scholarly journals The Impact of Variable Phytoplankton Stoichiometry on Projections of Primary Production, Food Quality, and Carbon Uptake in the Global Ocean

2018 ◽  
Vol 32 (4) ◽  
pp. 516-528 ◽  
Author(s):  
Lester Kwiatkowski ◽  
Olivier Aumont ◽  
Laurent Bopp ◽  
Philippe Ciais
Keyword(s):  
Primary Production ◽  
Food Quality ◽  
Global Ocean ◽  
Carbon Uptake ◽  
The Impact

scholarly journals Influence of consumer-driven nutrient recycling on primary production and the distribution of N and P in the ocean

2010 ◽  
Vol 7 (4) ◽  
pp. 1285-1305 ◽  
Author(s):  
A. Nugraha ◽  
P. Pondaven ◽  
P. Tréguer
Keyword(s):  
Primary Production ◽  
N2 Fixation ◽  
Nutrient Recycling ◽  
Deep Ocean ◽  
Global Ocean ◽  
N:P Ratios ◽  
Limiting Nutrient ◽  
Consumer Interactions ◽  
The Impact ◽  
N And P Cycling

Abstract. In this study we investigated the impact of consumer-driven nutrient recycling (CNR) on oceanic primary production and the distribution of nitrogen (N) and phosphorus (P) in the deep ocean. For this purpose, we used and extended two existing models: a 2-box model of N and P cycling in the global ocean (Tyrrell, 1999), and the model of Sterner (1990) which formalised the principles of CNR theory. The resulting model showed that marine herbivores may affect the supply and the stoichiometry of N and P in the ocean, thereby exerting a control on global primary production. The predicted global primary production was higher when herbivores were included in the model, particularly when these herbivores had higher N:P ratios than phytoplankton. This higher primary production was triggered by a low N:P resupply ratio, which, in turn, favoured the P-limited N2-fixation and eventually the N-limited non-fixers. Conversely, phytoplankton with higher N:P ratios increased herbivore yield until phosphorus became the limiting nutrient, thereby favouring herbivores with a low P-requirement. Finally, producer-consumer interactions fed back on the N and P inventories in the deep ocean through differential nutrient recycling. In this model, N deficit or N excess in the deep ocean resulted not only from the balance between N2-fixation and denitrification, but also from CNR, especially when the elemental composition of producers and consumers differed substantially. Although the model is fairly simple, these results emphasize our need for a better understanding of how consumers influence nutrient recycling in the ocean.

scholarly journals An explicit estimate of the atmospheric nutrient impact on global oceanic productivity

2020 ◽  
Author(s):  
Stelios Myriokefalitakis ◽  
Matthias Gröger ◽  
Jenny Hieronymus ◽  
Ralf Döscher
Keyword(s):  
Primary Production ◽  
Global Scale ◽  
Global Ocean ◽  
Deposition Fluxes ◽  
Nutrient Deposition ◽  
Atmospheric Processing ◽  
Atmospheric Forcings ◽  
Marine Productivity ◽  
Atmospheric Inputs ◽  
The Impact

Abstract. State-of-the-art global nutrient deposition fields are here coupled to the biogeochemistry model PISCES to investigate the effect on ocean biogeochemistry in the context of atmospheric forcings for preindustrial, present, and future periods. Present-day atmospheric deposition fluxes of inorganic N, Fe, and P over the global ocean are accounted equal to ~40 Tg-N yr−1, ~0.28 Tg-Fe yr−1 and ~0.10 Tg-P yr−1. The resulting globally integrated primary production of roughly 47 Pg-C yr−1 is well within the range of satellite-based estimates and other modeling predictions. Preindustrial atmospheric nutrient deposition fluxes are lower compared to present-day (~51 %, ~36 %, and ~40 % for N, Fe, and P, respectively), resulting here in a lower marine primary production by ~3 % globally. Future changes in air pollutants under the RCP8.5 scenario result in a modest decrease of the bioaccessible nutrients input into the global ocean compared to present-day (~13 %, ~14 % and ~20 % for N, Fe and P, respectively), without significantly affecting the projected primary production in the model. The global mean nitrogen-fixation rates changed only marginally from preindustrial to future conditions (111 ± 0.6 Tg-N yr−1). With regard to the atmospheric inputs to the ocean, sensitivity model simulations indicate that the contribution of nutrients' organic fraction results in an increase in primary production by about 2.4 %. This estimate is almost equal to the effect of emissions and atmospheric processing on the oceanic biogeochemistry since preindustrial times in the model when only the inorganic fraction of the nutrients is considered. Although the impact of the atmospheric organic nutrients may imply a relatively weak response of marine productivity on a global scale, stronger regional effects up to ~20 % are calculated in the oligotrophic subtropical gyres. Overall, this work provides a first explicit assessment of the contribution of the organic forms of atmospheric nutrients, highlighting the importance of their representation in biogeochemistry models and thus the oceanic productivity estimates.

scholarly journals Strong sensitivity of Southern Ocean carbon uptake and nutrient cycling to wind stirring

2013 ◽  
Vol 10 (9) ◽  
pp. 15033-15076 ◽  
Author(s):  
K. B. Rodgers ◽  
O. Aumont ◽  
S. E. Mikaloff Fletcher ◽  
Y. Plancherel ◽  
L. Bopp ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Southern Ocean ◽  
Ad Hoc ◽  
Global Ocean ◽  
Nutrient Concentrations ◽  
Carbon Uptake ◽  
Carbon Cycle Model ◽  
Ocean Biogeochemistry ◽  
Ocean Carbon ◽  
The Impact

Abstract. Here we test the hypothesis that winds have an important role in determining the rate of exchange of CO2 between the atmosphere and ocean through wind stirring over the Southern Ocean. This is tested with a sensitivity study using an ad hoc parameterization of wind stirring in an ocean carbon cycle model. The objective is to identify the way in which perturbations to the vertical density structure of the planetary boundary in the ocean impacts the carbon cycle and ocean biogeochemistry. Wind stirring leads to reduced uptake of CO2 by the Southern Ocean over the period 2000–2006, with differences of order 0.9 Pg C yr−1 over the region south of 45° S. Wind stirring impacts not only the mean carbon uptake, but also the phasing of the seasonal cycle of carbon and other species associated with ocean biogeochemistry. Enhanced wind stirring delays the seasonal onset of stratification, and this has large impacts on both entrainment and the biological pump. It is also found that there is a strong sensitivity of nutrient concentrations exported in Subantarctic Mode Water (SAMW) to wind stirring. This finds expression not only locally over the Southern Ocean, but also over larger scales through the impact on advected nutrients. In summary, the large sensitivity identified with the ad hoc wind stirring parameterization offers support for the importance of wind stirring for global ocean biogeochemistry, through its impact over the Southern Ocean.

scholarly journals Influence of consumer-driven nutrient recycling on primary production and the distribution of N and P in the ocean

2010 ◽  
Vol 7 (1) ◽  
pp. 111-164
Author(s):  
A. Nugraha ◽  
P. Pondaven ◽  
P. Tréguer
Keyword(s):  
Primary Production ◽  
N2 Fixation ◽  
Nutrient Recycling ◽  
Deep Ocean ◽  
Global Ocean ◽  
N:P Ratios ◽  
Limiting Nutrient ◽  
Consumer Interactions ◽  
The Impact ◽  
N And P Cycling

Abstract. In this study we investigated the impact of consumer-driven nutrient recycling (CNR) on oceanic primary production and the distribution of nitrogen (N) and phosphorus (P) in the deep ocean. For this purpose, we used and extended two existing models: a 2-box model of N and P cycling in the global ocean (Tyrrell, 1999), and the model of Sterner (1990) which formalised the principles of CNR theory. The resulting model showed that marine herbivores may affect the supply and the stoichiometry of N and P in the ocean, thereby exerting a control on global primary production. The predicted global primary production was higher when herbivores were included in the model, particularly when these herbivores had higher N:P ratios than phytoplankton. This higher primary production was triggered by a low N:P resupply ratio, which, in turn, favoured the P-limited N2-fixation and eventually the N-limited non-fixers. Conversely, phytoplankton with higher N:P ratios increased herbivore yield until phosphorus became the limiting nutrient, thereby favouring herbivores with a low P-requirement. Finally, producer-consumer interactions fed back on the N and P inventories in the deep ocean through differential nutrient recycling. In this model, N deficit or N excess in the deep ocean resulted not only from the balance between N2-fixation and denitrification, but also from CNR, especially when the elemental composition of producers and consumers differed substantially. Although the model is fairly simply, these results emphasize our need for a better understanding of how consumers influence nutrient recycling in the ocean.

scholarly journals Strong sensitivity of Southern Ocean carbon uptake and nutrient cycling to wind stirring

2014 ◽  
Vol 11 (15) ◽  
pp. 4077-4098 ◽  
Author(s):  
K. B. Rodgers ◽  
O. Aumont ◽  
S. E. Mikaloff Fletcher ◽  
Y. Plancherel ◽  
L. Bopp ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Southern Ocean ◽  
Ad Hoc ◽  
Global Ocean ◽  
Relative Reduction ◽  
Carbon Uptake ◽  
Carbon Cycle Model ◽  
Ocean Biogeochemistry ◽  
Ocean Carbon ◽  
The Impact

Abstract. Here we test the hypothesis that winds have an important role in determining the rate of exchange of CO2 between the atmosphere and ocean through wind stirring over the Southern Ocean. This is tested with a sensitivity study using an ad hoc parameterization of wind stirring in an ocean carbon cycle model, where the objective is to identify the way in which perturbations to the vertical density structure of the planetary boundary in the ocean impacts the carbon cycle and ocean biogeochemistry. Wind stirring leads to reduced uptake of CO2 by the Southern Ocean over the period 2000–2006, with a relative reduction with wind stirring on the order of 0.9 Pg C yr−1 over the region south of 45° S. This impacts not only the mean carbon uptake, but also the phasing of the seasonal cycle of carbon and other ocean biogeochemical tracers. Enhanced wind stirring delays the seasonal onset of stratification, and this has large impacts on both entrainment and the biological pump. It is also found that there is a strong reduction on the order of 25–30% in the concentrations of NO3 exported in Subantarctic Mode Water (SAMW) to wind stirring. This finds expression not only locally over the Southern Ocean, but also over larger scales through the impact on advected nutrients. In summary, the large sensitivity identified with the ad hoc wind stirring parameterization offers support for the importance of wind stirring for global ocean biogeochemistry through its impact over the Southern Ocean.

Seafood through time revisited: the Phanerozoic increase in marine trophic resources and its macroevolutionary consequences

Paleobiology ◽  
10.1666/13065 ◽  
2014 ◽  
Vol 40 (2) ◽  
pp. 256-287 ◽  
Author(s):  
Warren D. Allmon ◽  
Ronald E. Martin
Keyword(s):  
Primary Production ◽  
Food Quality ◽  
Primary Productivity ◽  
Food Supply ◽  
General Model ◽  
Fossil Record ◽  
Global Ocean ◽  
Geological Time ◽  
Trophic Resources ◽  
Marine Primary Productivity

We review and synthesize multiple biotic and abiotic proxies for marine nutrient and food availability, primary productivity, and food quality (stoichiometry) and propose what their relationships may have been to macroevolutionary processes, especially speciation. This review confirms earlier suggestions that there has been an overall increase in marine primary productivity over the Phanerozoic, but indicates that the increase has been irregular and that present levels may not be the peak. We integrate these indicators into a new estimate of relative primary productivity in the global ocean through the Phanerozoic. We then combine multiple, frequently conflicting ecological-evolutionary hypotheses into a general model for how primary production may affect speciation over geological time scales. This model, an elaboration and extension of the “speciation cycle” previously proposed by Grant and Grant, attempts to explain why an increase in food supply sometimes is associated with decreased diversity, and at other times with increased diversification. We propose some simple tests for the application of this model to the fossil record.

Managing Service Quality, Food Quality, Price Fairness and Customer Retention: A Holistic Perspective

2020 ◽  
Vol 2 (1) ◽  
pp. 1-5
Author(s):  
Ammar Ahmed ◽  
Rafat Naseer ◽  
Muhammad Asadullah ◽  
Hadia Khan
Keyword(s):  
Service Quality ◽  
Food Quality ◽  
Service Sector ◽  
Customer Retention ◽  
Price Fairness ◽  
Policy Makers ◽  
Restaurant Management ◽  
The Subject ◽  
Research Propositions ◽  
The Impact

In this competitive environment, organizations strive to satisfy their customer by providing best quality service at affordable and fair prices with a view to enhance their revenues. To achieve the objective of revenue maximization, organizations strive to identify the factors that help them in retaining their customers. Drawing from the signalling theory of marketing, the current study proposes a novel conceptual model representing the impact of service quality with food quality and price fairness on customer retention in restaurant sector of Pakistan. The paper underlines an important arena of knowledge for academicians as well as organizational scientists on the subject. On the basis of literature available on the variables understudy, the present study forwards eight research propositions worthy of urgent scholarly attention. The conceptualized model of the present article can also be viewed significant in unleashing further avenues for the restaurant management entities, policy makers and future researchers in the domain of managing in the service sector businesses.

On the impact of sea ice in a global ocean circulation model

1997 ◽  
Vol 25 ◽  
pp. 111-115 ◽  
Author(s):  
Achim Stössel
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Ocean Circulation ◽  
General Circulation ◽  
Thermohaline Circulation ◽  
Circulation Model ◽  
Deep Ocean ◽  
Global Ocean ◽  
Convective Activity ◽  
The Impact

This paper investigates the long-term impact of sea ice on global climate using a global sea-ice–ocean general circulation model (OGCM). The sea-ice component involves state-of-the-art dynamics; the ocean component consists of a 3.5° × 3.5° × 11 layer primitive-equation model. Depending on the physical description of sea ice, significant changes are detected in the convective activity, in the hydrographic properties and in the thermohaline circulation of the ocean model. Most of these changes originate in the Southern Ocean, emphasizing the crucial role of sea ice in this marginally stably stratified region of the world's oceans. Specifically, if the effect of brine release is neglected, the deep layers of the Southern Ocean warm up considerably; this is associated with a weakening of the Southern Hemisphere overturning cell. The removal of the commonly used “salinity enhancement” leads to a similar effect. The deep-ocean salinity is almost unaffected in both experiments. Introducing explicit new-ice thickness growth in partially ice-covered gridcells leads to a substantial increase in convective activity, especially in the Southern Ocean, with a concomitant significant cooling and salinification of the deep ocean. Possible mechanisms for the resulting interactions between sea-ice processes and deep-ocean characteristics are suggested.

scholarly journals Prediction of the Export and Fate of Global Ocean Net Primary Production: The EXPORTS Science Plan

2016 ◽  
Vol 3 ◽  
Author(s):  
David A. Siegel ◽  
Ken O. Buesseler ◽  
Michael J. Behrenfeld ◽  
Claudia R. Benitez-Nelson ◽  
Emmanuel Boss ◽  
...  
Keyword(s):  
Primary Production ◽  
Net Primary Production ◽  
Global Ocean
Sign in / Sign up

Export Citation Format

Share Document