Predicting the Invasion Risk of Miconia calvescens in the Marquesas Islands (South Pacific): A Modeling Approach

2019 ◽  
Vol 73 (1) ◽  
pp. 17
Author(s):  
Mélanie Libeau ◽  
Jean-Yves Meyer ◽  
Ravahere Taputuarai ◽  
Robin Pouteau
Keyword(s):  
South Pacific ◽  
Invasion Risk ◽  
Marquesas Islands ◽  
Modeling Approach ◽  
Miconia Calvescens

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 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 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 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 Wildfire risk for main vegetation units in a biodiversity hotspot: modeling approach in New Caledonia, South Pacific

2014 ◽  
Vol 5 (2) ◽  
pp. 377-390 ◽  
Author(s):  
Céline Gomez ◽  
Morgan Mangeas ◽  
Thomas Curt ◽  
Thomas Ibanez ◽  
Jérôme Munzinger ◽  
...  
Keyword(s):  
New Caledonia ◽  
South Pacific ◽  
Biodiversity Hotspot ◽  
Wildfire Risk ◽  
Modeling Approach

XXIII.—The Expedition to the South Pacific of the S.Y. “St. George.” Marine Ecology and Coral Formations in the Panama Region, the Galapagos and Marquesas Islands, and the Atoll of Napuka

1927 ◽  
Vol 55 (2) ◽  
pp. 531-554 ◽  
Author(s):  
Cyril Crossland
Keyword(s):  
South Pacific ◽  
Marine Ecology ◽  
The Other ◽  
Eastern Pacific ◽  
The South ◽  
Marquesas Islands ◽  
Physical Conditions ◽  
Considerable Size

Two contrasted oceanographical regions are dealt with in this paper, the fauna of the eastern Pacific being distinct from that of the Marquesas, which are the farthest outliers of the western ocean. In each of these two regions again are two divisions of markedly different ecology, physical conditions in the Galapagos being as great a contrast as could well be to those of the coast of Panama, while the Marquesas Islands differ from their neighbours farther west, which are either atolls, or high islands surrounded by broad reefs, in being without coral deposits of any considerable size, and certainly no true reefs. The corals afford a striking example of the contrast between the two main regions; in Panama the only abundant coral is Pocillopora, in the Marquesas the only “reef” is of Porites, and the other deposits depend upon this genus for their existence. Several species of Pocillopora are abundant in the Marquesas, but are all distinct from those of Panama.

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.

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