Island French Polynesia Research Articles

Marine Flora of French Polynesia: An Updated List Using DNA Barcoding and Traditional Approaches.

Located in the heart of the South Pacific Ocean, the French Polynesian islands represent a remarkable setting for biological colonization and diversification, because of their isolation. Our knowledge of this region's biodiversity is nevertheless still incomplete for many groups of organisms. In the late 1990s and 2000s, a series of publications provided the first checklists of French Polynesian marine algae, including the Chlorophyta, Rhodophyta, Ochrophyta, and Cyanobacteria, established mostly on traditional morphology-based taxonomy. We initiated a project to systematically DNA barcode the marine flora of French Polynesia. Based on a large collection of ~2452 specimens, made between 2014 and 2023, across the five French Polynesian archipelagos, we re-assessed the marine floral species diversity (Alismatales, Cyanobacteria, Rhodophyta, Ochrophyta, Chlorophyta) using DNA barcoding in concert with morphology-based classification. We provide here a major revision of French Polynesian marine flora, with an updated listing of 702 species including 119 Chlorophyta, 169 Cyanobacteria, 92 Ochrophyta, 320 Rhodophyta, and 2 seagrass species-nearly a two-fold increase from previous estimates. This study significantly improves our knowledge of French Polynesian marine diversity and provides a valuable DNA barcode reference library for identification purposes and future taxonomic and conservation studies. A significant part of the diversity uncovered from French Polynesia corresponds to unidentified lineages, which will require careful future taxonomic investigation.

Introduced rat assemblage affects feral cat threat to biodiversity in French Polynesian islands

Context Invasive feral cats strongly threaten native fauna on islands worldwide. The impact of feral cat populations is assumed to be higher in the presence of introduced rodents and may also vary according to an island’s rodent species assemblage. Aims This study assessed feral cat impacts on island biodiversity in French Polynesian islands harbouring differing assemblages of rat species, by investigating their abundance and trophic ecology. Methods We focused on the following six human-inhabited islands of three archipelagos in French Polynesia (South Pacific) with differing rat species assemblages: Tahiti and Moorea, Ua Huka and Tahuata, Rurutu and Rimatara. We studied (1) cat abundance, by setting up camera traps during 15 consecutive days to provide an abundance index, the general index (GI) or mean number of virtual captures per camera per occasion, and (2) cat diet, by performing macroscopic analyses of scat samples to determine the frequency of occurrence (FO) of prey categories. Key results Our study showed previously unreported patterns of cat-abundance index for the Society archipelago, with a GI of 0.30 ± 0.12 in Tahiti and 0.02 ± 0.02 in Moorea; for the Marquesas, with a GI of 0.75 ± 0.20 in Ua Huka and 0.20 ± 0.06 in Tahuata; and for the Austral, with a GI of 0.06 ± 0.04 in Rurutu and 0.19 ± 0.05 in Rimatara. Feral cats are shown to prey strongly on introduced rodents (FO = 91.3%), arthropods (37.8%), squamates (18.6%) and birds (13.3%) in our study sites. FO of birds are particularly high in Rimatara (31.9%) and Ua Huka (16.8%). Conclusions We demonstrated that feral cats represent a serious threat to biodiversity in French Polynesian islands, with 15 species preyed on, including eight endemic birds, four of them being considered threatened by the IUCN Red List. Surprisingly, relative abundances of feral cats were higher both on islands harbouring only one rat species (Ua Huka, with only Rattus exulans) and on islands free of black rats. This finding raises questions regarding the ‘hyperpredation’ hypothesis for multi-invaded island ecosystems. Implications This study on islands with differing assemblages of introduced rodents demonstrated the need for invasive predator studies in multi-invaded ecosystems, so as to improve bird conservation and guide management strategies and site prioritisation.

Considering waning immunity to better explain dengue dynamics

Life-long serotype-specific immunity following dengue virus infection may not always occur, but the true extent of this effect is unknown. Analysis of more than 20 years of monotypic epidemics in the isolated French Polynesian islands revealed that whilst the risk of symptomatic dengue infection did conform to the classical paradigms of homotypic immunity and increased disease risk in heterotypic secondary infections, incorporation of waning immunity improved the ability of epidemiological models to capture the observed epidemic dynamics. Not only does this show how inclusion of waning immunity into classical models can reveal important facets of the immune response to natural dengue virus infection, it also has significant ramifications for vaccine development and implementation in dengue endemic areas.

Coral conglomerate platforms as foundations for low-lying, reef islands in the French Polynesia (central south Pacific): New insights into the timing and mode of formation

In French Polynesia, low-lying, reef islands, composed of unconsolidated skeletal material rest on cemented conglomerate platforms. These are regarded as mainly generated by storm activity during the mid-late Holocene. Field observations and coral sampling were carried out on conglomerates from three atolls located in the north-western Tuamotu, namely, Takapoto, Takaroa and Fakarava. There, fifty-seven samples were dated using the uranium‑thorium (U/Th) method. The lateral age distribution of clasts indicates that conglomerate platforms have accreted from lagoon sides seawards.In addition to U/Th dating, the coral clast-age datasets include eighteen calibrated radiocarbon ages from Takopoto and other Tuamotu atolls – Takapoto, Mataiva, Rangiroa, Arutua, Apataki, Marokau, Hao, Pukarua, Nukutavake. As a matter of comparison, another seventy-seven, previously published radiometric conglomerate ages from various French Polynesian islands (Society, Tuamotu, Gambier) were incorporated in the present study. It appears that the formation of conglomerate platforms has taken place principally during a 2000-year interval, between 3000 and 1000 yr BP when sea level dropped from about +0.60 m to its present position. Before and after these periods, lower amounts of coral detritus have been provided to conglomerates, possibly due to clast deposition in adjacent lagoons and to trapping into reef rim-islands respectively.Age discrepancies of most coral clasts collected from multiple stacked layers at Takapoto and Fakarava do not exceed 500 years, strongly suggesting limited clast reworking before final stabilization. The superimposition of two to four firmly cemented conglomeratic layers at the same place gives evidence that marine cementation has operated shortly after clast deposition. This event is regarded as having taken place within both phreatic and vadose environments. Rubble sheets found seawards at some atoll-rim sites are interpreted to be conglomerates in the making, emplaced over the last centuries.Dating of atoll-islet material indicates clearly that, over the 2500–1000 yr-BP span, the building of conglomerates and overlying islets has interplayed. The former have evolved within subtidal to supratidal zones while the latter have been accreted subaerially. This may explain the firmly consolidated state of platforms and the unconsolidated state of islets. Due to their firmness, conglomerate platforms are assumed to be key structures for the maintenance of atoll islands subjected to sea level rise and increasing storminess in the coming centuries.

Xylocopa sonorina Smith, 1874 from Vancouver, British Columbia, Canada (Hymenoptera: Apidae, Xylocopinae) with comments on its taxonomy.

BackgroundOnly one species of large carpenter bee, Xylocopa virginica (Linnaeus, 1771), has been recorded from Canada, albeit restricted to southern Ontario and Quebec. However, a single female specimen identified by Hurd in 1954 as X. varipuncta Patton, 1879 from British Columbia is in the C.A. Triplehorn Insect Collection at The Ohio State University (OSUC), suggesting that this species was accidentally introduced into coastal western Canada. As wood-nesters, many large carpenter bees are likely capable of expanding their range great distances by natural and unnatural transport methods while nesting inside suitable substrates, the presumed mode of transport into western Canada, and likely elsewhere. The ease at which the nests are transported has likely contributed to the nomenclatural and distributional ambiguity surrounding this species due to morphological similarities of specimens from North America, Hawaii, and several South Pacific islands.New informationBy comparing DNA barcodes of specimens from the western United States to specimens from Hawaii, we confirm the early opinion of P.H. Timberlake (Timberlake 1922) that specimens long established on the Hawaiian Islands are the same X. varipuncta from continental North America. Furthermore, these DNA barcode sequences also match those of specimens identified as X. sonorina Smith, 1874 from the French Polynesian and Samoan Islands, thus fully supporting the opinion of Groom et al. (2017) that all are likely conspecific. As X. sonorina, a species described from and likely introduced to Hawaii is the oldest name available, X. varipuncta is here placed into synonymy. Additional research will be needed to trace the timing and pathway of introduction and establishment of X. sonorina; it is presumed that the species is native to the southwestern United States but has been established in Hawaii since the mid-1800s. It is also established in French Polynesia, the Samoan Islands, and likely other south Pacific islands, with additional records of occurrence from Java, New Zealand, and now Canada.

Strong genetic isolation of the black-lipped pearl oyster (Pinctada margaritifera) in the Marquesas archipelago (French Polynesia)

The French Polynesian islands are internationally known for their black pearls, produced by culture of the black lipped pearl oyster Pinctada margaritifera. The ongoing development of hatcheries for P. margaritifera in French Polynesia poses new challenges for the industry, particularly regarding the maintenance of genetic diversity in the hatchery stocks. This emphasizes the necessity to characterize the genetic diversity and differentiation within natural and exploited populations, to carefully select putative parental populations. The present study aimed at validating the phylogenetic status and investigating genetic attributes of populations from the only two non-exploited archipelagos of French Polynesia, the Marquesas archipelago, and the Australes archipelago, never analysed before. We found that individuals from both archipelagos belonged to P. margaritifera species. However, while the Australes population was genetically similar to non-exploited populations of the Tuamotu, the Marquesas populations were highly differentiated from the rest of the populations. This differentiation cannot not be only attributed to geographic distance and aquaculture status, but likely to hydrodynamic barriers allowing vicariant events to take place. Our results add up to other studies describing the Marquesas archipelago as a hotspot for biodiversity and differentiation, with some of the highest levels of endemism and vicariance found among marine species worldwide and provide precious information on available genetic resources for the implementation of P. margaritifera selective breeding and its genetic conservation in French Polynesia.

Inventory and vertical distribution of 137Cs, 239+240Pu and 238Pu in soil from Raivavae and Hiva Oa, two French Polynesian islands in the southern hemisphere

Atmospheric nuclear weapons tests carried out by the United States, the former Soviet Union, the United Kingdom, France and China between 1945 and 1980 resulted in radioactive fallout over the earth's surface of long-lived radionuclides, such as 137Cs, 239+240Pu and 238Pu that could be detected more than 50 years after their production. In addition, the burnup in the upper atmosphere of a thermoelectric generator fueled by 238Pu, SNAP-9A, contributed to the inventory of 238Pu deposited on the ground. In order to estimate the deposition densities of 137Cs, 239+240Pu and 238Pu in French Polynesia, we collected undisturbed soil samples up to 30 cm deep at eight sites in two islands (Hiva Oa, 139°W - 10°S and Raivavae, 148°W - 24°S) in 2015–2016. The top 0–10 cm of the soil cores were sliced into five 2-cm layers and the bottom 10–30 cm into four 5-cm layers for gamma spectrometry and alpha spectrometry measurements. We found that more than 50% of the radioactive inventories are still contained within the first 10 cm and that the average vertical migration velocities of 137Cs and Pu are less than 0.2 cm y−1. The average accumulated depositions, deduced from the profile measurements, are 236 ± 11 Bq.m−2 and 313 ± 39 Bq.m−2 for 137Cs, 12.1 ± 1.5 Bq.m−2 and 22.1 ± 1.7 Bq.m−2 for 239+240Pu, and 1.23 ± 0.46 Bq.m−2 and 1.58 ± 0.60 Bq.m−2 for 238Pu, in Hiva Oa and Raivavae, respectively. The 238Pu/239+240Pu ratios are 0.102 ± 0.050 at Hiva Oa and 0.072 ± 0.033 at Raivavae. Both values are higher than the ratio in nuclear weapons tests fallout estimated to be 0.016 in 2016 (Hardy et al., 1973), because of the contribution of 238Pu fallout from SNAP-9A, which is latitude dependent. The 137Cs/239+240Pu ratios, 19.5 ± 3.2 at Hiva Oa and 14.2 ± 2.8 at Raivavae are in the lower part of the range of values observed in other regions of the world.

Mechanical compressor-driven thermochemical storage for cooling applications in tropical insular regions

The energy situation in tropical insular regions, such as in the French Polynesian islands, presents a number of challenges, including high dependence on imported fuel, high transport costs from the mainland and weak electricity grids. With regards to electrical energy demand, the high temperatures in these regions throughout the entire year implies that a large proportion of electricity consumption (~40%) is used to cool buildings, even during evening hours. This paper presents an air conditioning system driven by photovoltaic (PV) electricity that combines a mechanical vapor refrigeration system and a thermochemical storage unit. Thermochemical processes are able to store energy in the form of chemical potential with virtually no losses, and this energy can be used to produce cooling during the evening hours without the need to run a compressor. The efficiency of such a hybrid system is evaluated and compared with alternative processes that utilize either electrochemical (Pb, Li-ion batteries) or thermal storage (ice, chilled water) for cooling production.

Semidiurnal internal tide incoherence in the equatorial Pacific

AbstractThe jets in the equatorial Pacific Ocean of a realistically forced global circulation model with a horizontal resolution of cause a strong loss of phase coherence in semidiurnal internal tides that propagate equatorward from the French Polynesian Islands and Hawaii. This loss of coherence is quantified with a baroclinic energy analysis, in which the semidiurnal‐band terms are separated into coherent, incoherent, and cross terms. For time scales longer than a year, the coherent energy flux approaches zero values at the equator, while the total flux is ∼500 W/m. The time variability of the incoherent energy flux is compared with the internal‐tide travel‐time variability, which is based on along‐beam integrated phase speeds computed with the Taylor‐Goldstein equation. The variability of monthly mean Taylor‐Goldstein phase speeds agrees well with the phase speed variability inferred from steric sea surface height phases extracted with a plane‐wave fit technique. On monthly time scales, the loss of phase coherence in the equatorward beams from the French Polynesian Islands is attributed to the time variability in the vertically sheared background flow associated with the jets and tropical instability waves. On an annual time scale, the effect of stratification variability is of equal or greater importance than the shear variability is to the loss of coherence. In the model simulations, low‐frequency equatorial jets do not noticeably enhance the dissipation of the internal tide, but merely decohere and scatter it.

Consistency in the supply of larval fishes among coral reefs in French Polynesia.

For marine fishes with a bipartite life cycle, pelagic larval dispersal can shape the distribution, connectivity, composition and resilience of adult populations. Numerous studies of larval dispersal, and associated settlement and recruitment processes, have examined the relationship between population connectivity and oceanographic features. However, relatively little is known about spatial and temporal variation in the abundance of larvae settling among different reefs and the extent to which the species assemblage of larvae settling at one location is reflective of the assemblage in neighbouring areas. Here, using crest nets, which provide a non-selective measure of the total abundance and assemblage of larvae settling to a reef (i.e. larval supply), we collected larval coral reef fishes at five locations surrounding two spatially disparate French Polynesian islands: Moorea and Nengo-Nengo. Overall, larval settlement patterns were correlated with the lunar cycle, with larval abundance peaking during the new moon. Although there were some spatial differences in larval supply among the five monitored sites, settlement patterns were largely consistent, even at the species level, irrespective of factors such as coastline orientation or distance between sites. This study provides further insights into the mechanisms driving patterns of dispersal and settlement of larval fishes over large spatial scales.

Reefs at the edge: coral community structure around Rapa, southernmost French Polynesia

Rapa (27°36′ S, 144°20′ W) is a small (~40 km2) volcanic island isolated in the Southern Austral Archipelago, where direct anthropogenic stressors are extremely limited. Here, we present the results of the first quantitative survey of coral community structure across habitats and depths around the island. Despite its geographical isolation in the depauperate South Central Pacific, its small size and unfavourable environmental conditions (competition with macroalgae, low sea surface temperatures, reduced reef accretion), the diversity of scleractinian corals at Rapa is particularly high (112 species from 32 genera, including 37 species of Acropora) in comparison to other French Polynesian islands and subtropical Pacific locations. Our results indicate that the abundance (>100 colonies per 10 m2 recorded at nine of the 17 sampling stations) and cover (>40% at four stations) of corals are relatively high for a marginal reef location. Strong spatial heterogeneity was found, with high variation in diversity, abundance, cover and community composition among stations. Variation in community composition was related to habitat types, with distinct assemblages among fringing reefs within bays, reef formations at bay entrances, and those on the submerged platform surrounding the island. On the platform, a depth gradient was detected, with generic richness, abundance and cover generally greater at deeper stations (18–20 m depth) compared with medium-depth (10–12 m) and shallow (1–3 m) stations. A gradient was also recorded along bays, with increasing coral diversity and abundance from the bay heads to the bay entrances. The coral community at Rapa was characterized by the presence of several taxa not found in other French Polynesian archipelagos and the rarity of others that are common and abundant in the Society and the Tuamotu islands. Another distinctive feature of reef communities at Rapa is the high cover and dominance of macroalgae, particularly in the shallower parts of the surrounding platform, which probably explains the lower densities of coral colonies recorded there. These characteristics of the diversity and biogeographical composition of coral assemblages at Rapa provide considerable ecological grounds for its conservation.

Species Assembly Patterns in Polynesian Ants

The islands of remote Polynesia contain ant faunas that have been largely introduced anthropogenically. I employed nonmetric multidimensional scaling ordination analyses to evaluate patterns of ant species assembly on 42 islands across remote Polynesia. Patterns on islands in the Hawaiian archipelago were distinctly separate from those of more southerly islands. Patterns on high islands were distinctly separate from those of atolls and low-lying islands. Patterns on small islets on the barrier reefs of high islands were more similar to those of distant atolls than those of the nearby high islands. Latitude and elevation were most strongly correlated with ordination axes; area and longitude were weakly correlated with ordination axes. Patterns are consistent with humanassisted dispersal through long-distance shipping as a primary vector of colonization, and with a greater diversity of habitat types with increasing island elevation. Similar results were obtained when a subset of 19 islands that had been more thoroughly surveyed was analyzed. I also examined patterns in species composition among communities (within islands) on three French Polynesian islands (Bora Bora, Huahine, and Moorea). On all three islands, sites grouped together distinctly in ordination space as a function of the dominant ant species. A substantial number of species pairs co-occurred less frequently than predicted by chance. Although interspecific competition appears to be important in structuring ant communities within islands, habitat affinities probably also play a role.

Evaluation of seafood toxicity in the Australes archipelago (French Polynesia) using the neuroblastoma cell-based assay

Ciguatera fish poisoning (CFP), a disease caused by consuming fish that have accumulated ciguatoxins (CTXs) in their tissue, is regarded as the most prevalent form of intoxication in French Polynesia. Recently, the Australes, one of the least affected archipelago until the early 1980s, has shown a dramatic increase in its incidence rates in 2009 with unusual CFP cases. In the present work, potential health hazards associated with the proliferation of various marine phytoplankton species and the consumption of fish and marine invertebrates highly popular among local population were assessed in three Australes islands: Raivavae, Rurutu and Rapa. Extracts from the marine dinoflagellates Gambierdiscus, Ostreospis and mat-forming cyanobacteria as well as fish, giant clams and sea urchin samples were examined for the presence of CTXs and palytoxin (PLTX) by using the neuroblastoma cell-based assay (CBA-N2a). Cytotoxic responses observed with both standards (Pacific CTX-3C and PLTX) and targeted marine products indicate that CBA-N2a is a robust screening tool, with high sensitivity and good repeatability and reproducibility. In Rurutu and Raivavae islands, our main findings concern the presence of CTX-like compounds in giant clams and sea urchins, suggesting a second bio-accumulation route for CFP toxins in the ciguatera food chain. In Rapa, the potential CFP risk from Gambierdiscus bloom and fish was confirmed for the first time, with levels of CTXs found above the consumer advisory level of 0.01 ng Pacific CTX-1B g−1 of flesh in three fish samples. However, despite the presence of trace level of PLTX in Ostreopsis natural assemblages of Rapa, no sign of PLTX accumulation is yet observed in tested fish samples. Because this multi-toxinic context is likely to emerge in most French Polynesian islands, CBA-N2a shows great potential for future applications in the algal- and toxin-based field monitoring programmes currently on hand locally.

Population dynamics of three Bactrocera spp. fruit flies (Diptera: Tephritidae) and two introduced natural enemies, Fopius arisanus (Sonan) and Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae), after an invasion by Bactrocera dorsalis (Hendel) in Tahiti

Oriental fruit fly, Bactrocera dorsalis (Hendel), invaded French Polynesia in 1996. In 2002 a natural enemy, Fopius arisanus (Sonan), was released and established. By 2009 mean (±SD) F. arisanus parasitism for fruit flies infesting Psidium guajava (common guava), Inocarpus fagifer (Polynesian chestnut) and Terminalia catappa (tropical almond) fruits on Tahiti Island was 64.8±2.0%. A second parasitoid, Diachasmimorpha longicaudata (Ashmead), was released and established in 2008. Although widespread, parasitism rates have not been higher than 10%. From 2003 (parasitoid establishment) to 2009 (present survey) numbers of B. dorsalis, Bactrocera tryoni (Froggatt), Queensland fruit fly, and Bactrocera kirki (Froggatt) emerging (per kg of fruit) declined. For example, for P. guajava there was a decline of 92.3%, 96.8%, and 99.6%, respectively. Analysis of co-infestation patterns (1998–2009) of B. dorsalis, B. tryoni, and B. kirki, suggest B. dorsalis is now the most abundant species in many common host fruits. Establishment of F. arisanus is the most successful example of classical biological control of fruit flies in the Pacific outside of Hawaii and can be introduced if B. dorsalis spreads to other French Polynesian islands, as was the recent case when B. dorsalis spread to the Marquesas Islands. These studies support F. arisanus as a prime biological control candidate for introduction into South America and Africa where Bactrocera carambolae Drew and Hancock and Bactrocera invadens Drew, Tsuruta, and White, respectively, have become established.

A SVM-based model for predicting distribution of the invasive tree Miconia calvescens in tropical rainforests

Advances in spatial and spectral resolution of sensors can be useless to detect directly understory and subcanopy species but make remote sensing of some ecosystems components increasingly feasible. We propose to use support vector machines (SVM) to integrate multisource-derived biophysical descriptors (overstory plant species, physiography and climate) for the indirect detection of the small invasive tree Miconia calvescens in tropical rainforests on the island of Tahiti (South Pacific). Our model consists in classifying overstory plant species from an optical Quickbird scene, with the output then used in a subsequent fusion process with digital elevation model (DEM) extracted physiographic and climatic descriptors. A range of accuracy metrics was calculated to assess the SVM-based model which widely outperforms the commonly used GARP model. Biophysical descriptors alone are necessary and sufficient to explain M. calvescens distribution and suggest that the potential invaded area is currently saturated in our study site on Tahiti. Rainfall, elevation and slope steepness are the major variables explaining the species distribution. In addition, our results show that morning insolation plays a critical role on M. calvescens height whether it is restricted to the subcanopy or reaches the forest surface. The model can be used to map the potential distribution of M. calvescens in areas where it has been recently introduced and rapidly spreading, such as in the Hawaiian islands, New Caledonia and Australia or in other French Polynesian islands. It also may be adapted to detect other species (plants or animals, alien invasives or rare endemics) in the understory and subcanopy of forest ecosystems.

A possible link between gabbros bearing High Temperature Iddingsite alteration and huge pegmatoid intrusions: The Society Islands, French Polynesia

This paper reports new field observations and new petrological, textural and geochemical data on two gabbroic intrusions and one pegmatoid dyke from the French Polynesian islands Maupiti and Bora Bora, respectively. Olivine crystals from the Faataufi and Barque de Hiro gabbros (Maupiti) include High Temperature Iddingsite (HTI), exhibiting three distinct morphological facies. Chemical and crystallographical data performed by electron microprobe, scanning microscope, X-ray diffractometry and Near InfraRed spectroscopy show that HTI results from modifications of olivine structure through intense hydroxylation and Fe-oxidation. The HTI-free 120 m-wide Cloche de Hiro dyke (Bora Bora) exhibits a textural zonation from heterogranular/intergranular gabbro (peripheral part) to typical pegmatoid (inner area). We propose a textural tetrahedral classificatory diagram which can be used to clearly distinguish the textural characteristics of the pegmatoids from those of the other coarse-grained samples. Through comparison with a lava flow containing vesicle-rich segregation sheets, we suggest that the Cloche de Hiro dyke may correspond to a huge segregation structure derived from a Maupiti-type HTI-bearing gabbro through a vapor-differentiation process. Both intrusions might be considered as representative of two superposed levels in a vertically arranged magmatic complex. In this view, the Maupiti gabbroic bodies would represent the lower part of the postulated system. Under high oxygen fugacity, olivine crystals would have undergone important modifications of their structure, leading to HTI. The huge Bora Bora pegmatoid dyke would be the upper part of the complex. After expulsion from the HTI-bearing gabbroic solidification zone by build-up of gas pressure, vesicle-rich residual melt would have gathered into a shallow level and crystallized there as a pegmatoid body.

New perspectives on aquarium fish trade

Since the 1990s, the international market for importing aquarium fish is suspicious of stock coming from South-East Asia. Fish catches are still executed with cyanide-based toxic products. In the present paper, the potential of the French Polynesian Islands to develop a marine aquarium fish business with a new approach is explored. Coral reef fish are captured at the larval stage with crest nets, then larvae are reared in aquaria before being put on the world ornamental fish market. This approach offers several advantages: (i) larvae are captured with a passive system placed on the reef crest (crest net) that does not destroy the environment and limits the stress on collected larvae; (ii) larvae are then put into farmed basins that allow them to be controlled sanitarily; and (iii) larvae are weaned at the farm and fed rapidly with artificial food. This method increases survival rates as it eliminates the food acclimatization problem of fish captured at adult stage (main cause of fish mortality in aquaria). Overall, reared larvae will constitute a new product in terms of species, sizes and quality of ornamental fish on the aquarium market.

Hermit crabs of the genus Calcinus Dana, 1851 (Decapoda: Anomura: Diogenidae) from the Austral Islands, French Polynesia, with description of a new species

Knowledge of morphology, coloration, and distribution of species of Calcinus Dana, 1851 from French Polynesia is expanded based primarily on collections obtained during the French BENTHAUS Expedition in 2002 to the Austral Islands, the southernmost of the French Polynesian islands. Six species of Calcinus were obtained from inshore to depths of 280 m. Of these, one proved to be a new species, C. albengai, and is fully described. This new species has two colour variants, one with pale pink to cream chelipeds that lives in shallow-water from the intertidal to about 50 m, the other with bright orange chelipeds, from deeper waters from about 50 to 280 m. Morphologically this new species is distinguished by differences in the armature of the ocular acicles, aspects of the left and right palms, ventrodistal pilosity of third pereopods, and telson armature. Five species were collected by dredging, trawling, or using traps, in depths of 40 to 280 m: C. anani Poupin & McLaughlin, 1998, C. gouti Poupin, 1997, C. haigae Wooster, 1984, C. spicatus Forest, 1951, and C. aff. sirius Morgan, 1991. Of these, C. gouti was previously known exclusively based on the holotype from Tuamotu, and a more complete diagnosis is presented; the others are also diagnosed, including new details on coloration. Inshore and scuba collecting on Rapa Island produced four additional, but better known species: C. elegans (H. Milne Edwards, 1836), C. latens (Randall, 1840), C. laevimanus (Randall, 1840), and C. vachoni Forest, 1958. The inshore Calcinus fauna of Rapa is briefly compared with its counterpart on Easter Island, located at the same latitude 3500 km to the east. A total of 19 (or possibly 20, should C. sirius be confirmed in the future) Calcinus species are now known from French Polynesia. Cases of sibling species of Calcinus, distinguished almost exclusively by coloration, are summarized.

The role of passive migration in the dispersal of resistance genes in Culex pipiens quinquefasciatus within French Polynesia

SummaryWe have investigated the distribution of resistance genes in relation to genetic structure and gene flow between various islands of French Polynesia in Culex pipiens quinquefasciatus. We show that (1) resistance to organophosphorous insecticides, mediated by A2–B2 esterases, is present in all islands, (2) A2–B2 frequency decreases as distance from Tahiti increases, and (3) genetic differentiation (measured as estimates of the Fst, parameter from allozyme polymorphism) between islands is significantly correlated to geographic distances which is also correlated to air or sea commercial traffic. These data are discussed in relation to A2–B2 invasion of French Polynesian islands.

Origin of anomalous rare-earth element and yttrium enrichments in subaerially exposed basalts: Evidence from French Polynesia

Basalts from French Polynesian islands occasionally display extremely high abundances and anomalous distributions of rare-earth elements (REE) and yttrium, whereas other incompatible element concentrations and O, Sr, Nd and Pb isotopic ratios do not differ from those of “normal” basalts from the same area. The REE- and Y-enriched basalts contribute up to 15% of the sample set, suggesting that this feature is more widespread than previously thought. REE-Y enrichment is related to the presence of rhabdophane-type REE-Y-phosphate identified through electron microprobe analyses in the most enriched sample and inferred from leaching experiments in the others. This phenomenon is confined to subaerially exposed basaltic sequences, indicating a close relationship to supergene processes. This is supported by negative Ce anomalies in these basalts, since decoupling of Ce from the other REE is restricted to oxidizing, low-temperature, aqueous environments. Similar Nd isotopic ratios for enriched and normal basalts allow us to exclude the possibility that additional REE and Y are derived from marine sediments or guano, but rather suggest an origin from the local basalts. Moreover, light REE enrichment in the REE-Y-phosphates suggests short migration distances of the fluids, supporting the conclusion that additional REE and Y were mobilized from weathered basalts and transported by descending meteoric waters.