scholarly journals Primary production sensitivity to phytoplankton light attenuation parameter increases with transient forcing

2017 ◽  
Vol 14 (20) ◽  
pp. 4767-4780 ◽  
Author(s):  
Karin F. Kvale ◽  
Katrin J. Meissner
Keyword(s):  
Primary Production ◽  
Net Primary Production ◽  
Light Attenuation ◽  
Climate Scenario ◽  
Sensitivity Study ◽  
Climate Forcing ◽  
Deep Time ◽  
Underwater Light Field ◽  
Attenuation Parameter ◽  
Biogeochemical Models

Abstract. Treatment of the underwater light field in ocean biogeochemical models has been attracting increasing interest, with some models moving towards more complex parameterisations. We conduct a simple sensitivity study of a typical, highly simplified parameterisation. In our study, we vary the phytoplankton light attenuation parameter over a range constrained by data during both pre-industrial equilibrated and future climate scenario RCP8.5. In equilibrium, lower light attenuation parameters (weaker self-shading) shift net primary production (NPP) towards the high latitudes, while higher values of light attenuation (stronger shelf-shading) shift NPP towards the low latitudes. Climate forcing magnifies this relationship through changes in the distribution of nutrients both within and between ocean regions. Where and how NPP responds to climate forcing can determine the magnitude and sign of global NPP trends in this high CO2 future scenario. Ocean oxygen is particularly sensitive to parameter choice. Under higher CO2 concentrations, two simulations establish a strong biogeochemical feedback between the Southern Ocean and low-latitude Pacific that highlights the potential for regional teleconnection. Our simulations serve as a reminder that shifts in fundamental properties (e.g. light attenuation by phytoplankton) over deep time have the potential to alter global biogeochemistry.

scholarly journals Primary production sensitivity to phytoplankton light attenuation parameter increases with transient forcing

2017 ◽  
Author(s):  
Karin F. Kvale ◽  
Katrin J. Meissner
Keyword(s):  
Steady State ◽  
Primary Production ◽  
Net Primary Production ◽  
Light Attenuation ◽  
Climate Forcing ◽  
Deep Time ◽  
Underwater Light Field ◽  
Fundamental Properties ◽  
Attenuation Parameter ◽  
Biogeochemical Models

Abstract. Treatment of the underwater light field in ocean biogeochemical models has been attracting increasing interest, with some models moving towards more complex parameterisations. A simple test of the sensitivity of a typical, highly simplified parameterisation, to adjustment of the phytoplankton light attenuation parameter using both steady-state and future projections reveals a range of values to which the model primary production is relatively insensitive in steady-state but to which it becomes increasingly sensitive under climate forcing. Parameter value choice can determine the magnitude and sign of global net primary production trends in a high CO2 forcing scenario. Ocean oxygen is particularly sensitive to parameter choice. With climate forcing, two simulations establish a strong biogeochemical feedback between the Southern Ocean and low latitude Pacific that highlights the potential for regional teleconnection and serves as a reminder that shifts in fundamental properties (e.g., light attenuation by phytoplankton) over deep time have the potential to alter biogeochemical climate.

scholarly journals Catastrophic shifts in the aquatic primary production revealed by a small low-flow section of tropical downstream after dredging

2015 ◽  
Vol 75 (4) ◽  
pp. 804-811
Author(s):  
H. Marotta ◽  
A. Enrich-Prast
Keyword(s):  
Primary Production ◽  
Aquatic Macrophytes ◽  
Net Primary Production ◽  
Gross Primary Production ◽  
Light Attenuation ◽  
Low Flow ◽  
Flow Section ◽  
Net Heterotrophy ◽  
The Tropics ◽  
Catastrophic Shifts

Abstract Dredging is a catastrophic disturbance that directly affects key biological processes in aquatic ecosystems, especially in those small and shallow. In the tropics, metabolic responses could still be enhanced by the high temperatures and solar incidence. Here, we assessed changes in the aquatic primary production along a small section of low-flow tropical downstream (Imboassica Stream, Brazil) after dredging. Our results suggested that these ecosystems may show catastrophic shifts between net heterotrophy and autotrophy in waters based on three short-term stages following the dredging: (I) a strongly heterotrophic net primary production -NPP- coupled to an intense respiration -R- likely supported by high resuspended organic sediments and nutrients from the bottom; (II) a strongly autotrophic NPP coupled to an intense gross primary production -GPP- favored by the high nutrient levels and low solar light attenuation from suspended solids or aquatic macrophytes; and (III) a NPP near to the equilibrium coupled to low GPP and R rates following, respectively, the shading by aquatic macrophytes and high particulate sedimentation. In conclusion, changes in aquatic primary production could be an important threshold for controlling drastic shifts in the organic matter cycling and the subsequent silting up of small tropical streams after dredging events.

scholarly journals Prioritising Carbon Sequestration Areas in Southern Queensland using Time Series MODIS Net Primary Productivity (NPP) Imagery

2014 ◽  
Vol XL-8 ◽  
pp. 549-553
Author(s):  
A. Apan ◽  
L. A. Suarez Cadavid ◽  
L. Richardson ◽  
T. Maraseni
Keyword(s):  
Carbon Sequestration ◽  
Primary Production ◽  
Net Primary Productivity ◽  
Net Primary Production ◽  
Climate Scenario ◽  
Forest Growth ◽  
Tree Canopy ◽  
Annual Rainfall ◽  
Primary Input ◽  
Tree Canopy Cover

The aim of this study was to develop a method that will use satellite imagery to identify areas of high forest growth and productivity, as a primary input in prioritising revegetation sites for carbon sequestration. Using the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data, this study analysed the annual net primary production (NPP) values (gC/m<sup>2</sup>) of images acquired from 2000 to 2013, covering the Condamine Catchment in southeast Queensland, Australia. With the analysis of annual rainfall data during the same period, three transitions of "normal to dry" years were identified to represent the future climate scenario considered in this study. The difference in the corresponding NPP values for each year was calculated, and subsequently averaged to the get the "<i>Mean of Annual NPP Difference</i>" (MAND) map. This layer identified the areas with increased net primary production despite the drought condition in those years. Combined with key thematic maps (i.e. regional ecosystems, land use, and tree canopy cover), the priority areas were mapped. The results have shown that there are over 42 regional ecosystem (RE) types in the study area that exhibited positive vegetation growth and productivity despite the decrease in annual rainfall. However, seven (7) of these RE types represents the majority (79 %) of the total high productivity area. A total of 10,736 ha were mapped as priority revegetation areas. This study demonstrated the use of MODIS-NPP imagery to map vegetation with high carbon sequestration rates necessary in prioritising revegetation sites.

scholarly journals A skill assessment of the biogeochemical model REcoM2 coupled to the finite element sea-ice ocean model (FESOM 1.3)

2014 ◽  
Vol 7 (4) ◽  
pp. 4153-4249
Author(s):  
V. Schourup-Kristensen ◽  
D. Sidorenko ◽  
D. A. Wolf-Gladrow ◽  
C. Völker
Keyword(s):  
Finite Element ◽  
Southern Ocean ◽  
Primary Production ◽  
Net Primary Production ◽  
Global Scale ◽  
Ocean Model ◽  
Biogeochemical Model ◽  
Biogeochemical Models ◽  
The Pacific ◽  
The Pacific Ocean

Abstract. In coupled ocean-biogeochemical models, the choice of numerical schemes in the ocean circulation component can have a large influence on the distribution of the biological tracers. Biogeochemical models are traditionally coupled to ocean general circulation models (OGCMs), which are based on dynamical cores employing quasi regular meshes, and therefore utilize limited spatial resolution in a global setting. An alternative approach is to use an unstructured-mesh ocean model, which allows variable mesh resolution. Here, we present initial results of a coupling between the Finite Element Sea-ice Ocean Model (FESOM) and the biogeochemical model REcoM2, with special focus on the Southern Ocean. Surface fields of nutrients, chlorophyll a and net primary production were compared to available data sets with focus on spatial distribution and seasonal cycle. The model produced realistic spatial distributions, especially regarding net primary production and chlorophyll a, whereas the iron concentration became too low in the Pacific Ocean. The modelled net primary production was 32.5 Pg C yr−1 and the export production 6.1 Pg C yr−1. This is lower than satellite-based estimates, mainly due to the excessive iron limitation in the Pacific along with too little coastal production. Overall, the model performed better in the Southern Ocean than on the global scale, though the assessment here is hindered by the lower availability of observations. The modelled net primary production was 3.1 Pg C yr−1 in the Southern Ocean and the export production 1.1 Pg C yr−1. All in all, the combination of a circulation model on an unstructured grid with an ocean biogeochemical model shows similar performance to other models at non-eddy-permitting resolution. It is well suited for studies of the Southern Ocean, but on the global scale deficiencies in the Pacific Ocean would have to be taken into account.

scholarly journals Seasonal Variation in Biomass and Production of the Macrophytobenthos in two Lagoons in the Southern Baltic Sea

2021 ◽  
Vol 8 ◽  
Author(s):  
Martin Paar ◽  
Maximilian Berthold ◽  
Rhena Schumann ◽  
Sven Dahlke ◽  
Irmgard Blindow
Keyword(s):  
Primary Production ◽  
Net Primary Production ◽  
Coastal Lagoons ◽  
Light Attenuation ◽  
Seasonal Succession ◽  
Trophic Levels ◽  
Seasonal Development ◽  
Nutrient Concentrations ◽  
Eutrophic Lagoon ◽  
The Impact

Baltic coastal lagoons are severely threatened by eutrophication. To evaluate the impact of eutrophication on macrophytobenthos, we compared the seasonal development in macrophytobenthic composition, biomass and production, water column parameters (light, nutrients), phytoplankton biomass and production in one mesotrophic and one eutrophic German coastal lagoon. We hypothesized that light availability is the main driver for primary production, and that net primary production is lower at a higher eutrophication level. In the mesotrophic lagoon, macrophytobenthic biomass was much higher with distinct seasonal succession in species composition. Filamentous algae dominated in spring and late summer and probably caused reduced macrophytobenthic biomass and growth during early summer, thus decreasing vegetation stability. Light attenuation was far higher in the eutrophic lagoon, due to high phytoplankton densities, explaining the low macrophytobenthic biomass and species diversity in every season. Areal net primary production was far lower in the eutrophic lagoon. The “paradox of enrichment” hypothesis predicts lower production at higher trophic levels with increased nutrient concentrations. Our results prove for the first time that this hypothesis may be valid already at the primary producer level in coastal lagoons.

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