Iron depletion in the deep chlorophyll maximum: mesoscale eddies as natural iron fertilization experiments

2021 ◽  
Author(s):  
Nicholas J. Hawco ◽  
Benedetto Barone ◽  
Matthew J Church ◽  
Lydia Babcock-Adams ◽  
Daniel J Repeta ◽  
...  
Keyword(s):  
Mesoscale Eddies ◽  
Deep Chlorophyll Maximum ◽  
Iron Depletion ◽  
Chlorophyll Maximum ◽  
Iron Fertilization ◽  
Natural Iron ◽  
Fertilization Experiments

scholarly journals Iron depletion in the deep chlorophyll maximum: Mesoscale eddies as natural iron fertilization experiments

2021 ◽  
Author(s):  
Nicholas J. Hawco ◽  
Benedetto Barone ◽  
Matthew J. Church ◽  
Lydia Babcock‐Adams ◽  
Daniel J. Repeta ◽  
...  
Keyword(s):  
Mesoscale Eddies ◽  
Deep Chlorophyll Maximum ◽  
Iron Depletion ◽  
Chlorophyll Maximum ◽  
Iron Fertilization ◽  
Natural Iron ◽  
Fertilization Experiments

scholarly journals Pigments, elemental composition (C, N, P, Si) and stoichiometry of particulate matter, in the naturally iron fertilized region of Kerguelen in the Southern Ocean

2014 ◽  
Vol 11 (6) ◽  
pp. 8259-8324 ◽  
Author(s):  
M. Lasbleiz ◽  
K. Leblanc ◽  
S. Blain ◽  
J. Ras ◽  
V. Cornet-Barthaux ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Community Structure ◽  
Elemental Composition ◽  
Phytoplankton Community ◽  
Reference Station ◽  
Phytoplankton Community Structure ◽  
Iron Fertilization ◽  
Phytoplankton Communities ◽  
Natural Iron ◽  
Fertilization Experiments

Abstract. The particulate matter distribution and phytoplankton community structure of the iron-fertilized Kerguelen region were investigated in early austral spring (October–November 2011) during the KEOPS2 cruise. The iron-fertilized region was characterized by a complex mesoscale circulation resulting in a patchy distribution of particulate matter. Integrated concentrations over 200 m ranged from 72.2 to 317.7 mg m−2 for chlorophyll a, 314 to 744 mmol m−2 for biogenic silica (BSi), 1106 to 2268 mmol m−2 for particulate organic carbon, 215 to 436 mmol m−2 for particulate organic nitrogen, and 29.3 to 39.0 mmol m−2 for particulate organic phosphorus. Three distinct high biomass areas were identified: the coastal waters of Kerguelen Islands, the easternmost part of the study area in the Polar Front Zone, and the southeastern Kerguelen Plateau. As expected from previous artificial and natural iron-fertilization experiments, the iron-fertilized areas were characterized by the development of large diatoms revealed by BSi size–fractionation and HPLC pigment signatures, whereas the iron-limited reference area was associated to a low biomass dominated by a mixed (nanoflagellates and diatoms) phytoplankton assemblage. A major difference from previous artificial iron fertilization studies was the observation of much higher Si : C, Si : N, and Si : P ratios (respectively 0.31 ± 0.16, 1.6 ± 0.7 and 20.5 ± 7.9) in the iron-fertilized areas compared to the iron-limited reference station (respectively 0.13, 1.1, 5.8). A second difference is the patchy response of the elemental composition of phytoplankton communities to large scale natural iron fertilization. Comparison to the previous KEOPS1 cruise also allowed to address the seasonal dynamics of phytoplankton bloom over the southeastern plateau. From POC, PON, and BSi evolutions, we showed that the elemental composition of the particulate matter also varies at the seasonal scale. This temporal evolution followed changes of the phytoplankton community structure as well as major changes in the nutrient stocks progressively leading to silicic acid exhaustion at the end of the productive season. Our observations suggest that the specific response of phytoplankton communities under natural iron fertilization is much more diverse than what has been regularly observed in artificial iron fertilization experiments and that the elemental composition of the bulk particulate matter reflects phytoplankton taxonomic structure rather than being a direct consequence of iron availability.

scholarly journals Pigments, elemental composition (C, N, P, and Si), and stoichiometry of particulate matter in the naturally iron fertilized region of Kerguelen in the Southern Ocean

2014 ◽  
Vol 11 (20) ◽  
pp. 5931-5955 ◽  
Author(s):  
M. Lasbleiz ◽  
K. Leblanc ◽  
S. Blain ◽  
J. Ras ◽  
V. Cornet-Barthaux ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Community Structure ◽  
Elemental Composition ◽  
Organic Nitrogen ◽  
Phytoplankton Community ◽  
Phytoplankton Community Structure ◽  
Iron Fertilization ◽  
Phytoplankton Communities ◽  
Natural Iron ◽  
Fertilization Experiments

Abstract. The particulate matter distribution and phytoplankton community structure of the iron-fertilized Kerguelen region were investigated in early austral spring (October–November 2011) during the KEOPS2 cruise. The iron-fertilized region was characterized by a complex mesoscale circulation resulting in a patchy distribution of particulate matter. Integrated concentrations over 200 m ranged from 72.2 to 317.7 mg m−2 for chlorophyll a 314 to 744 mmol m−2 for biogenic silica (BSi), 1106 to 2268 mmol m−2 for particulate organic carbon, 215 to 436 mmol m−2 for particulate organic nitrogen, and 29.3 to 39.0 mmol m−2 for particulate organic phosphorus. Three distinct high biomass areas were identified: the coastal waters of Kerguelen Islands, the easternmost part of the study area in the polar front zone, and the southeastern Kerguelen Plateau. As expected from previous artificial and natural iron-fertilization experiments, the iron-fertilized areas were characterized by the development of large diatoms revealed by BSi size–fractionation and high performance liquid chromatography (HPLC) pigment signatures, whereas the iron-limited reference area was associated with a low biomass dominated by a mixed (nanoflagellates and diatoms) phytoplankton assemblage. A major difference from most previous artificial iron fertilization studies was the observation of much higher Si : C, Si : N, and Si : P ratios (0.31 ± 0.16, 1.6 ± 0.7 and 20.5 ± 7.9, respectively) in the iron-fertilized areas compared to the iron-limited reference station (0.13, 1.1, and 5.8, respectively). A second difference is the patchy response of the elemental composition of phytoplankton communities to large scale natural iron fertilization. Comparison to the previous KEOPS1 cruise also allowed to address the seasonal dynamics of phytoplankton bloom over the southeastern plateau. From particulate organic carbon (POC), particulate organic nitrogen (PON), and BSi evolutions, we showed that the elemental composition of the particulate matter also varies at the seasonal scale. This temporal evolution followed changes of the phytoplankton community structure as well as major changes in the nutrient stocks progressively leading to silicic acid exhaustion at the end of the productive season. Our observations suggest that the specific response of phytoplankton communities under natural iron fertilization is much more diverse than what has been regularly observed in artificial iron fertilization experiments and that the elemental composition of the bulk particulate matter reflects phytoplankton taxonomic structure rather than being a direct consequence of iron availability.

Deep chlorophyll maximum (DCM) in the Red Sea

2021 ◽  
Vol 14 (3) ◽  
Author(s):  
Mohideen Wafar ◽  
Mohammad Ali Qurban ◽  
Zahid Nazeer ◽  
Karuppusamy Manikandan
Keyword(s):  
Red Sea ◽  
Deep Chlorophyll Maximum ◽  
Chlorophyll Maximum

The Deep Chlorophyll Maximum: Comparing Vertical Profiles of Chlorophyll a

1982 ◽  
Vol 39 (5) ◽  
pp. 791-803 ◽  
Author(s):  
John J. Cullen
Keyword(s):  
Chlorophyll A ◽  
Phytoplankton Biomass ◽  
Physiological Adaptation ◽  
Organic Carbon Content ◽  
Deep Chlorophyll Maximum ◽  
Vertical Profiles ◽  
In Vivo Fluorescence ◽  
Chlorophyll Maximum ◽  
Vertical Distributions

The relationship between chlorophyll a and phytoplankton biomass (organic carbon content) is highly variable as is the yield of in vivo fluorescence per unit chlorophyll. Thus, vertical profiles of chlorophyll or in vivo fluorescence must be interpreted with caution if their ecological significance is to be established. Although the variability of carbon-to-chlorophyll ratios and fluorescence yield is large, much of it can be anticipated, corrected for, and usefully interpreted. Vertical profiles from different regions of the sea are presented; each has a deep chlorophyll maximum, but the probable mechanisms of their formation and maintenance differ widely. Most vertical distributions of chlorophyll can be explained by the interaction between hydrography and growth, behavior, or physiological adaptation of phytoplankton with no special consideration of grazing by herbivores, even though vertical distributions of epizooplankton are not uniform. The interaction between vertical profiles of zooplankton and chlorophyll will be better understood when the relationships between chlorophyll and phytoplankton biomass in those profiles is determined.Key words: chlorophyll a, fluorescence, phytoplankton, vertical structure

The contribution of the deep chlorophyll maximum to primary production in a seasonally stratified shelf sea, the North Sea

2013 ◽  
Vol 113 (1-3) ◽  
pp. 153-166 ◽  
Author(s):  
Liam Fernand ◽  
Keith Weston ◽  
Tom Morris ◽  
Naomi Greenwood ◽  
Juan Brown ◽  
...  
Keyword(s):  
Primary Production ◽  
North Sea ◽  
Deep Chlorophyll Maximum ◽  
Chlorophyll Maximum ◽  
The North ◽  
Shelf Sea ◽  
The North Sea

Prochlorococcuscontributes to new production in the Sargasso Sea deep chlorophyll maximum

2007 ◽  
Vol 34 (10) ◽  
Author(s):  
John R. Casey ◽  
Michael W. Lomas ◽  
Joanna Mandecki ◽  
Donald E. Walker
Keyword(s):  
Sargasso Sea ◽  
Deep Chlorophyll Maximum ◽  
New Production ◽  
Chlorophyll Maximum
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