HAL Portal UPF (Université de la Polynésie française)
Not a member yet
3802 research outputs found
Sort by
Data, supplementary tables and code for cold stress experiment
No full textIn this study, we assessed the effects of a non-linear cold stress experiment on the physiology and metabolite profiles of the emerging sea anemone model system Aiptasia couchii. This repository hosts Supplementary Tables S1-S7 along with R scripts used for the analyses.In this study, we assessed the effects of a non-linear cold stress experiment on the physiology and metabolite profiles of the emerging sea anemone model system Aiptasia couchii. This repository hosts Supplementary Tables S1-S7 along with R scripts used for the analyses. Manuscript status: submitted. Description: Supplementary Tables Supplementary Table S1. Mean annual summer surface temperatures (SST; °C) off Collioure, France, Western Mediterranean Sea (2015 - 2025), obtained from Copernicus Marine Service (last accessed in February 2026). Values presented as mean ± SE (included in Supplementary Material published alongside manuscript). Supplementary Table S2. Physiological response parameters of Aiptasia couchii holobionts under control and cold-stressed conditions on day 28 of the experiment. Supplementary Table S3. Weekly maximum quantum yields (Fv/Fm) of dark-adapted Aiptasia couchii holobionts under control and cold-stressed conditions. Temperatures in cold-stress treatment: Weeks 0-4 = 17, 12, 9, 7 and 6 °C, respectively. Supplementary Table S4. Absolute abundance data (peak area) for metabolite features identified in the positive ionization mode. Supplementary Table S5. Absolute abundance data (peak area) for metabolite features identified in the negative ionization mode. Supplementary Table S6. Annotation table for 25 significantly and most differentially regulated VIP metabolites for positive and negative ionization mode, respectively. Supplementary Table S7. Output from Wilcoxon Rank Sum exact tests to assess statistical differences in the intensity of statistically significantly differentially regulated VIP features between control and cold-stressed sea anemone holobionts. Supplementary File S8. R code used for the analysis of algal endosymbiont densities normalized to host tissue protein content in control and cold-stressed A. couchii holobionts. Supplementary File S9. R code used for the analysis of chlorophyll a content of algal endosymbionts in control and cold-stressed A. couchii holobionts. Supplementary File S10. R code used for the analysis of maximum quantum yield (Fv/Fm) of algal endosymbionts in control and cold-stressed A. couchii holobionts. Supplementary File S11. R code used for the analysis of superoxide dismutase activity in the tissues of control and cold-stressed A. couchii hosts
INSEPARABLE ENDOMORPHISMS AND RANK-2 SUBLATTICES OF THE GROSS LATTICE
No full textWe answer a question posed by Love asking about a correspondence between isogenies from a supersingular elliptic curve to its Frobenius base-change and rank-2 sublattices of its Gross lattice. We recast the question as one about the inseparable endomorphisms of the curve, and show that the correspondence holds when the trace of the endomorphism is zero, and may not hold otherwise.</div
Trait-dependent declines of threatened endemic trees following plant invasion on a tropical oceanic island
No full textInternational audienceBiological invasions are a leading cause of the ongoing biodiversity crisis, and particularly so on islands. However, the role of invasive alien plants (IAPs) as a driver of native plant declines and extinctions remains unclear. The inherently slow and gradual nature of plant extinctions, especially that of long-lived woody species, could be a reason. Here, we examined temporal trends in subpopulations of 28 threatened endemic tree (TET) taxa. We questioned the frequency with which they decline in association with IAPs on Reunion Island (South-West Indian Ocean), and asked whether the most susceptible TET taxa exhibit characteristics that could reveal the underlying ecological mechanisms. We resurveyed 182 historically described subpopulations and tested whether observed trends of juvenile and adult TETs correlate with the abundance in IAPs using path analyses, while distinguishing TET taxa with respect to their leaf–height–seed characteristics and extinction risk. The trend of adult TETs was not affected by IAPs but that of juvenile TETs was negatively correlated with the abundance of IAPs in the understory layer. This was particularly the case for TET taxa with conservative resource-use strategies (low specific leaf area or low maximum height), whose juveniles might be particularly susceptible to competition with IAPs, but not for TET taxa with large seeds, whose metabolic reserves make seedlings more likely to attain a critical size. These findings suggest that IAPs can significantly contribute to the extinction dynamics of trees, primarily by limiting regeneration through competitive exclusion, and that their impacts vary depending on the traits of the affected taxa
SWOT Sheds Light on Seiche Oscillations Within Atoll Islands
No full textInternational audienceAbstractThis study investigates the occurrence of surface elevation oscillations, known as seiches, at the atoll scale. We show that the innovative Ka-band Radar Interferometer (KaRIn) onboard the Surface Water Ocean Topography (SWOT) satellite makes it possible to visualize seiche-like structures within lagoons of French Polynesia. This ability to capture two-dimensional sea surface undulations of low amplitude (on the order of a few centimeters) in relatively small water bodies (less than 80 km in length) is unprecedented in satellite altimetry, and opens new avenues of research into these events and their contribution to coastal erosion and flooding. Our study combines sea surface height observations from SWOT with in situ measurements conducted in the Raroia lagoon and theoretical calculations based on an eigenvalue model. These three complementary approaches-satellite remote sensing, in situ data, and theoretical modeling-allow us to investigate both the spatial and spectral properties of seiches in atoll islands.Plain Language SummaryIn closed or semi-enclosed water bodies, a resonant phenomenon can happen in which the water surface performs standing oscillations. These oscillations, known as seiches, have well-defined periods and geometries at the basin scale. Here we investigate their presence in the lagoon of atoll islands using in situ measurements, modeling, and the Surface Water Ocean Topography (SWOT) mission, a new satellite that provides for the first time two-dimensional images of the ocean surface elevation with an unprecedented precision and resolution. We show that SWOT does capture seiche-like structures, and our in situ measurements confirm that such resonant modes do occur in the lagoon of Raroia. This is a first step toward understanding and assessing the importance of these modes in Pacific atoll islands, where they have received relatively little attention though they appear to play a role in sediment transport and submersion events
Impacts of Nearby Algae on Recruitment Success and Early Microbiome Development of the Coral Acropora cytherea
No full textInternational audienceThe persistence of coral reefs is dependent on the arrival and settlement of coral larvae followed by their post‐settlement growth and survival. Despite evidence showing that benthic algae have variable effects on corals, it is still unclear how benthic communities of the coral nursery habitat impact the early development of the coral microbiome and if these impacts relate to the survival and growth of newly settled corals. Here, we tested whether the survival and growth of Acropora cytherea recruits are impacted by surrounding algae, and whether specific algae influence their associated bacterial and Symbiodiniaceae communities. A 6‐month survey of coral larvae experimentally settled near different algae showed that crustose coralline algae enhanced recruit survival. However, despite variation in their microbiome, the presence of different algae did not impact the coral microbial community composition. The recruit microbiome was colonised by bacteria shared among all benthic substrates rather than bacteria unique to specific algae. Furthermore, the microbiome of coral larvae was different from that of the recruits. We conclude that the microbiome of corals in their early life stages is structured by host ontogeny rather than by their surrounding benthos, but that the surrounding benthos contributes to the transfer of opportunistic bacteria
Entre secret et monstration de la bombe. L’espionnage lié au Centre d’expérimentation du Pacifique et aux essais nucléaires atmosphériques en Polynésie française (1962-1975)
No full textInternational audienceCet article examine de quelle manière les États-Unis, le Royaume-Uni et l’Union soviétique espionnent le Centre d’expérimentation du Pacifique (CEP) et les essais nucléaires atmosphériques de la France réalisés en Polynésie française. L’existence de cet espionnage spécifique par ses formes et ses pratiques nous conduit à analyser sa complexité et ses paradoxes : l’espionnage est à la fois assumé et constaté, permettant à la France de montrer la puissance de sa bombe tout en maintenant le secret de sa conception, au risque de révéler ses retards scientifiques et techniques qu’elle tente de pallier en espionnant par ailleurs ses propres alliés. La circulation de savoirs et d’acteurs est révélatrice de la dimension internationale et transnationale des essais français, par-delà le caractère national de l’obtention de la bombe
Inundation flow velocities generated by tropical cyclones across atoll islands, derived from two centuries of megaclast deposits in French Polynesia
No full textInternational audienceUnderstanding potential flow velocities during high-energy marine inundation events is crucial for coastal risk assessment. However, modelling struggles to simulate wave energy dissipation across atoll island coastlines. Here, we examined coral reefblocks transported by past tropical cyclones to calculate the minimum flow velocities (MFVs) responsible. Fieldwork on 6 atolls in the Tuamotu archipelago (South Pacific) examined 196 reefblocks, some megaclasts exceeding 300 cubic metres in size. These blocks are scattered between the oceanside reef edge and the atoll lagoon over several hundred metres and suggest flow velocities much higher than those modelled in an assumed ‘extreme reference scenario’ (HS = 12 m). Through U/Th dating and by studying archives and historical aerial photos, the cyclones that moved these reefblocks were identified. Inundation flows generated by two recent cyclones (March and April 1983), two historical cyclones (1903 AD and 1906 AD) and one prehistorical cyclone (54–80 AD) were calculated (storms with swells 10–18.5 m in height). Calculations reveal that previous modelling underestimates flow velocities across atoll islands (inhabited areas) for two reasons: the underestimation of extreme swell heights and the unaccounted-for degradation of shoreline rubble ramparts. During a supercyclone (HS > 15 m), flows can exceed 3 m/s at 350 m from the reef edge and are capable of transporting 20-ton coral blocks. Findings have a wider significance to tropical coral reef coastlines beyond these atolls studied, where the presence of reefblocks can allow hindcasting of the characteristics of prehistorical cyclone inundations
