Search Results (140)

The Union of the Comoros, located in the Indian Ocean, faces persistent energy challenges due to its geographic isolation, heavy dependence on imported fossil fuels, and underdeveloped electricity infrastructure. This study investigates the techno-economic optimization of a hybrid microgrid designed to supply electricity to a rural village in Grande Comore. The proposed system integrates photovoltaic (PV) panels, wind turbines, a diesel generator, and battery storage. Detailed modeling and simulation were conducted using HOMER Energy, accompanied by a sensitivity analysis on solar irradiance, wind speed, and diesel price. The results indicate that the optimal configuration consists solely of PV and battery storage, meeting 100% of the annual electricity demand with a competitive levelized cost of energy (LCOE) of 0.563 USD/kWh and zero greenhouse gas emissions. Solar PV contributes over 99% of the total energy production, while wind and diesel components remain unused under optimal conditions. Furthermore, the system generates a substantial energy surplus of 63.7%, which could be leveraged for community applications such as water pumping, public lighting, or future system expansion. This study highlights the technical viability, economic competitiveness, and environmental sustainability of 100% solar microgrids for non-interconnected island territories. The approach provides a practical and replicable decision-support framework for decentralized energy planning in remote and vulnerable regions. Full article

Closed-circuit rebreather diving has opened new opportunities for direct observation of the rich biodiversity of unexplored mesophotic coral ecosystems. We recently encountered four specimens of a rare benthic ctenophore genus, Lyrocteis. The specimens were found on the east coast of Réunion Island off the harbor of Sainte Rose at ~95 m. This finding contributes to the limited number of records of the genus in the Indian Ocean. Continued exploration of mesophotic zones remains essential, as each dive has the potential to reveal remarkable and unexpected discoveries. Full article

The concentration of microplastics [300–5000 µm] in the surface water of the Mayotte lagoon, Western Indian Ocean, was measured over two snapshot campaigns conducted during the dry and rainy seasons. The concentration in the surface water varied from 0.01 MP m⁻³ to 1.23 MP m⁻³ and was higher during the rainy season. All particles were analyzed via µFTIR, enabling systematic polymer and surface area determination. Polypropylene dominated over polyethylene and polystyrene, representing 70% of the microplastic particles observed. The microplastics, which were predominantly in the [0.3–1000 µm] fraction, presented a similar seasonal trend of distribution with respect to their occurrence, suggesting that turbulence and the subsequent settling of microplastics in the lagoon’s surface water were identical during the two campaigns. PCA was performed to deconvolute the effects of season and hydrodynamic features on the observed surface water concentrations and median size distribution. It evidenced a high degree of disparity in concentration and median area in surface water during the rainy season, while a lower concentration of smaller particles was observed during the end of the dry season. A microplastic risk assessment was performed for the surface water of the lagoon and evidenced a low pollution load index and low to high polymer risk assessment and potential ecological risk indexes. Full article

Giant clams are ecologically important coral reef animals, with many species facing imminent local extinction. While many regions have undertaken recent assessments of their biodiversity assets, persistent gaps remain even in otherwise well-surveyed areas. This study sought to understand the geographic distribution of smaller-bodied and morphologically similar giant clams, specifically Tridacna maxima and T. noae, in the eastern Indian Ocean. Due to the difficulties in reliably identifying these species using morphological characters, we confirmed species identity and investigated intraspecific variation using sequence data from the mitochondrial cytochrome C oxidase subunit I gene (COI). Seventy whole animal vouchers were newly sampled from a 1500 km span of remote northwestern Australian coastline over a decade, as part of an ongoing coral reef survey expedition of the Western Australian Museum and partners. Tridacna maxima had a limited distribution and was only genotyped from offshore oceanic reefs in the Rowley Shoals and Cocos Keeling Islands. In contrast, T. noae was well established beyond Ningaloo Reef, and was abundant at inshore sites throughout the Pilbara and Kimberley, and even offshore to Ashmore Reef. Phylogeographically, T. maxima did not group with conspecifics from the Western Pacific Ocean, including the east coast of Australia, but instead clustered with individuals from Malaysia, China, Taiwan, and Indonesia; T. noae exhibited a similar pattern. The affinity of Western Australian individuals with representatives from the Indo-Malay region and not eastern Australia will be an important consideration for these commercially important species. Novel haplotypes in both tested species occur in Western Australia. Continued sampling of eastern and central Indian Ocean giant clams, especially to continue to document the range of T. noae, is encouraged to understand connectivity in this basin. Together, these findings contribute to an improved baseline for conservation initiatives of these iconic coral reef animals in Western Australia. Full article

The Southern Ocean, located between Antarctica and the southern tips of South America, Africa and Australia, encompasses an immense area across the southern Atlantic, Pacific and Indian oceans with no clearly defined limits. For the purposes of studying marine heterobranch sea slugs, we consider the Southern Ocean to include all ocean areas located south of latitude 41° S. South of this latitude, we consider different areas and zones: the area of South America (the Patagonia/Magellanic area), the island of Tasmania, the southern island of New Zealand, the Subantarctic area (the Falkland Islands, South Georgia Island, the South Orkney Islands, South Sandwich Island, Bouvet Island, the islands of Crozet and Prince Edward, the Kerguelen Islands, and Macquarie Island) and the area of Antarctica, in which we consider four zones (Weddell Sea, West Antarctica, Ross Sea and East Antarctica). Reviewing all available references and unpublished data from the authors, in total, 394 species of heterobranch sea slugs have been recorded to date in the Southern Ocean > 41° S, with Nudibranchia standing out with 209 species and Cephalaspidea with 90 species. The marine heterobranchs of Tasmania (154 species) and southern New Zealand (120 species) have been well studied. Sea slug fauna of the Antarctic and Subantarctic regions have been the subject of several partial studies; however, there are still many gaps in knowledge across both areas. Eighty-nine different species of sea slug have been recorded so far in strictly Antarctic waters (West Antarctica, 45 species; Weddell Sea, 48 species; Ross Sea, 51 species; East Antarctica, 42 species), while in the various Subantarctic regions, there are 93 species (36 species from South Georgia, 17 species from the South Orkneys, 12 species from south Sandwich, 6 species from Bouvet, 10 species from Prince Edward and Crozet Islands, 15 species from Kerguelen, 3 species from Macquarie Island, 29 species from the Falkland Islands and 71 species from the coast of South America). In the taxonomic section, for each of the species, the location and the authors of the records are indicated, and for many of the species, interesting biological, taxonomic or biogeographic observations are also provided. The importance of sampling in underexplored areas is discussed, as well as greater-depth sampling for a better understanding of the sea slugs of the Southern Ocean. Full article

The Southeastern Tropical Indian Ocean (SETIO) forms part of the global ocean conveyor belt and thermohaline circulation that has a significant influence in controlling the global climate. This region of the ocean has very few observations using surface drifters, and this study presents, for the first time, paths of satellite tracked drifters released in the Timor Sea (123.3° E, 13.8° S). The drifter data were used to identify the ocean dynamics, forcing mechanisms and connectivity in the SETIO region. The data set has high temporal (~5 min) and spatial (~120 m) resolution and were collected over an 8-month period between 17 September 2020 and 25 May 2021. At the end of 250 days, drifters covered a region separated by ~8000 km (83–137° E, 4–21° S) and transited through several forcing mechanisms including semidiurnal and diurnal tides, submesoscale and mesoscale eddies, channel and headland flows, and inertial currents generated by tropical storms. Initially, all the drifters moved as a single cluster, and at 120° E longitude they entered a region of high eddy kinetic energy defined here as the ‘SETIO Mixing Zone’ (SMZ), and their movement was highly variable. All the drifters remained within the SMZ for periods between 3 and 5 months. Exiting the SMZ, drifters followed the major ocean currents in the system (either South Java or South Equatorial Current). Two of the drifters moved north through Lombok and Sape Straits and travelled to the east as far as Aru Islands. The results of this study have many implications for connectivity and transport of buoyant materials (e.g., plastics), as numerical models do not have the ability to resolve many of the fine-scale physical processes that contribute to surface transport and mixing in the ocean. Full article

Background: Indonesia is an archipelagic country with 17,508 islands spread over the Pacific and Indian Oceans, with thousands of inter-island routes requiring a large and engaged fleet. The vast expanse of the country also leads to challenges related to optimal fleet coverage, routing, and oil distribution while maintaining cost-effectiveness and reliable supply. Methods: This study combined a mixed-integer linear-programming (MILP) model with a response surface methodology (RSM) approach to optimize vessel assignment, vessel routes, and inventory control simultaneously and comprehensively across three regional clusters (i.e., Western, Central, and Eastern Indonesia). The model takes into account a fleet of 28 vessels (13 medium range [MR] and 15 general purpose [GP]) that can distribute three oil products: gasoline, diesel, and kerosene. Results: The optimized solution yields 100% service reliability at an operational cost of $ 2.83 million per month—far lower than currently operating services. The model is robust against variations in demand (±20%), port congestion (±50%), and changing fuel prices (±50%), which is confirmed by a sensibility analysis. The close correlation coefficient (0.987) between the MILP and RSM results confirms the framework’s accuracy. At the same time, the critical performance factors were found to be vessel speed (13.5 knots), fleet size, and port operation time. Conclusions: The study offers a cost-efficient and data-intensive model that could be implemented as a maritime logistics framework, as well as potential areas for future work and insight for relevant stakeholders. Future research will have to integrate real-time data fusion, mainly due to the need for environmental and stochastic modeling methods to foster operational resilience in dynamic maritime business ecosystems. Full article

Historically known for its tin mining industry, Phuket Island has undergone significant transformation into a global tourism hub. This study aims at analyzing the evolutionary dynamics of Phuket Island from the years 1987 to 2024. We integrate Landsat satellite images and sophisticated analytical methods to assess the effects of tourism and economic policies on changes in land use and land cover using Google Earth Engine (GEE) for cloud-based data processing and Random Forest (RF) models for classification, and the Urban Expansion Intensity Index (UEII) and Shannon Entropy metrics for measuring the intensity of urban expansion and diversity, respectively. The results show that there has been a dynamic change in the patterns of land use which was brought about by the economic and environmental forces. Some of the major events that have had a great effect on Phuket’s landscape include the 1997 Asian Financial Crisis, the 2004 Indian Ocean Tsunami, and the COVID-19 pandemic; this highlights how the island is fragile and can be affected easily by events happening around the world. This work reveals a dramatic reduction in forest and mangrove cover, which calls for increased conservation measures to prevent the loss of biodiversity and to preserve the natural balance. Full article

On 28 March 2005, a major M_w 8.6 earthquake occurred near Nias and Simeulueislands, in the vicinity of northwestern Sumatra (Indonesia). The earthquake generated a significant tsunami. Although it was not as destructive as the 2004 Sumatra tsunami, the 2005 event was of sufficient strength to be recorded by tide gauges throughout the entire Indian Ocean. We selected 12 records for analysis, most from open-ocean islands but also some from continental stations. The maximum wave heights were measured at Salalah (Oman) (87 cm), Colombo (Sri Lanka), Pointe La Rue (Seychelles) and Rodrigues Island (53–54 cm). The dominant wave periods, estimated from frequency–time (f-t) diagrams, were 60–66 min, 40–48 min, and 20 min, which we assume are associated with the 2005 tsunami source. From the same stations, we calculated the mean ratio of the 2004 to 2005 tsunami heights as 5.11 ± 0.60, with the maximum and minimum heights to the west and south of the source region as 9.0 and 2.49, respectively. We also used these data to estimate the mean energy index, $E_0$ = 65 cm², for the 2005 tsunami, which was 16 times smaller than for the 2004 event. The USGS seismic solution was used to construct a numerical model of the 2005 tsunami and to simulate the tsunami waveforms for all 12 tide gauge stations. The results of the numerical computations were in general agreement with the observations and enabled us to map the spatial wave field of the event. To estimate the influence of location and orientation of the source area on the propagating tsunami waves, we undertook a set of additional numerical experiments and found that this influence is substantial and that these factors explain some of the differences between the physical properties of the 2004 and 2005 events. Full article

After virtually disappearing from domestic dwellings in the Western world at the end of the Second World War, bed bugs have re-emerged in recent years. Few studies, however, have been carried out on these insects in tropical islands. In this study, we focussed on describing bed bug specimens collected from dwellings in a high-altitude village in Grande Comore, an island in the Comoros, in the Indian Ocean. We also aimed to detect the bacteria associated with them. Using MALDI-TOF MS coupled with molecular biology, we were able to confirm that the C. hemipterus species (the tropical bug) was the bug infesting these homes. Interestingly, the results also show that MALDI-TOF MS can differentiate between the developmental stages of bed bugs (immature and adult). Screening for bacteria was carried out using qPCR, regular PCR, and sequencing, with only Wolbachia DNA being found. Widespread surveys throughout the country are needed to ascertain the level of bed bug infestation, with a view to implementing appropriate control measures. Full article

Objective: In some regions of the globe, accidental food confusion regarding plants can cause severe poisoning events and deaths. The aim of this study was to report on those confusions from the Marseille Poison Control Centre’s (PCC) experience from 2002 to 2023. Results: Over 22 years, 2197 food confusion events were managed with 321 different species. The most frequently involved plant was Nerium oleander (289 cases, 13.1%), then Cucurbitaceae genus (3.3%), Colchicum autumnale (3.3%), Prunus amygdalus (3%), Mahinot esculenta (3%), Cytisus laburnum (2.6%), Aesculus hippocastanum (2.5%) and Narcissus Jonquilla (2%). Many botanical confusion events were also reported (n = 1386, 63%), but with fewer than five identical species. Only one death was reported for this review, in an event involving Aconitum napellus. Two antidotes were used for all the series: Datura genus and Prunus dulcis. Discussion: The most implicated plant was Nerium oleander. This is explained by its distribution. This rate is very low compared to that of suicide attempts with this plant. Many cases were symptomatic (53.6%), but very few of them described severe symptoms (only 0.5% severe poisonings). Few patients needed to be admitted to intensive care (0.4%), and even fewer needed an antidote (two cases). Only one death occurred, involving Aconitum napellus. Food confusions were more common than suicide attempts with plants, but seem to be less severe. However, death and serious complications can occur, so it is important to identify and manage the plants concerned. Material and Methods: For each food confusion event managed between 2002 and 2023 at the Southeastern France PCC based in Marseille, we performed a retrospective review. This PCC is responsible for the Provence–Alpes–Côte d’Azur Region, Corsica Island and Indian Ocean French overseas territories. For each case, severity was calculated with the Poison Severity Score (PSS). Full article

Understanding the factors influencing the variability in the composition of fish assemblages is essential for bolstering the resilience of coral reef ecosystems, effective coral reef management and maintaining sustainable fisheries. The benthic composition and reef fish assemblages at eight sites at the poorly studied St. Brandon, also known as a bank fisheries area in the Indian Ocean, were assessed to discern distribution patterns, including differences between channel (Passe Grand Capitaine, Passe Ile Longue-Canal Coco and Passe La Cayane) and non-channel (Chaloupe, Anchor Points 1 and 2, Bain des Dames, Pearl Island) sites and fisheries sustainability. The benthic composition exhibited clusters, revealing the distinct separation of Chaloupe which predominantly featured sand (75.26%) interspersed with sporadic coral patches characterized by live and dead corals and rubble. The three channel sites composed a cluster. Coral species across eight families were identified, with significant variability (p < 0.05) observed in their benthic cover, particularly live coral cover (LCC). Fish density and diversity analyses unveiled 58 fish species from 12 families, with no statistically significant disparity in density among sites. Total fish biomass (TFB) and target fish biomass (TB) ranged from 138.02 ± 65.04 to 4110.16 ± 3048.70 kg/ha and from 28.31 ± 24.52 to 3851.27 ± 2753.18 kg/ha, respectively. TFB and TB differed significantly (p < 0.05) among sites irrespective of channel and non-channel sites, with Pearl Island recording the highest biomass. TFB and TB recorded at five out of the eight surveyed sites exceeded the mean biomass benchmark (B₀) for the Western Indian Ocean, set at 1150.00 and 560.00 kg/ha for TFB and TB, respectively. Functional group analysis unveiled six discrete groups influencing TFB, with scrapers being the most dominant. This study presents the first report on fish biomass surveys in St. Brandon, highlighting a case for sustainable fisheries in the waters of the Republic of Mauritius. Full article

Swahili coastal forests, spanning the Kenyan and Tanzanian coastlines and the Zanzibar Archipelago, are integral to the biodiverse Eastern Arc and Coastal Forest region. These forest ecosystems face considerable anthropogenic threats. This study contributes to the available knowledge on the floral composition and plant community assemblages of Mnemba Island, a small sandy cay in the Zanzibar Archipelago, which helps to establish baseline data for conservation purposes. Two main coastal forest plant communities were identified: (1) the Casuarina cunninghamiana–Suriana maritima open to closed sandy dry coastal forest, and (2) the Eugenia capensis–Mimusops obtusifolia coastal forest. A total of 91 different plant species belonging to 54 plant families were identified for the island. Community 2, an indigenous forest, supports diverse bird breeding colonies and is a crucial habitat for the threatened Aders’ duiker. Understory development is limited due to the historical Suni antelope overpopulation. Environmental factors like salt spray, allelochemicals, herbivore browsing, and climate fluctuations influence the vegetation abundance and composition. The study underscores differences in species diversity and composition between the planted Casuarina community and the natural atoll vegetation. The natural vegetation shows affinities with the Zanzibar–Inhambane edaphic coral-rag scrub forest and the transitional rainforest. Several species characteristic of Indian Ocean atolls were identified, providing insights into invasion ecology and conservation strategies. The study contributes conceptually to our understanding of vegetation dynamics in island ecosystems by highlighting the interplay between plant communities, environmental processes, and human activities. The fragile yet resilient nature of Mnemba’s unique ecosystem is emphasised, offering insights for conservation management, long-term monitoring, and adaptive approaches tailored to island environments. Full article

There has been substantial research on the factors that structure reef fish assemblages, but this has mostly focused on nearshore or continental reefs. This study examines patterns of abundance and species composition for two iconic groups of coral reef fishes, angelfishes (family Pomacanthidae) and butterflyfishes (family Chaetodontidae) at two isolated, oceanic reefs in the Indian Ocean: Christmas Island and the Cocos (Keeling) Islands. Six explanatory variables were investigated to determine whether large-scale physical factors are more important than fine-scale biotic factors in structuring reef fish communities on oceanic islands. For angelfishes, depth was the factor that most explained patterns in abundance (explaining 46.5% of the variation), species richness (44.8%) and composition (15.3%), with both abundance and species richness being greater at 20 m than at 5 m. Differences in species composition were greater between depths than between islands. For butterflyfishes, variation in abundance and species richness was best explained by the difference in aspect or exposure among sites, though abundance and composition also differed significantly between Christmas Island and the Cocos (Keeling) Islands. Large-scale variation in the structure of these reef fish assemblages could not be explained based on differences in habitat diversity, or coral and algal cover. This study indicates that large-scale physical factors (island location, exposure, depth) are more important than fine-scale biotic factors in structuring reef fish assemblages on oceanic islands. Full article

The Myanmar region experienced the subduction of the Indian Ocean plate to the West Burma block and suffered from the land–land collision between the Indian continent and the West Burma block that occurred from the Late Cretaceous to the Cenozoic. Its tectonic evolution has been complex; thus, oil and gas exploration is difficult, and the overall degree of research has been low. Recent exploration has been hindered by a lack of knowledge on the evolution of the petroleum system. To address this, we conducted hydrocarbon generation and accumulation modeling using both the 2D MOVE and Petro-Mod software 2017 for a complex tectonic section in the Northern Central Myanmar Basin. The results show that the maturity threshold depth of the Cretaceous source rocks in the study area is shallow, and the underground depth of 1200 m to 1400 m has reached the hydrocarbon generation threshold, indicating the start of hydrocarbon generation. Since 48 Ma, the Ro of the source rocks has reached 0.7%, became mature quite early. The Late Cretaceous Paleocene and Eocene formation, located in the southeastern part of the study area, migrated and accumulated hydrocarbons towards the western arc zone in the Eocene and Miocene, respectively. It is worth noting that although the oil and gas potential of each layer in the island arc uplift zone is relatively low, which is conducive to the migration and accumulation of oil and gas generated by the source rocks of the depression towards the island arc zone, shallow areas with developed extensional faults should be avoided. This study is the first to conduct a preliminary assessment and prediction of oil and gas resources, which will provide exploration guidance and reference for the study area and its surrounding areas in the future. Full article