scholarly journals Balance between resource supply and demand determines nutrient limitation of primary productivity in the ocean

2016 ◽  
Author(s):  
George I. Hagstrom ◽  
Simon A. Levin ◽  
Adam C. Martiny
Keyword(s):  
Nutrient Cycling ◽  
Primary Productivity ◽  
Supply And Demand ◽  
Marine Ecology ◽  
N Fixation ◽  
P Availability ◽  
Surface Ocean ◽  
Ocean Region ◽  
Limiting Nutrient ◽  
Resource Ratios

AbstractWhat is the ultimate limiting nutrient in the ocean? The dominant theory, which was first proposed by Redfield and later formalized by Tyrrell[1, 2], states that despite the scarcity of fixed nitrogen (N) in the surface ocean, phosphorus (P) availability ultimately determines primary productivity. Two recent findings directly challenge the assumptions of the Redfield-Tyrrell paradigm: the discovery of systematic variations of phytoplankton cellular N:P:Fe and widespread iron-limitation of phytoplankton. Here we use a simple model of nitrogen, phosphorus, and iron (Fe) cycling to show how the resource demand ratios and biogeography of phytoplankton interact with external resource supply ratios to govern nutrient cycling and primary productivity. We find that all three nutrients can limit global primary productivity, and that the ratio of geochemical supply to biological demand of each nutrient in each ocean region determines the limiting nutrients, with nitrogen N fixation providing a mechanism for the cycles to interact. These results have important consequences for our understanding of biogeochemical cycles, ocean-atmosphere interactions, marine ecology, and the response of ocean ecosystems to climate change. Our work demonstrates the importance of resource ratios and suggests that future studies of the physiological and geochemical regulation of these ratios are indispensable to building accurate theories and future predictions of nutrient cycling and primary productivity.

scholarly journals On the potential vegetation feedbacks that enhance phosphorus availability – insights from a process-based model linking geological and ecological timescales

2014 ◽  
Vol 11 (13) ◽  
pp. 3661-3683 ◽  
Author(s):  
C. Buendía ◽  
S. Arens ◽  
T. Hickler ◽  
S. I. Higgins ◽  
P. Porada ◽  
...  
Keyword(s):  
Biomass Production ◽  
Primary Productivity ◽  
Chemical Weathering ◽  
Production Efficiency ◽  
Root Exudation ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
P Uptake ◽  
P Availability ◽  
P Limitation

Abstract. In old and heavily weathered soils, the availability of P might be so small that the primary production of plants is limited. However, plants have evolved several mechanisms to actively take up P from the soil or mine it to overcome this limitation. These mechanisms involve the active uptake of P mediated by mycorrhiza, biotic de-occlusion through root clusters, and the biotic enhancement of weathering through root exudation. The objective of this paper is to investigate how and where these processes contribute to alleviate P limitation on primary productivity. To do so, we propose a process-based model accounting for the major processes of the carbon, water, and P cycles including chemical weathering at the global scale. Implementing P limitation on biomass synthesis allows the assessment of the efficiencies of biomass production across different ecosystems. We use simulation experiments to assess the relative importance of the different uptake mechanisms to alleviate P limitation on biomass production. We find that active P uptake is an essential mechanism for sustaining P availability on long timescales, whereas biotic de-occlusion might serve as a buffer on timescales shorter than 10 000 yr. Although active P uptake is essential for reducing P losses by leaching, humid lowland soils reach P limitation after around 100 000 yr of soil evolution. Given the generalized modelling framework, our model results compare reasonably with observed or independently estimated patterns and ranges of P concentrations in soils and vegetation. Furthermore, our simulations suggest that P limitation might be an important driver of biomass production efficiency (the fraction of the gross primary productivity used for biomass growth), and that vegetation on old soils has a smaller biomass production rate when P becomes limiting. With this study, we provide a theoretical basis for investigating the responses of terrestrial ecosystems to P availability linking geological and ecological timescales under different environmental settings.

Nitrogen cycling in microbial mat communities: The quantitative importance of N-fixation and other sources of N for primary productivity

1994 ◽  
pp. 265-271 ◽  
Author(s):  
Brad M. Bebout ◽  
Hans W. Paerl ◽  
James E. Bauer ◽  
Donald E. Canfield ◽  
David J. Des Marais
Keyword(s):  
Nitrogen Cycling ◽  
Primary Productivity ◽  
Microbial Mat ◽  
N Fixation ◽  
Quantitative Importance

Dynamics of a cyanobacterial bloom in a hypereutrophic, stratified weir pool

2003 ◽  
Vol 54 (1) ◽  
pp. 27 ◽  
Author(s):  
P. A. Thompson ◽  
A. M. Waite ◽  
K. McMahon
Keyword(s):  
Growth Rates ◽  
Algal Blooms ◽  
Dissolved Inorganic Carbon ◽  
Cyanobacterial Bloom ◽  
Nutrient Concentrations ◽  
P Availability ◽  
The Public ◽  
Limiting Nutrient ◽  
Bottom Waters ◽  
Oxygenated Water

In summer 1997–1998, a bloom of the cyanobacteria Anabaena circinalis (Rabenhorst) and Anabaena spiroides (Klebahn) contaminated the Canning River (Perth, WA), forcing its closure to the public for swimming and fishing. We investigated the major nutrient fluctuations before, during and after the bloom. The river was persistently temperature stratified at least 1 month prior to the bloom. The surface and bottom layers of water had distinctly different nutrient concentrations, which meant that biomass and growth rates of the phytoplankton within each layer were limited by different nutrients. At the peak of the bloom, in the bottom waters growth rates were light limited and biomass was nitrogen limited, whereas in the surface waters biomass was controlled by phosphorus (P) availability and growth rates were probably limited by the lack of dissolved inorganic carbon. Another consequence of stratification was that, at the peak of the bloom (0.25 mg chlorophyll L−1), the mostly buoyant cyanobacteria could not access 83% of the P released from sediments during the summer period of anoxia. In this situation, the injection of oxygenated water, tested as a remediation measure for algal blooms, is likely to exacerbate a bloom by providing more of the limiting nutrient to the surface layer. However, aeration prior to the bloom may reduce P release from the sediments by preventing anoxia.

Phosphorus speciation and dynamics in river sediments, floodplain soils and leaf litter from the Lower Murray River region

2019 ◽  
Vol 70 (11) ◽  
pp. 1522 ◽  
Author(s):  
F. T. Watson ◽  
R. J. Smernik ◽  
A. L. Doolette ◽  
L. M. Mosley
Keyword(s):  
Leaf Litter ◽  
Primary Productivity ◽  
River Sediments ◽  
P Availability ◽  
River Systems ◽  
P Concentration ◽  
Floodplain Soils ◽  
Murray River ◽  
River Region ◽  
River Red Gum

Phosphorus (P) availability, which depends on both P concentration and speciation, often controls primary productivity and algal-bloom formation in river systems. The river P pool is also connected to P pools of adjacent sediments, soils and vegetation. Thus, informed management of P in floodplain–river systems requires detailed understanding of P concentration and speciation in all of these interconnected components. We studied P speciation in river sediments and water, floodplain soils and river red gum (Eucalyptus camaldulensis) leaf litter from the Lower Murray region using conventional spectroscopic measurements, solution 31P nuclear magnetic resonance (31P NMR) spectroscopy, and leaching experiments to simulate floodplain re-wetting of leaf litter. Almost all (>85%) of the P in river sediments was in the orthophosphate form, whereas floodplain soils had higher proportions of organic P (PO) species. Both fresh and senescent river red gum leaf litter also had a much higher concentration of PO, primarily in the form of phytate. On submersion, there was a rapid (0–96h) loss of dissolved P from senescent leaves; release of dissolved organic carbon showed similar kinetics. Loss of P from the leaves included both organic and inorganic forms. The results have important implications for aquatic primary productivity and environmental management strategies.

scholarly journals Lower nodule biomass with increased nitrogenase efficiency in Robinia pseudoacacia seedlings when grown under low soil phosphorus conditions

2020 ◽  
Vol 2 (11) ◽  
Author(s):  
Lindsay A. McCulloch ◽  
Stephen Porder
Keyword(s):  
Nitrogen Fixation ◽  
Plant Growth ◽  
Symbiotic Nitrogen Fixation ◽  
Soil Phosphorus ◽  
Robinia Pseudoacacia ◽  
Nodule Development ◽  
N Fixation ◽  
P Availability ◽  
Nodule Biomass ◽  
P Fertilizer

AbstractSymbiotic nitrogen (N) fixation is the largest non-anthropogenic N input to many terrestrial ecosystems. The energetic expense of symbiotic N fixation suggests soil phosphorus (P) availability may regulate symbiotic nitrogen fixation directly through nodule development and function, and/or indirectly through plant growth. Since P availability is heterogenous in the landscape, we sought to understand if symbiotic nitrogen fixation responds to both P availability and heterogeneity. To test how P availability affects symbiotic nitrogen fixation, we grew Robinia pseudoacacia seedlings under high (8.1 g P m−2) and low (0.2 g P m−2) conditions. Soil P heterogeneity was simulated by splitting roots into soil patches receiving P or no-P fertilizer. At the whole plant level, P availability limited seedling and nodule biomass. However, the low P treatment had higher nitrogenase efficiency (acetylene reduced (AR) g−1 nodule; a nodule efficiency proxy). High P seedlings had significantly more root and nodule biomass in the patches directly receiving P fertilizer, but patch proliferation was absent in the low P treatment. AR g−1 seedling did not differ between P treatments, suggesting P indirectly limited symbiotic nitrogen fixation through plant growth, rather than directly limiting symbiotic nitrogen fixation. This relatively consistent AR g−1 seedling across treatments demonstrates the ability of seedlings to respond to low P conditions with increased nitrogenase efficiency.

scholarly journals The El Niño – La Niña cycle and recent trends in supply and demand of net primary productivity in African drylands

2016 ◽  
Vol 138 (1-2) ◽  
pp. 111-125 ◽  
Author(s):  
A. M. Abdi ◽  
A. Vrieling ◽  
G. T. Yengoh ◽  
A. Anyamba ◽  
J. W. Seaquist ◽  
...  
Keyword(s):  
Primary Productivity ◽  
El Niño ◽  
Net Primary Productivity ◽  
El Nino ◽  
Supply And Demand ◽  
La Niña ◽  
La Nina ◽  
Recent Trends

scholarly journals Barley shoot biomass responds strongly to N:P stoichiometry and intraspecific competition, whereas roots only alter their foraging

2020 ◽  
Author(s):  
Amit Kumar ◽  
Richard van Duijnen ◽  
Benjamin M. Delory ◽  
Rüdiger Reichel ◽  
Nicolas Brüggemann ◽  
...  
Keyword(s):  
Root System ◽  
Plant Competition ◽  
Specific Root Length ◽  
Plant Performance ◽  
Shoot Biomass ◽  
Plant Responses ◽  
P Availability ◽  
N:P Stoichiometry ◽  
Limiting Nutrient ◽  
Plant Plant

AbstractBackground and AimsPlants respond to various environmental stimuli, and root systems are highly responsive to the availability and distribution of nutrients in the soil. Root system responses to the limitation of either nitrogen (N) or phosphorus (P) are well documented, but how the early root system responds to (co-) limitation of one (N or P) or both (N and P) in a stoichiometric framework is not well known despite its relevance in agriculture. In addition, how plant-plant competition (here intra-specific) alters plant responses to N:P stoichiometry is understudied. Therefore, we aimed to investigate the effects of N:P stoichiometry and competition on root system responses and overall plant performance.MethodsPlants (Hordeum vulgare L.) were grown in rhizoboxes for 24 days in the presence or absence of competition (three vs. one plant per rhizobox), and fertilized with different combinations of N:P (low N+low P, low N+high P, high N+low P, and high N+high P).Key ResultsShoot biomass was highest when both N and P were provided in high amounts. In competition, shoot biomass decreased on average by 22%. Interestingly, N:P stoichiometry and competition had no clear effect on root biomass. However, we found distinct root responses in relation to biomass allocation across depths. Specific root length depended on the identity of limiting nutrient (N or P) and presence/absence of competition. Plants rooted deeper when N was the most limiting compared to shallower rooting when P was the most limiting nutrient.ConclusionsOverall, our study sheds light on the early plant responses to plant-plant competition and stoichiometric availability of two macronutrients most limiting plant performance. With low N and P availability during early growth, higher investments in root system development can significantly trade off with aboveground productivity, and strong intra-specific competition can further strengthen such effects.

scholarly journals Taxon-specific phytoplankton growth, nutrient utilization, and light limitation in the oligotrophic Gulf of Mexico

2021 ◽  
Author(s):  
Natalia Yingling ◽  
Thomas B. Kelly ◽  
Taylor A. Shropshire ◽  
Michael R. Landry ◽  
Karen E. Selph ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Primary Productivity ◽  
Nitrate Uptake ◽  
Euphotic Zone ◽  
Nutrient Utilization ◽  
Ammonium Uptake ◽  
Light Limitation ◽  
Surface Ocean ◽  
Biogeochemical Models ◽  
Diel Variability

ABSTRACTThe highly stratified, oligotrophic regions of the oceans are predominantly nitrogen limited in the surface ocean and light limited at the deep chlorophyll maximum (DCM). Hence, determining light and nitrogen co-limitation patterns for diverse phytoplankton taxa is crucial to understanding marine primary production throughout the euphotic zone. During two cruises in the deep-water Gulf of Mexico, we measured primary productivity (H13CO3−), nitrate uptake (15NO3−), and ammonium uptake (15NH4+) throughout the water column. Primary productivity declined with depth from the mixed-layer to the DCM, averaging 27.1 mmol C m−2 d−1. The fraction of growth supported by NO3− was consistently low, with upper euphotic zone values ranging from 0.01 to 0.14 and lower euphotic zone values ranging from 0.03 to 0.44. Nitrate uptake showed strong diel patterns (maximum during the day), while ammonium uptake exhibited no diel variability. To parameterize taxon-specific phytoplankton nutrient and light utilization, we used a data assimilation approach (Bayesian Markov Chain Monte Carlo) including primary productivity, nutrient uptake, and taxon-specific growth rate measurements. Parameters derived from this analysis define distinct niches for five phytoplankton taxa (Prochlorococcus, Synechococcus, diatoms, dinoflagellates, and prymnesiophytes) and may be useful for constraining biogeochemical models of oligotrophic open-ocean systems.

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