scholarly journals Volume distribution for particles between 3.5 to 2000 μm in the upper 200 m region of the South Pacific Gyre

2008 ◽  
Vol 5 (2) ◽  
pp. 299-310 ◽  
Author(s):  
L. Stemmann ◽  
D. Eloire ◽  
A. Sciandra ◽  
G. A. Jackson ◽  
L. Guidi ◽  
...  
Keyword(s):  
Weight Ratio ◽  
South Pacific ◽  
Dry Weight ◽  
Volume Distribution ◽  
The South ◽  
Size Spectra ◽  
Marquesas Islands ◽  
Large Particles ◽  
Living Organisms ◽  
South Pacific Gyre

Abstract. The French JGOFS BIOSOPE cruise crossed the South Pacific Gyre (SPG) on a transect between the Marquesas Islands and the Chilean coast on a 7500 km transect (8° S–34° S and 8° W–72° W). The number and volume distributions of small (3.5100 μm) were analysed combining two instruments, the HIAC/Royco Counter (for the small particles) and the Underwater Video Profiler (UVP, for the large particles). For the HIAC analysis, samples were collected from 12 L CTD Rosette bottles and immediately analysed on board while the UVP provided an estimate of in situ particle concentrations and size in a continuous profile. Out of 76 continuous UVP and 117 discrete HIAC vertical profiles, 25 had both sets of measurements, mostly at a site close to the Marquesas Islands (site MAR) and one in the center of the gyre (site GYR). At GYR, the particle number spectra from few μm to few mm were fit with power relationships having slopes close to −4. At MAR, the high abundance of large objects, probably living organisms, created a shift in the full size spectra of particles such that a single slope was not appropriate. The small particle pool at both sites showed a diel pattern while the large did not, implying that the movement of mass toward the large particles does not take place at daily scale in the SPG area. Despite the relatively simple nature of the number spectra, the volume spectra were more variable because what were small deviations from the straight line in a log-log plot were large variations in the volume estimates. In addition, the mass estimates from the size spectra are very sensitive to crucial parameters such as the fractal dimension and the POC/Dry Weight ratio. Using consistent values for these parameters, we show that the volume of large particles can equal the volume of the smaller particles. However the proportion of material in large particles decreased from the mesotrophic conditions at the border of the SPG to the ultra-oligotrophy of the center in the upper 200 m depth. We expect large particles to play a major role in the trophic interaction in the upper waters of the South Pacific Gyre.

scholarly journals Volume distribution for particles between 3.5 to 2000 μm in the upper 200 m region of the South Pacific Gyre

2007 ◽  
Vol 4 (5) ◽  
pp. 3377-3407 ◽  
Author(s):  
L. Stemmann ◽  
D. Eloire ◽  
A. Sciandra ◽  
G. A. Jackson ◽  
L. Guidi ◽  
...  
Keyword(s):  
South Pacific ◽  
Power Relationships ◽  
Volume Distribution ◽  
The South ◽  
Marquesas Islands ◽  
Large Particles ◽  
Living Organisms ◽  
A Site ◽  
South Pacific Gyre ◽  
Volume Estimates

Abstract. The French JGOFS BIOSOPE cruise crossed the South Pacific Gyre (SPG) on a transect between the Marquesas Islands and the Chilean coast on a 7500 km transect (8° S–34° S and 8° W–72° W). The number and volume distributions of small (3.5100 μm) were analysed combining two instruments, the HIAC/Royco Counter (for the small particles) and the Underwater Video Profiler (UVP, for the large particles). For the HIAC analysis, samples were collected from 12 L CTD Rosette bottles and immediately analysed on board while the UVP provided an estimate of in situ particle concentrations and size in a continuous profile. Out of 76 continuous UVP and 117 discrete HIAC vertical profiles, 25 had both sets of measurements, mostly at a site close to the Marquesas Islands (site MAR) and one in the center of the gyre (site GYR). At GYR, the particle number spectra from few μm to few mm were fit with power relationships having slopes close to −4. At MAR, the high abundance of large objects, probably living organisms, created a shift in the full size spectra of particles such as a single slope was not appropriate. The small particle pool at both sites showed a diel pattern while the large did not, implying that the movement of mass toward the large particles does not take place at daily scale in the SPG area. Despite the relatively simple nature of the number spectra, the volume spectra was more variable because what were small deviations from the straight line in a log-log plot were large variations in the volume estimates. Results showed that the volume of large particles can equal the volume of the smaller particles. However the proportion of material in large particles decreased from the mesotrophic conditions at the border of the SPG to the ultra-oligotrophy of the center in the upper 200 m depth. We expect large particles to play a major role in the trophic interaction in the upper waters of the South Pacific Gyre.

scholarly journals Carbon and nitrogen uptake in the South Pacific Ocean: evidence for efficient dinitrogen fixation and regenerated production leading to large accumulation of dissolved organic matter in nitrogen-depleted waters

2007 ◽  
Vol 4 (5) ◽  
pp. 3531-3579 ◽  
Author(s):  
P. Raimbault ◽  
N. Garcia
Keyword(s):  
Organic Matter ◽  
Nitrogen Uptake ◽  
Inorganic Nitrogen ◽  
South Pacific ◽  
Dinitrogen Fixation ◽  
The South ◽  
New Production ◽  
Marquesas Islands ◽  
South Pacific Ocean ◽  
South Pacific Gyre

Abstract. A major goal of the BIOSOPE cruise on the R/V Atalante to the South Pacific Ocean (conducted in October–November 2004) was to establish rate of productivity along a longitudinal section across the oligotrophic South Pacific Gyre (SPG), and compared these measurements with those obtained in nutrient–repleted waters from Chilean upwelling and around Marquesas Islands. A dual 13C/15N isotopic technique was used to estimate rates of carbon fixation, inorganic nitrogen uptake (including dinitrogen fixation), ammonium (NH4) and nitrate (NO3) regeneration, and dissolved organic nitrogen (DON) release resulting from both NH4 and NO3 uptake. The SPG had revealed the lowest rates of primary production (0.1 gC.m−2.d−1), while rates were 7 to 20 fold higher around the Marquesas Islands and in the Chilean upwelling, respectively. In this very low productive area, most of primary production was sustained by active regeneration processes which fuelled up to 95% of the biological nitrogen demand. Since nitrification was very active in the surface layer and often balanced the biological demand of nitrate, dinitrogen fixation, although acting at low daily rate (≈1–2 nmoles l−1d−1), sustained the main part of new production. Then, new production in the SPG (0.008±0.007 gC m−2.d−1) was two orders of magnitude lower than this measured in the upwelling where it essentially sustained by nitrate (0.69±0.49 gC.m−2.d−1). In the whole investigated region, the percentage of nitrogen release as DON represented a large part of the inorganic nitrogen uptake (13–15% in average), and reaching 26–41% in the SPG where the production of DON appeared to be a major part of the nitrogen cycle. Due to the lack of annual vertical mixing and very low lateral advection, the high release rates could explain the large accumulation of dissolved organic matter observed in the nitrogen-depleted and low productive waters of the South Pacific Gyre.

scholarly journals Evidence for efficient regenerated production and dinitrogen fixation in nitrogen-deficient waters of the South Pacific Ocean: impact on new and export production estimates

2008 ◽  
Vol 5 (2) ◽  
pp. 323-338 ◽  
Author(s):  
P. Raimbault ◽  
N. Garcia
Keyword(s):  
Pacific Ocean ◽  
Nitrogen Uptake ◽  
N2 Fixation ◽  
Inorganic Nitrogen ◽  
South Pacific ◽  
Dinitrogen Fixation ◽  
The South ◽  
New Production ◽  
Marquesas Islands ◽  
South Pacific Ocean

Abstract. One of the major objectives of the BIOSOPE cruise, carried out on the R/V Atalante from October-November 2004 in the South Pacific Ocean, was to establish productivity rates along a zonal section traversing the oligotrophic South Pacific Gyre (SPG). These results were then compared to measurements obtained from the nutrient – replete waters in the Chilean upwelling and around the Marquesas Islands. A dual 13C/15N isotope technique was used to estimate the carbon fixation rates, inorganic nitrogen uptake (including dinitrogen fixation), ammonium (NH4) and nitrate (NO3) regeneration and release of dissolved organic nitrogen (DON). The SPG exhibited the lowest primary production rates (0.15 g C m−2 d−1), while rates were 7 to 20 times higher around the Marquesas Islands and in the Chilean upwelling, respectively. In the very low productive area of the SPG, most of the primary production was sustained by active regeneration processes that fuelled up to 95% of the biological nitrogen demand. Nitrification was active in the surface layer and often balanced the biological demand for nitrate, especially in the SPG. The percentage of nitrogen released as DON represented a large proportion of the inorganic nitrogen uptake (13–15% in average), reaching 26–41% in the SPG, where DON production played a major role in nitrogen cycling. Dinitrogen fixation was detectable over the whole study area; even in the Chilean upwelling, where rates as high as 3 nmoles l−1 d−1 were measured. In these nutrient-replete waters new production was very high (0.69±0.49 g C m−2 d−1) and essentially sustained by nitrate levels. In the SPG, dinitrogen fixation, although occurring at much lower daily rates (≈1–2 nmoles l−1 d−1), sustained up to 100% of the new production (0.008±0.007 g C m−2 d−1) which was two orders of magnitude lower than that measured in the upwelling. The annual N2-fixation of the South Pacific is estimated to 21×1012g, of which 1.34×1012g is for the SPG only. Even if our "snapshot" estimates of N2-fixation rates were lower than that expected from a recent ocean circulation model, these data confirm that the N-deficiency South Pacific Ocean would provide an ideal ecological niche for the proliferation of N2-fixers which are not yet identified.

scholarly journals Modern and Pleistocene Reservoir Ages Inferred from South Pacific Corals

Radiocarbon ◽  
2009 ◽  
Vol 51 (1) ◽  
pp. 319-335 ◽  
Author(s):  
G S Burr ◽  
J W Beck ◽  
Thierry Corrège ◽  
G Cabioch ◽  
F W Taylor ◽  
...  
Keyword(s):  
Papua New Guinea ◽  
South Pacific ◽  
New Guinea ◽  
Easter Island ◽  
The South ◽  
Marquesas Islands ◽  
Surface Ocean ◽  
Reservoir Age ◽  
Age Determinations

This paper presents radiocarbon results from modern South Pacific corals from the Marquesas Islands, Vanuatu, Papua New Guinea (PNG), and Easter Island. All of the measurements are from pre-bomb Porites corals that lived during the 1940s and 1950s. The data reflect subannual to multiannual surface ocean 14C variability and allow for precise, unambiguous reservoir age determinations. The results are compared with published values from other coral records throughout the South Pacific, with striking consistency. By comparisons with other published values, we identify 3 South Pacific regions with uniform pre-bomb reservoir ages (1945 to 1955). These are 1) the Central Equatorial South Pacific (361.6 − 8.2 14C yr, 2 σ); 2) the Western Equatorial South Pacific (322.1 − 8.6 14C yr, 2 σ); and 3) the subtropical Pacific (266.8 − 13.8 14C yr, 2 σ).

scholarly journals Microbial community composition and nitrogen availability influence DOC remineralization in the South Pacific Gyre

2015 ◽  
Vol 177 ◽  
pp. 325-334 ◽  
Author(s):  
Robert T. Letscher ◽  
Angela N. Knapp ◽  
Anna K. James ◽  
Craig A. Carlson ◽  
Alyson E. Santoro ◽  
...  
Keyword(s):  
Microbial Community ◽  
Community Composition ◽  
Nitrogen Availability ◽  
Microbial Community Composition ◽  
South Pacific ◽  
The South ◽  
South Pacific Gyre

scholarly journals Dust, volcanic ash, and the evolution of the South Pacific Gyre through the Cenozoic

2015 ◽  
Vol 30 (8) ◽  
pp. 1078-1099 ◽  
Author(s):  
Ann G. Dunlea ◽  
Richard W. Murray ◽  
Justine Sauvage ◽  
Arthur J. Spivack ◽  
Robert N. Harris ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
South Pacific ◽  
The South ◽  
South Pacific Gyre

scholarly journals Heterotrophic bacterial production in the South East Pacific: longitudinal trends and coupling with primary production

2007 ◽  
Vol 4 (4) ◽  
pp. 2761-2791 ◽  
Author(s):  
F. Van Wambeke ◽  
I. Obernosterer ◽  
T. Moutin ◽  
S. Duhamel ◽  
O. Ulloa ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Primary Production ◽  
Bacterial Production ◽  
South Pacific ◽  
Leucine Incorporation ◽  
The South ◽  
Phytoplankton Primary Production ◽  
East Pacific ◽  
Wide Range ◽  
South Pacific Gyre

Abstract. Spatial variations of heterotrophic bacterial production and phytoplankton primary production were investigated across South East Pacific Ocean (–141° W, –8° S to –72° W, –35° S) in November–December 2004. Bacterial production (³H leucine incorporation) integrated over the euphotic zone encompassed a wide range of values, from 43 mg C m−2 d−1 in the hyper-oligotrophic South Pacific Gyre to 392 mg C m−2 d−1 in the upwelling off Chile. Within the gyre (120° W, 22° S) records of low phytoplankton biomass (7 mg TChla m−2) were obtained and in situ 14C based particulate primary production rates were as low as 153 mg C m−2 d−1, thus equal to the value considered as a limit for primary production under strong oligotrophic conditions. In the South Pacific gyre average rates of ³H leucine incorporation rates, and leucine incorporation rates per cell (5–21 pmol L−1 h−1 and 15–56×10−21 mol cell−1 h−1, respectively), were in the same range as those reported for other oligotrophic sub tropical and temperate waters. Rates of dark community respiration, determined at selected stations across the transect varied in a narrow range (42–97 mmol O2 m−2 d−1), except for one station in the upwelling off Chile (245 mmol O2 m−2 d−1). Bacterial growth efficiencies varied between 5 and 38% and bacterial carbon demand largely exceeded 14C particulate primary production across the South Pacific Ocean. Net community production also revealed negative values in the South Pacific Gyre (–13±20 to –37±40 mmol O2 m−2 d−1). Such imbalances being impossible in this area far from any external input, we discuss the techniques involved for determining the coupling between primary production and bacterial heterotrophic production.

Hyperiid amphipods in the eastern part of the South Pacific gyre

1991 ◽  
Vol 109 (2) ◽  
pp. 259-265 ◽  
Author(s):  
G. M. Vinogradov
Keyword(s):  
South Pacific ◽  
The South ◽  
South Pacific Gyre

scholarly journals IODP Expedition 329: Life and Habitability Beneath the Seafloor of the South Pacific Gyre

2013 ◽  
Vol 15 ◽  
pp. 4-10 ◽  
Author(s):  
S. D'Hondt ◽  
F. Inagaki ◽  
C. Alvarez Zarikian ◽  
Keyword(s):  
Solid Phase ◽  
South Pacific ◽  
Fluid Replacement ◽  
The South ◽  
Ocean Drilling Program ◽  
Sediment Column ◽  
Ocean Drilling ◽  
Integrated Ocean Drilling Program ◽  
Cell Counts ◽  
South Pacific Gyre

Integrated Ocean Drilling Program (IODP) Expedition 329 made major strides toward fulfilling its objectives. Shipboard studies documented (1) fundamental aspects of habitability and life in this very low activity subseafloor sedimentary ecosystem and (2) first-order patterns of habitability within the igneous basement. A broad range of postexpedition studies will complete the expedition objectives. Throughout the South Pacific Gyre (SPG; Sites U1365–U1370), dissolved oxygen and nitrate are present throughout the entire sediment sequence, and sedimentary microbial cell counts are lower than at all previously drilled IODP/ Ocean Drilling Program (ODP)/Deep Sea Drilling Program (DSDP) sites. In contrast, at Site U1371 in the upwelling zone just south of the gyre, detectable oxygen and nitrate are limited to the top and bottom of the sediment column, manganese reduction is a prominent electron-accepting process, and cell concentrations are higher than at the same depths in the SPG sites throughout the sediment column. Geographic variation in subseafloor profiles of dissolved and solid-phase chemicals are consistent with the magnitude of organic-fueled subseafloor respiration declining from outside the gyre to the gyre center. <br><br> Chemical profiles in the sedimentary pore water and secondary mineral distributions in the basaltic basement indicate that basement alteration continues on the timescale of formation fluid replacement, even at the sites with the oldest basement (84–120 Ma at Sites U1365 and U1366). <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.15.01.2013" target="_blank">10.2204/iodp.sd.15.01.2013</a>

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