Southern Ocean Primary Productivity: Variability and a View to the Future

Monitoring ocean primary productivity especially Chlorophyll-a (Chl-a) concentration is important as it contributes to the carbon cycle, global climate change and ocean health study. This study aims to examine the effects of cyclone events on the ocean productivity in the Bay of Bengal (BOB) considering its importance on global climate change. Level 2 SeaWiFS daily data from 2001 to 2010 were used to determine Chl-a concentration and data from the Indian Meteorological Department (IMD) were used to get information and locations of the cyclone events. Variation of Chl-a concentration was determined from the Chl-a concentration maps (pre-, during, and post-cyclone) using several transect lines parallel to the cyclone passages. Results indicated that there is a relationship between the variation of Chl-a concentration and the cyclone events at the BOB but the effect is varied according to the type of cyclone where very severe cyclonic storm (VSCS) has higher impact on Chl-a concentration compared to cyclonic storm (CS) and severe cyclonic storm (SCS). In most cases, Chl-a concentration was increased right after the cyclone event and the influence was observed over a wide area surrounding the cyclone passage.Monitoring ocean primary productivity especially Chlorophyll-a (Chl-a) concentration is important as it contributes to the carbon cycle, global climate change and ocean health study. This study aims to examine the effects of cyclone events on the ocean productivity in the Bay of Bengal (BOB) considering its importance on global climate change. Level 2 SeaWiFS daily data from 2001 to 2010 were used to determine Chl-a concentration and data from the Indian Meteorological Department (IMD) were used to get information and locations of the cyclone events. Variation of Chl-a concentration was determined from the Chl-a concentration maps (pre-, during, and post-cyclone) using several transect lines parallel to the cyclone passages. Results indicated that there is a relationship between the variation of Chl-a concentration and the cyclone events at the BOB but the effect is varied according to the type of cyclone where very severe cyclonic storm (VSCS) has higher impact on Chl-a concentration compared to cyclonic storm (CS) and severe cyclonic storm (SCS). In most cases, Chl-a concentration was increased right after the cyclone event and the influence was observed over a wide area surrounding the cyclone passage.Monitoring ocean primary productivity especially Chlorophyll-a (Chl-a) concentration is important as it contributes to the carbon cycle, global climate change and ocean health study. This study aims to examine the effects of cyclone events on the ocean productivity in the Bay of Bengal (BOB) considering its importance on global climate change. Level 2 SeaWiFS daily data from 2001 to 2010 were used to determine Chl-a concentration and data from the Indian Meteorological Department (IMD) were used to get information and locations of the cyclone events. Variation of Chl-a concentration was determined from the Chl-a concentration maps (pre-, during, and post-cyclone) using several transect lines parallel to the cyclone passages. Results indicated that there is a relationship between the variation of Chl-a concentration and the cyclone events at the BOB but the effect is varied according to the type of cyclone where very severe cyclonic storm (VSCS) has higher impact on Chl-a concentration compared to cyclonic storm (CS) and severe cyclonic storm (SCS). In most cases, Chl-a concentration was increased right after the cyclone event and the influence was observed over a wide area surrounding the cyclone passage.

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Satellites for the study of ocean primary productivity

Advances in Space Research ◽

10.1016/0273-1177(83)90049-2 ◽

1983 ◽

Vol 3 (9) ◽

pp. 123-133

Author(s):

R.C. Smith ◽

K.S. Baker

Keyword(s):

Primary Productivity ◽

Ocean Primary Productivity

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Greenland fjord productivity under climate change - multiproxy late-Holocene records from two contrasting fjord systems

10.5194/egusphere-egu2020-853 ◽

2020 ◽

Author(s):

Anna Bang Kvorning ◽

Tania Beate Thomsen ◽

Mimmi Oksman ◽

Marit-Solveig Seidenkrantz ◽

Christof Pearce ◽

...

Keyword(s):

Climate Change ◽

Primary Productivity ◽

Negative Impact ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Ice Age ◽

Dinoflagellate Cyst ◽

Coastal Marine ◽

The Future ◽

The Impact

<p>The Greenland Ice Sheet has been losing mass at an increasing rate over the past decades due to atmospheric and oceanic warming. As a result, freshwater discharge from the Greenland Ice sheet has doubled in the last two decades and is expected to strongly increase in the future, with a large impact on the functioning of coastal marine ecosystems. While glacier runoff delivers nutrients and labile carbon into the fjords, an increase in sediment inputs is expected to have a negative impact in primary productivity, due to increased turbidity and subsequent reduction in available light for photosynthesis. Bridging modern satellite, historical and paleo-records is a key approach, as our capacity to project future scenarios requires an understanding of long-term dynamics, and insight into past warm(er) climate periods that may serve as analogues for the future. We will present results from a master&#8217;s project developed within the framework of project GreenShift: Greenland fjord productivity under climate change. Two high-resolution sediment core records from two contrasting fjord systems in NE and SW Greenland were analysed to assess the impact of Greenland Ice Sheet melt on sediment fluxes and primary productivity, focusing on the time period from the Little Ice Age until present. The overall goal of this work is to gain a better understanding of the possible linkages between GIS melt and productivity in Greenland fjord systems, with a view to improve future projections. We followed a multiproxy approach including grain-size distribution, organic carbon and biogenic silica fluxes; and dinoflagellate cyst analyses. Our preliminary results show an overall trend towards sea-surface freshening in recent decades for both fjords influenced by land-terminating (NE) and marine-terminating (SW) glaciers, alongside with important differences both in terms of sedimentary organic composition and dinoflagellate cyst assemblages. &#160;</p>

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Primary productivity, new productivity, and their relation to carbon flux during two Southern Ocean Gas Exchange tracer experiments

Journal of Geophysical Research Atmospheres ◽

10.1029/2011jc007687 ◽

2012 ◽

Vol 117 (C4) ◽

pp. n/a-n/a ◽

Cited By ~ 4

Author(s):

Veronica P. Lance ◽

Peter G. Strutton ◽

Robert D. Vaillancourt ◽

Bruce R. Hargreaves ◽

Jia-Zhong Zhang ◽

...

Keyword(s):

Gas Exchange ◽

Southern Ocean ◽

Primary Productivity ◽

Carbon Flux ◽

Tracer Experiments

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Fueling primary productivity: nutrient return pathways from the deep ocean and their dependence on the Meridional Overturning Circulation

Biogeosciences Discussions ◽

10.5194/bgd-7-4045-2010 ◽

2010 ◽

Vol 7 (3) ◽

pp. 4045-4088 ◽

Cited By ~ 3

Author(s):

J. B. Palter ◽

J. L. Sarmiento ◽

A. Gnanadesikan ◽

J. Simeon ◽

D. Slater

Keyword(s):

Southern Ocean ◽

Primary Productivity ◽

Deep Ocean ◽

Ocean Model ◽

Surface Fluxes ◽

Meridional Overturning Circulation ◽

Overturning Circulation ◽

Nutrient Return ◽

Mode Water ◽

Meridional Overturning

Abstract. In the Southern Ocean, mixing and upwelling in the presence of heat and freshwater surface fluxes transform subpycnocline water to lighter densities as part of the upward branch of the Meridional Overturning Circulation (MOC). One hypothesized impact of this transformation is the restoration of nutrients to the global pycnocline, without which biological productivity at low latitudes would be catastrophically reduced. Here we use a novel set of modeling experiments to explore the causes and consequences of the Southern Ocean nutrient return pathway. Specifically, we quantify the contribution to global productivity of nutrients that rise from the ocean interior in the Southern Ocean, the northern high latitudes, and by mixing across the low latitude pycnocline. In addition, we evaluate how the strength of the Southern Ocean winds and the parameterizations of subgridscale processes change the dominant nutrient return pathways in the ocean. Our results suggest that nutrients upwelled from the deep ocean in the Antarctic Circumpolar Current and subducted in Subantartic Mode Water support between 33 and 75% of global primary productivity between 30° S and 30° N. The high end of this range results from an ocean model in which the MOC is driven primarily by wind-induced Southern Ocean upwelling, a configuration favored due to its fidelity to tracer data, while the low end results from an MOC driven by high diapycnal diffusivity in the pycnocline. In all models, the high preformed nutrients subducted in the SAMW layer are converted rapidly (in less than 40 years) to remineralized nutrients, explaining previous modeling results that showed little influence of the drawdown of SAMW surface nutrients on atmospheric carbon concentrations.

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The Southern Ocean diatom Pseudo-nitzschia subcurvata flourished better under simulated glacial than interglacial ocean conditions: Combined effects of CO2 and iron

PLoS ONE ◽

10.1371/journal.pone.0260649 ◽

2021 ◽

Vol 16 (12) ◽

pp. e0260649

Author(s):

Anna Pagnone ◽

Florian Koch ◽

Franziska Pausch ◽

Scarlett Trimborn

Keyword(s):

Southern Ocean ◽

Primary Productivity ◽

Climatic Conditions ◽

The Other ◽

Combined Effects ◽

Dust Deposition ◽

Carbon Export ◽

Negative Effect ◽

Ocean Conditions ◽

Fe Addition

The ‘Iron Hypothesis’ suggests a fertilization of the Southern Ocean by increased dust deposition in glacial times. This promoted high primary productivity and contributed to lower atmospheric pCO2. In this study, the diatom Pseudo-nitzschia subcurvata, known to form prominent blooms in the Southern Ocean, was grown under simulated glacial and interglacial climatic conditions to understand how iron (Fe) availability (no Fe or Fe addition) in conjunction with different pCO2 levels (190 and 290 μatm) influences growth, particulate organic carbon (POC) production and photophysiology. Under both glacial and interglacial conditions, the diatom grew with similar rates. In comparison, glacial conditions (190 μatm pCO2 and Fe input) favored POC production by P. subcurvata while under interglacial conditions (290 μatm pCO2 and Fe deficiency) POC production was reduced, indicating a negative effect caused by higher pCO2 and low Fe availability. Under interglacial conditions, the diatom had, however, thicker silica shells. Overall, our results show that the combination of higher Fe availability with low pCO2, present during the glacial ocean, was beneficial for the diatom P. subcurvata, thus contributing more to primary production during glacial compared to interglacial times. Under the interglacial ocean conditions, on the other hand, the diatom could have contributed to higher carbon export due to its higher degree of silicification.

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Variability in primary productivity and bio-optical properties in the Indian sector of the Southern Ocean during an austral summer

Polar Biology ◽

10.1007/s00300-020-02722-2 ◽

2020 ◽

Vol 43 (10) ◽

pp. 1469-1492

Author(s):

Anvita U. Kerkar ◽

S. C. Tripathy ◽

P. Minu ◽

N. Baranval ◽

P. Sabu ◽

...

Keyword(s):

Optical Properties ◽

Southern Ocean ◽

Primary Productivity ◽

Austral Summer ◽

Indian Sector

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Bioavailability of organically bound Fe to model phytoplankton of the Southern Ocean

Biogeosciences ◽

10.5194/bg-6-2281-2009 ◽

2009 ◽

Vol 6 (10) ◽

pp. 2281-2296 ◽

Cited By ~ 66

Author(s):

C. S. Hassler ◽

V. Schoemann

Keyword(s):

Southern Ocean ◽

Primary Productivity ◽

Iron Bioavailability ◽

Organic Ligands ◽

Relative Importance ◽

Organic Amine ◽

Organic Form ◽

Short Term ◽

Dissolved Phase ◽

Ubiquitous Presence

Abstract. Iron (Fe) is known to be mostly bound to organic ligands and to limit primary productivity in the Southern Ocean. It is thus important to investigate the bioavailability of organically bound Fe. In this study, we used four phytoplankton species of the Southern Ocean (Phaeocystis sp., Chaetoceros sp., Fragilariopsis kerguelensis and Thalassiosira antarctica Comber) to measure the influence of various organic ligands on Fe solubility and bioavailability. Short-term uptake Fe:C ratios were inversely related to the surface area to volume ratios of the phytoplankton. The ratio of extracellular to intracellular Fe is used to discuss the relative importance of diffusive supply and uptake to control Fe bioavailability. The effect of excess organic ligands on Fe bioavailability cannot be solely explained by their effect on Fe solubility. For most strains studied, the bioavailability of Fe can be enhanced relative to inorganic Fe in the presence of porphyrin, catecholate siderophore and saccharides whereas it was decreased in presence of hydroxamate siderophore and organic amine. For Thalassiosira, iron bioavailability was not affected by the presence of porphyrin, catecholate siderophore and saccharides. The enhancement of Fe bioavailability in presence of saccharides is presented as the result from both the formation of bioavailable (or chemically labile) organic form of Fe and the stabilisation of Fe within the dissolved phase. Given the ubiquitous presence of saccharides in the ocean, these compounds might represent an important factor to control the basal level of soluble and bioavailable Fe. Results show that the use of model phytoplankton is promising to improve mechanistic understanding of Fe bioavailability and primary productivity in HNLC regions of the ocean.

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