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

scholarly journals Silicon cycle in the tropical South Pacific: contribution to the global Si cycle and evidence for an active pico-sized siliceous plankton

2018 ◽  
Vol 15 (18) ◽  
pp. 5595-5620 ◽  
Author(s):  
Karine Leblanc ◽  
Véronique Cornet ◽  
Peggy Rimmelin-Maury ◽  
Olivier Grosso ◽  
Sandra Hélias-Nunige ◽  
...  
Keyword(s):  
Community Structure ◽  
Chlorophyll A ◽  
Biogenic Silica ◽  
New Caledonia ◽  
Size Fraction ◽  
South Pacific ◽  
Size Class ◽  
Biogeochemical Cycle ◽  
Standing Stocks ◽  
Negligible Contribution

Abstract. This article presents data regarding the Si biogeochemical cycle during two oceanographic cruises conducted in the tropical South Pacific (BIOSOPE and OUTPACE cruises) in 2005 and 2015. It involves the first Si stock measurements in this understudied region, encompassing various oceanic systems from New Caledonia to the Chilean upwelling between 8 and 34∘ S. Some of the lowest levels of biogenic silica standing stocks ever measured were found in this area, notably in the southern Pacific gyre, where Chlorophyll a concentrations are the most depleted worldwide. Integrated biogenic silica stocks are as low as 1.08±0.95 mmol m−2 and are the lowest stocks measured in the South Pacific. Size-fractionated biogenic silica concentrations revealed a non-negligible contribution of the pico-sized fraction (<2–3 µm) to biogenic silica standing stocks, representing 26%±12% of total biogenic silica during the OUTPACE cruise and 11%±9% during the BIOSOPE cruise. These results indicate significant accumulation in this size class, which was undocumented for 2005, but has since then been related to Si uptake by Synechococcus cells. Si uptake measurements carried out during BIOSOPE confirmed biological Si uptake by this size fraction. We further present diatoms community structure associated with the stock measurements for a global overview of the Si cycle in the tropical South Pacific.

scholarly journals Trace elements in two odontocete species (Kogia breviceps and Globicephala macrorhynchus) stranded in New Caledonia (South Pacific)

2003 ◽  
Vol 124 (2) ◽  
pp. 263-271 ◽  
Author(s):  
P Bustamante ◽  
C Garrigue ◽  
L Breau ◽  
F Caurant ◽  
W Dabin ◽  
...  
Keyword(s):  
Trace Elements ◽  
New Caledonia ◽  
South Pacific ◽  
Kogia Breviceps

scholarly journals Preface: The Oligotrophy to the UlTra-oligotrophy PACific Experiment (OUTPACE cruise, 18 February to 3 April 2015)

2017 ◽  
Vol 14 (13) ◽  
pp. 3207-3220 ◽  
Author(s):  
Thierry Moutin ◽  
Andrea Michelangelo Doglioli ◽  
Alain de Verneil ◽  
Sophie Bonnet
Keyword(s):  
Biological Diversity ◽  
New Caledonia ◽  
Austral Summer ◽  
South Pacific ◽  
Adaptive Strategy ◽  
French Polynesia ◽  
Biogenic Elements ◽  
General Context ◽  
Western Boundary ◽  
South Pacific Ocean

Abstract. The overall goal of OUTPACE (Oligotrophy to UlTra-oligotrophy PACific Experiment) was to obtain a successful representation of the interactions between planktonic organisms and the cycle of biogenic elements in the western tropical South Pacific Ocean across trophic and N2 fixation gradients. Within the context of climate change, it is necessary to better quantify the ability of the oligotrophic ocean to sequester carbon through biological processes. OUTPACE was organized around three main objectives, which were (1) to perform a zonal characterization of the biogeochemistry and biological diversity of the western tropical South Pacific during austral summer conditions, (2) to study the production and fate of organic matter (including carbon export) in three contrasting trophic regimes (increasing oligotrophy) with a particular emphasis on the role of dinitrogen fixation, and (3) to obtain a representation of the main biogeochemical fluxes and dynamics of the planktonic trophic network. The international OUTPACE cruise took place between 18 February and 3 April 2015 aboard the RV L'Atalante and involved 60 scientists (30 onboard). The west–east transect covered  ∼  4000 km from the western part of the Melanesian archipelago (New Caledonia) to the western boundary of the South Pacific gyre (French Polynesia). Following an adaptive strategy, the transect initially designed along the 19° S parallel was adapted along-route to incorporate information coming from satellite measurements of sea surface temperature, chlorophyll a concentration, currents, and diazotroph quantification. After providing a general context and describing previous work done in this area, this introductory paper elucidates the objectives of OUTPACE, the implementation plan of the cruise and water mass and climatological characteristics and concludes with a general overview of the other papers that will be published in this special issue.

scholarly journals Remote sensing of <i>Trichodesmium</i> spp. mats in the western tropical South Pacific

2018 ◽  
Vol 15 (16) ◽  
pp. 5203-5219 ◽  
Author(s):  
Guillaume Rousset ◽  
Florian De Boissieu ◽  
Christophe E. Menkes ◽  
Jérôme Lefèvre ◽  
Robert Frouin ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Large Scale ◽  
New Caledonia ◽  
Hot Spot ◽  
Regional Scale ◽  
Atmospheric Correction ◽  
South Pacific ◽  
Aggregation Processes ◽  
Modis Imagery ◽  
Generate Surface

Abstract. Trichodesmium is the major nitrogen-fixing species in the western tropical South Pacific (WTSP) region, a hot spot of diazotrophy. Due to the paucity of in situ observations, remote-sensing methods for detecting Trichodesmium presence on a large scale have been investigated to assess the regional-to-global impact of this organism on primary production and carbon cycling. A number of algorithms have been developed to identify Trichodesmium surface blooms from space, but determining with confidence their accuracy has been difficult, chiefly because of the scarcity of sea-truth information at the time of satellite overpass. Here, we use a series of new cruises as well as airborne surveys over the WTSP to evaluate their ability to detect Trichodesmium surface blooms in the satellite imagery. The evaluation, performed on MODIS data at 250 m and 1 km resolution acquired over the region, shows limitations due to spatial resolution, clouds, and atmospheric correction. A new satellite-based algorithm is designed to alleviate some of these limitations, by exploiting optimally spectral features in the atmospherically corrected reflectance at 531, 645, 678, 748, and 869 nm. This algorithm outperforms former ones near clouds, limiting false positive detection and allowing regional-scale automation. Compared with observations, 80 % of the detected mats are within a 2 km range, demonstrating the good statistical skill of the new algorithm. Application to MODIS imagery acquired during the February-March 2015 OUTPACE campaign reveals the presence of surface blooms northwest and east of New Caledonia and near 20∘ S–172∘ W in qualitative agreement with measured nitrogen fixation rates. Improving Trichodesmium detection requires measuring ocean color at higher spectral and spatial (<250 m) resolution than MODIS, taking into account environment properties (e.g., wind, sea surface temperature), fluorescence, and spatial structure of filaments, and a better understanding of Trichodesmium dynamics, including aggregation processes to generate surface mats. Such sub-mesoscale aggregation processes for Trichodesmium are yet to be understood.

scholarly journals Genetic structure of the Coconut Rhinoceros Beetle (Oryctes rhinoceros) population and the incidence of its biocontrol agent (Oryctes rhinoceros nudivirus) in the South Pacific Islands

2020 ◽  
Author(s):  
Kayvan Etebari ◽  
James Hereward ◽  
Apenisa Sailo ◽  
Emeline M Ahoafi ◽  
Robert Tautua ◽  
...  
Keyword(s):  
Biocontrol Agent ◽  
New Caledonia ◽  
Solomon Islands ◽  
South Pacific ◽  
The Philippines ◽  
Mitochondrial Lineage ◽  
The South ◽  
Oryctes Rhinoceros ◽  
Rhinoceros Beetle ◽  
The Pacific

Incursions of the Coconut rhinoceros beetle (CRB), Oryctes rhinoceros, have been detected in several countries of the south-west Pacific in recent years, resulting in an expansion of the pest's geographic range. It has been suggested that this resurgence is related to an O. rhinoceros mitochondrial lineage (previously referred to as the CRB-G biotype) that is reported to show reduced susceptibility to the well-established classical biocontrol agent, Oryctes rhinoceros nudivirus (OrNV). We investigated O. rhinoceros population genetics and the OrNV status of adult specimens collected in the Philippines and seven different South Pacific island countries (Fiji, New Caledonia, Papua New Guinea (PNG), Samoa, Solomon Islands, Tonga, and Vanuatu). Based on the presence of single nucleotide polymorphisms (snps) in the mitochondrial Cytochrome C Oxidase subunit I (CoxI) gene, we found three major mitochondrial lineages (CRB-G, a PNG lineage (CRB-PNG) and the South Pacific lineage (CRB-S)) across the region. Haplotype diversity varied considerably between and within countries. The O. rhinoceros population in most countries was monotypic and all individuals tested belonged to a single mitochondrial lineage (Fiji, CRB-S; Tonga, CRB-S; Vanuatu, CRB-PNG; PNG (Kimbe), CRB-PNG; New Caledonia CRB-G; Philippines, CRB-G). However, in Samoa we detected CRB-S and CRB-PNG and in Solomon Islands we detected all three haplotype groups. Genotyping-by-Sequencing (GBS) methods were used to genotype 10,000 snps from 230 insects across the Pacific and showed genetic differentiation in the O. rhinoceros nuclear genome among different geographical populations. The GBS data also provided evidence for gene flow and admixture between different haplotypes in Solomon Islands. Therefore, contrary to earlier reports, CRB-G is not solely responsible for damage to the coconut palms reported since the pest was first recorded in Solomon Islands in 2015. We also PCR-screened a fragment of OrNV from 260 insects and detected an extremely high prevalence of viral infection in all three haplotypes in the region. We conclude that the haplotype groups CRB-G, CRB-S, and PNG, do not represent biotypes, subspecies, or cryptic species, but simply represent different invasions of O. rhinoceros across the Pacific. This has important implications for management, especially biological control, of Coconut rhinoceros beetle in the region.

scholarly journals Mesozooplankton structure and functioning in the western tropical South Pacific along the 20° parallel south during the OUTPACE survey (February–April 2015)

2018 ◽  
Author(s):  
François Carlotti ◽  
Marc Pagano ◽  
Loïc Guilloux ◽  
Katty Donoso ◽  
Valentina Valdés ◽  
...  
Keyword(s):  
Primary Production ◽  
New Caledonia ◽  
Size Structure ◽  
South Pacific ◽  
French Polynesia ◽  
Grazing Impact ◽  
Coral Sea ◽  
Carbon Demand ◽  
Excretion Rates ◽  
Density And Biomass

Abstract. This paper presents results on the spatial and temporal distribution patterns of mesozooplankton in the western tropical South Pacific along the 20 °S south visited during austral summer (February–April 2015). By contributing to the interdisciplinary OUTPACE (Oligotrophy to UlTra-oligotrophy PACific Experiment) project (Moutin et al., 2017), the specific aims of this study dedicated to mesozooplankton observations were (1) to document the responses of zooplankton in terms of species diversity, density and biomass along the transect, and (2) to characterize the trophic pathways from primary production to large mesozooplanktonic organisms. Along a West-East transect of 4000 km from New Caledonia to the French Polynesia, 15 short-duration stations (SD-1 to SD-15, 8 hours each) dedicated to a large-scale description, and three long-duration stations (LD-A to LD-C, 5days each), respectively positioned (1) in offshore northern waters of New Caledonia, (2) near Niue Island, and (3) in the subtropical Pacific gyre near the Cook Islands, were sampled with a Bongo Net with 120 μm mesh size net for quantifying mesozooplankton abundance, biomass, community taxonomy and size structure, and size fractionated content of δ15N. Subsequently, the contribution of Diazotroph Derived Nitrogen (DDN (%) to zooplankton δ15N (ZDDN) values at each station was calculated, as well as an estimation of zooplankton carbon demand and grazing impact and of zooplankton excretion rates. The mesozooplankton community showed a general decreasing trend in abundance and biomass from West to East, with a clear drop in the ultra-oligotrophic waters of the subtropical Pacific gyre (LD-C, SD-14 and SD-15). Higher abundance and biomass corresponded to higher primary production of more or less ephemeral blooms linked to complex mesoscale circulation in the Coral Sea and between the longitudes 170–180 °W. Copepods were the most abundant group (68 to 86 % of total abundance), slightly increasing in contribution from west to east while, in parallel, gelatinous plankton decreased (dominated by appendicularians) and other holoplankton. Detritus in the net tow samples represented 20–50 % of the biomass, the lowest and the highest values being obtained in the subtropical Pacific gyre and in the Coral Sea, respectively, linked to the local primary production and the biomass and growth rates of zooplanktonic populations. Taxonomic compositions showed a high degree of similarity across the whole region, however, with a moderate difference in subtropical Pacific gyre. Several copepod taxa, known to have trophic links with Trichodesmium, presented positive relationships with Trichodesmium abundance, such as the Harpacticoids Macrosetella, Microsetella and Miracia, and the Poecilostomatoids Corycaeus and Oncaea. At the LD stations, the populations initially responded to local spring blooms with a large production of larval forms, reflected in increasing abundances but with limited (station LD-A) or no (station LD-A) biomass changes. Diazotrophs contributed up to 67 and 75 % to zooplankton biomass in the western and central Melanesian Archipelago regions respectively, but strongly decreased to an average of 22 % in the subtropical Pacific gyre (GY) and down to 7 % occurring in the most eastern station (SD-15). Using allometric relationships, specific zooplankton ingestion rates were estimated between 0.55 and 0.64 d−1 with the highest mean value at the bloom station (LD-B) and the lowest in GY, whereas estimated weight specific excretion rates ranged between 0.1 and 0.15 d−1 for NH4 and between 0.09 and 9.12 d−1 for PO4. Daily grazing pressure on phytoplankton stocks and daily regeneration by zooplankton were as well estimated for the different regions showing contrasted impacts between MA and GY regions. For the 3 LD stations, it was not possible to find any relationship between the abundance and biomass in the water column and swimmers found in sediment traps. Diel vertical migration of zooplankton, which obviously occurs from observed differences in day and night samples, might strongly influence the community of swimmers in traps.

Two thousand parasites on a single ray: An infection with two species of skin monogeneans on a blotched fantail ray kept in an aquarium

2010 ◽  
Vol 55 (3) ◽  
Author(s):  
Jean-Lou Justine ◽  
Adeline Grugeaud ◽  
Florent Keller ◽  
Philippe Leblanc
Keyword(s):  
New Caledonia ◽  
Dorsal Surface ◽  
South Pacific ◽  
Ventral Surface ◽  
Heavy Infection ◽  
Public Aquarium

AbstractA blotched fantail ray, Taeniurops meyeni (Müller et Henle, 1841), was captured in New Caledonia, South Pacific, and kept in a tank for quarantine before exhibition at the Nouméa public aquarium. After 24 days, the ray exhibited a heavy infection with two species of skin monogeneans. A freshwater bath allowed the collection of 1,914 monogeneans, including 1,453 capsalids, Neoentobdella taiwanensis Whittington et Kearn, 2009, on the ventral surface, and 461 monocotylids, Dendromonocotyle pipinna Chisholm et Whittington, 2004, on the dorsal surface. More than 300 monogeneans were prepared on slides to allow precise measurements. Capsalids and monocotylids occupied about 6% and 0.2% of the total ventral and dorsal ray surfaces, respectively.

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