and estuarine circulation. As a result, oxygen decreased and ammonium increased throughout the Bay in the bottom portion of the water column, due to reduced photosynthesis in the northernmost portion of the Bay and increased remineralization in the central Bay. Averaged over the channel, resuspension decreased oxygen by ~ 25% and increased ammonium by ~ 50% for the bottom water column. Changes due to resuspension were of the same order of magnitude as, and generally exceeded, short-term variations within individual summers, as well as interannual variability between 2002 and 2003, which were wet and dry years, respectively. Our results quantify the degree to which sediment resuspension and transport affect biogeochemistry, and provide insight into how coastal systems may respond to management efforts and environmental changes.

scholarly journals Primary productivity, new productivity, and their relation to carbon flux during two Southern Ocean Gas Exchange tracer experiments

2012 ◽  
Vol 117 (C4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Veronica P. Lance ◽  
Peter G. Strutton ◽  
Robert D. Vaillancourt ◽  
Bruce R. Hargreaves ◽  
Jia-Zhong Zhang ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Southern Ocean ◽  
Primary Productivity ◽  
Carbon Flux ◽  
Tracer Experiments

scholarly journals On modeling the Southern Ocean Phytoplankton Functional Types

2019 ◽  
Author(s):  
Svetlana N. Losa ◽  
Stephanie Dutkiewicz ◽  
Martin Losch ◽  
Julia Oelker ◽  
Mariana A. Soppa ◽  
...  
Keyword(s):  
Southern Ocean ◽  
General Circulation ◽  
Circulation Model ◽  
Biogeochemical Model ◽  
Massachusetts Institute Of Technology ◽  
Pigment Analysis ◽  
Functional Types ◽  
Model Configuration ◽  
Institute Of Technology

Abstract. This study highlights recent advances and challenges of applying coupled physical-biogeochemical modeling for investigating the distribution of the key phytoplankton groups in the Southern Ocean, an area of strong interest for understanding biogeochemical cycling and ecosystem functioning under present climate change. Our simulations of the phenology of various Phytoplankton Functional Types (PFTs) are based on a version of the Darwin biogeochemical model coupled to the Massachusetts Institute of Technology (MIT) general circulation model (Darwin-MITgcm). The ecological module version was adapted for the Southern Ocean by: 1) improving coccolithophores abundance relative to the original model by introducing a high affinity for nutrients and an ability to escape grazing control for coccolithophores; 2) including two different (small vs. large) size classes of diatoms; and 3) accounting for two distinct life stages for Phaeocystis (single cell vs. colonial). This new model configuration describes best the competition and co-occurrence of the PFTs in the Southern Ocean. It improves significantly relative to an older version the agreement of the simulated abundance of the coccolithophores and diatoms with in situ scanning electron microscopy observations in the Subantarctic Zone as well as with in situ diatoms and haptophytes (including coccolithophores and Phaeocystis) chlorophyll a concentrations within the Patagonian Shelf and along the Western Antarctic Peninsula obtained by diagnostic pigment analysis. The modeled Southern Ocean PFT dominance also agrees well with satellite-based PFT information.

scholarly journals Pan-organ model integration of metabolic and regulatory processes in type 1 diabetes

2019 ◽  
Author(s):  
Marouen Ben Guebila ◽  
Ines Thiele
Keyword(s):  
Type 1 Diabetes ◽  
Systemic Disease ◽  
Coarse Grained ◽  
Whole Body ◽  
Correct Prediction ◽  
Long Term Effects ◽  
Modeling Framework ◽  
Human Pathology ◽  
The Impact

SummaryType 1 diabetes mellitus (T1D) is a systemic disease triggered by a local autoimmune inflammatory reaction in insulin-producing cells that disrupts the glucose-insulin-glucagon system and induces organ-wide, long-term effects on glycolytic and nonglycolytic processes. Mathematical modeling of the whole-body regulatory bihormonal system has helped to identify intervention points to ensure better control of T1D but was limited to a coarse-grained representation of metabolism. To extend the depiction of T1D, we developed a whole-body model using a novel integrative modeling framework that links organ-specific regulation and metabolism. The developed framework allowed the correct prediction of disrupted metabolic processes in T1D, highlighted pathophysiological processes common with neurodegenerative disorders, and suggested calcium channel blockers as potential adjuvants for diabetes control. Additionally, the model predicted the occurrence of insulin-dependent rewiring of interorgan crosstalk. Moreover, a simulation of a population of virtual patients allowed an assessment of the impact of inter and intraindividual variability on insulin treatment and the implications for clinical outcomes. In particular, GLUT4 was suggested as a potential pharmacogenomic regulator of intraindividual insulin efficacy. Taken together, the organ-resolved, dynamic model may pave the way for a better understanding of human pathology and model-based design of precise allopathic strategies.

scholarly journals Fueling primary productivity: nutrient return pathways from the deep ocean and their dependence on the Meridional Overturning Circulation

2010 ◽  
Vol 7 (3) ◽  
pp. 4045-4088 ◽  
Author(s):  
J. B. Palter ◽  
J. L. Sarmiento ◽  
A. Gnanadesikan ◽  
J. Simeon ◽  
D. Slater
Keyword(s):  
Southern Ocean ◽  
Primary Productivity ◽  
Deep Ocean ◽  
Ocean Model ◽  
Surface Fluxes ◽  
Meridional Overturning Circulation ◽  
Overturning Circulation ◽  
Nutrient Return ◽  
Mode Water ◽  
Meridional Overturning

Abstract. In the Southern Ocean, mixing and upwelling in the presence of heat and freshwater surface fluxes transform subpycnocline water to lighter densities as part of the upward branch of the Meridional Overturning Circulation (MOC). One hypothesized impact of this transformation is the restoration of nutrients to the global pycnocline, without which biological productivity at low latitudes would be catastrophically reduced. Here we use a novel set of modeling experiments to explore the causes and consequences of the Southern Ocean nutrient return pathway. Specifically, we quantify the contribution to global productivity of nutrients that rise from the ocean interior in the Southern Ocean, the northern high latitudes, and by mixing across the low latitude pycnocline. In addition, we evaluate how the strength of the Southern Ocean winds and the parameterizations of subgridscale processes change the dominant nutrient return pathways in the ocean. Our results suggest that nutrients upwelled from the deep ocean in the Antarctic Circumpolar Current and subducted in Subantartic Mode Water support between 33 and 75% of global primary productivity between 30° S and 30° N. The high end of this range results from an ocean model in which the MOC is driven primarily by wind-induced Southern Ocean upwelling, a configuration favored due to its fidelity to tracer data, while the low end results from an MOC driven by high diapycnal diffusivity in the pycnocline. In all models, the high preformed nutrients subducted in the SAMW layer are converted rapidly (in less than 40 years) to remineralized nutrients, explaining previous modeling results that showed little influence of the drawdown of SAMW surface nutrients on atmospheric carbon concentrations.

scholarly journals Accumulation of Zn, Cu, Fe, Mn and Pb due to brick manufacturing in agricultutral soils and plants

2016 ◽  
Vol 25 (1) ◽  
pp. 75-81 ◽  
Author(s):  
Abdul Halim Farhad Sikder ◽  
Sayma Khanom ◽  
Md Faruque Hossain ◽  
Zakia Parveen
Keyword(s):  
Heavy Metals ◽  
Agricultural Soil ◽  
Poor Quality ◽  
Maximum Amount ◽  
Agricultural Crops ◽  
Brick Kilns ◽  
Fe And Mn ◽  
Iron And Manganese

Experiment was carried out to assess the concentration of Zn, Cu, Pb, Fe and Mn in agricultural soil and plant near selected brick kilns. Soils and plants samples were collected from four points such as 250, 500, 1000 and 1500 m away from brick kilns. Three metals were found at elevated levels in the soils near brick kilns such as, Pb (92.5 to 214 mg/kg), Zn (86 to 156 mg/kg) and Cu (24.7 to 46.9 mg/kg). It may be caused due to burning of poor quality coal and fire woods. The uptake of heavy metals in the nearest areas (250 m) of the brick kilns was significantly higher than the areas far from the brick production and their concentrations range from 7 to 543 mg/kg for Pb, 23 to 101 mg/kg for Zn, 10 to 41 mg/kg for Cu, 35 to 1309 mg/kg for Fe and 26 to 126 mg/kg for Mn. Results indicated that soils and plants accumulated maximum amount of micronutrients within 500 to 1000 m distance from brick kilns significantly decreased with distance. Iron and manganese were not polluting the soils near brick kilns but affecting the plants. Therefore, it can be suggested that no agricultural crops should be grown within 1000 m distance from a brick kiln.Dhaka Univ. J. Biol. Sci. 25(1): 75-81, 2016

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