Vanuatu Research Articles

Improving resolution and accuracy of mean sea surface from kinematic GPS, Vanuatu subduction zone

Satellite altimetry provides an ocean mean sea surface (MSS) map with global coverage and overall excellent precision. However, in some areas, like the Vanuatu archipelago, the coverage and resolution of this tool are not sufficient to correctly map the short scale undulations of the sea surface, due to numerous islands and to strong lithospheric and mantle heterogeneities. New applications such as seafloor geodesy may require local mean surface representation with improved resolution in specific areas. We used sea surface height collected with kinematic GPS during three different cruises in 2004, 2006 and 2007 to reconstruct a homogeneous sea surface map around Santo Island, Vanuatu. We assess the accuracy of this GPS-derived local sea surface to 6–19 cm and evaluate the quality of existing altimetry and gravity-derived MSSs on the Vanuatu archipelago. Observed short scale undulations are interpreted as due to local geodynamics.

Island area and species diversity in the southwest Pacific Ocean: is the lizard fauna of Vanuatu depauperate?

One island group suggested to be an exception to the species–area Relationship is the Vanuatu Archipelago, a group of 13 large and 80 small islands in the southwest Pacific Ocean. To test the hypothesis that the lizard fauna of the Vanuatu Archipelago does not meet the predictions of the species‐area relationship, and thus is depauperate, we compare diversity among several island groups in the southwest Pacific: Fiji, the Loyalty Islands, New Caledonia, Samoa, the Solomon Islands, Tonga, and Vanuatu. We found that the lizard diversity of Vanuatu meets the pattern of diversity predicted by the species‐area relationship. The Solomon Islands, the largest and least isolated oceanic archipelago considered, has the greatest species diversity and endemism of the oceanic islands. Inclusion or exclusion of island groups based on factors such as geologic history or faunal source affects the strength of the relationship between diversity, area, and history of emergence, and influences perceptions of diversity within individual archipelagos. In addition to island size, factors such evolutionary time scale, speciation, and archipelago complexity influence species richness on islands.

Preliminary results on epidemiology of Coconut Lethal Yellowing in Ghana

Epidemiological studies are of major importance in understanding the determinants of plant diseases in order to control the risks of their spreading. A research programme on the epidemiology of coconut lethal yellowing, or Cape Saint Paul Wilt Disease (CSPWD), in Ghana was launched in March 2007. The objective was to characterize the distribution and spread of the disease in space and time at various scales, and their relation with the environment. This article presents the general strategy used to evaluate the incidence of CSPWD along with the environmental, ecological and agronomical variables at regional level. A survey was undertaken on 1,166 plots of Coconut Sector Development Project (CSDP) planted with Malayan Yellow Dwarf (MYD) × Vanuatu Tall (VTT) hybrids in Western Region and Central Region. Preliminary results on the distribution of CSPWD and outside variables at regional scale, along with their relations, are given.

Arieta Gonelevu Bright Lights, Little Islands

Arieta Gonelevu's latest challenge is to light up the only school on the South Pacific island of Tongariki using solar power. It won't be easy. Tongariki, which is home to about 500 people in five villages, doesn't have roads or airports. Even cargo boats don't stop at this island in the Vanuatu archipelago, about 1800 kilometers off the coast of Australia.

A New Genus and New Species of Ethusidae (Decapoda, Brachyura) from Vanuatu, Western Pacific

[A new genus and new species of ethusid crab is described from Vanuatu. The new genus is superficially similar to Parethusa in its smooth carapace and long second and third pereopods, but is unique in its bifurcated G2 and the absence of an interantennular septum. Eine neue Gattung und eine neue Art ethusider Krabben wird von Vanuatu hier beschrieben. Die neue Gattung ahnelt Parethusa auf den ersten Blick wegen ihres glatten Carapaxes und der langen zweiten und dritten Pereiopoden, unterscheidet sich aber durch einen gegabelten zweiten Gnathopoden und das Fehlen eines interantennularen Septums., A new genus and new species of ethusid crab is described from Vanuatu. The new genus is superficially similar to Parethusa in its smooth carapace and long second and third pereopods, but is unique in its bifurcated G2 and the absence of an interantennular septum. Eine neue Gattung und eine neue Art ethusider Krabben wird von Vanuatu hier beschrieben. Die neue Gattung ahnelt Parethusa auf den ersten Blick wegen ihres glatten Carapaxes und der langen zweiten und dritten Pereiopoden, unterscheidet sich aber durch einen gegabelten zweiten Gnathopoden und das Fehlen eines interantennularen Septums.]

A Political History of Nagriamel on Santo, Vanuatu

ABSTRACT This article relates the political history of the Nagriamel movement on Santo, Vanuatu, and tries to account for its traditionalist excesses by reference to biographical aspects of its charismatic leader Jimmy Stevens. Stevens was the main architect in the unification of the ‘dak bus pipol’ (communities living in the island's remote interior) under a form of custom (kastom) he himself partially devised. This review of the life of this unusual character, who started as a ‘boy’ serving his colonial masters and became an ‘island king’, a self‐proclaimed ‘Prince’ of ‘Santo Custom’, and of the way he exploited the nativist assertions of his indigenous supporters, will also provide an opportunity to take a fresh look at the troubled period surrounding Independence in the Republic of Vanuatu.

Evolution of cassava (Manihot esculentaCrantz) after recent introduction into a South Pacific Island system: the contribution of sex to the diversification of a clonally propagated crop

Cassava (Manihot esculenta Crantz) is a clonally propagated crop that was introduced into the South Pacific archipelago of Vanuatu in the 1850s. Based on a survey conducted in 10 different villages throughout the archipelago, we present here a study of its diversity. Farmers' knowledge about cultivation cycle and sexual reproduction of cassava was recorded during group interviews in each village. Using a set of 11 SSR markers, we genotyped the 104 landraces collected and 60 supplementary accessions from a within-landrace study (12 landraces x 5 plants). Out of the 104 landraces collected, we discovered 77 different multilocus genotypes and the within-landrace study identified several polyclonal landraces. Our data suggest a number of hypotheses about the dynamics of diversity of cassava in Vanuatu.

A new genus and species of hermit crab of the family Paguridae (Crustacea: Anomura: Paguroidea) from the Vanuatu Archipelago

During a survey of the biodiversity of the southeastern part of Espiritu Santo, Vanuatu Archipelago, specimens of a tiny but distinctive new hermit crab species, referable to a new genus, were discovered in the shallow waters off the island. Herein, Pumilopagurus tuberculomanus new genus, new species, is described and illustrated. The genus is characterized by the development of a massive right cheliped, more than 0.7 total body length; male with a short left sexual tube directed from left to right across the ventral body surface and very short right sexual tube; and female with single left gonopore. Its relationship to other pagurid genera of comparable small body size is discussed.

Fruit development, not GPP, drives seasonal variation in NPP in a tropical palm plantation

We monitored seasonal variations in net primary production (NPP), estimated by allometric equations from organ dimensions, gross primary production (GPP), estimated by the eddy covariance method, autotrophic respiration (R(a)), estimated by a model, and fruit production in a coconut (Cocos nucifera L.) plantation located in the sub-tropical South Pacific archipelago of Vanuatu. Net primary production of the vegetative compartments of the trees accumulated steadily throughout the year. Fruits accounted for 46% of tree NPP and showed large seasonal variations. On an annual basis, the sum of estimated NPP (16.1 Mg C ha(-1) year(-1)) and R(a) (24.0 Mg C ha(-1) year(-1)) for the ecosystem (coconut trees and herbaceous understory) closely matched GPP (39.0 Mg C ha(-1) year(-1)), suggesting adequate cross-validation of annual C budget methods. However, seasonal variations in NPP + R(a) were smaller than the seasonal variations in GPP, and maximum tree NPP occurred 6 months after the midsummer peak in GPP and solar radiation. We propose that this discrepancy reflects seasonal variation in the allocation of dry mass to carbon reserves and new plant tissue, thus affecting the allometric relationships used for estimating NPP.

Bifurcation of the Subtropical South Equatorial Current against New Caledonia in December 2004 from a Hydrographic Inverse Box Model*

Abstract The South Equatorial Current (SEC), the westward branch of the South Pacific subtropical gyre, extends from the equator to 30°S at depth. Linear ocean dynamics predict that the SEC forms boundary currents on the eastern coasts of the South Pacific islands it encounters. Those currents would then detach at the northern and southern tips of the islands, and cross the Coral Sea in the form of jets. The Fiji Islands, the Vanuatu archipelago, and New Caledonia are the major topographic obstacles on the SEC pathway to the Australian coast. Large-scale numerical studies, as well as climatologies, suggest the formation of three jets in their lee: the north Vanuatu jet (NVJ), the north Caledonian jet (NCJ), and the south Caledonian jet (SCJ), implying a bifurcation against the east coast of each island. The flow observed during the SECALIS-2 cruise in December 2004 between Vanuatu and New Caledonia is presented herein. An inverse box model is used to provide quantitative transport estimates with uncertainties and to infer the pathways and boundary current formation. For that particular month, the 0–2000-m SEC inflow was found to be 20 ± 4 Sv (1 Sv ≡ 106 m3 s−1) between Vanuatu and New Caledonia. Of that, 6 ± 2 Sv bifurcated to the south in a boundary current against the New Caledonia coast (the Vauban Current), and the remainder exited north of New Caledonia, feeding the NCJ. The flow is comparable both above and below the thermocline, while complex topography, associated with oceanic eddy generation, introduces several recirculation features. To the north, the NCJ, which extends down to 1500 m, was fed not only by the SEC inflow, but also by waters coming from the north, which have possibly been recirculated. To the south, a westward current rounds the tip of New Caledonia. A numerical simulation suggests a partial continuity with the deep extension of the Vauban Current (this current would then be the SCJ) while the hydrographic sections are too distant to confirm such continuity.

Clutch Size in the Tropical Scincid Lizard Emoia sanfordi, a Species Endemic to the Vanuatu Archipelago

The majority of species in the scincid genus Emoia (Squamata: Scincidae) have a fixed clutch size of two eggs per clutch and produce between two and four clutches per year. One lineage within Emoia, the Emoia samoensis species group, consists of 13 species occurring in Melanesia and the islands of the southwestern Pacific Ocean, and exhibits variation in clutch size, with previously reported clutch sizes of two to five eggs. Little is known about reproduction in several members of this lineage including Emoia sanfordi, a large-bodied lizard endemic to the archipelago of Vanuatu in the South Pacific. We analyzed reproduction and clutch size in E. sanfordi females and discovered that there is a substantial amount of intraspecific variation, with clutch size ranging from two to seven eggs, with a modal clutch size of five eggs. Females were reproductively active throughout the study period of June through October and appear to be laying multiple clutches. The variation in clutch size seen in E. sanfordi is congruent with the variation previously reported within other closely related species.

Cavascope: The Broadband Seismological Network of the New Hebrides Subduction Zone and Its Associated Data Base

Beginning in 1993, a seismological broadband network (named the Cavascope network) was set up in New Caledonia and Vanuatu in the Southwest Pacific, within a collaborative framework of researchers from the Institut de Recherche pour le Developpement, Noumea, New Caledonia (IRD); Ecole et Observatoire des Sciences de la Terre, Strasbourg, France (EOST); and the Department of Geology, Mines and Water Resources of Vanuatu (DGMWR). This seismological network, located in a particularly fast converging area, i.e. , the New Hebrides subduction zone, and surrounded by numerous other very active seismic zones (Papua New Guinea, Salomon Islands, Fiji, Tonga-Kermadec, and New Zealand) is of great interest to the scientific community. In this article, we give a short overview of the tectonic setting of the region and past seismological surveys, and then we present the instrumental characteristics of the Cavascope network and its associated database. The active margin of New Hebrides is associated with the subduction of the Australian plate under the North Fiji Basin. This extends 1,500 km from the Santa Cruz archipelago in the north up to 23 degrees south, including the entire Vanuatu archipelago (figure 1). This seismic zone is dipping with an angle of 60–70° down to a depth of 300 km. The plate convergence axis trends ENE, perpendicular to the trench, and the convergence rate reaches 12 cm/year in the south and 16 cm/year in the north, with a minimum of 4 cm/year observed near the central part of the margin (Pelletier et al. 1998; Calmant et al. 2003). These high convergence rates produce a high level of seismicity that each year yields more than 10 earthquakes of moment magnitude (Mw) higher or equal to 6.0. Despite the area's high seismic potential and volcanic hazards (Louat and Baldassari 1989; Eissen et al. 1991; Robin and …

Comparative bioaccumulation of trace elements between Nautilus pompilius and Nautilus macromphalus (Cephalopoda: Nautiloidea) from Vanuatu and New Caledonia

The concentrations of 16 trace elements were investigated and compared for the first time in the digestive and excreting tissues of two Nautilus species (Cephalopoda: Nautiloidea) from two geologically contrasted areas: (1) N. macromphalus from New Caledonia, a region characterized by its richness in nickel ores and its lack of tectonic activities and (2) N. pompilius from the Vanuatu archipelago showing high volcanic and tectonic activities. In both Nautilus species, results clearly highlighted that the digestive gland played a key role in the bioaccumulation and storage of Ag, Cd, Ce, Co, Cu, Fe, La, Nd, V, and Zn whereas As, Cr, Mn, Ni, Pb, and Se were accumulated in a greater extent in the excreting tissues (i.e. pericardial and renal appendages). Despite contrasting environments, no significant difference ( p<0.05) was found between the two Nautilus species in the concentrations of most of the essential and non-essential elements, including Ni and associated metals in Ni ores (i.e. Co and Mn). As nautilus lives on the outer shelf of barrier reefs, these results strongly support the hypothesis that the New Caledonian lagoon traps the major amount of the trace elements derived from natural erosion and the intense mining activities conducted on land. In contrast, the concentrations of the rare earth elements (Ce, La, and Nd) were significantly higher in N. pompilius than in N. macromphalus, probably as a result of the local enrichment of Vanuatu waters by specific environmental processes, such as volcanism or upwelling.

Malaria transmission pattern resilience to climatic variability is mediated by insecticide-treated nets

BackgroundMalaria is an important public-health problem in the archipelago of Vanuatu and climate has been hypothesized as important influence on transmission risk. Beginning in 1988, a major intervention using insecticide-treated bed nets (ITNs) was implemented in the country in an attempt to reduce Plasmodium transmission. To date, no study has addressed the impact of ITN intervention in Vanuatu, how it may have modified the burden of disease, and whether there were any changes in malaria incidence that might be related to climatic drivers.Methods and findingsMonthly time series (January 1983 through December 1999) of confirmed Plasmodium falciparum and Plasmodium vivax infections in the archipelago were analysed. During this 17 year period, malaria dynamics underwent a major regime shift around May 1991, following the introduction of bed nets as a control strategy in the country. By February of 1994 disease incidence from both parasites was reduced by at least 50%, when at most 20% of the population at risk was covered by ITNs. Seasonal cycles, as expected, were strongly correlated with temperature patterns, while inter-annual cycles were associated with changes in precipitation. Following the bed net intervention, the influence of environmental drivers of malaria dynamics was reduced by 30–80% for climatic forces, and 33–54% for other factors. A time lag of about five months was observed for the qualitative change ("regime shift") between the two parasites, the change occurring first for P. falciparum. The latter might be explained by interspecific interactions between the two parasites within the human hosts and their distinct biology, since P. vivax can relapse after a primary infection.ConclusionThe Vanuatu ITN programme represents an excellent example of implementing an infectious disease control programme. The distribution was undertaken to cover a large, local proportion (~80%) of people in villages where malaria was present. The successful coverage was possible because of the strategy for distribution of ITNs by prioritizing the free distribution to groups with restricted means for their acquisition, making the access to this resource equitable across the population. These results emphasize the need to implement infectious disease control programmes focusing on the most vulnerable populations.

Validating upper‐wind models using infrasound from active volcanoes

Known and quasipermanent infrasonic sources are needed to evaluate and improve upper‐wind models. Infrasounds generated by active volcanoes offer a unique opportunity for atmospheric studies. The Yasur volcano in the Vanuatu archipelago is an outstanding source of infrasonic waves due to its regular activity. This volcano is permanently monitored by the IS22 infrasound station located in New Caledonia and by one microbarometer installed close to its crater. A five‐year monitoring period of Yasur at short and large propagation range provides new insights on quantitative relationships between infrasonic observables and atmospheric specifications. This experimental setting is proposed to validate consistently the Naval Research Laboratory Ground to Space (NRL‐G2S) semi‐empirical atmospheric model up to the stratosphere. The propagation modeling results accurately explain seasonal changes as well as small short‐timescale variations of the infrasonic observables. This study demonstrates that the use of appropr...

Fragmenting Land and the Laws that Govern It

In 1980 the Constitution of the newly independent Republic of Vanuatu returned all land to the custom owners and their descendants and declared that “[t]he rules of custom shall form the basis of ownership and use of land” (Articles 73 and 74). What the Constitution did not state was what these rules were or should be, leaving it to Parliament to implement a national land law. As a result of Parliamentary inaction there is a plurality of rules of custom which govern customary land tenure, varying from place to place and island to island in a country of over eighty islands. Traditionally these rules are unwritten, but increasingly they are being recorded, in the reports of courts and tribunals, in published research and in the policy documents of councils of chiefs. These are processes which in themselves are re-shaping the rules of custom but also providing a partial codification of customary practices. However, these are not the only rules which regulate land transactions. Introduced laws and post-independence national legislation are also important and exist alongside customary law. Different interests over the same land may therefore be regulated by different legal frameworks. Moreover the boundaries between these are shifting as land is used and developed in different ways to meet changing social and economic demands and pressures, both internal and external. There is therefore a pluralism of legal sources; a pluralism of values and concepts; and a pluralism of interests which in combination present substantial challenges for the articulation of a national land policy or the development a national land law.

Multiyear validation of the NRL‐G2S wind fields using infrasound from Yasur

The Yasur volcano in the Vanuatu archipelago is an outstanding source of infrasonic waves due to its regular activity. This volcano is permanently monitored by the IS22 infrasound station located in New Caledonia, about 400 km from it, and by one microbarometer installed close to its crater. A multiyear monitoring of Yasur is proposed to validate consistently the Naval Research Laboratory Ground to Space (NRL‐G2S) semiempirical atmospheric model up to the stratosphere. The results of propagation modeling accurately explain seasonal changes as well as small short‐timescale variations of the infrasonic observables. The azimuthal deviation is predicted with an uncertainty in general lower than 0.5°. The fluctuations of the trace velocity and the celerity are simulated with errors as large as 5 m/s. This study demonstrates that the use of appropriate propagation tools along with the NRL‐G2S specifications provides accurate enough results for most of the long‐range observations for the purpose of operational infrasound monitoring.

What a state we're in

On my way into work this morning, I was reading a copy of the Metro. British people, it said, are ranked a lowly 108th happiest people in the world. The happiest people, according to a Happy Planet index compiled by New Economics Foundation, live in the Pacific archipelago of Vanuatu.

Identification of natural sunken wood samples

Sunken woods are abundant in deep oceanic environments, housing a huge faunal diversity. Studies on that substrate firstly focused on the associated organisms, but since a few years, identification of wood is a further aim. The purpose is to appreciate its degradation state, diversity, geographical origin and to identify specific associations between colonizing organisms and substrates. The first determinations were made on sunken woods from Taiwan/Philippines, the Vanuatu Archipelago, and the Mediterranean Sea. Samples’ identification was based on histological studies. Different preparation techniques were used, depending on their degradation state. Detailed anatomy descriptions were made and compared to the native flora and the introduced species. Wood samples were well preserved. Diversified species were encountered, seemingly originating from local floras. In situ settlements of known wood species will enhance the knowledge of degradation and colonization degrees.

What are the origins of the Antarctic Intermediate Waters transported by the North Caledonian Jet?

The trajectories of several Argo floats are studied to investigate the mid‐depth circulation in the southwest Pacific that coincides with the spreading of the Antarctic Intermediate Waters (AAIW). Before entering the Coral Sea, the floats converge and join the North Caledonian Jet (NCJ) south of 15°S. These observations suggest that the waters transported by this jet do not have a unique source. Hydrologic parameters and oxygen concentration confirm that the characteristics of the AAIW in the NCJ result from a convergence and a mixing of waters from the northern limb of the subtropical gyre and from the south‐eastern New Caledonian region. The northern contribution is associated with the water masses transported by the North Vanuatu jet that re‐circulate in the region between the D'Entrecasteaux reefs and the Vanuatu archipelago. It is shown that such complex dynamical features could be reproduced by numerical models when their horizontal resolution is sufficiently high.