scholarly journals Artificial Upwelling in Singular and Recurring Mode: Consequences for Net Community Production and Metabolic Balance

2022 ◽  
Vol 8 ◽  
Author(s):  
Joaquin Ortiz ◽  
Javier Arístegui ◽  
Jan Taucher ◽  
Ulf Riebesell
Keyword(s):  
Deep Water ◽  
Large Scale ◽  
Phytoplankton Community ◽  
Metabolic Balance ◽  
Net Community Production ◽  
Marine Fishery ◽  
Local Responses ◽  
Water Pulse ◽  
Community Production

Artificial upwelling of nutrient-rich waters and the corresponding boost in primary productivity harbor the potential to enhance marine fishery yields and strengthen the biological pump for sequestration of atmospheric CO2. There is increasing urgency to understand this technology as a “ocean-based solution” for counteracting two major challenges of the 21st century—climate change and overfishing. Yet, little is known about the actual efficacy and/or possible side effects of artificial upwelling. We conducted a large-scale off-shore mesocosm study (∼44 m3) in the oligotrophic waters of the Canary Islands to identify the community-level effects of artificial upwelling on a natural oligotrophic plankton community. Four upwelling intensities were simulated (approx. 1.5/3/5.7/10 μmol L–1 of nitrate plus phosphate and silicate) via two different upwelling modes (a singular deep-water pulse vs. recurring supply every 4 days) for 37 days. Here we present results on the response of net community production (NCP), metabolic balance and phytoplankton community composition (<250 μm). Higher upwelling intensities yielded higher cumulative NCP. Following upwelling onset, the phytoplankton community became dominated by diatoms in all treatments, but other taxa such as Coccolithophores increased later in the experiment. The magnitude of effects on the metabolic balance scaled with the amount of added deep water, leading to (i) a balanced to net-heterotrophic system in the singular and (ii) a net-autotrophic system in the recurring upwelling treatments. Accordingly, the mode in which nutrients are supplied to an oligotrophic system plays a crucial role in the ecosystem response, with recurring upwelling leading to higher long-term positive NCP than singular upwelling. These results highlight the importance of empirically measured local responses to upwelling such as community structure and metabolism, with major implications for the potential employment of artificial upwelling as an ocean-based solution to generate (primary) production.

scholarly journals Net community production and stoichiometry of nutrient consumption in a pelagic ecosystem of a northern high latitude fjord: mesocosm CO<sub>2</sub> perturbation study

2012 ◽  
Vol 9 (8) ◽  
pp. 11705-11737 ◽  
Author(s):  
A. Silyakova ◽  
R. G. J. Bellerby ◽  
J. Czerny ◽  
K. G. Schulz ◽  
G. Nondal ◽  
...  
Keyword(s):  
Large Scale ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
P Uptake ◽  
Nutrient Addition ◽  
Net Community Production ◽  
Cumulative Change ◽  
Nutrient Consumption ◽  
Community Production ◽  
Three Phases

Abstract. Net community production (NCP) and ratios of carbon to nutrient consumption were studied during a large-scale mesocosm experiment on ocean acidification in Kongsfjorden, West Spitsbergen, during June–July 2010. Nutrient-deplete fjord water with natural phyto- and bacteriaplankton assemblages, enclosed in nine mesocosms of ~ 50 m3 volume, was exposed to pCO2 levels ranging from 185 to 1420 μatm on initial state. Mean values of pCO2 levels during experiment ranged from 175 to 1085 μatm in different mesocosms. Phytoplankton growth was stimulated by nutrient addition. In this study NCP is estimated as a cumulative change in dissolved inorganic carbon concentrations. Stoichiometric couping between inorganic carbon and nutrient is shown as a ratio of a cumulative NCP to a cumulative change in inorganic nutrients. Three peaks of chlorophyll a concentration occurred during the experiment. Accordingly the experiment was divided in three phases. Overall cumulative NCP was similar in all mesocosms by the final day of experiment. However, NCP varied among phases, showing variable response to CO2 perturbation. Carbon to nitrogen (C : N) and carbon to phosphorus (C : P) uptake ratios were estimated only for the period after nutrient addition (post-nutrient period). For the total post-nutrient period ratios were close to Redfield proportions, however varied from it in different phases. The response of C : N and C : P uptake ratios to CO2 perturbation was different for three phases of the experiment, reflecting variable NCP and dependence on changing microbial community. Through the variable NCP, C : N and C : P uptake ratios for 31 days of the experiment we show a flexibility of biogeochemical response establishing a strong microbial loop in Kongsfjorden under different CO2 scenarios.

scholarly journals The influence of net community production and phytoplankton community structure on CO2uptake in the Gulf of Alaska

2013 ◽  
Vol 27 (3) ◽  
pp. 664-676 ◽  
Author(s):  
Hilary I. Palevsky ◽  
Francois Ribalet ◽  
Jarred E. Swalwell ◽  
Catherine E. Cosca ◽  
Edward D. Cokelet ◽  
...  
Keyword(s):  
Community Structure ◽  
Phytoplankton Community ◽  
Gulf Of Alaska ◽  
Phytoplankton Community Structure ◽  
Net Community Production ◽  
Community Production

scholarly journals A simple nutrient-dependence mechanism for predicting the stoichiometry of marine ecosystems

2015 ◽  
Vol 112 (27) ◽  
pp. 8199-8204 ◽  
Author(s):  
Eric D. Galbraith ◽  
Adam C. Martiny
Keyword(s):  
Ocean Circulation ◽  
Large Scale ◽  
Phytoplankton Community ◽  
Simple Relationship ◽  
Low Latitude ◽  
Average Composition ◽  
Biogeochemical Models ◽  
The Relationship ◽  
Globally Distributed

It is widely recognized that the stoichiometry of nutrient elements in phytoplankton varies within the ocean. However, there are many conflicting mechanistic explanations for this variability, and it is often ignored in global biogeochemical models and carbon cycle simulations. Here we show that globally distributed particulate P:C varies as a linear function of ambient phosphate concentrations, whereas the N:C varies with ambient nitrate concentrations, but only when nitrate is most scarce. This observation is consistent with the adjustment of the phytoplankton community to local nutrient availability, with greater flexibility of phytoplankton P:C because P is a less abundant cellular component than N. This simple relationship is shown to predict the large-scale, long-term average composition of surface particles throughout large parts of the ocean remarkably well. The relationship implies that most of the observed variation in N:P actually arises from a greater plasticity in the cellular P:C content, relative to N:C, such that as overall macronutrient concentrations decrease, N:P rises. Although other mechanisms are certainly also relevant, this simple relationship can be applied as a first-order basis for predicting organic matter stoichiometry in large-scale biogeochemical models, as illustrated using a simple box model. The results show that including variable P:C makes atmospheric CO2 more sensitive to changes in low latitude export and ocean circulation than a fixed-stoichiometry model. In addition, variable P:C weakens the relationship between preformed phosphate and atmospheric CO2 while implying a more important role for the nitrogen cycle.

scholarly journals Consequences of respiration in the light on the determination of production in pelagic systems

2007 ◽  
Vol 4 (1) ◽  
pp. 105-114 ◽  
Author(s):  
O. Pringault ◽  
V. Tassas ◽  
E. Rochelle-Newall
Keyword(s):  
Primary Production ◽  
Dark Respiration ◽  
Gross Primary Production ◽  
Community Respiration ◽  
Metabolic Balance ◽  
Net Community Production ◽  
Respiration Rates ◽  
Seawater Samples ◽  
Community Production

Abstract. Oxygen microprobes were used to estimate Community Respiration (R), Net Community Production (NCP) and Gross Primary Production (GPP) in coastal seawater samples. Using this highly stable and reproducible technique to measure oxygen change during alternating dark and light periods, we show that respiration in the light could account for up to 640% of respiration in the dark. The light enhanced dark respiration can remain elevated for several hours following a 12 h period of illumination. Not including Rlight into calculations of production leads to an underestimation of GPP, which can reach up to 650% in net heterotrophic systems. The production: respiration (P:R) ratio is in turn affected by the higher respiration rates and by the underestimation of GPP. While the integration of Rlight into the calculation of P:R ratio does not change the metabolic balance of the system, it decreases the observed tendency, thus net autotrophic systems become less autotrophic and net heterotrophic systems become less heterotrophic. As a consequence, we propose that efforts have to be focused on the estimation and the integration of Rlight into the determination of GPP and R for a better understanding of the aquatic carbon cycle.

scholarly journals Fluxes of carbon and nutrients to the Iceland Sea surface layer and inferred primary productivity and stoichiometry

2015 ◽  
Vol 12 (3) ◽  
pp. 875-885 ◽  
Author(s):  
E. Jeansson ◽  
R. G. J. Bellerby ◽  
I. Skjelvan ◽  
H. Frigstad ◽  
S. R. Ólafsdóttir ◽  
...  
Keyword(s):  
Surface Layer ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Vertical Mixing ◽  
Sea Surface ◽  
Net Community Production ◽  
Horizontal Advection ◽  
Vertical Fluxes ◽  
Community Production

Abstract. This study evaluates long-term mean fluxes of carbon and nutrients to the upper 100 m of the Iceland Sea. The study utilises hydro-chemical data from the Iceland Sea time series station (68.00° N, 12.67° W), for the years between 1993 and 2006. By comparing data of dissolved inorganic carbon (DIC) and nutrients in the surface layer (upper 100 m), and a sub-surface layer (100–200 m), we calculate monthly deficits in the surface, and use these to deduce the long-term mean surface layer fluxes that affect the deficits: vertical mixing, horizontal advection, air–sea exchange, and biological activity. The deficits show a clear seasonality with a minimum in winter, when the mixed layer is at the deepest, and a maximum in early autumn, when biological uptake has removed much of the nutrients. The annual vertical fluxes of DIC and nitrate amounts to 2.9 ± 0.5 and 0.45 ± 0.09 mol m−2 yr−1, respectively, and the annual air–sea uptake of atmospheric CO2 is 4.4 ± 1.1 mol C m−2 yr−1. The biologically driven changes in DIC during the year relates to net community production (NCP), and the net annual NCP corresponds to export production, and is here calculated as 7.3 ± 1.0 mol C m−2 yr−1. The typical, median C : N ratio during the period of net community uptake is 9.0, and clearly higher than the Redfield ratio, but is varying during the season.

scholarly journals The relation of mixed-layer net community production to phytoplankton community composition in the Southern Ocean

2015 ◽  
Vol 29 (4) ◽  
pp. 446-462 ◽  
Author(s):  
Nicolas Cassar ◽  
Simon W. Wright ◽  
Paul G. Thomson ◽  
Thomas W. Trull ◽  
Karen J. Westwood ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Community Composition ◽  
Mixed Layer ◽  
Phytoplankton Community ◽  
Net Community Production ◽  
Phytoplankton Community Composition ◽  
Community Production

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

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