Publications
Assessment of spatial distribution of organic contaminants and metallic compounds on a tropical island’ coral reef fish communities
Contamination by mining-related elements (Ni, Cr) and persistent organic pollutants (POPs) is widespread throughout New Caledonia's lagoon, extending from coastal areas to the barrier reef. A study analyzing 36 contaminants in ~400 coral reef fish revealed that fish body size was the strongest predictor of contaminant concentrations, followed by monthly rainfall for POPs and reef area for metallic compounds (MTEs). Mining activity significantly influenced contamination levels, particularly for Ni and Cr, while mercury (Hg) contamination showed strong dependence on biological variables. The research used boosted regression trees modeling to predict and map contaminant distribution at the community level, providing critical spatial data for policy-making.
Geomorphological patterns and sedimentary facies in a modern mixed carbonate-siliciclastic lagoon (New Caledonia)
A detailed sedimentary mapping of the New Caledonian lagoon reveals distinct geomorphological patterns and sedimentary facies between its southwestern and southeastern zones, highlighting differences likely driven by inherited morphologies and contrasting hydrodynamic conditions. The southwestern lagoon, bordered by a massive barrier reef, is more prone to fine-grained sedimentation, while the narrower eastern lagoon exhibits meandering channels parallel to the shore due to a discontinuous and partially submerged barrier reef. This high-resolution mapping at a 1/70,000 scale, utilizing bathymetric imagery and seabed sampling, provides insights into the surface sediment distribution, bioconstructed morphologies, and drainage network architecture in this mixed carbonate-siliciclastic system.
Spaghetti worms from the reef: two new species of Loimia (Polychaeta: Terebellidae) from Bora-Bora and Moorea (Society Islands, French Polynesia) and a range extension of L. tuberculata Nogueira, Hutchings & Carrerette, 2015
Researchers have identified two new species of spaghetti worms, Loimia poraporaensis and L. aimehoensis, from the lagoons of Bora-Bora and Moorea (Society Islands, French Polynesia). These species exhibit distinct morphological traits, such as large lateral lobes and banded buccal tentacles, which differentiate them from other known Pacific coral reef worms. The study also extends the known range of L. tuberculata, previously documented only in Australia and Papua New Guinea, to include New Caledonia. Using molecular analysis (COI and 16S genes) alongside morphological comparisons, the team constructed phylogenetic trees and provided an identification key for these species. Their findings highlight the biodiversity of UNESCO-listed lagoons while emphasizing the importance of coral associations in their habitats.
The role of barrier reef protection to storm surge during tropical cyclones in a narrow lagoon, New Caledonia, south west Pacific
Storm surge in the narrow, shallow lagoon of Poe, New Caledonia, is primarily driven by wave setup—accounting for 70% to 90% of extreme water levels during tropical cyclones. This finding, derived from a coupled numerical model and synthetic cyclone tracks, reveals that irregular reef structures can mitigate wave setup intensity while tidal variations over the reef crest further influence surge dynamics. The study highlights the critical role of reef morphology in coastal hazard prediction, offering insights for climate-resilient land use planning in reef island environments.
Effects of physical forcing on short-term plankton dynamics in a narrow coral reef lagoon (Ouano, New Caledonia): a two-week high-frequency study
A two-week high-frequency study in the narrow coral reef lagoon of Ouano, New Caledonia, revealed that short-term climatic events—such as wind, waves, and rainfall—significantly alter plankton dynamics at a lagoon scale. These events disrupted typical tidal and diel patterns by increasing nutrient concentrations, leading to rapid growth of microphytoplankton (dominated by diatoms) and opportunistic herbivorous zooplankton (e.g., tintinnids, appendicularians). Unlike larger lagoons where spatial variability dominates, this study demonstrated that physical forcing in channel-like lagoons drives large-scale biological responses, highlighting the sensitivity of these ecosystems to external environmental changes.
A world of taxonomic pain: cryptic species, inexplicable host-specificity, and host-induced morphological variation among species of Bivesicula Yamaguti, 1934 (Trematoda: Bivesiculidae) from Indo-Pacific Holocentridae, Muraenidae and Serranidae
A comprehensive genetic and morphological analysis reveals that the genus Bivesicula, parasitic trematodes infecting Indo-Pacific fishes, is not monophyletic, with three distinct clades identified. The study distinguishes 10 species, including five new ones, highlighting significant host-specificity and geographical distribution patterns. Cryptic species, where morphological differences are minimal but genetic markers show clear distinctions, were found in both Clade 1 and Clade 2, infecting serranids with some also affecting holocentrids or muraenids. The research underscores the complexity of taxonomic classification in this genus due to low resolving power of ribosomal markers, regional mtDNA populations, and host-induced morphological variation.
Ecoregional and temporal dynamics of dugong habitat use in a complex coral reef lagoon ecosystem
Research reveals distinct ecoregional and temporal patterns in dugong habitat use within the complex coral reef lagoon ecosystems of New Caledonia, offering critical insights for conservation. By analyzing 9371 hourly positions from 16 satellite-tagged dugongs, scientists identified significant differences in the intensity of dugong presence across shallow waters, deeper lagoon areas, and fore-reef shelves. These findings were validated using aerial survey data, extending our understanding of dugong distribution beyond traditional surveys, particularly highlighting their nocturnal preference for shallow waters during high tide. This study underscores the potential of satellite tracking and dynamic habitat modeling to inform effective spatial management strategies for elusive marine mammals like the dugong.
Extremely high but localized pulses of coral recruitment in the southwestern lagoon of New Caledonia and implications for conservation
A study of coral recruitment in the southwestern lagoon of New Caledonia revealed exceptionally high and localized pulses, with rates reaching up to 13572.8 recruits per square meter—far surpassing global averages. These extreme peaks, observed between 2012 and 2014, were dominated by Acroporidae and contrasted sharply with declining trends reported elsewhere, suggesting resilience in this UNESCO World Heritage Site. Researchers analyzed 14 reef stations, uncovering marked spatial and interannual variability that complicates conservation efforts. While the findings highlight potential for population replenishment, the unpredictability of recruitment hotspots challenges targeted protection strategies.
Hydrodynamic and hydrological processes within a variety of coral reef lagoons: field observations during six cyclonic seasons in New Caledonia
Extreme weather events significantly alter lagoon dynamics, including surges and thermal drops. The study, part of the PRESENCE project, monitored five coral reef lagoons in New Caledonia over six cyclonic seasons (2014–2021), capturing data on ocean-lagoon exchanges, circulation, temperature, salinity, and currents during events ranging from tropical depressions to category 4 cyclones. Using autonomous instruments, drifter buoys, and CTD profiles, researchers identified key processes such as internal waves, wave-driven fluxes over reef barriers, and flash flood plume dispersion. The comprehensive dataset, now publicly available, provides critical data for high-resolution hydrodynamic models, aiding in the understanding of lagoon resilience under climate stress.
Unsupervised Optical Classification of the Seabed Color in Shallow Oligotrophic Waters from Sentinel-2 Images: A Case Study in the Voh-Koné-Pouembout Lagoon (New Caledonia)
Research demonstrates that unsupervised optical classification using Sentinel-2 images can effectively distinguish seabed colors in shallow, oligotrophic waters, even in complex bathymetric settings. The study applied Lyzenga correction and spectral standardization to separate water column reflectance from seabed signals, revealing five distinct seafloor clusters when standardized data were used—an improvement over the three clusters identified without standardization. This method achieved over 75% explanatory power for each wavelength band and improved classification accuracy, highlighting its potential for remote sensing of biogeochemical indicators like chlorophyll-a concentration in fragile coastal ecosystems such as New Caledonia's lagoons.
High connectivity within restricted distribution range in Pocillopora corals
Research reveals that Pocillopora corals, previously classified as two morphospecies, are actually complexes of cryptic species with highly restricted distributions—some confined to the Indian Ocean and others to the Pacific. Despite these narrow ranges, genetic analysis of 4837 coral colonies across six ecoregions in the Western Indian and Southern Pacific Oceans shows high connectivity within each ocean basin, suggesting a strong barrier limiting gene flow between them. The study used 13 microsatellite markers to assess genetic partitioning and diversity, uncovering variable connectivity patterns among sympatric species. These findings underscore the need for multi-species connectivity models in coral reef management, particularly in the face of ongoing declines.
Hindcast and Near Real-Time Monitoring of Green Macroalgae Blooms in Shallow Coral Reef Lagoons Using Sentinel-2: A New-Caledonia Case Study
Sentinel-2 satellite data proves effective for monitoring and hindcasting green macroalgae blooms in shallow coral reef lagoons, as demonstrated in a New Caledonia case study. The research found that spectral indices using blue and green bands, when paired with field observations, explained up to 64.9% of algal abundance variance, depending on seabed composition and data correction methods. Supervised image segmentation accurately captured two significant Ulva blooms in 2018, showcasing the potential of Sentinel-2 for real-time and historical monitoring of these nuisance events.
Shallow Water Bathymetry Retrieval Using a Band-Optimization Iterative Approach: Application to New Caledonia Coral Reef Lagoons Using Sentinel-2 Data
A groundbreaking method for bathymetry retrieval, the Iterative Multiple Band Ratio (IMBR) algorithm, demonstrates superior accuracy compared to traditional techniques when applied to shallow coral reef lagoons. Using Sentinel-2 data from the 25 km² Poe LagoonIMBR achieved a mean absolute error of just 46 cm, significantly outperforming Multiple Band Ratio (MBR) and Single Band Ratio (SBR) methods. The algorithm's effectiveness hinges on training datasets that define depth thresholds for optimal band ratios, making it adaptable to other sites with minimal ground-truth data. While MBR and SBR may suffice for less precise applications, IMBR offers unparalleled precision, ideal for hydrodynamic modeling in New Caledonia's lagoons.
The Bouraké semi-enclosed lagoon (New Caledonia) – a natural laboratory to study the lifelong adaptation of a coral reef ecosystem to extreme environmental conditions
A thriving coral reef ecosystem in the Bouraké semi-enclosed lagoon (New Caledonia) defies expectations, surviving under extreme conditions of acidification, deoxygenation, and temperature fluctuations. Unlike projected future ocean scenarios, this lagoon experiences predictable, rapid changes in seawater pH (down to 7.2), dissolved oxygen (as low as 1.9 mg/L), and temperature (up to 6.5°C variation daily) due to tidal cycles. Despite these harsh conditions, the reef hosts a diverse community of corals (66 species), sponges (11 species), and macroalgae (28 species). The study used a multi-scale approach to map benthic composition and characterize physical-chemical parameters, revealing that environmental variability and nutrient imbalances may contribute to the resilience of these organisms. This natural laboratory offers unique insights into potential adaptive mechanisms for reef ecosystems facing climate change.
A regionally scalable habitat typology for assessing benthic habitats and fish communities: Application to New Caledonia reefs and lagoons
A scalable habitat typology for New Caledonia's reefs and lagoons reveals five distinct benthic habitat types, each characterized by unique abiotic and biotic attributes. This methodology, combining clustering techniques and supervised classification rules, enables consistent habitat descriptions across vast spatial scales (1.4 million km²) and predicts habitat types with high confidence using new survey data. The study highlights significant fish abundance in rarely monitored soft-bottom habitats, underscoring the importance of ecosystem-based monitoring strategies. By applying data mining to in situ measurements, this approach sets a precedent for characterizing and predicting local ecological assets at regional scales, offering a robust framework for adaptive coastal ecosystem management.
Chapter 7 Post-obduction evolution of New Caledonia
New Caledonia's post-obduction evolution, spanning from the Late Oligocene to the present, reveals significant tectonic and sedimentary dynamics. The study highlights two key granitoid intrusions into the Peridotite Nappe, alongside extensive regolith development controlled by tectonic uplift and subsidence. The Népoui Group, a mix of marine carbonate and siliciclastic deposits, reflects this dynamic history, while remnants like the Gwa N'Doro Formation and Fluvio-lacustrine Formation showcase Miocene to present-day river systems. Offshore seismic surveys indicate substantial Neogene subsidence, though undated sedimentary successions remain. Quaternary formations, including aeolianite and calcrete inland, and a barrier reef–lagoon complex offshore (dated to ~400 ka), further illustrate New Caledonia's complex geological narrative. The chapter synthesizes models for this evolution, integrating field observations, seismic data, and sediment analysis.
Dugong (Dugong dugon) movements and habitat use in a coral reef lagoonal ecosystem
Dugongs (Dugong dugon) exhibit extensive movements within the coral reef lagoons of New Caledonia, often traveling over 15 km from their capture sites, with some covering up to 72.9 km. This study used GPS satellite tracking on 12 dugongs across three locations—Cap Goulvain, Ouano, and Nouméa—to reveal their space use patterns, including intensive habitat use in unconfirmed seagrass areas or those not previously observed during aerial surveys. While dugongs primarily stayed within the lagoons (99.4% of GPS locations), some ventured onto the fore reef shelf in narrow, confined sections to navigate between bays. These findings highlight the importance of lagonal ecosystems for dugong conservation and management, offering critical insights for protecting this Vulnerable species, particularly in regions with similar geomorphology where dugongs are Critically Endangered.
Estimating the potential for coral adaptation to global warming across the Indo‐West Pacific
Some reefs, including those in Vietnam, Japan, Taiwan, New Caledonia, and the southern Great Barrier Reef, show high potential to adapt to rapid warming, maintaining coral cover under a 'business-as-usual' scenario. This resilience is linked to present-day temperature and the proportion of recruits immigrating from warmer locations, with the latter being the strongest predictor of adaptive potential. The study used individual-based simulations across 680 reefs in the Central Indo-West Pacific, revealing that most reefs risk collapse within a century without selection or migration. These findings can guide conservation efforts and assisted gene flow interventions to enhance coral adaptation.
Extreme Wave Events on Barrier Reefs: A Driver for Critical Regime?
Extreme wave events on barrier reefs can trigger critical hydrodynamic regimes, significantly impacting reef ecosystems. This study, conducted in the Ouano reef-lagoon system of New Caledonia, combines in-situ experiments with advanced numerical modeling to analyze these dynamics. Researchers found that extreme waves alter the physical environment of barrier reefs, potentially leading to regime shifts that affect biodiversity and ecosystem stability. The findings highlight the importance of understanding wave-driven processes in coastal management strategies for UNESCO World Heritage Sites like the Lagoons of New Caledonia.
Impact of Contrasted Weather Conditions on CDOM Absorption/Fluorescence and Biogeochemistry in the Eastern Lagoon of New Caledonia
Contrasted weather conditions significantly influence the biogeochemistry and dissolved organic matter (CDOM) dynamics in the Eastern Lagoon of New Caledonia. Rainfall events increase riverine inputs, boosting humic-like CDOM fluorescence and nutrient concentrations while shifting phytoplankton size classes toward larger forms. Windy conditions, however, enhance autochthonous biological activity, with notable increases in protein-like fluorophores (tyrosine 1-like and tryptophan-like) linked to sediment resuspension, atmospheric deposition, and water mixing. These findings highlight the differential impacts of weather on lagoon ecosystems, emphasizing the importance of understanding environmental forcing in tropical coastal systems.
Momentum Balance Across a Barrier Reef
Barrier reefs exhibit distinct hydrodynamic behaviors that contrast with sandy beaches and fringing reefs, according to a combined experimental and numerical study conducted over the Ouano reef barrier in New Caledonia. The research reveals that cross-reef currents induced by wave breaking significantly influence momentum budgets, particularly through frictional processes. Unlike classical beach behavior, where radiation stress gradients balance barotropic pressure gradients associated with wave setup, barrier reefs transition to an open-channel regime dominated by frictional head loss. Numerical simulations using a non-hydrostatic wave-resolving model coupled with turbulence modeling highlight the vertical flow structure, showing a log-layer profile over the reef flat and an anticlockwise circulation under breaking waves on the forereef. These findings underscore the complex, depth-dependent hydrodynamic behavior of barrier reefs, particularly during extreme wave events.
Tropical Cyclone Induced Wave Setup around New Caledonia during Cyclone COOK (2017)
Coastlines with double protection from barrier and fringing reefs are significantly sheltered from tropical cyclone-induced waves, experiencing only 3 meters of significant wave height at the coast compared to 13 meters offshore. In contrast, shores fronting reef passes are more severely exposed, with waves reaching up to 9 meters near the coast. This study investigates these coastal impacts using an unstructured wave-current model simulation that encompasses New Caledonia and Vanuatu, describing the complete tropical cyclone-induced wave impact from generation to propagation and transformation in coastal areas. The research compares model simulations with in-situ measurements during Cyclone COOK in 2017, revealing that wave breaking on barrier reefs induces strong lagoon currents and localized sea level anomalies. In more sheltered bays, wave breaking at the entrance acts against outgoing currents, leading to an additional elevation of mean water levels.
Acclimatization of massive reef-building corals to consecutive heatwaves
Research on massive reef-building corals from the Lagoons of New Caledonia reveals that some coral species are acclimatizing to consecutive heatwaves, offering a potential resilience against rapid global warming. Analyzing skeletal cores from 14 reefs across the northern Great Barrier Reef, Coral Sea, and New Caledonia since 1815, scientists observed an increase in thermal tolerance despite rising temperatures. While stress bands—indicative of bleaching—became more frequent post-20th century, their decline after repeated bleaching events suggests corals may adapt faster than previously assumed. This finding challenges projections of widespread coral devastation and provides a glimmer of hope for reef ecosystems under climate change.
Spatial Patterns and Short-term Changes of Coral Assemblages Along a Cross-shelf Gradient in the Southwestern Lagoon of New Caledonia
A significant correlation between juvenile and adult coral distributions suggests that adult assemblages are partly shaped by short-term recruitment patterns. This finding highlights the dynamic nature of coral reef ecosystems, where past recruitment events can influence current assemblage structures. The study investigated spatial distribution and interannual variability (2006–2008) of coral assemblages across 10 stations in New Caledonia's southwestern lagoon, evaluating cross-shelf gradients. Coral cover, generic richness, and abundance varied among fringing, mid-shelf, and barrier reefs, with abundance increasing with distance from shore. While assemblage composition was generally habitat-related, some overlap existed between mid-shelf and fringing reefs. Interannual changes were minimal but detected in specific genera at mid-shelf and barrier reefs, indicating localized high turnover rates.
Wave transformation over a barrier reef
Barrier reefs act as depth-dependent filters for incoming wave energy, significantly reducing its transmission while allowing certain low-frequency standing waves to persist. This finding emerges from a two-month observational and numerical study conducted over the Ouano reef barrier in New Caledonia, which revealed distinct wave patterns, including reflection-induced standing waves and undular bore trains developing over the reef flat. The research combined cross-shore pressure sensor networks with high-resolution velocity profiling to quantify these phenomena, offering critical insights into how barrier reefs modulate wave dynamics—a key factor for coastal protection and lagoon ecosystem stability.
Bio-Optical Characterization and Ocean Colour Inversion in the Eastern Lagoon of New Caledonia, South Tropical Pacific
A study on the Eastern Lagoon of New Caledonia (ELNC) reveals significant variability in bio-optical properties, with coastal stations dominated by non-algal particles and coloured dissolved organic matter due to allochthonous sources. The research found that existing ocean colour algorithms, including empirical and semi-analytical models, showed high biases in estimating chlorophyll a concentration (Chla), particularly at coastal sites. However, the GSM01 algorithm performed best for Chla retrievals with 35–40% relative percent differences when excluding these stations. Additionally, algorithms for detecting absorption slopes of coloured dissolved organic matter plus non-algal particles and particle backscattering coefficients showed reasonable accuracy (~18% and ~40% RPD, respectively). The study highlights the potential of satellite monitoring to track water quality in the ELNC, provided atmospheric correction is accurate, and suggests that regionally tuned algorithms could improve future Chla estimates. The findings underscore the need for better parameterization schemes to account for spatiotemporal variability in specific inherent optical properties.
Dissolved Organic Matter Influences N2 Fixation in the New Caledonian Lagoon (Western Tropical South Pacific)
Heterotrophic diazotrophs, which rely on dissolved organic matter (DOM) for nitrogen fixation, contribute minimally to overall N2 fixation activity in the New Caledonian lagoon compared to photosynthetic cyanobacterial diazotrophs. A study using the photosynthesis inhibitor DCMU revealed that heterotrophic diazotrophs accounted for less than 10% of total N2 fixation, with their activity increasing near shore where labile DOM was more abundant. Experimental additions of carbohydrates (DOC), amino acids (DON), and phosphonates (DOP) showed significant increases in nifH gene expression and bulk N2 fixation rates only under DOP treatment, suggesting a nuanced relationship between DOM composition and diazotroph activity. The research highlights the dominance of cyanobacterial diazotrophs like Trichodesmium while emphasizing the need for further exploration of heterotrophic diazotrophs in response to rising anthropogenic DOM inputs.
Distributions and Abundances of Sublineages of the N2-Fixing Cyanobacterium Candidatus Atelocyanobacterium thalassa (UCYN-A) in the New Caledonian Coral Lagoon
Researchers have identified distinct environmental factors influencing the abundance and diversity of sublineages of the nitrogen-fixing cyanobacterium Candidatus Atelocyanobacterium thalassa (UCYN-A) in the Noumea lagoon, New Caledonia. The study found that UCYN-A1, the dominant sublineage, thrives in cooler temperatures (<23°C), lower nitrate concentrations, and specific wind conditions, while UCYN-A2 is more abundant under different environmental parameters, including higher silica and chlorophyll a levels. Using qPCR and oligotyping to analyze nifH gene diversity, the study revealed that these sublineages exhibit unique ecological niches, contributing to our understanding of nitrogen fixation in tropical coral lagoons. This research highlights the importance of UCYN-A in supporting primary production in oligotrophic marine environments.
Rain-derived particles and CDOM distribution along the east coast of New Caledonia
Heavy rainfall or tropical storms can dramatically increase chlorophyll-a concentration, turbidity, and colored dissolved organic matter (CDOM) in New Caledonia's lagoons, with effects detectable up to 50 km offshore. The eastern coast is more affected due to its geomorphology, frequent intense rains, and erosive lateritic formations from ultramafic rocks. Satellite imagery and oceanographic measurements reveal that these increases—visible as plumes extending offshore—affect deeper lagoon areas (>20 m) and extend to coral barrier reefs. While large particles settle near river outflows, fine particles (<10 µm), colloids, and CDOM are transported to reefs, potentially benefiting corals by shielding them from UV radiation or providing nutrients. However, the impact of trace metal distribution from these particles on coral health remains uncertain.
Tidal variability of CO2 and CH4 emissions from the water column within a Rhizophora mangrove forest (New Caledonia)
CO₂ and CH₄ emissions from the water column within a Rhizophora mangrove forest in New Caledonia exhibit significant tidal variability, driven primarily by flow/ebb cycles, water column thickness, and neap/spring tides. Emissions were inversely proportional to water column depth, with higher rates observed during ebb tides due to increased residence time over the forest floor, leading to progressive enrichment of the water column. Spring tides further amplified emissions, suggesting enhanced soil-water exchange and electron acceptor renewal. δ¹³CO₂ values indicated mixing between CO₂-enriched pore waters and lagoon waters. This study highlights that such emissions cannot be overlooked in mangrove carbon budgets, emphasizing the need for tidal dynamics to be integrated into future assessments.
Application of the Support Vector Regression Method for Turbidity Assessment with MODIS on a Shallow Coral Reef Lagoon (Voh-Koné-Pouembout, New Caledonia)
A novel Support Vector Regression (SVR) model successfully addresses the challenges of turbidity assessment in shallow, oligotrophic coral reef lagoons using MODIS satellite imagery. Unlike traditional algorithms, which struggle with bottom reflection in such environments, this model incorporates bathymetry and bottom color data alongside reflectance, significantly improving accuracy in retrieving in-situ turbidity values. Tested on New Caledonia's Voh-Koné-Pouembout lagoon—a critical part of the world's second-longest continuous coral reef—it demonstrates potential for global application in similar oligotrophic shallow lagoons. This breakthrough enhances monitoring capabilities for biodiversity and ecosystem health in pristine tropical lagoons, particularly those affected by river plumes from ultramafic watersheds.
Dynamics of Suspended Sediments during a Dry Season and Their Consequences on Metal Transportation in a Coral Reef Lagoon Impacted by Mining Activities, New Caledonia
Research reveals that particle aggregation reduces metal concentrations in suspended particulate matter (SPM) during dry seasons, significantly impacting metal transportation in coral reef lagoons affected by mining activities. The study quantified vertical fluxes of SPM and metals across three bays in New Caledonia's lagoon system—Boulari Bay (moderately impacted), St Vincent Bay (highly impacted), and Dumbéa Bay (weakly impacted)—finding average SPM fluxes of 37.70 ± 14.60 g·m²·d⁻¹, with fine particles dominating. Wind and tidal cycles emerged as key drivers, particularly in St Vincent and Dumbéa Bays, where metal dynamics were closely tied to clay, iron minerals, and carbonate transport from rivers and lagoonal sources. The decline in metal distribution constants (Kd) underscored the role of aggregation in mitigating metal loads, offering critical insights for managing mining impacts on these fragile ecosystems.
Wave forcing and morphological changes of New Caledonia lagoon islets: Insights on their possible relations
Research suggests that wave dynamics significantly influence the morphological changes of islets within the UNESCO-listed Lagoons of New Caledonia. The study identifies three dominant wave types affecting these islets: high-frequency lagoon-generated waves, low-frequency swells from the Tasman Sea, and infragravity waves. High-frequency waves primarily drive islet morphology during typical wind events year-round, while infragravity waves dominate during seasonal swell events, often generated by breaking low-frequency waves or propagated through reef channels. Topographic surveys revealed both seasonal changes and longer-term erosion patterns, hinting at a potential link between wave forcing and islet evolution. Though further validation is needed, this work provides critical insights into the complex interactions shaping these fragile ecosystems.
Contribution and pathways of diazotroph-derived nitrogen to zooplankton during the VAHINE mesocosm experiment in the oligotrophic New Caledonia lagoon
A groundbreaking study reveals that unicellular diazotrophic cyanobacteria (UCYN-C) significantly contribute to zooplankton nitrogen biomass through direct grazing, marking the first evidence of such a pathway. Conducted during the VAHINE mesocosm experiment in New Caledonia's oligotrophic lagoon, researchers deployed large-scale mesocosms to stimulate diazotroph production and track its impact on zooplankton. Using isotopic mixing models and 15N2 labeling, they found that UCYN-C-derived nitrogen accounted for up to 73% of zooplankton biomass in one mesocosm, while other diazotrophs like het-1 and Trichodesmium relied more on secondary pathways. The study highlights the dual role of UCYN-C in the lagoon's food web, providing critical insights into nitrogen cycling in low-nutrient tropical ecosystems.
Diurnal temporal patterns of the diversity and the abundance of reef fishes in a branching coral patch in New Caledonia
A study on the Lagoons of New Caledonia reveals significant diurnal variability in reef fish diversity and abundance. Researchers used autonomous video systems to record fish assemblages 10 times daily for 34 days, capturing over 50,000 observations from 114 taxa. The findings indicate that fish richness and abundance peak during early morning and late afternoon, with notable temporal patterns in the abundance of 14 taxa, primarily herbivore-detritus feeders. These patterns suggest diel migration behaviors, emphasizing the importance of accounting for small-scale temporal variability in ecological studies and habitat connectivity assessments.
Heterotrophic bacterial production and metabolic balance during the VAHINE mesocosm experiment in the New Caledonia lagoon
Heterotrophic bacterial production (BP) was found to be significantly stimulated by nitrogen enrichment, suggesting nitrogen limitation of heterotrophic bacteria throughout the experiment. The study, conducted during the VAHINE mesocosm experiment in New Caledonia's lagoon, revealed that BP was highly correlated with particulate primary production and chlorophyll biomass but only slightly correlated with N2 fixation rates during the second phase (P2). Bacterial growth efficiency, at 27–43%, was notably higher than expected for oligotrophic environments, possibly due to the presence of proteorhodopsin-expressing bacteria. The main fates of gross primary production were respiration (67%) and sedimentation (17%). Diazotroph-derived nitrogen primarily fueled the heterotrophic bacterial community through indirect processes like mortality, lysis, and grazing.
Lagoon islets as indicators of recent environmental changes in the South Pacific – The New Caledonian example
Nineteen percent of the 21 lagoon islets studied in New Caledonia are in a highly critical state, likely to disappear within the next few years due to climate change and environmental degradation. Researchers developed a typology of islet stages and a life expectancy index to assess their vulnerability, revealing that sea level rise, reef ecosystem degradation, sediment loss, human activity, and coastal development collectively threaten these fragile indicators of environmental and climatic change in the South Pacific.
Succession within the prokaryotic communities during the VAHINE mesocosms experiment in the New Caledonia lagoon
A study on the Lagoons of New Caledonia reveals that nitrogen fixation, driven by diazotrophs, significantly boosts primary production in oligotrophic coastal ecosystems. The VAHINE experiment used large-volume mesocosms to track the impact of phosphorus fertilization on microbial communities and biogeochemical processes over 23 days. While enclosure effects were observed, no pronounced 'bottle effect' occurred, and phosphorus addition did not immediately alter community structure but influenced later population dynamics. Notably, UCYN-C-type cyanobacteria exhibited among the highest nitrogen-fixation rates recorded in the region, stimulating growth of heterotrophic groups like Rhodobacteraceae. Temporal changes were more influential than enclosure location, with prokaryotic diversity remaining relatively stable, underscoring the resilience and complexity of lagoon ecosystems.
Diazotroph community succession during the VAHINE mesocosm experiment (New Caledonia lagoon)
A study conducted in the low-nutrient, low-chlorophyll waters of the Noumea lagoon (New Caledonia) revealed that unicellular cyanobacterial Group C (UCYN-C) exhibited rapid growth under specific conditions, reaching among the highest net growth rates reported for diazotrophs. The VAHINE mesocosm experiment demonstrated that UCYN-C became dominant in response to fertilization with dissolved inorganic phosphate (DIP), despite low abundances outside the mesocosms. This suggests that DIP fertilization and increasing temperatures created favorable conditions for UCYN-C growth, while other diazotrophs like heterocyst-forming Richelia associated with Rhizosolenia (Het-1) dominated early in the experiment. The study also highlighted a diverse field population of diazotrophs in the lagoon, including two ecotypes of Braarudosphaera bigelowii symbiont unicellular group A (UCYN-A), with UCYN-A2 being more abundant than UCYN-A1.
Dinitrogen fixation and dissolved organic nitrogen fueled primary production and particulate export during the VAHINE mesocosm experiment (New Caledonia lagoon)
A significant finding from the VAHINE mesocosm experiment in New Caledonia's lagoons reveals that dinitrogen (N2) fixation and dissolved organic nitrogen (DON) play crucial roles in fueling primary production and particulate export, especially under nitrate-depleted conditions. The study demonstrated that while diazotrophic communities, such as diatom–diazotroph associations (DDAs) and unicellular cyanobacteria UCYN-C, both contribute to N2 fixation, UCYN-C-driven production was more efficient at promoting carbon export compared to DDAs. Additionally, DON consumption during the latter phase of the experiment suggested its importance as an additional nitrogen source, highlighting its potential significance in nitrogen-limited oceanic ecosystems.
In situ orientation of fish larvae can vary among regions
Larval coral-reef fishes exhibit location-dependent orientation at regional scales, a discovery that challenges assumptions about their dispersal behavior. Research on the damselfish Chromis atripectoralis revealed significant differences in through-water swimming direction across three regions: the northern Great Barrier Reef (NGBR), central Great Barrier Reef (CGBR), and New Caledonia reef lagoon (NCRL). While larvae swam southerly at NGBR, they oriented easterly at CGBR and NCRL. Over-bottom orientation varied similarly, with strong westerly currents observed in NCRL. This regional variation suggests an evolutionary adaptation to local hydrodynamic conditions, limiting downstream dispersal. The study used in situ diver observations and GPS tracking over 20 years, providing the first evidence of such behavior at a regional scale.
Major Sources of Organic Matter in a Complex Coral Reef Lagoon: Identification from Isotopic Signatures (δ13C and δ15N)
A comprehensive analysis of the Lagoons of New Caledonia reveals that coral reef trophic networks are sustained by a diverse range of organic matter (OM) sources, varying significantly in origin and composition. The study found that δ13C isotopic signatures were more effective than δ15N in identifying these sources, which include mangroves, seagrass beds, rivers, and marine particulate OM. Spatial variations along a coast-to-barrier reef gradient showed that while river-derived OM dominates near the coast, marine-derived OM becomes prevalent on barrier reefs. The relative importance of different OM sources shifts seasonally and spatially, with seagrass, Trichodesmium spp., and macroalgae gaining prominence further from the coast. This research underscores substantial trophic connections between coral reefs and surrounding ecosystems, emphasizing the need for fine-scale environmental assessments to understand broader patterns.
Pattern of movements within a home reef in the Chesterfield Islands (Coral Sea) by the endangered Giant Grouper,Epinephelus lanceolatus
A Giant Grouper, Epinephelus lanceolatus, exhibited consistent residency within a home reef in the Chesterfield Islands (Coral Sea), with increased activity during dawn and dusk, likely for foraging. Acoustic tracking over 2.5 years revealed seasonal absences from October to December in 2010 and 2012, coinciding with known spawning periods, while a skipped spawning event was suspected in 2011. The study highlights the need for future research to locate spawning sites to inform conservation strategies. Given its ecological significance as part of the Coral Sea—linking two UNESCO World Heritage Sites—the Chesterfield Islands warrant designation as a Marine Protected Area (MPA) to safeguard this endangered species and associated ecosystems.
Preliminary identification of key coral species from N ew C aledonia ( S outhwest P acific O cean), their significance to reef formation, and responses to environmental change
A study identifies at least 19 genera and 33 coral species, including Goniastrea retiformis, Isopora palifera, and Porites spp., as key contributors to reef formation in New Caledonia's Pleistocene and Holocene barrier reefs. These species, termed 'key coral species' (KCS), are critical for the resilience of coral ecosystems under projected sea-level rise (0.2–0.6 m/100 years). However, their current decline underscores urgent conservation needs. The research analyzed six core samples from three reefs—Islets Kendec, Amédée, and Bayes—to assess species' roles in reef maintenance, highlighting the vulnerability of these ecosystems to environmental change.
Sedimentology and magnetic susceptibility of recent sediments from New Caledonia
Recent sediments from New Caledonia's lagoons reveal distinct magnetic susceptibility (MS) patterns linked to sediment composition and environmental conditions. Key findings indicate that carbonate sediments exhibit lower MS compared to detrital sediments, with mixed sediments showing MS influenced predominantly by the proportion of detrital material. Strong correlations between MS and manganese/iron content were observed, while beachrocks displayed lower MS than equivalent loose sediments. Additionally, reducing subsurface sediments exhibited higher MS than surface counterparts, suggesting environmental factors play a significant role in magnetic signal variability. The study analyzed over 300 samples for grain size, sediment nature, MS, and geochemistry, providing new insights into the primary origin of minerals carrying the MS signal in tropical coastal environments.
Segregation in Diet between Black Noddy (Anous minutus) and Brown Noddy (A. stolidus) from the Southern Lagoon of New Caledonia
Research on the Lagoons of New Caledonia reveals distinct dietary segregation between Black Noddy (Anous minutus) and Brown Noddy (A. stolidus), indicating spatial separation in foraging zones. While both species primarily consume fish, Black Noddies target small pelagic fishes like round herrings (Spratelloides spp.) closer to shore, whereas Brown Noddies prey on larger offshore species such as buccaneer anchovy (Encrasicholina punctifer) and squid. This segregation is more pronounced than observed in other sympatric populations, suggesting niche partitioning driven by body size and foraging distance. The study analyzed regurgitations from birds nesting at Kouaré Islet over two breeding seasons (2002/2003 and 2003/2004), providing insights into the ecological dynamics of these seabirds in a UNESCO World Heritage Site.
Diversity of trypanorhynch metacestodes in teleost fishes from coral reefs off eastern Australia and New Caledonia
A study of trypanorhynch metacestodes in teleost fishes from coral reefs off eastern Australia and New Caledonia revealed 33 named species, including three undescribed tentacularioids, with over 100 new host records. The research found that lacistorhynchoid and tentacularioid taxa were predominant, while otobothrioid and gymnorhynchoids were less common. Notably, five trypanorhynch species exhibited low host specificity, suggesting broader ecological roles. The study also indicated higher diversity in larger piscivorous fish families and a 45% similarity between the fauna of the Great Barrier Reef and New Caledonia. Additionally, several extensively surveyed fish families showed no presence of trypanorhynch larvae.
Fluid chemistry of the low temperature hyperalkaline hydrothermal system of Prony Bay (New Caledonia)
Researchers have uncovered the unique fluid chemistry of Prony Bay's hyperalkaline hydrothermal system, revealing a distinct low-temperature environment unlike any other known serpentinizing systems. The study identified submarine vents discharging high-pH fluids (up to pH 11) with temperatures reaching 37°C and hydrogen-rich gases (12-30% H₂). Chemical analysis of 45 water samples from six sites showed that these fluids, originating from meteoric sources, mix with seawater, creating sharp gradients in pH, salinity, and dissolved elements. Notably, the system exhibits supersaturation of Mg- and Mg-Ca carbonates at pH ~10, indicating active brucite formation due to reducing conditions. Unlike fully continental or marine systems (e.g., Oman or Lost City), Prony Bay's hyperalkaline discharge is unique, offering insights into serpentinization processes in ultramafic environments.
Influence of CDOM and particle composition on ocean color of the Eastern New Caledonia Lagoon during the CALIOPE cruises
The ocean color of the Eastern New Caledonia Lagoon, a UNESCO World Heritage Site renowned for its marine biodiversity, is significantly influenced by chromophoric dissolved organic matter (CDOM) and particle composition. High rainfall events can introduce substantial CDOM and particulate loads, impacting ecosystem functioning and potentially causing localized effects from river runoff and sewage effluents. The study, conducted during two oceanographic cruises (CALIOPE 1 in 2011 and CALIOPE 2 in 2014), employed multi- and hyper-spectral radiometers alongside inherent optical property measurements to assess these influences. Findings highlight the importance of spatial variations in flushing times on trophic states, while also evaluating the performance of ocean color algorithms using a Linear Matrix Inversion method. This research provides critical tools for remote sensing in this under-sampled coastal region, offering insights into the complex interactions between optical properties and ecosystem dynamics.
Migrations of Green Turtles (Chelonia mydas) between Nesting and Foraging Grounds across the Coral Sea
A significant discovery in the study of green turtle migrations reveals that turtles foraging in New Caledonia's lagoons nest along the Great Barrier Reef (Australia) and vice versa, despite the availability of local foraging grounds. This long-distance migration pattern, spanning 1200 to 2680 kilometers, challenges conventional understanding of energetically efficient movement behaviors. Analysis of 50 years of tagging data from Queensland and New Caledonia identified 97 migrations, with most recovered turtles in New Caledonia originating from the southern Great Barrier Reef genetic stock. Notably, two females exhibited fidelity to distant foraging sites, highlighting previously unknown migration pathways within the Coral Sea. This research sheds light on the complex movement patterns of endangered marine megafauna and their implications for conservation management.
Atmospheric correction and inherent optical property estimation in the southwest New Caledonia lagoon using AVNIR-2 high-resolution data
A novel method for estimating inherent optical properties (IOPs) and chlorophyll-a concentration (Chla) using high-resolution AVNIR-2 satellite data was successfully validated in the southwest lagoon of New Caledonia. By iteratively correcting atmospheric and sea-surface reflectance, followed by seafloor reflectance adjustments, researchers achieved estimates that closely matched in situ measurements—even in complex lagoon environments. This approach demonstrates the potential for local optimization of IOPs and Chla retrievals with high-resolution sensors, offering a practical tool for monitoring coastal ecosystems.
Control of paleoshorelines by trench forebulge uplift, Loyalty Islands
The Loyalty Islands, part of the UNESCO World Heritage Site Lagoons of New Caledonia, exhibit unique paleoshoreline features shaped by neotectonic uplift. Unlike most tropical Pacific islands, these islands formed due to the uplift of pre-existing atolls on the flexural forebulge of the New Hebrides Trench. The study reveals that island morphology and topography vary with distance from the trench crest, influencing emergent paleoatolls like Maré and Lifou, which display ancient barrier reefs forming high-standing annular ridges around interior plateaus representing paleolagoon floors. Ouvea's partially emergent rim flanks a drowned lagoon, showcasing diverse paleoshoreline features such as paleoreef flats and tidal notches. These features record uplift rates since the last interglacial and mid-Holocene sea-level highstands, aligning with theoretical predictions based on trench subduction rates. The research highlights the Loyalty Islands as a case study for neotectonically controlled island environments.
Influence of Water Column Chlorophyll Concentration on Bathymetric Estimations in the Lagoon of New Caledonia, Using Several MERIS Images
Variations in water column chlorophyll concentration significantly impact bathymetric estimations derived from multispectral satellite imagery, particularly in optically complex environments like the Lagoon of New Caledonia. The study demonstrates that a method using Medium Resolution Imaging Spectrometer (MERIS) images—rotating red and green spectral bands to isolate depth-dependent and reflectance-dependent components—yields accurate bathymetric results only when chlorophyll concentrations remain low (<3) and stable (<10% variation). Exceeding these thresholds leads to increased root mean square error (RMSE) in bathymetric maps, underscoring the critical role of water composition in remote sensing accuracy. This finding highlights the need for careful consideration of chlorophyll variability when using satellite data for underwater topography mapping.
Molecular diversity of the Caulerpa racemosa–Caulerpa peltata complex (Caulerpaceae, Bryopsidales) in New Caledonia, with new Australasian records for C. racemosa var. cylindracea
A molecular analysis of the Caulerpa racemosa–Caulerpa peltata complex in New Caledonia revealed five distinct lineages, suggesting hidden species diversity within the group. Globally, the complex comprises six lineages, with two distributed pantropically and four confined to the Indo-Pacific region. Notably, this study reports new Australasian records for Caulerpa racemosa var. cylindracea, a fast-spreading invasive species previously thought limited to southwestern Australia, including its presence in New Caledonia and northern Australian locations, such as the Great Barrier Reef. The research used plastid-encoded tufA gene sequencing to assess genetic diversity, providing critical insights into the biogeography and taxonomic structure of this ecologically significant group.
Resurrection of New Caledonian maskray Neotrygon trigonoides (Myliobatoidei: Dasyatidae) from synonymy with N. kuhlii, based on cytochrome-oxidase I gene sequences and spotting patterns
A new study challenges the long-standing classification of the New Caledonian maskray, revealing it as a distinct species separate from the widely distributed blue-spotted maskray. Using cytochrome-oxidase I (COI) gene sequences and spotting pattern analysis, researchers identified a significant genetic divergence (2.6%) between the New Caledonian maskray and typical N. kuhlii samples from the Indian Ocean and Coral Triangle. The study's findings, based on specimens collected across multiple regions, demonstrate that the New Caledonian maskray forms a phylogenetically distinct haplogroup, justifying its resurrection as Neotrygon trigonoides. This research sheds light on the cryptic biodiversity within UNESCO World Heritage Sites like the Lagoons of New Caledonia and underscores the importance of genetic analysis in species delimitation.
Sex-based spatial segregation of adult bull sharks,Carcharhinus leucas, in the New Caledonian great lagoon
Adult bull sharks (Carcharhinus leucas) in New Caledonia exhibit sex-based spatial segregation, with males found exclusively at an oceanic barrier coral reef over 100 km from the nearest river mouth, while females reside in coastal waters. This unusual pattern likely stems from the unique estuarine-marine continuum of the New Caledonian great lagoon. The study, the first to track adult bull sharks in the region using passive acoustic tags, monitored two females for up to 707 days, revealing transient behavior and short-term residency around a coastal reef bay, with movements linked to seasonal river dynamics. These findings challenge traditional assumptions about bull shark habitat preferences and underscore the need for targeted conservation strategies to manage shark-human interactions and protect threatened populations.
Eviota atriventris, a New Goby Previously Misidentified as Eviota pellucida Larson (Teleostei: Gobiidae)
A species of goby previously misidentified as Eviota pellucida has been correctly described as the new species, Eviota atriventris. This discovery clarifies taxonomic confusion and expands the known distribution of this genus in the Indo-Pacific region. Eviota atriventris is distinguished from its look-alike by differences in coloration—both in preserved and live states—and pectoral-fin ray counts. While E. pellucida is restricted to a few island groups, including the Gilbert and Marshall Islands, E. atriventris has a broader range spanning the Ryukyu, Philippine, Palau, Indonesian, Papua New Guinean, Solomon, and New Caledonian waters, as well as the Great Barrier Reef in Australia. This correction is based on morphological comparisons, ensuring accurate species identification for future ecological and taxonomic studies.
Can differences in the structure of larval, juvenile and adult coral‐reef fish assemblages be detected at the family level?
Research reveals that coral-reef fish assemblages exhibit distinct spatial structures at different life stages—larval, juvenile, and adult—even when analyzed at the family level. This finding challenges the assumption that coarse taxonomic resolution obscures critical insights into reef ecology. The study compared fish communities across a coast-to-barrier reef gradient in New Caledonia using standardized surveys from 2004 to 2005. Larvae were sampled via light-traps, while juveniles and adults were assessed through underwater visual counts. Multivariate analyses demonstrated significant variability among life stages, locations, and years, with differences detectable even at the family level. These results suggest that large-scale studies using broad taxonomic categories can effectively capture changes in reef fish spatial structure across life stages.
Incongruence between morphotypes and genetically delimited species in the coral genus Stylophora: phenotypic plasticity, morphological convergence, morphological stasis or interspecific hybridization?
A genetic analysis of the coral genus Stylophora reveals that species boundaries do not align with morphological traits, challenging traditional taxonomic classifications. The study, conducted across Madagascar, Okinawa, the Philippines, and New Caledonia, identified three distinct species (A, B, and C) using mitochondrial and nuclear markers. Species A and B are endemic to Madagascar, while species C is widespread in the Indo-Pacific, including New Caledonia's lagoons. Contrary to morphological data suggesting higher diversity in the western Indian Ocean and Red Sea, genetic evidence indicates that species C also occurs in the Coral Triangle, with a distinct fourth species (D) found only in the Red Sea. The research rejects interspecific hybridization as an explanation for morphological incongruence but suggests phenotypic plasticity or morphological stasis may play roles. The findings imply the western Indian Ocean as the likely center of origin for Stylophora, influencing its biodiversity distribution.
Use of fluorescence spectroscopy and voltammetry for the analysis of metal-organic matter interactions in the New Caledonia lagoon
A groundbreaking analysis of the Lagoons of New Caledonia reveals how organic matter (OM) interacts with metals such as Ni, Zn, Pb, Cu, and Cd, providing critical insights into both natural and anthropogenic pollution sources. By combining fluorescence spectroscopy, polarography, and potentiometry, researchers determined the conditional stability constants of OM-metal complexes, enabling predictions about metal pollution's fate in the lagoon. This study also distinguished between terrigenous (natural) and anthropogenic OM origins for the first time, using advanced geochemical modeling with discrete pKa distributions. The findings underscore the sensitivity of nearby coral reef biocenosis to these metal complexes, which originate from nickel extraction and coastal erosion, offering a novel framework for understanding and mitigating environmental impacts on this UNESCO World Heritage Site.
An annotated list of fish parasites (Copepoda, Monogenea, Digenea, Cestoda and Nematoda) collected from Emperors and Emperor Bream (Lethrinidae) in New Caledonia further highlights parasite biodiversity estimates on coral reef fish
A comprehensive study of parasites from 17 species of emperors and emperor bream (Lethrinidae) in New Caledonia's lagoons reveals a rich biodiversity, with an estimated 340 metazoan parasite species associated with lethrinids—averaging 13 per fish species. The research identified 52 parasite species at the species level, including 40 new host records, and highlighted significant biogeographical differences when compared to Heron Island on Australia's Great Barrier Reef. Notably, only five parasite taxa were shared between New Caledonia and Heron Island for a single fish species, Lethrinus miniatus. The study also confirmed that parasite biodiversity in lethrinids is comparable to that in groupers (Serranidae Epinephelinae) in the same region, supporting earlier predictions of 10 parasite species per coral reef fish species. Despite extensive sampling and identification efforts, only 13% of lethrinid parasites are currently known in New Caledonia, underscoring the need for further exploration.
Diploproctodaeum spp. (Digenea, Lepocreadiidae) in Australian and New Caledonian waters including two new species from Tetraodontiformes and new records of related species
Researchers have identified two new species of trematodes, Diploproctodaeum monstrosum and Diploproctodaeum triodoni, from Tetraodontiformes fish hosts in Australian and New Caledonian waters. D. monstrosum, found on Arothron stellatus and A. mappa off Lizard Island, is distinguished by a unique body-length ventral scoop, while D. triodoni, discovered in Triodon macropterus off New Caledonia, features extensive vitelline fields extending to the ventral sucker with folded margins. The study also reports new records of related trematode species from additional hosts or localities, including Diploproctodaeum haustrum and several others, highlighting potential convergent evolution in body form among trematodes infecting tetraodontids, particularly Arothron species. The findings contribute to the understanding of parasitic diversity and host-parasite relationships in these regions.
Multitestis Manter 1931 (Digenea: Lepocreadiidae) in ephippid and chaetodontid fishes (Perciformes) in the south-western Pacific Ocean and the Indian Ocean off Western Australia
Research identifies five species of the genus Multitestis (Digenea: Lepocreadiidae) from ephippid and chaetodontid fishes across the southwestern Pacific Ocean and Western Australia, including two novel species: M. coradioni n. sp. and M. paramagnacetabulum n. sp. The study distinguishes these species based on morphological traits such as body shape, testicular field positioning, and egg size, clarifying taxonomic ambiguities in the region's parasitic flatworms. Morphological analysis of specimens from key locations—Lizard Island, Heron Island (Great Barrier Reef), New Caledonia, and Ningaloo Reef—reveals distinct differences between M. pyriformis and its synonyms, as well as between M. magnacetabulum and the newly described M. paramagnacetabulum. This work contributes to the understanding of digenean diversity in coral reef ecosystems.
New Caledonia surface lagoon chlorophyll modeling as coastal reef area health indicator
A novel 3D coupled physical-biogeochemical model (ECO3M_LAGOON and MARS3D) successfully predicts eutrophication events in New Caledonia's UNESCO-listed lagoon, a critical indicator of reef health. The model integrates nitrogen and carbon cycles, microbial loop dynamics, and environmental variables like tides, wind, light, temperature, and freshwater inputs to simulate phytoplankton biomass, bacterial production, dissolved organic matter, and nutrient recycling. Validated against in situ (ValHyBio 2008) and satellite data (MODIS/MERIS), it reveals spatial-temporal interactions between water motion and biology across the lagoon's complex barrier reef and ocean-lagoon interface. This approach offers a robust tool for monitoring and preserving the biodiversity of this oligotrophic, semi-enclosed tropical ecosystem.
Records of Great White Sharks (Carcharodon carcharias) in New Caledonian Waters
Great white sharks (Carcharodon carcharias) are confirmed to inhabit New Caledonian waters, with 34 individual sharks documented across 30 observation events between 1943 and 2009. These observations, including sightings, captures, and forensic examinations, were predominantly concentrated in the southern lagoon or along the barrier reef, with a seasonal peak from July to March, particularly in September and November. Nearly all sharks were solitary, and some were recorded feeding on whale carcasses or tagged in New Zealand's Chatham Islands. The study highlights the presence of this apex predator in New Caledonia, offering insights into its distribution and behavior, which may coincide with large cetacean occurrences.
Reef Corals of the Eastern Lagoon (Touho-Ponerihouen) of Grande-Terre, New Caledonia
A survey of the northeastern lagoon of New Caledonia identified 333 coral species, including 36 new to the region and nine newly described. This brings the total known coral species in New Caledonia to 457, surpassing previous estimates. The study found higher diversity than other parts of New Caledonia and comparable levels to the Coral Triangle. Notably, five species were listed as endangered and 68 as vulnerable by the IUCN Red List. The research also confirmed the presence of rare species like Heliopora coerulea and Millepora tuberosa, extending their known biogeographic ranges. Coral diversity was highest in lagoon sites, correlated with depth range, and certain sites exhibited high replenishment and rarity indices.
Reproductive Synchrony inAcroporaAssemblages on Reefs of New Caledonia
Research on the Lagoons of New Caledonia, a UNESCO World Heritage Site and home to the world's second largest barrier reef, reveals that Acropora coral reproduction is highly synchronized across eight sites spanning 200 km. The study found that 80% of 1,055 Acropora colonies contained mature oocytes, with 34 out of 37 species exhibiting at least one mature colony. This suggests a multispecies spawning event following the full moon in November, aligning with the mass spawning period on Australia's Great Barrier Reef. The high synchrony implies that even brief disruptions to fertilization and early development, such as liquid waste discharge from ore processing, could significantly impact these globally valued reefs.
Seafloor mapping with MeRIS images in the lagoon of New Caledonia
A novel method for seafloor mapping in the lagoon of New Caledonia has been successfully validated using MeRIS (Medium Resolution Imaging Spectrometer) images. The study demonstrates that light attenuation by water columns can be corrected to obtain absolute seabed reflectance and determine bathymetry through spectral band analysis. By comparing radiance from standard seabed features at varying depths and applying supervised classification, researchers accurately mapped the seafloor in the southwestern part of the lagoon. Validations with ground measurements confirmed the method's reliability, providing a critical tool for understanding reef diversity and associated ecosystems in this ecologically significant region.
Varialvus gen. nov. (Digenea, Cryptogonimidae), from species of Lutjanidae (Perciformes) off the Great Barrier Reef, New Caledonia and the Maldives
Researchers have discovered four new species of cryptogonimid trematodes, prompting the establishment of a novel genus, Varialvus gen. nov., which infects Lutjanidae (Perciformes) across the Indo-West Pacific. This genus is distinguished by unique morphological traits, including a fusiform to oval body, distinct gonadal structures, and specific vitelline follicle distribution. Bayesian inference analysis of genetic data confirmed that these species form a monophyletic clade, despite some morphological variations that might have suggested otherwise. Notably, one species (V. charadrus sp. nov.) exhibits a widespread biogeographic range spanning over 10,000 kilometers, from the Great Barrier Reef to New Caledonia and the Maldives. Additionally, Siphoderina lutjani was reclassified as V. lutjani n. comb. based on morphological and host group agreement with Varialvus gen. nov.
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