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During the COVID-19 pandemic, the reduced exports and imports as well as the lack of activity due to the interruption in the international tourism economy seriously impacted food security in many Pacific Islands. People often returned to natural resources to provide for themselves, their families, or to generate income. On Bora-Bora Island, the major tourist destination in French Polynesia, roadside sales are widespread. Our study analyses the impact of the COVID-19 pandemic on roadside sales activities through a census of roadside stalls on the five Bora-Bora districts conducted before (January and February 2020), during (from March 2020 to October 2021) and after (from November to December 2021) health-related activity and travel restrictions. Our results showed that the marketing system for local products (fruits, vegetables, cooked meals, and fish) increased in the form of roadside sales during the COVID-19 in two of the five districts of Bora-Bora. Roadside selling would be an alternative system for providing food to the population at Bora-Bora during a global crisis and that could reveal itself sustainable after this pandemic.

Understanding the processes that shape biodiversity is essential for effective environmental management. Across the world’s coral reefs, algal farming damselfish ( Stegastes sp.) modify the surrounding benthic community through their creation of algae “farms”. Using a long-term monitoring dataset (2005–2019) from Moorea Island, French Polynesia, we investigated whether the density of dusky damselfish ( Stegastes nigricans ) is associated with benthic habitat composition, the density of predators and/or competitors, and whether the survey area was inside or outside of a Marine Protected Area (MPA). We found no evidence that benthic cover or number of competitors were associated with dusky damselfish densities, both inside and outside MPAs. In contrast, fluctuations in dusky damselfish densities were negatively associated with the density of predators (e.g. Serranidae, Muraenidae and Scorpaenidae) in the preceding year in non-MPA areas, and both within and outside of MPAs when predator densities were high (2005–2010). These results suggest that healthy predator populations may be important for regulating the abundances of keystone species, such as algal farming damselfish, especially when predator densities are high.

Collin, A.; James, D.; Gairin, E.; Aubert, M.; Daniel, Y.; Feunteun, E., and Dubois, S., 2024. The spatial network of the largest honeycomb reef in the world as revealed by an ultra-high resolution lidar drone. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 961-965. Charlotte (North Carolina), ISSN 0749-0208. On temperate coastal areas, Sabellaria alveolata worms are honeycomb reef-builders, providing multiple ecosystem services. The largest honeycomb reef in the world is located in the Bay of Mont-Saint-Michel (France) and has never been surveyed in its entirety at ultra-high spatial resolution. This original research addresses this gap by using a medium-cost drone topographic lidar system over the time window of a low spring tide. A denoised lidar point cloud, composed of 702 million illuminations (on average, 118 points/m2), enabled to compute point-scaled height above the ground at an accuracy of 0.06 m. The 3033 reef patches of height ≥ 0.5 m allowed to draw a graph-based network, woven with 3032 edges. The contribution of each node and edge was estimated and mapped using Betweenness Centrality, a local weighted connectivity metric. The nodes of the central and seaward front sub-reefs primarily contributed to the network's anchoring, while the edges linking the easternmost and westernmost sub-reefs were crucial to ensure full connectivity. The use of ultra-high spatial resolution, at very high temporal resolution, paves the way to seasonally monitor the world's largest honeycomb reef in order to outline areas subjected to erosion, and rapidly manage threats upon that ecosystem.

Coral reefs encompass different habitats that have their own living communities. The present study aimed to test the hypothesis that these different kinds of habitats were characterized by specific soundscapes. Within the lagoon of Bora-Bora, acoustic recordings and visual surveys of substrate type and fish communities were conducted on four reef sites belonging to the three main geomorphological habitats (fringing reef, channel reef, barrier reef) from February to April 2021. Two acoustic parameters were measured for each site and month, during the day and at night: the peak frequency (Fpeak, in Hz) and the corresponding power spectral density (PSDpeak, in dB re 1 µPa2 Hz−1). Our results showed that each geomorphological unit could be characterized by these two parameters and therefore had a specific acoustic signature. Moreover, our study showed that a higher living coral cover was significantly positively correlated with Fpeak in the low-frequency band (50–2000 Hz) during day-time. Although biodiversity indices based on visual surveys did not differ significantly, fish communities and soundscapes were significantly different between sites. Overall, our study underlines the importance of passive acoustics in coral reef monitoring as soundscapes are habitat specific.

Throughout the world, anthropogenic pressure on natural ecosystems is intensifying, notably through urbanisation, economic development, and tourism. Coral reefs have become exposed to stressors related to tourism. To reveal the impact of human activities on fish communities, we used COVID-19-related social restrictions in 2021. In French Polynesia, from February to December 2021, there was a series of restrictions on local activities and international tourism. We assessed the response of fish populations in terms of changes in the species richness and density of fish in the lagoon of Bora-Bora (French Polynesia). We selected sites with varying human pressures—some dedicated to tourism activities, others affected by boat traffic, and control sites with little human presence. Underwater visual surveys demonstrated that fish density and richness differed spatially and temporally. They were lowest on sites affected by boat traffic regardless of pandemic-related restrictions, and when activities were authorised; they were highest during lockdowns. Adult fish density increased threefold on sites usually affected by boat traffic during lockdowns and increased 2.7-fold on eco-tourism sites during international travel bans. Human activities are major drivers of fish density and species richness spatially across the lagoon of Bora-Bora but also temporally across pandemic-related restrictions, with dynamic responses to different restrictions. These results highlight the opportunity provided by pauses in human activities to assess their impact on the environment and confirm the need for sustainable lagoon management in Bora-Bora and similar coral reef settings affected by tourism and boat traffic.

The diverse pigmentation patterns of animals are crucial for predation avoidance and behavioral display. This diversity arises from interactions among distinct pigment cell types, yet mechanisms generating pattern variation across teleost fishes remain incompletely understood. In zebrafish, Turing models have been proposed to explain stripe patterns, but it is unclear if they apply to other fishes. Here, we investigate the Snowflake mutant of the anemonefish Amphiprion ocellaris , which displays enlarged white bars with irregular boundaries. Using genome-wide association mapping and targeted sequencing, we identify a missense mutation (E42K) in gja5b , encoding the gap junction protein Connexin 41.8. CRISPR/Cas9-mediated genome editing recapitulates the Snowflake phenotype, while pharmacological inhibition of gap junctions phenocopies the boundary defects, supporting a causal role for impaired intercellular communication. Expression analyses reveal that, unlike zebrafish, anemonefish gja5b is predominantly expressed in iridophores. With functional in vitro assays we demonstrate that the E42K mutation acts as a dominant negative, strongly reducing gap junctional coupling. Introducing the same mutation in zebrafish reveals context-dependent effects on pigment patterning. Taken together our findings highlighting gap junction–mediated communication as a conserved but flexible mechanism controlling pigment boundary positioning and pattern diversification. This study shows that the Snowflake mutant in clownfish results from altered communication between pigment cells, producing enlarged white bars with jagged edges. It points to cell–cell communication as a driver of color pattern diversity in fishes.

Coastal urbanisation is a widespread phenomenon throughout the world and is often linked to increased erosion. Small Pacific islands are not spared from this issue, which is of great importance in the context of climate change. The French Polynesian island of Bora Bora was used as a case study to investigate the historical evolution of its coastline classification and position from 1955 to 2019. A time series of very high-resolution aerial imagery was processed to highlight the changes of the island’s coastline. The overall length of natural shores, including beaches, decreased by 46% from 1955 to 2019 while human-made shores such as seawalls increased by 476%, and as of 2019 represented 61% of the coastline. This evolution alters sedimentary processes: the time series of aerial images highlights increased erosion in the vicinity of seawalls and embankments, leading to the incremental need to construct additional walls. In addition, the gradual removal of natural shoreline types modifies landscapes and may negatively impact marine biodiversity. Through documenting coastal changes to Bora Bora over time, this study highlights the impacts of human-made structures on erosional processes and underscores the need for sustainable coastal management plans in French Polynesia.

Anemonefish are an emerging group of model organisms for studying genetic, ecological, evolutionary, and developmental traits of coral reef fish. The yellowtail clownfish Amphiprion clarkii possesses species-specific characteristics such as inter-species co-habitation, high intra-species color variation, no anemone specificity, and a broad geographic distribution, that can increase our understanding of anemonefish evolutionary history, behavioral strategies, fish-anemone symbiosis, and color pattern evolution. Despite its position as an emerging model species, the genome of A. clarkii is yet to be published. Using PacBio long-read sequencing and Hi-C chromatin capture technology, we generated a high-quality chromosome-scale genome assembly initially comprised of 1,840 contigs with an N50 of 1,203,211 bp. These contigs were successfully anchored into 24 chromosomes of 843,582,782 bp and annotated with 25,050 protein-coding genes encompassing 97.0% of conserved actinopterygian genes, making the quality and completeness of this genome the highest among all published anemonefish genomes to date. Transcriptomic analysis identified tissue-specific gene expression patterns, with the brain and optic lobe having the largest number of expressed genes. Further analyses revealed higher copy numbers of erbb3b (a gene involved in melanocyte development) in A. clarkii compared with other anemonefish, thus suggesting a possible link between erbb3b and the natural melanism polymorphism observed in A. clarkii. The publication of this high-quality genome, along with A. clarkii's many unique traits, position this species as an ideal model organism for addressing scientific questions across a range of disciplines.

In the context of the general overexploitation of South Pacific reef fisheries, there is a global push to precisely define fishery parameters such as fishing effort, annual landings, and exploitation levels. In Bora-Bora, several surveys were performed to define the fishing grounds and the fishing effort of the reef fishery for the first time. Maps of the fishing grounds under different fishing pressures were created for the Bora-Bora reef fishery. The average fishing effort throughout the lagoon was 40 trips week −1 km −2 . Annual landings were estimated following two different methods: school participatory surveys and landing based on the catch per unit effort. These estimations were used to determine that the maximum sustainable yield of the island's fisheries was 6.5 tons km −2 year −1 . the reported annual yield in 2022 was 5.35 tons km −2 year −1 , under the estimated maximum sustainable yield. The level of exploitation of the fisheries was also estimated based on the catch size composition of the ten most fished species. This revealed that fishing is responsible for more than 50% of fish mortality in six of the ten studied species, and that catch length could be increased to optimize both catches and biomass. Overall, the Bora-Bora reef fishery may be experiencing growth overfishing (i.e., the catching of fish that are too small to maximise biological sustainability and economical yield), which can endanger stock recruitment in the future if no actions are taken.

Giraud-Renard, E.; Dolique, F.; Collin, A.; James, D.; Gairin, E.; Courteille, M.; Beaufort, O.; René-Trouillefou, M.; Dulormne, M.; Jeanson, M., and Lecchini, D., 2022. Long-term evolution of the Guadeloupean shoreline (1950–2017). Journal of Coastal Research, 38(5), 976–987. Coconut Creek (Florida), ISSN 0749-0208. Insular environments have long been recognized as sensitive to issues linked to natural forces that occur every day (swells, currents, and winds) or that are exceptional (storms and cyclones). However, over the past few decades, additional pressure has arisen throughout many already-fragile islands: anthropization, the modification of natural areas by humans and for human usage. Since the 1970s, the number of tourists visiting Guadeloupe Island has strongly increased, driving coastline modifications (building of houses, hotels, diving clubs, etc.). Using panchromatic and high-resolution aerial imagery, the evolution of the coastline from 1950 to 2017 of 19 Guadeloupean beaches was assessed. This evolution was compared with a coastal vulnerability index to determine the sensitivity to morphological, hydrodynamic, and anthropic factors of each studied beach. The results showed that the Guadeloupe coast has become increasingly urbanized since the 1950s, with a transition from 4% of manmade structures along the shoreline in 1950 to 18% in 2017 across the study sites. Across all beaches, coastal erosion was noted and was caused by the simultaneous action of natural factors (hydrodynamics, storms, etc.) or anthropogenic factors (mass tourism, economic development, etc.). Overall, this study highlights the issue of coastal artificialization in Guadeloupe. To avoid irreversible detrimental effects of coastal degradation on the local population and the country's economy, new decisions favoring natural coastal environment buffers must be made rapidly. □ ABSTRACT IN NATIVE LANGUAGE □ Les milieux insulaires sont depuis longtemps reconnus comme sensibles aux problématiques liées aux processus naturels quotidiens (houles, courants, vents) et exceptionnels (tempêtes, cyclones). Cependant, au cours des dernières décennies, une pression supplémentaire s'est ajoutée sur ces milieux insulaires déjà fragiles: l'anthropisation. Depuis les années 1970, l'archipel Guadeloupéen a connu chaque année une augmentation significative du nombre de touristes, ce qui a entraîné des modifications du littoral. Grâce aux imageries aériennes panchromatiques et à haute résolution, l'évolution du littoral de 19 plages guadeloupéennes de 1950 à 2017 a été évaluée. Cette évolution a été comparée à un indice de vulnérabilité côtière afin de déterminer la sensibilité aux facteurs morphologiques, hydrodynamiques et anthropiques de chaque plage étudiée. Les résultats ont montré que le littoral Guadeloupéen s'est fortement urbanisé depuis les années 1950, passant d'un littoral rocheux (18% en 1950 et 19% en 2017), sableux (28% en 1950 et 19% en 2017) ou de mangroves (50% en 1950 et 42% en 2017) à un littoral fortement anthropisé dans les années 2000 (4% en 1950 et 18% en 2017). Sur l'ensemble des plages étudiées, une érosion côtière a été constatée causée par l'action simultanée de facteurs naturels (hydrodynamisme, tempêtes, etc.), de facteurs anthropiques (tourisme de masse, développement économique, etc.) et des effets du changement climatique (élévation du niveau de la mer). Globalement, cette étude met en évidence la problématique de l'artificialisation du littoral en Guadeloupe, problématique répandue à l'échelle mondiale. Afin d'éviter des effets néfastes irréversibles sur la population locale et l'économie du pays lié à la dégradation du littoral, de nouvelles décisions favorisant les zones tampons naturelles du milieu côtier doivent être rapidement mises en place.