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.
You are here:
World Heritage Explorer > World Heritage Research > World Heritage Sites > Lagoons of New Caledonia: Reef Diversity and Associated Ecosystems