scholarly journals Satellite observations of new phytoplankton blooms in the Maud Rise Polynya, Southern Ocean

2019 ◽  
Author(s):  
Babula Jena ◽  
Anilkumar Narayana Pillai
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Primary Production ◽  
Chlorophyll A ◽  
Carbon Fixation ◽  
Net Primary Production ◽  
Light Condition ◽  
Upper Ocean ◽  
Phytoplankton Blooms ◽  
Maud Rise

Abstract. Appearance of new phytoplankton blooms with in the sea-ice cover has large importance considering the upper ocean primary production that controls the biological pump with the implications for atmospheric CO2 and global climate. Satellite derived chlorophyll-a concentration showed the unprecedented phytoplankton blooms in the Maud Rise polynya, Southern Ocean with chlorophyll-a reached up to 4.67 mg m-3. Multi-satellite data indicated that the bloom appeared for the first time in the entire mission records started since 1978. Argo float located in the polynya edge provided evidence of bloom condition in austral spring 2017 (chlorophyll-a up to 5.47 mg m-3) compared to the preceding years of prevailed low chlorophyll-a. The occurrence of bloom was associated with the supply of nutrients into the upper ocean through the Ekman upwelling (driven by wind stress curl and cyclonic ocean eddies), and improved light condition up to 61.9 Einstein m-2 day-1. The net primary production from Aqua-MODIS chlorophyll-based algorithm showed that the Maud Rise polynya was as productive as the Antarctic coastal polynyas with the carbon fixation rates reached up to 415.08 mg C m-2 day-1. The study demonstrates how the phytoplankton in the Southern Ocean (specifically over the shallow bathymetric region) would likely respond in the future under a warming climate condition and continued melting of Antarctic sea-ice since 2016.

scholarly journals Satellite observations of unprecedented phytoplankton blooms in the Maud Rise polynya, Southern Ocean

2020 ◽  
Vol 14 (4) ◽  
pp. 1385-1398 ◽  
Author(s):  
Babula Jena ◽  
Anilkumar N. Pillai
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Primary Production ◽  
Chlorophyll A ◽  
Carbon Fixation ◽  
Net Primary Production ◽  
Upper Ocean ◽  
Phytoplankton Blooms ◽  
Austral Spring ◽  
Maud Rise

Abstract. The appearance of phytoplankton blooms within sea ice cover is of high importance considering the upper ocean primary production that controls the biological pump, with implications for atmospheric CO2 and global climate. Satellite-derived chlorophyll a concentration showed unprecedented phytoplankton blooms in the Maud Rise polynya, Southern Ocean, with chlorophyll a reaching up to 4.67 mg m−3 during 2017. Multi-satellite data indicated that the bloom appeared for the first time since the entire mission records started in 1978. An Argo float located in the polynya edge provided evidence of bloom conditions in austral spring 2017 (chlorophyll a up to 5.47 mg m−3) compared to the preceding years with prevailing low chlorophyll a. The occurrence of bloom was associated with the supply of nutrients into the upper ocean through Ekman upwelling (driven by wind stress curl and cyclonic ocean eddies) and improved light conditions of up to 61.9 einstein m−2 d−1. The net primary production from the Aqua Moderate Resolution Imaging Spectroradiometer chlorophyll-based algorithm showed that the Maud Rise polynya was as productive as the Antarctic coastal polynyas, with carbon fixation rates reaching up to 415.08 mg C m−2 d−1. The study demonstrates how the phytoplankton in the Southern Ocean (specifically over the shallow bathymetric region) would likely respond in the future under warming climate conditions and continued melting of Antarctic sea ice.

scholarly journals The relationship between sea ice bacterial community structure and biogeochemistry: A synthesis of current knowledge and known unknowns

Elem Sci Anth ◽  
2015 ◽  
Vol 3 ◽  
Author(s):  
Jeff S. Bowman
Keyword(s):  
Bacterial Community ◽  
Carbon Cycle ◽  
Sea Ice ◽  
Primary Production ◽  
Chlorophyll A ◽  
Carbon Fixation ◽  
Current Knowledge ◽  
Active Role ◽  
Rrna Gene ◽  
Modeling Framework

Abstract Sea ice plays an important role in high latitude biogeochemical cycles, ecosystems, and climate. A complete understanding of how sea ice biogeochemistry contributes to these processes must take into account the metabolic functions of the sea ice bacterial community. While the roles of sea ice bacteria in the carbon cycle and sea ice microbial loop are evidenced by high rates of bacterial production (BP), their metabolic diversity extends far beyond heterotrophy, and their functionality encompasses much more than carbon turnover. Work over the last three decades has identified an active role for sea ice bacteria in phosphate and nitrogen cycling, mutualistic partnerships with ice algae, and even prokaryotic carbon fixation. To better understand the role of sea ice bacteria in the carbon cycle the existing sea ice BP and primary production data were synthesized. BP in sea ice was poorly correlated with primary production, but had a strong, variable relationship with chlorophyll a, with a positive correlation below 50 mg chlorophyll a m-3 and a negative correlation above this value. These results concur with previous work suggesting that BP can be inhibited by grazing or the production of bacteriostatic compounds. To extend existing observations and predictions of other community functions a metabolic inference technique was used on the available 16S rRNA gene data. This analysis provided taxonomic support for some observed metabolic processes, as well as underexplored processes such as sulfur oxidation and nitrogen fixation. The decreasing spatial and temporal extent of sea ice, and altered timing of ice formation and melt, are likely to impact the structure and function of sea ice bacterial communities. An adequate modeling framework and studies that can resolve the functional dynamics of the sea ice bacterial community, such as community gene expression studies, are urgently needed to predict future change.

scholarly journals Characterizing Spatial Variability of Ice Algal Chlorophyll a and Net Primary Production between Sea Ice Habitats Using Horizontal Profiling Platforms

2017 ◽  
Vol 4 ◽  
Author(s):  
Benjamin A. Lange ◽  
Christian Katlein ◽  
Giulia Castellani ◽  
Mar Fernández-Méndez ◽  
Marcel Nicolaus ◽  
...  
Keyword(s):  
Sea Ice ◽  
Spatial Variability ◽  
Primary Production ◽  
Chlorophyll A ◽  
Net Primary Production

scholarly journals Changes in the upper ocean mixed layer and phytoplankton productivity along the West Antarctic Peninsula

2018 ◽  
Vol 376 (2122) ◽  
pp. 20170173 ◽  
Author(s):  
Oscar Schofield ◽  
Michael Brown ◽  
Josh Kohut ◽  
Schuyler Nardelli ◽  
Grace Saba ◽  
...  
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Mixed Layer ◽  
Carbon Fixation ◽  
Upper Ocean ◽  
The West ◽  
Phytoplankton Productivity ◽  
West Antarctic ◽  
West Antarctic Peninsula

The West Antarctic Peninsula (WAP) has experienced significant change over the last 50 years. Using a 24 year spatial time series collected by the Palmer Long Term Ecological Research programme, we assessed long-term patterns in the sea ice, upper mixed layer depth (MLD) and phytoplankton productivity. The number of sea ice days steadily declined from the 1980s until a recent reversal that began in 2008. Results show regional differences between the northern and southern regions sampled during regional ship surveys conducted each austral summer. In the southern WAP, upper ocean MLD has shallowed by a factor of 2. Associated with the shallower mixed layer is enhanced phytoplankton carbon fixation. In the north, significant interannual variability resulted in the mixed layer showing no trended change over time and there was no significant increase in the phytoplankton productivity. Associated with the recent increases in sea ice there has been an increase in the photosynthetic efficiency (chlorophyll a -normalized carbon fixation) in the northern and southern regions of the WAP. We hypothesize the increase in sea ice results in increased micronutrient delivery to the continental shelf which in turn leads to enhanced photosynthetic performance. 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 The potential impacts of a sulfur- and halogen-rich supereruption such as Los Chocoyos on the atmosphere and climate

2020 ◽  
Vol 20 (11) ◽  
pp. 6521-6539 ◽  
Author(s):  
Hans Brenna ◽  
Steffen Kutterolf ◽  
Michael J. Mills ◽  
Kirstin Krüger
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Net Primary Production ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Surface Cooling ◽  
Aerosol Chemistry ◽  
Surface Climate ◽  
Column Ozone

Abstract. The supereruption of Los Chocoyos (14.6∘ N, 91.2∘ W) in Guatemala ∼84 kyr ago was one of the largest volcanic events of the past 100 000 years. Recent petrologic data show that the eruption released very large amounts of climate-relevant sulfur and ozone-destroying chlorine and bromine gases (523±94 Mt sulfur, 1200±156 Mt chlorine, and 2±0.46 Mt bromine). Using the Earth system model (ESM) of the Community Earth System Model version 2 (CESM2) coupled with the Whole Atmosphere Community Climate Model version 6 (WACCM6), we simulated the impacts of the sulfur- and halogen-rich Los Chocoyos eruption on the preindustrial Earth system. Our simulations show that elevated sulfate burden and aerosol optical depth (AOD) persists for 5 years in the model, while the volcanic halogens stay elevated for nearly 15 years. As a consequence, the eruption leads to a collapse of the ozone layer with global mean column ozone values dropping to 50 DU (80 % decrease) and leading to a 550 % increase in surface UV over the first 5 years, with potential impacts on the biosphere. The volcanic eruption shows an asymmetric-hemispheric response with enhanced aerosol, ozone, UV, and climate signals over the Northern Hemisphere. Surface climate is impacted globally due to peak AOD of >6, which leads to a maximum surface cooling of >6 K, precipitation and terrestrial net primary production decrease of >25 %, and sea ice area increases of 40 % in the first 3 years. Locally, a wetting (>100 %) and strong increase in net primary production (NPP) (>700 %) over northern Africa is simulated in the first 5 years and related to a southward shift of the Intertropical Convergence Zone (ITCZ) to the southern tropics. The ocean responds with pronounced El Niño conditions in the first 3 years that shift to the southern tropics and are coherent with the ITCZ change. Recovery to pre-eruption ozone levels and climate takes 15 years and 30 years, respectively. The long-lasting surface cooling is sustained by an immediate increase in the Arctic sea ice area, followed by a decrease in poleward ocean heat transport at 60∘ N which lasts up to 20 years. In contrast, when simulating Los Chocoyos conventionally by including sulfur and neglecting halogens, we simulate a larger sulfate burden and AOD, more pronounced surface climate changes, and an increase in column ozone. By comparing our aerosol chemistry ESM results to other supereruption simulations with aerosol climate models, we find a higher surface climate impact per injected sulfur amount than previous studies for our different sets of model experiments, since the CESM2(WACCM6) creates smaller aerosols with a longer lifetime, partly due to the interactive aerosol chemistry. As the model uncertainties for the climate response to supereruptions are very large, observational evidence from paleo archives and a coordinated model intercomparison would help to improve our understanding of the climate and environment response.

Antarctic marine primary production, biogeochemical carbon cycles and climatic change

1992 ◽  
Vol 338 (1285) ◽  
pp. 289-297 ◽  
Keyword(s):  
Climate Change ◽  
Southern Ocean ◽  
Primary Production ◽  
Climatic Change ◽  
Carbon Fixation ◽  
Algal Growth ◽  
Ice Cover ◽  
Phytoplankton Production ◽  
Numerical Predictions ◽  
Model Predictions

In the Southern Ocean, inorganic macronutrients are very rarely depleted by phytoplankton growth. This has led to speculation on possible additional CO 2 drawdown in this region. However, the effects of climate change can only be predicted once the role of environmental and biotic factors limiting phytoplankton carbon fixation are understood. It is clear that the Southern Ocean is heterogeneous, and no single factor controls prim ary production overall. Ice cover and vertical mixing influence algal growth rates by m odulating radiance flux. Micronutrients, especially iron, may limit growth in some areas. Primary production is also suppressed by high removal rates of algal biomass. Grazing by zooplankton is the major factor determining magnitude and quality of vertical particle flux. Several of the physical controls on phytoplankton production are sensitive to climate change. Although it is impossible to make numerical predictions of future change on the basis of our present knowledge, qualitative assessments can be put forward on the basis of model predictions of climate change and known factors controlling prim ary production. Changes in water temperature and in windinduced mixing are likely to be slight and have little effect. Model predictions of changes in sea-ice cover vary widely, making prediction of biogeochemical effects impossible. Even if climatic change induces increased nutrient uptake, there are several reasons to suspect that carbon sequestration will be ineffective in comparison with continuing anthropogenic CO 2 emission.

scholarly journals Effects of sea ice cover on satellite-detected primary production in the Arctic Ocean

2016 ◽  
Vol 12 (11) ◽  
pp. 20160223 ◽  
Author(s):  
Mati Kahru ◽  
Zhongping Lee ◽  
B. Greg Mitchell ◽  
Cynthia D. Nevison
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Arctic Ocean ◽  
Barents Sea ◽  
Net Primary Production ◽  
Arctic Sea Ice ◽  
The Arctic ◽  
Primary Input ◽  
High Productivity ◽  
The Arctic Ocean

The influence of decreasing Arctic sea ice on net primary production (NPP) in the Arctic Ocean has been considered in multiple publications but is not well constrained owing to the potentially large errors in satellite algorithms. In particular, the Arctic Ocean is rich in coloured dissolved organic matter (CDOM) that interferes in the detection of chlorophyll a concentration of the standard algorithm, which is the primary input to NPP models. We used the quasi-analytic algorithm (Lee et al . 2002 Appl. Opti. 41 , 5755−5772. ( doi:10.1364/AO.41.005755 )) that separates absorption by phytoplankton from absorption by CDOM and detrital matter. We merged satellite data from multiple satellite sensors and created a 19 year time series (1997–2015) of NPP. During this period, both the estimated annual total and the summer monthly maximum pan-Arctic NPP increased by about 47%. Positive monthly anomalies in NPP are highly correlated with positive anomalies in open water area during the summer months. Following the earlier ice retreat, the start of the high-productivity season has become earlier, e.g. at a mean rate of −3.0 d yr −1 in the northern Barents Sea, and the length of the high-productivity period has increased from 15 days in 1998 to 62 days in 2015. While in some areas, the termination of the productive season has been extended, owing to delayed ice formation, the termination has also become earlier in other areas, likely owing to limited nutrients.

scholarly journals Particulate organic carbon dynamics in the Gulf of Lion shelf (NW Mediterranean) using a coupled hydrodynamic–biogeochemical model

2021 ◽  
Vol 18 (19) ◽  
pp. 5513-5538
Author(s):  
Gaël Many ◽  
Caroline Ulses ◽  
Claude Estournel ◽  
Patrick Marsaleix
Keyword(s):  
Organic Carbon ◽  
Primary Production ◽  
Particulate Organic Carbon ◽  
Chlorophyll A ◽  
Net Primary Production ◽  
Biogeochemical Model ◽  
Eastern Region ◽  
Gulf Of Lion ◽  
Poc Export ◽  
Nw Mediterranean

Abstract. The Gulf of Lion shelf (GoL, NW Mediterranean) is one of the most productive areas in the Mediterranean Sea. A 3D coupled hydrodynamic–biogeochemical model is used to study the mechanisms that drive the particulate organic carbon (POC) dynamics over the shelf. A set of observations, including temporal series from a coastal station, remote sensing of surface chlorophyll a, and a glider deployment, is used to validate the distribution of physical and biogeochemical variables from the model. The model reproduces the time and spatial evolution of temperature, chlorophyll a, and nitrate concentrations well and shows a clear annual cycle of gross primary production and respiration. We estimate an annual net primary production of ∼ 200 × 104 t C yr−1 at the scale of the shelf. The primary production is marked by a coast-slope increase with maximal values in the eastern region. Our results show that the primary production is favoured by the inputs of nutrients imported from offshore waters, representing 3 and 15 times the inputs of the Rhône in terms of nitrate and phosphate. In addition, the empirical orthogonal function (EOF) decomposition highlights the role of solar radiation anomalies and continental winds that favour upwellings, and inputs of the Rhône River, in annual changes in the net primary production. Annual POC deposition (27 × 104 t C yr−1) represents 13 % of the net primary production. The delivery of terrestrial POC favours the deposition in front of the Rhône mouth, and the mean cyclonic circulation increases the deposition between 30 and 50 m depth from the Rhône prodelta to the west. Mechanisms responsible for POC export (24 × 104 t C yr−1) to the open sea are discussed. The export off the shelf in the western part, from the Cap de Creus to the Lacaze-Duthiers canyon, represents 37 % of the total POC export. Maximum values are obtained during shelf dense water cascading events and marine winds. Considering surface waters only, the POC is mainly exported in the eastern part of the shelf through shelf waters and Rhône inputs, which spread to the Northern Current during favourable continental wind conditions. The GoL shelf appears as an autotrophic ecosystem with a positive net ecosystem production and as a source of POC for the adjacent NW Mediterranean basin. The undergoing and future increase in temperature and stratification induced by climate change could impact the trophic status of the GoL shelf and the carbon export towards the deep basin. It is crucial to develop models to predict and assess these future evolutions.

scholarly journals Explicit silicate cycling in the Kiel Marine Biogeochemistry Model, version 3 (KMBM3) embedded in the UVic ESCM version 2.9

2020 ◽  
Author(s):  
Karin Kvale ◽  
David P. Keller ◽  
Wolfgang Koeve ◽  
Katrin J. Meissner ◽  
Chris Somes ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Primary Production ◽  
Large Scale ◽  
Climate Model ◽  
Net Primary Production ◽  
Coupled Model ◽  
Co2 Concentration ◽  
Ecosystem Model ◽  
New Model ◽  
Fully Coupled

Abstract. We describe and test a new model of biological marine silicate cycling, implemented in the University of Victoria Earth System Climate Model (UVic ESCM) version 2.9. This new model adds diatoms, which are a key aspect of the biological carbon pump, to an existing ecosystem model. The new model performs well against important ocean biogeochemical indicators and captures the large-scale features of the marine silica cycle. Furthermore it is computationally efficient, allowing both fully-coupled, long-timescale transient simulations, as well as "offline" transport matrix spinups. We assess the fully-coupled model against modern ocean observations, the historical record since 1960, and a business-as-usual atmospheric CO2 forcing to the year 2300. The model simulates a global decline in net primary production (NPP) of 1.3 % having occurred since the 1960s, with the strongest declines in the tropics, northern mid-latitudes, and Southern Ocean. The simulated global decline in NPP reverses after the year 2100 (forced by the extended RCP CO2 concentration scenario), and NPP returns to pre-industrial rates by 2300. This recovery is dominated by increasing primary production in the Southern Ocean, mostly by calcifying phytoplankton. Large increases in calcifying phytoplankton in the Southern Ocean offset a decline in the low latitudes, producing a global net calcite export in 2300 that varies only slightly from pre-industrial rates. Diatoms migrate southward in our simulations, following the receding Antarctic ice front, but are out-competed by calcifiers across most of their pre-industrial Southern Ocean habitat. Global opal export production thus drops to 50 % of its pre-industrial value by 2300. Model nutrients phosphate, silicate, and nitrate build up along the Southern Ocean particle export pathway, but dissolved iron (for which ocean sources are held constant) increases in the upper ocean. This different behaviour of iron is attributed to a reduction of low-latitude NPP (and consequently, a reduction in both uptake and export and particle, including calcite, scavenging), an increase in seawater temperatures (raising the solubility of particle forms), and stratification that "traps" the iron near the surface. These results are meant to serve as a baseline for sensitivity assessments to be undertaken with this model in the future.

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