scholarly journals Temperature Affects the Time Required to Discern the Relationship between Primary Production and Export Production in the Ocean

Water ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3085
Author(s):  
Edward Laws ◽  
Kanchan Maiti
Keyword(s):  
Primary Production ◽  
Food Web ◽  
Net Primary Production ◽  
Weighted Average ◽  
Time Interval ◽  
High Latitudes ◽  
New Production ◽  
Return To Equilibrium ◽  
Export Production ◽  
The Relationship

Knowledge of the relationship between net primary production (NPP) and export production (EP) in the ocean is required to estimate how the ocean’s biological pump is likely to respond to climate change effects. Here, we show with a theoretical food web model that the relationship between NPP and EP is obscured by the following phenomena: (1) food web dynamics, which cause EP to be a weighted average of new production (NP) over a previous temperature-dependent time interval that can vary between several weeks at 25 °C to several months at 0 °C and, hence, to be much less temporally variable than NP and (2) the temperature dependence of the resiliency of the food web to perturbations, which causes the return to equilibrium to vary from roughly 50 days at 0 °C to 5–10 days at 25 °C. The implication is that the relationship between NPP and EP can be discerned at tropical and subtropical latitudes if measurements of NPP and EP are averages or climatologies over a timeframe of roughly one month. At high latitudes, however, measurements may need to be averaged over a timeframe of roughly one year because the food webs at high latitudes are very likely far from equilibrium with respect to NPP and EP much of the time, and the model can describe only the average behavior of such physically dynamic systems.

scholarly journals Spring–summer net community production, new production, particle export and related water column biogeochemical processes in the marginal sea ice zone of the Western Antarctic Peninsula 2012–2014

2018 ◽  
Vol 376 (2122) ◽  
pp. 20170177 ◽  
Author(s):  
Hugh W. Ducklow ◽  
Michael R. Stukel ◽  
Rachel Eveleth ◽  
Scott C. Doney ◽  
Tim Jickells ◽  
...  
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Water Column ◽  
Antarctic Peninsula ◽  
Net Primary Production ◽  
Western Antarctic Peninsula ◽  
New Production ◽  
Net Community Production ◽  
Particle Export ◽  
Community Production

New production (New P, the rate of net primary production (NPP) supported by exogenously supplied limiting nutrients) and net community production (NCP, gross primary production not consumed by community respiration) are closely related but mechanistically distinct processes. They set the carbon balance in the upper ocean and define an upper limit for export from the system. The relationships, relative magnitudes and variability of New P (from 15 NO 3 – uptake), O 2  : argon-based NCP and sinking particle export (based on the 238 U :  234 Th disequilibrium) are increasingly well documented but still not clearly understood. This is especially true in remote regions such as polar marginal ice zones. Here we present a 3-year dataset of simultaneous measurements made at approximately 50 stations along the Western Antarctic Peninsula (WAP) continental shelf in midsummer (January) 2012–2014. Net seasonal-scale changes in water column inventories (0–150 m) of nitrate and iodide were also estimated at the same stations. The average daily rates based on inventory changes exceeded the shorter-term rate measurements. A major uncertainty in the relative magnitude of the inventory estimates is specifying the start of the growing season following sea-ice retreat. New P and NCP(O 2 ) did not differ significantly. New P and NCP(O 2 ) were significantly greater than sinking particle export from thorium-234. We suggest this is a persistent and systematic imbalance and that other processes such as vertical mixing and advection of suspended particles are important export pathways. This article is part of the theme issue ‘The marine system of the west Antarctic Peninsula: status and strategy for progress in a region of rapid change’.

scholarly journals Production regime and associated N cycling in the vicinity of Kerguelen Island, Southern Ocean

2015 ◽  
Vol 12 (21) ◽  
pp. 6515-6528 ◽  
Author(s):  
A. J. Cavagna ◽  
F. Fripiat ◽  
M. Elskens ◽  
P. Mangion ◽  
L. Chirurgien ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Primary Production ◽  
Mixed Layer ◽  
Nitrate Uptake ◽  
Net Primary Production ◽  
N Uptake ◽  
Euphotic Zone ◽  
Global Ocean ◽  
Kerguelen Plateau ◽  
New Production

Abstract. Although the Southern Ocean is considered a high-nutrient, low-chlorophyll (HNLC) area, massive and recurrent blooms are observed over and downstream of the Kerguelen Plateau. This mosaic of blooms is triggered by a higher iron supply resulting from the interaction between the Antarctic Circumpolar Current and the local bathymetry. Net primary production, N uptake (NO3− and NH4+), and nitrification rates were measured at eight stations in austral spring 2011 (October–November) during the KEOPS 2 cruise in the Kerguelen Plateau area. Natural iron fertilization stimulated primary production, with mixed layer integrated net primary production and growth rates much higher in the fertilized areas (up to 315 mmol C m−2 d−1 and up to 0.31 d−1 respectively) compared to the HNLC reference site (12 mmol C m−2 d−1 and 0.06 d−1 respectively). Primary production was mainly sustained by nitrate uptake, with f ratios (corresponding to NO3−-uptake / (NO3−-uptake + NH4+-uptake)) lying at the upper end of the observations for the Southern Ocean (up to 0.9). We report high rates of nitrification (up to ~ 3 μmol N L−1 d−1, with ~ 90 % of them < 1 μmol N L−1 d−1) typically occurring below the euphotic zone, as classically observed in the global ocean. The specificity of the studied area is that at most of the stations, the euphotic layer was shallower than the mixed layer, implying that nitrifiers can efficiently compete with phytoplankton for the ammonium produced by remineralization at low-light intensities. Nitrate produced by nitrification in the mixed layer below the euphotic zone is easily supplied to the euphotic zone waters above, and nitrification sustained 70 ± 30 % of the nitrate uptake in the productive area above the Kerguelen Plateau. This complicates estimations of new production as potentially exportable production. We conclude that high productivity in deep mixing system stimulates the N cycle by increasing both assimilation and regeneration.

Bacterial abundance and production, and their relation to primary production in tropical coastal waters of Peninsular Malaysia

2008 ◽  
Vol 59 (1) ◽  
pp. 10 ◽  
Author(s):  
Choon Weng Lee ◽  
Chui Wei Bong
Keyword(s):  
Primary Production ◽  
Chlorophyll A ◽  
Coastal Waters ◽  
Bacterial Production ◽  
Bacterial Abundance ◽  
Net Primary Production ◽  
Correlation Coefficients ◽  
Peninsular Malaysia ◽  
Chl A ◽  
The Relationship

In the present study, the relationship between bacteria and phytoplankton in tropical coastal waters was investigated. The bacterial abundance, bacterial production, chlorophyll a concentration and net primary production were measured at several locations in the coastal waters of Peninsular Malaysia. Chlorophyll a concentration ranged from 0.40 to 32.81 μg L–1, whereas bacterial abundance ranged from 0.1 to 97.5 × 106 cells mL–1. Net primary production ranged from 8.49 to 55.95 μg C L–1 h–1, whereas bacterial production ranged from 0.17 to 70.66 μg C L–1 h–1. In the present study, the carbon conversion factor used to convert bacterial production (cells mL–1 h–1) into carbon units ranged from 10 to 32.8 fg C cell–1, and was estimated from the bacterial size distribution measured at each location. Both phototrophic and heterotrophic biomass (bacteria–chlorophyll a) and activity (bacterial production–net primary production) were significantly correlated, although their correlation coefficients (r2) were relatively low (r2 = 0.188 and r2 = 0.218 respectively). Linear regression analyses provided the following equations to represent the relationship between: bacteria and chlorophyll a (Chl a), log Bacteria = 0.413 log Chl a + 6.057 (P = 0.003); and between bacterial production (BP) and net primary production (NPP), log BP = 0.896 log NPP – 0.394 (P = 0.004), which fitted with published results well. Comparison of annual carbon fluxes confirmed the prevalence of net heterotrophy in these coastal waters, and together with the low correlation coefficients, suggested the role of allochthonous organic matter in supporting heterotrophic activity.

scholarly journals Net primary production of Chinese fir plantation ecosystems and its relationship to climate

2014 ◽  
Vol 11 (4) ◽  
pp. 5639-5667 ◽  
Author(s):  
L. Wang ◽  
B. Duan ◽  
Y. Zhang ◽  
F. Berninger
Keyword(s):  
Climate Change ◽  
Primary Production ◽  
Net Primary Production ◽  
Regional Scale ◽  
Chinese Fir ◽  
Distribution Area ◽  
Natural Forests ◽  
Sequestration Potential ◽  
The Impact ◽  
The Relationship

Abstract. This article focuses on the relationship between the net primary production (NPP) of Chinese fir and the climate. Spatial-temporal NPP pattern in the potential distribution area of Chinese fir from 2000 to 2010 was characterized utilizing the Moderate Resolution Imaging Spectroradiometer (MODIS) data in a Geographic Information Systems (GIS) environment. The results showed that the production of Chinese fir was higher in southern and eastern regions than in northern and western areas, which was consistent with the spatial pattern of temperature and precipitation. The relationship between NPP of Chinese fir and climate variables was analyzed comprehensively on three scales: regional scale, zonal gradients and pixel scale. On the regional scale, precipitation showed higher correlation coefficients with NPP than did temperature. When scaling to pixels, the spatial variability pattern indicated that temperature was more important in central and eastern regions, while precipitation was crucial in the northern part. Negative correlations between NPP and precipitation and temperature were found in the southern region. The zonal analysis revealed that the impact of precipitation on the production was more complicated than that of temperature. When compared to natural forests, plantations appear to be more sensitive to the mode of precipitation, which indicates their higher vulnerability under climate change which could potentially lead to increasing variability in rainfall. Temporally, NPP values decreased despite of increasing temperatures, and more in plantations than among other vegetation types, which draws attention to carbon sequestration potential by plantations under current climate change.

scholarly journals Climate change impacts on net primary production (NPP) and export production (EP) regulated by increasing stratification and phytoplankton community structure in the CMIP5 models

2016 ◽  
Vol 13 (18) ◽  
pp. 5151-5170 ◽  
Author(s):  
Weiwei Fu ◽  
James T. Randerson ◽  
J. Keith Moore
Keyword(s):  
Climate Change ◽  
Community Structure ◽  
Primary Production ◽  
Phytoplankton Community ◽  
Net Primary Production ◽  
Climate Change Impacts ◽  
Cmip5 Models ◽  
Nutrient Concentrations ◽  
Phytoplankton Community Structure ◽  
Export Production

Abstract. We examine climate change impacts on net primary production (NPP) and export production (sinking particulate flux; EP) with simulations from nine Earth system models (ESMs) performed in the framework of the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Global NPP and EP are reduced by the end of the century for the intense warming scenario of Representative Concentration Pathway (RCP) 8.5. Relative to the 1990s, NPP in the 2090s is reduced by 2–16 % and EP by 7–18 %. The models with the largest increases in stratification (and largest relative declines in NPP and EP) also show the largest positive biases in stratification for the contemporary period, suggesting overestimation of climate change impacts on NPP and EP. All of the CMIP5 models show an increase in stratification in response to surface–ocean warming and freshening, which is accompanied by decreases in surface nutrients, NPP and EP. There is considerable variability across the models in the magnitudes of NPP, EP, surface nutrient concentrations and their perturbations by climate change. The negative response of NPP and EP to increasing stratification reflects primarily a bottom-up control, as upward nutrient flux declines at the global scale. Models with dynamic phytoplankton community structure show larger declines in EP than in NPP. This pattern is driven by phytoplankton community composition shifts, with reductions in productivity by large phytoplankton as smaller phytoplankton (which export less efficiently) are favored under the increasing nutrient stress. Thus, the projections of the NPP response to climate change are critically dependent on the simulated phytoplankton community structure, the efficiency of the biological pump and the resulting levels of regenerated production, which vary widely across the models. Community structure is represented simply in the CMIP5 models, and should be expanded to better capture the spatial patterns and climate-driven changes in export efficiency.

scholarly journals From Miami to Madison: Investigating the relationship between climate and terrestrial net primary production

2007 ◽  
Vol 21 (3) ◽  
pp. n/a-n/a ◽  
Author(s):  
David P. M. Zaks ◽  
Navin Ramankutty ◽  
Carol C. Barford ◽  
Jonathan A. Foley
Keyword(s):  
Primary Production ◽  
Net Primary Production ◽  
The Relationship

scholarly journals Net primary production of Chinese fir plantation ecosystems and its relationship to climate

2014 ◽  
Vol 11 (19) ◽  
pp. 5595-5606 ◽  
Author(s):  
L. Wang ◽  
Y. Zhang ◽  
F. Berninger ◽  
B. Duan
Keyword(s):  
Primary Production ◽  
Net Primary Production ◽  
Regional Scale ◽  
Chinese Fir ◽  
Distribution Area ◽  
Natural Forests ◽  
Fujian Province ◽  
Study Region ◽  
The Impact ◽  
The Relationship

Abstract. This article investigates the relationship between net primary production (NPP) of Chinese fir, temperature and precipitation. The spatial–temporal NPP pattern in the potential distribution area of Chinese fir from 2000–2010 was estimated utilizing a MODIS MOD17 product in a geographic information system (GIS) environment. The results showed that the highest NPP value of Chinese fir is in the Fujian province in the eastern part of the study region. The relationship between NPP of Chinese fir and climate variables was analyzed spatially and temporally. On the regional scale, precipitation showed higher correlation coefficients with NPP than did temperature. The spatial variability pattern indicated that temperature was more important in central and eastern regions (e.g. Hunan and Fujian province), while precipitation was crucial in the northern part (e.g. Anhui province). Zonal analysis revealed that the impact of precipitation on the production was more complicate than that of temperature; larger amount of precipitation is not always corresponding with greater NPP value. When compared to natural forests, plantations appear to be more sensitive to the variability of precipitation, which indicates their higher vulnerability under climate change. Temporally, NPP values decreased despite of increasing temperatures, and the decrease was larger in plantations than among other vegetation types.

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