Primary productivity induced by iron and nitrogen in the Tasman Sea: an overview of the PINTS expedition

2014 ◽  
Vol 65 (6) ◽  
pp. 517 ◽  
Author(s):  
C. S. Hassler ◽  
K. R. Ridgway ◽  
A. R. Bowie ◽  
E. C. V. Butler ◽  
L. A. Clementson ◽  
...  
Keyword(s):  
Phytoplankton Community ◽  
Carbon Fixation ◽  
Light Limitation ◽  
Atmospheric Nitrogen ◽  
The North ◽  
Tasman Sea ◽  
Limiting Nutrient ◽  
Particulate Nutrients ◽  
Atmospheric Nitrogen Fixation

The Tasman Sea and the adjacent subantarctic zone (SAZ) are economically important regions, where the parameters controlling the phytoplankton community composition and carbon fixation are not yet fully resolved. Contrasting nutrient distributions, as well as phytoplankton biomass, biodiversity and productivity were observed between the North Tasman Sea and the SAZ. In situ photosynthetic efficiency (FV/FM), dissolved and particulate nutrients, iron biological uptake, and nitrogen and carbon fixation were used to determine the factor-limiting phytoplankton growth and productivity in the North Tasman Sea and the SAZ. Highly productive cyanobacteria dominated the North Tasman Sea. High atmospheric nitrogen fixation and low nitrate dissolved concentrations indicated that non-diazotroph phytoplankton are nitrogen limited. Deck-board incubations also suggested that, at depth, iron could limit eukaryotes, but not cyanobacteria in that region. In the SAZ, the phytoplankton community was dominated by a bloom of haptophytes. The low productivity in the SAZ was mainly explained by light limitation, but nitrogen, silicic acid as well as iron were all depleted to the extent that they could become co-limiting. This study illustrates the challenge associated with identification of the limiting nutrient, as it varied between phytoplankton groups, depths and sites.

scholarly journals Observing and modelling phytoplankton community structure in the North Sea

2017 ◽  
Vol 14 (6) ◽  
pp. 1419-1444 ◽  
Author(s):  
David A. Ford ◽  
Johan van der Molen ◽  
Kieran Hyder ◽  
John Bacon ◽  
Rosa Barciela ◽  
...  
Keyword(s):  
Community Structure ◽  
North Sea ◽  
Phytoplankton Community ◽  
Marine Biodiversity ◽  
Phytoplankton Community Structure ◽  
Pigment Analysis ◽  
The North ◽  
The North Sea ◽  
In Situ Observations

Abstract. Phytoplankton form the base of the marine food chain, and knowledge of phytoplankton community structure is fundamental when assessing marine biodiversity. Policy makers and other users require information on marine biodiversity and other aspects of the marine environment for the North Sea, a highly productive European shelf sea. This information must come from a combination of observations and models, but currently the coastal ocean is greatly under-sampled for phytoplankton data, and outputs of phytoplankton community structure from models are therefore not yet frequently validated. This study presents a novel set of in situ observations of phytoplankton community structure for the North Sea using accessory pigment analysis. The observations allow a good understanding of the patterns of surface phytoplankton biomass and community structure in the North Sea for the observed months of August 2010 and 2011. Two physical–biogeochemical ocean models, the biogeochemical components of which are different variants of the widely used European Regional Seas Ecosystem Model (ERSEM), were then validated against these and other observations. Both models were a good match for sea surface temperature observations, and a reasonable match for remotely sensed ocean colour observations. However, the two models displayed very different phytoplankton community structures, with one better matching the in situ observations than the other. Nonetheless, both models shared some similarities with the observations in terms of spatial features and inter-annual variability. An initial comparison of the formulations and parameterizations of the two models suggests that diversity between the parameter settings of model phytoplankton functional types, along with formulations which promote a greater sensitivity to changes in light and nutrients, is key to capturing the observed phytoplankton community structure. These findings will help inform future model development, which should be coupled with detailed validation studies, in order to help facilitate the wider application of marine biogeochemical modelling to user and policy needs.

scholarly journals High-resolution analysis of a North Sea phytoplankton community structure based on in situ flow cytometry observations and potential implication for remote sensing

2015 ◽  
Vol 12 (13) ◽  
pp. 4051-4066 ◽  
Author(s):  
M. Thyssen ◽  
S. Alvain ◽  
A. Lefèbvre ◽  
D. Dessailly ◽  
M. Rijkeboer ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Community Structure ◽  
North Sea ◽  
High Frequency ◽  
Phytoplankton Community ◽  
Phytoplankton Community Structure ◽  
The North ◽  
The North Sea ◽  
Daily Scale

Abstract. Phytoplankton observation in the ocean can be a challenge in oceanography. Accurate estimations of its biomass and dynamics will help to understand ocean ecosystems and refine global climate models. Relevant data sets of phytoplankton defined at a functional level and on a sub-meso- and daily scale are thus required. In order to achieve this, an automated, high-frequency, dedicated scanning flow cytometer (SFC, Cytobuoy b.v., the Netherlands) has been developed to cover the entire size range of phytoplankton cells whilst simultaneously taking pictures of the largest of them. This cytometer was directly connected to the water inlet of a PocketFerryBox during a cruise in the North Sea, 08–12 May 2011 (DYMAPHY project, INTERREG IV A "2 Seas"), in order to identify the phytoplankton community structure of near surface waters (6 m) with a high spatial resolution basis (2.2 ± 1.8 km). Ten groups of cells, distinguished on the basis of their optical pulse shapes, were described (abundance, size estimate, red fluorescence per unit volume). Abundances varied depending on the hydrological status of the traversed waters, reflecting different stages of the North Sea blooming period. Comparisons between several techniques analysing chlorophyll a and the scanning flow cytometer, using the integrated red fluorescence emitted by each counted cell, showed significant correlations. For the first time, the community structure observed from the automated flow cytometry data set was compared with PHYSAT reflectance anomalies over a daily scale. The number of matchups observed between the SFC automated high-frequency in situ sampling and remote sensing was found to be more than 2 times better than when using traditional water sampling strategies. Significant differences in the phytoplankton community structure within the 2 days for which matchups were available suggest that it is possible to label PHYSAT anomalies using automated flow cytometry to resolve not only dominant groups but also community structure.

Protein Synthesis by Lake Plankton Measured Using in situ Carbon Dioxide and Sulfate Assimilation

1987 ◽  
Vol 44 (12) ◽  
pp. 2102-2117 ◽  
Author(s):  
Russell L. Cuhel ◽  
David R. S. Lean
Keyword(s):  
Carbon Dioxide ◽  
Protein Synthesis ◽  
Carbon Fixation ◽  
Total Carbon ◽  
Light Limitation ◽  
Sulfate Assimilation ◽  
Sulfate Uptake ◽  
Chl A ◽  
Total Sulfate

Sequential 4- to 6-h in situ measurements of carbon dioxide and sulfate uptake showed midday deepening of the depth of Pmax and photoinhibition of upper water column samples. Analysis of subcellular fractions accentuated total uptake measurements, with net protein synthesis providing a direct measure of growth. The percentage of carbon assimilated into protein was smallest at the depth of maximum photosynthesis and increased with light limitation. Summed incubations agreed well with all-day deployments for total carbon fixation and protein synthesis. Assimilation numbers were consistently low (<2.5 g C∙g Chl a−1∙h-1 with integrated (0–20 m) areal production of 616–1467 mg C∙m−2 and 7.5–32.4 mg S∙m−2 during the light day. Nonreductive sulfate assimilation (predominantly ester-SO4−) accounted for up to 40% of the total sulfate uptake when diatoms predominated. Protein synthesis measured with 35S (200–1000 mg protein∙m−2 during the light day) increased 57–89% overnight. Hourly rates were similar during light and scotophase incubations. Night metabolism substantially altered the biochemical composition (e.g. protein, lipid, and carbohydrate) of the plankton with respect to newly incorporated carbon. Combined plant-specific H14CO3− and general microbial 3SSO42− techniques suggested algal dominance in the mixed layer.

scholarly journals Coupling physics and biogeochemistry thanks to high resolution observations of the phytoplankton community structure in the North-Western Mediterranean Sea

2017 ◽  
Author(s):  
Pierre Marrec ◽  
Andrea M. Doglioli ◽  
Gérald Grégori ◽  
Mathilde Dugenne ◽  
Alice Della Penna ◽  
...  
Keyword(s):  
High Resolution ◽  
Surface Waters ◽  
Phytoplankton Community ◽  
Western Mediterranean ◽  
Fine Scale ◽  
Phytoplankton Community Structure ◽  
The North ◽  
Cold Core ◽  
North Western

Abstract. Fine-scale physical structures and ocean dynamics strongly influence and regulate biogeochemical and ecological processes. These processes are particularly challenging to describe and understand because of their ephemeral nature. The OSCAHR (Observing Submesoscale Coupling At High Resolution) campaign has been conducted in fall 2015 in which, a fine-scale structure in the North Western Mediterranean Ligurian subbasin was pre-identified using both satellite and numerical modeling data. Along the ship track, various variables were measured at the surface (temperature, salinity, chlorophyll-a and nutrients concentrations) with ADCP current velocity. We also deployed a new model of CytoSense automated flow cytometer (AFCM) optimized for small and dim cells, for near real-time characterization of surface phytoplankton community structure of surface waters with a spatial resolution of few km and a hourly temporal resolution. For the first time with this type of AFCM we were able to resolve Prochlorococcus and Synechococcus picocyanobacteria. The vertical physical dynamics and biogeochemical properties of the studied area were investigated by continuous high resolution CTD profiles thanks to a moving vessel profiler (MVP) during the vessel underway associated to a 1-m vertical resolution pumping system deployed during fixed stations. The observed fine-scale feature presented a cyclonic structure with a relatively cold core surrounded by warmer waters. Surface waters were totally depleted in nitrate and phosphate. In addition to the doming of the isopycnals by the cyclonic circulation, an intense wind event induced Ekman pumping. The upwelled subsurface cold nutrient-rich water fertilized surface waters, characterized by an increase in Chl-a concentration. Prochlorococcus, pico- and nano-eukaryotes were more abundant in cold core waters while Synechococcus dominated in warm boundary waters. Nanoeukaryote were the main contributors (> 50 %) in terms of pigment content (FLR) and biomass. Biological observations based on the mean cell's red fluorescence recorded by AFCM combined with physical properties of surface waters suggest a distinct origin for two warm boundary waters. Finally, the application of a matrix growth population model based on high-frequency AFCM measurements in warm boundary surface waters provides estimates of in-situ growth rate and apparent net primary production for Prochlorococcus (μ = 0.21 d−1, NPP = 0.11 mgC m−3 d−1) and Synechococcus (μ = 0.72 d−1, NPP = 2.68 mgC m−3 d−1), which corroborate their opposite surface distribution pattern. The innovative adaptive strategy applied during OSCAHR with a combination of several multidisciplinary and complementary approaches involving high-resolution in-situ observations and sampling, remote-sensing and model simulations provided a deeper understanding of the marine biogeochemical dynamics through the first trophic levels.

In situ plasma-assisted atmospheric nitrogen fixation using water and spray-type jet plasma

2018 ◽  
Vol 54 (23) ◽  
pp. 2886-2889 ◽  
Author(s):  
Peng Peng ◽  
Paul Chen ◽  
Min Addy ◽  
Yanling Cheng ◽  
Yaning Zhang ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Atmospheric Nitrogen ◽  
The Novel ◽  
Jet Plasma ◽  
Atmospheric Nitrogen Fixation

An in situ nitrogen fixation process is introduced, using the novel spray-type jet plasma, to co-synthesize nitrate, nitrite, and ammonium.

scholarly journals Phytoplankton community structure in the North Sea: coupling between remote sensing and automated in situ analysis at the single cell level

2014 ◽  
Vol 11 (11) ◽  
pp. 15621-15662
Author(s):  
M. Thyssen ◽  
S. Alvain ◽  
A. Lefèbvre ◽  
D. Dessailly ◽  
M. Rijkeboer ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Community Structure ◽  
North Sea ◽  
High Frequency ◽  
Phytoplankton Community ◽  
Flow Cytometer ◽  
Phytoplankton Community Structure ◽  
The North ◽  
The North Sea

Abstract. Phytoplankton observation in the ocean can be a challenge in oceanography. Accurate estimations of their biomass and dynamics will help to understand ocean ecosystems and refine global climate models. This requires relevant datasets of phytoplankton at a functional level and on a daily and sub meso scale. In order to achieve this, an automated, high frequency, dedicated scanning flow cytometer (SFC, Cytobuoy, NL), has been developed to cover the entire size range of phytoplankton cells whilst simultaneously taking pictures of the largest of them. This cytometer was directly connected to the water inlet of a~pocket Ferry Box during a cruise in the North Sea, 8–12 May 2011 (DYMAPHY project, INTERREG IV A "2 Seas"), in order to identify the phytoplankton community structure of near surface waters (6 m) with a high resolution spacial basis (2.2 ± 1.8 km). Ten groups of cells, distinguished on the basis of their optical pulse shapes, were described (abundance, size estimate, red fluorescence per unit volume). Abundances varied depending on the hydrological status of the traversed waters, reflecting different stages of the North Sea blooming period. Comparisons between several techniques analyzing chlorophyll a and the scanning flow cytometer, using the integrated red fluorescence emitted by each counted cell, showed significant correlations. The community structure observed from the automated flow cytometry was compared with the PHYSAT reflectance anomalies over a daily scale. The number of matchups observed between the SFC automated high frequency in situ sampling and the remote sensing was found to be two to three times better than when using traditional water sampling strategies. Significant differences in the phytoplankton community structure within the two days for which matchups were available, suggest that it is possible to label PHYSAT anomalies not only with dominant groups, but at the level of the community structure.

scholarly journals Observing and modelling phytoplankton community structure in the North Sea: can ERSEM-type models simulate biodiversity?

2016 ◽  
Author(s):  
David A. Ford ◽  
Johan van der Molen ◽  
Kieran Hyder ◽  
John Bacon ◽  
Rosa Barciela ◽  
...  
Keyword(s):  
Community Structure ◽  
North Sea ◽  
Phytoplankton Community ◽  
Marine Biodiversity ◽  
Phytoplankton Community Structure ◽  
Pigment Analysis ◽  
The North ◽  
The North Sea ◽  
In Situ Observations

Abstract. Phytoplankton form the base of the marine food chain, and knowledge of phytoplankton community structure is fundamental when assessing marine biodiversity. Policy makers and other users require information on marine biodiversity and other aspects of the marine environment for the North Sea, a highly productive European shelf sea. This information must come from a combination of observations and models, but currently the coastal ocean is greatly under-sampled for phytoplankton data, and outputs of phytoplankton community structure from models have therefore yet to be properly validated. This study presents a novel set of in situ observations of phytoplankton community structure for the North Sea using accessory pigment analysis. The observations allow a good understanding of the patterns of surface phytoplankton biomass and community structure in the North Sea for the observed months of August 2010 and 2011. Two physical-biogeochemical ocean models, the biogeochemical components of which are different variants of the widely-used European Regional Seas Ecosystem Model (ERSEM), were then validated against these and other observations. Both models were a good match for sea surface temperature observations, and a reasonable match for remotely sensed ocean colour observations. However, the two models displayed very different phytoplankton community structures, with one better matching the in situ observations than the other. Nonetheless, both models shared some similarities with the observations in terms of spatial features and inter-annual variability. A comparison of the formulations and parameterisations of the two models suggests that diversity between the parameter settings of model phytoplankton functional types, along with formulations which promote a greater sensitivity to changes in light and nutrients, is key to capturing the observed biodiversity. These findings will help inform future model development, which should be coupled with detailed validation studies, in order to help facilitate the wider application of marine biogeochemical modelling to user and policy needs.

scholarly journals Correction: In situ plasma-assisted atmospheric nitrogen fixation using water and spray-type jet plasma

2018 ◽  
Vol 54 (89) ◽  
pp. 12658-12658
Author(s):  
Peng Peng ◽  
Paul Chen ◽  
Min Addy ◽  
Yanling Cheng ◽  
Yaning Zhang ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Atmospheric Nitrogen ◽  
Jet Plasma ◽  
Atmospheric Nitrogen Fixation

Correction for ‘In situ plasma-assisted atmospheric nitrogen fixation using water and spray-type jet plasma’ by Peng Peng et al., Chem. Commun., 2018, 54, 2886–2889.

Carbon fixation by the phytoplankton community across Lake Winnipeg

2021 ◽  
Author(s):  
Yekaterina Yezhova ◽  
David Capelle ◽  
Michael Stainton ◽  
Tim Papakyriakou
Keyword(s):  
Phytoplankton Community ◽  
Carbon Fixation ◽  
Lake Winnipeg

New determinations of tides on the north-western Ross Ice Shelf

2020 ◽  
pp. 1-14
Author(s):  
Richard D. Ray ◽  
Kristine M. Larson ◽  
Bruce J. Haines
Keyword(s):  
Time Series ◽  
Tide Gauge ◽  
High Rate ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
The North ◽  
Global Positioning ◽  
North Western

Abstract New determinations of ocean tides are extracted from high-rate Global Positioning System (GPS) solutions at nine stations sitting on the Ross Ice Shelf. Five are multi-year time series. Three older time series are only 2–3 weeks long. These are not ideal, but they are still useful because they provide the only in situ tide observations in that sector of the ice shelf. The long tide-gauge observations from Scott Base and Cape Roberts are also reanalysed. They allow determination of some previously neglected tidal phenomena in this region, such as third-degree tides, and they provide context for analysis of the shorter datasets. The semidiurnal tides are small at all sites, yet M2 undergoes a clear seasonal cycle, which was first noted by Sir George Darwin while studying measurements from the Discovery expedition. Darwin saw a much larger modulation than we observe, and we consider possible explanations - instrumental or climatic - for this difference.

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