University of New Caledonia

Sulfate (SO42-) is the second most abundant anion in seawater. Nevertheless, its long-term accumulation and variability throughout Earth's history remains largely uncertain. Considering the preservation potential of benthic foraminifera in the fossil record, geochemical signatures of large tropical benthic foraminifera (LBF) are an important tool for paleoclimatic proxies. Considering their significant deposit of high-magnesium calcite within fragile tropical ecosystems largely threatened by climate change, an improved understanding of both their calcification processes and geochemical signatures in the face of climate change environmental variables, is of main interest, particularly as LBF have not been as intensively studied as planktonic - and smaller benthic foraminifera. The study of Marginopora sp., an ubiquitous LBF in tropical regions of the Pacific Ocean, provides a unique opportunity to reconstruct changes in environmental parameters in seawater over time. Cultures of Marginopora sp. from New Caledonian environments were performed with modern and decreased seawater pH values and modern and increased [SO42-]sw to calibrate impact of seawater sulfate concentration on both S/Ca concentrations and δ34S composition of the S incorporated in the shells of Marginopora sp.. Here, we present S/Ca data and other Element/Calcium ratios derived from LA-Q-ICP-MS (NWR193UC & Thermo Fisher Scientific iCAP-Q) and solution SF-ICP-MS (Thermo Fisher Scientific Element-2) analyses, as well as sulfur isotope data acquired from Isotope Ratio Mass Spectromety (IRMS with Elementar vario EL cube). As already described in previous studies looking at the geochemical signatures of small benthic foraminifera, S/Ca ratios within Marginopora sp. test, increased with increasing seawater S/Ca concentration. However, and contrarily to what was reported previously, the Mg/Ca content of Marginopora was observed to decrease with increasing S/Ca calcite content, highlighting potential differences in calcification disruption between low-Mg and high-Mg calcitic foraminifers when exposed to an increase in seawater sulfate concentrations.

Dengue virus (DENV) is a major public health concern in tropical and subtropical regions, including the Pacific. Temperature is recognised as a major driver of transmission under climate change. Understanding how higher temperatures may alter DENV transmission is essential to anticipate future dengue risk. Therefore, we assessed the effect of temperature on DENV-1 in Aedes aegypti from New Caledonia. Mosquitoes were orally infected and maintained for 14 days at 26.6 °C (average temperatures during recent outbreaks) or 31.1 °C (SSP5-8.5 scenario projected temperatures). Mosquito bodies, heads, and saliva were analysed separately to determine infection, dissemination, and transmission rates as well as transmission efficiencies. Infectious virus was detected by using a fluorescent focus assay, and viral titres were quantified via TCID50 assays. No significant differences were observed in infection, dissemination, and transmission rates or transmission efficiencies between the two temperatures. However, DENV titres in mosquito bodies and heads were significantly higher at 31.1 °C than 26.6 °C. Our results indicate that elevated temperature increases viral loads within the insect but not the proportion of infectious mosquitoes, highlighting the importance of considering temperature as a key parameter in assessing dengue risk under climate change. Further studies are needed to investigate the effects of temperature on virus-mosquito interactions.

Illustrated digital picture books are widely used for second-language reading and vocabulary growth. We ask how close current generative AI (GenAI) tools are to producing such books on demand for specific learners. Using the ChatGPT-based Learning And Reading (C-LARA) platform with GPT-5 for text/annotation and GPT-Image-1 for illustration, we ran three pilot studies. Study 1 used six AI-generated English books glossed into Chinese, French, and Ukrainian and evaluated them using page-level and whole-book Likert questionnaires completed by teachers and students. Study 2 created six English books targeted at low-intermediate East-Asian adults who had recently arrived in Adelaide and gathered student and teacher ratings. Study 3 piloted an individually tailored German mini-course for one anglophone learner, with judgements from the learner and two germanophone teachers. Images and Chinese glossing were consistently strong; French glossing was good but showed issues with gender agreement, register, and naturalness of phrasing; and Ukrainian glossing underperformed, with morphosyntax and idiom errors. Students rated tailored English texts positively, while teachers requested tighter briefs and curricular alignment. The German pilot was engaging and largely usable, with minor image-consistency and cultural-detail issues. We conclude that for well-supported language pairs (in particular, English–Chinese), the workflow is close to classroom/self-study usability, while other language pairs need improved multi-word expression handling and glossing. All resources are reproducible on the open-source platform. We adopt an interdisciplinary stance which combines aspects taken from computer science, linguistics, and language education.

Abstract. Marine Heatwaves (MHWs) have emerged as one of the most important threat for marine ecosystems, with impacts such as coral bleaching, massive fish mortality and displacement of mobile fauna. In the context of climate change, it is urgent to develop strategies such as subseasonal to seasonal forecasting to help human societies adapt and react to the increasing frequency, duration and intensity of these events. Here we evaluate the predictability of MHWs at the scale of a South Pacific island country, New Caledonia, using ensemble forecasts from a dynamical coupled ocean-atmosphere model. We show that implementing a probabilistic approach where we extract information from the dispersion in the ensemble results in a higher skill than a deterministic approach where we simply compute the ensemble average. We find that longer, more intense, and wider MHWs, are more predictable than weaker, less intense, and shorter MHWs. We also find that the longest and widest MHWs occur in the cold season (June–October) during strong La Niña episodes, and that they can successfully be predicted up to 7 months in advance. In contrast, MHWs occurring during the warm season have poor or no predictability of more than a few weeks in advance. We discuss how this information can be efficiently transferred to marine stakeholders in terms of the usefulness and useability of the forecast. We recommend that future research should focus on identifying the drivers of different types of MHWs in order to understand their sources of predictability.

Abstract Diffuse midline glioma (DMG) is a universally fatal high-grade glioma. Its immunologically cold tumor immune microenvironment (TIME) presents a major barrier to durable anti-tumor responses. Dordaviprone (ONC201) is a brain-penetrant DRD2 antagonist and ClpP agonist that disrupts mitochondrial complex II (CII) activity; currently under clinical evaluation for DMG. In melanoma, CII inhibition has been shown to enhance MHC presentation and T cell–mediated killing. Here, we investigated the immunomodulatory effects of dordaviprone in DMG mouse models, patient tumor tissues, and blood samples. Immunocompetent DMG-PPK mice (PdgfraD842V, Trp53DN, H3f3aK27M mutations) were treated with dordaviprone (125 mg/kg, twice weekly) for 1 week (acute) or 3 weeks (chronic) and compared to naïve, sham (orthotopic surgery without tumor engraftment), and vehicle-treated controls. Murine tumors were analyzed by single-cell multiome (scRNA-seq and scATAC-seq) and spatial transcriptomics. Murine blood and bone marrow (BM) and human blood samples were profiled by scRNA-seq and flow cytometry. In models, dordaviprone promoted microglial activation and macrophage infiltration within the TIME. Spatial transcriptomics identified increased expression of the MHC-I subunit B2m in tumor cells and tumor-infiltrating Cd8+ T cells following dordaviprone treatment. Flow cytometry of murine and human peripheral blood confirmed CD4+ and CD8+ lymphopenia at baseline. Dordaviprone increased circulating lymphocytes in models (log2 fold change=1.03; patient data pending), reversing DMG-induced CD3+ T cell sequestration in the BM. Immunohistochemistry confirmed elevated levels of B2M (p=0.0281) and tumor-infiltrating lymphocytes (TILs), including CD45+ (p=0.0275) and CD3+ T cells (p=0.0103) in dordaviprone-treated mice. Despite enhanced TIL recruitment, dordaviprone did not improve survival (n=10), likely due to persistent immunosuppressive myeloid activity, i.e. Havcr2 (TIM-3), Cd74, Cd274 (PD-L1). This study demonstrates that DMG tumors contribute to systemic lymphopenia, partially reversed by dordaviprone. While supporting its immunomodulatory effects, including enhanced antigen presentation and TIL recruitment, our findings highlight future combination strategies to leverage dordaviprone-induced immunoreactive TIME.

Biodiversity faces several global threats and communities are likely to show complex delayed responses. Accurately measuring these lags is critical to properly understand diversity dynamics. Here, we investigated these delays with minimal data availability and found critical mismatches between the temporal dynamics of taxonomic and functional diversity in Wadden Sea bird communities. By analysing 17 long‐term time series spanning an average of 30+ years, we quantified the net imbalance between colonisations and extinctions (NICE) to measure delays in taxonomic (tNICE) and functional (fNICE) diversity. Our approach used empirically measured (trophic and morphological) traits, and in parallel, traits inferred through diffusion maps, allowing to quantify species traits only based on their co‐occurrence patterns over time. First, we found that diffusion maps are a relevant tool to quantify species traits when trait data are scarce. Moreover, we found that, while initial colonisations outnumbered extinctions, the taxonomic balance shifted dramatically toward local species losses, deviating significantly from neutral expectations. Yet despite this concerning trend, functional diversity was stable. This stability likely stems from functional redundancy among declining species, temporarily preventing functional changes. However, despite current functional resilience, the on‐going loss of taxonomically distinct species threatens to erode unique functional roles, potentially triggering abrupt shifts and/or collapse in ecosystem functions. Most critically, our study show how seemingly stable functional diversity can mask accelerating taxonomic losses, highlighting the urgent need for multi‐faceted biodiversity monitoring. As global changes intensify, combining taxonomic and functional assessments through advanced analytical methods becomes essential for detecting early warning signals of ecosystem deterioration and implementing effective conservation strategies.

Microbiota play a pivotal role in holobionts, influencing nutrient intake, growth, and overall health. In this context, microbial dysbiosis of Penaeus stylirostris larvae seem to be associated with huge larval mortalities in hatcheries in New Caledonia. To understand larval dysbiosis establishment, our purpose was to identify bacterial biomarkers, as bioindicators, related to a given larval stage and health condition. To this end, larvae were sampled daily to access their active microbiota through sequencing of the V4 region of the 16S rRNA molecule, while their stage and their health were also observed. We identified three biomarkers strongly related to healthy zoea, and some may act as probiotics or play key roles in larval ontogeny and nutrition. We also found six biomarkers linked to unhealthy zoea and eight related to healthy mysis. Biomarkers were mostly related to diseased shrimps (Lewinella) or healthy shrimps (Cognitishimia, Thalassolituus) or were known to prey on cells (P30B-42), suggesting that the larvae might be battling against detrimental conditions. No biomarker related to unhealthy mysis was identified. Finally, our data showed that bacterial bioindicators could be used as an effective biosurveillance proxy in hatcheries, to monitor larval development, and as an early warning tool to predict rearing outcomes.

• First complete pig mitogenomes from the Lapita period show a continuous pig population in Remote Oceania from ∼3000 BP. • Western Remote Oceania shows sustained pig mitochondrial diversity from the Lapita period into modern times. • Eastern Remote Oceania lacks pig mitochondrial diversity, suggesting a bottleneck during the East Polynesian expansion. • Contrasting genetic signatures between west and east suggest minimal movement of pigs between these regions. • First Pacific Clade pig detected in ancient China, extending their range to mainland East Asia, and back to 7000-6000 BP. The movement of Lapita peoples into western Remote Oceania ∼ 3000 BP, and subsequent dispersal into Polynesia, is one of the most extensive migration events in human history. While the origins of these settlers and their commensal animals in the west are generally well understood, questions remain about their dispersal into eastern Remote Oceania, and post-settlement interactions. The pig, Sus scrofa , is one of the commensal animals carried across Remote Oceania, and previous genetic studies identified a single lineage, the “Pacific Clade”, linking Pacific pigs to Island and Peninsular Southeast Asia. Here, we present 16 complete mitogenomes (>99 % coverage) and 8 partial mitogenomes (>80 % coverage) from eleven Remote Oceanic archaeological sites, spanning the Lapita period to the historic period. Phylogenetic analyses show a continuous pig population in Remote Oceania from their first introduction ∼ 3000 BP. Furthermore, sustained pig mitochondrial diversity is detected in western Remote Oceania from the Lapita period until today. In comparison, very limited diversity is found in eastern Remote Oceania, suggesting a bottleneck associated with human expansion into East Polynesia. The contrasting genetic signatures between west and east suggest that little to no pig movement occurred between these regions following the initial settlement of Polynesia. Comparison of the newly generated sequences to previously published ancient pig mitogenomes reveals the first ancient Pacific Clade pig in China, extending their range geographically to mainland East Asia, and temporally to 7000–6000 BP. Overall, this study contributes to a more nuanced understanding of Remote Oceania’s settlement and pig husbandry.