Indian Ocean Islands Research Articles

Emergence of ECSA-IOL E1-K211E/E2-V264A Lineage of Chikungunya virus during Malaysian 2021 outbreak

BackgroundChikungunya cases was reported to be on the rise in Malaysia from 2019 to 2021. Although potential endemicity was described previously, genotype shift during 2008 outbreak originating from the 2004 Indian Ocean Islands outbreak presents the probability of current CHIKV spread from neighboring countries. This is due to the prevalence of the new IOL sub-lineage which consists of E1-226A wildtype or reverted strains that are circulating in the Indian subcontinent before spreading to neighboring Thailand during 2018–2019 outbreak.MethodIn this study, samples received mostly from the Tangkak, Johor were analyzed. A total 56 CHIKV positive serum samples received in 2021 by Institute of Medical Research Malaysia (IMR), were collected based on sample selection criteria. Selected samples were subjected to total RNA extraction, whole-genome sequencing as well as bioinformatic analysis such as phylogenetic, variant and mutation analysis.ResultsBased on the genomic and phylogenetic analysis, the CHIKV samples from 2021 outbreak were of ECSA-IOL genotype. Genome similarity analysis also revealed that these CHIKVs were highly similar to 2018–2019 outbreak strain from Thailand. In comparison to the 2008 outbreak CHIKV isolate, the current CHIKVs lacked the E1-A226V mutation and harbored the new E1-K211E/E2-V264A sub-linage mutation. Since the E1-K211E/E2-V264A mutation facilitates adaptation to Ae. aegypti as opposed to the E1-A226V mutation which improves adaptation to Ae. albopictus, the emergence 2021 CHIKV outbreak in Malaysia can be postulated due to vector shift. Interestingly, a novel nsP3-T441A/V mutation detected in this study, may also play a role in virus transmission, pathogenicity, fitness and vector adaptation.ConclusionIn summary, the current CHIKV outbreak are strains originated from the Indian subcontinent through Thailand which may have capitalized on vector shifting by adapting to Ae. aegypti. The presence of novel nsP3-T441A/V mutation may also contribute to the spread of this virus across peninsular Malaysia.

A Taxonomic Account of Mucuna (Leguminosae–Papilionoideae) in Africa, Madagascar, and the Indian Ocean Islands, with Comments on Its Biogeographic History

A taxonomic account of the papilionoid legume genus Mucuna Adans. in Africa, Madagascar, and the Indian Ocean islands is presented. Fifteen large herbaria that host representative collections of African specimens were visited and online databases consulted. A new phylogenetic analysis is also presented. Nineteen taxa are described and mapped. Twelve species and six infraspecific taxa (including autonyms, thus 15 terminal taxa) of Mucuna are present on the African mainland, where three species are representatives of Mucuna subg. Mucuna and the other nine are members of Mucuna subg. Stizolobium (P. Browne) Baker. In the Madagascar and Indian Ocean islands biodiversity hotspot, Mucuna is represented by six species, two of which (M. gigantea (Willd.) DC. and M. pruriens (L.) DC.) also occur on the African mainland. The other four species are endemic to Madagascar or adjacent islands and are representatives of Mucuna subg. Mucuna. The only representative of Mucuna subg. Stizolobium in Madagascar is M. pruriens. Our study suggests that the African mainland is the center of origin of Mucuna subg. Stizolobium. It is also revealed as the world’s most species-rich region in representatives of this subgenus, whereas on the other continents, subgenus Mucuna is the most diverse.

Chikungunya Virus Vaccines: A Review of IXCHIQ and PXVX0317 from Pre-Clinical Evaluation to Licensure.

Chikungunya virus is an emerging mosquito-borne alphavirus that causes febrile illness and arthritic disease. Chikungunya virus is endemic in 110 countries and the World Health Organization estimates that it has caused more than 2 million cases of crippling acute and chronic arthritis globally since it re-emerged in 2005. Chikungunya virus outbreaks have occurred in Africa, Asia, Indian Ocean islands, South Pacific islands, Europe, and the Americas. Until recently, no specific countermeasures to prevent or treat chikungunya disease were available. To address this need, multiple vaccines are in human trials. These vaccines use messenger RNA-lipid nanoparticles, inactivated virus, and viral vector approaches, with a live-attenuated vaccine VLA1553 and a virus-like particle PXVX0317 in phase III testing. In November 2023, the US Food and Drug Administration (FDA)approved the VLA1553 live-attenuated vaccine, which is marketed as IXCHIQ. In June 2024, Health Canada approved IXCHIQ, and in July 2024, IXCHIQ was approved by the European Commission. On August 13, 2024, the US FDA granted priority review for PXVX0317. The European Medicine Agency is considering accelerated assessment review of PXVX0317, with potential for approval by both agencies in 2025.In this review, we summarize published data from pre-clinical and clinical trials for the IXCHIQ and PXVX0317 vaccines. We also discuss unanswered questions including potential impacts of pre-existing chikungunya virus immunity on vaccine safety and immunogenicity, whether long-term immunity can be achieved, safety in children, pregnant, and immunocompromised individuals, and vaccine efficacy in people with previous exposure to other emerging alphaviruses in addition to chikungunya virus.

Plastic debris beaching on two remote Indian Ocean islands originates from handful of Indonesian rivers

Abstract Large amounts of plastic waste from non-local sources (>200 tonnes) wash up on Christmas Island and the Cocos Keeling Islands, two remote Indian Ocean islands, every year. Local communities on these islands organize beach clean-ups regularly to tackle this problem and, because their waste systems cannot handle the enormous amounts of plastic, predominantly incinerate the collected waste. However, as long as plastic waste keeps entering the ocean, beach clean-ups alone cannot be sustained. The first crucial step to solving this problem is to determine the main sources of plastic waste to the islands. In this study, we simulate the transport of floating plastic waste to determine the main riverine sources of plastic reaching the islands. We find that the majority of simulated plastic waste comes from just 4 Indonesian rivers: the Solo, Brantas, Ci Tanduy, and Wai Sekampung. We suggest that further numerical and field studies, as well as potential river clean-up efforts focus on these rivers to stop plastic waste inundating Christmas Island and the Cocos Keeling Islands.

Movement of the A-strain maize streak virus in and out of Madagascar

The maize streak virus belongs in the genus Mastrevirus, in the family Geminiviridae. The A-strain of the virus (MSV-A) is recognised as the principal causative agent of the most severe manifestation of maize streak disease (MSD). This disease continues to be a persistent limitation on maize output across sub-Saharan Africa and the nearby Indian Ocean islands. Irrespective of the causes behind the spread of MSV-A, we can determine the paths and speeds with which MSV-A spreads by analysing MSV genome sequence data along with information on when and where samples were taken. This information is valuable for identifying the geographical origins of viral strains that cause sporadic MSD epidemics in specific places and the geographical regions where viruses remain in reservoirs and contribute to prolonged epidemics during outbreaks. Our aim is to utilise these analyses to estimate the timing and origin of the MSV-A that arrived on the island of Madagascar in the Indian Ocean. Specifically, we employ model-based phylogeographic analyses on 524 complete MSV-A genome sequences, which consist of 56 newly obtained genomes from infected maize plants collected in Madagascar. These studies allow us to reconstruct the most likely paths of MSV-A to Madagascar. We found strong evidence for the existence of at least four separate movements of MSV-A variants from East and southern Africa to Madagascar. These movements took place between roughly 1979 (with a 95% highest probability density interval [HPD] ranging from 1976 to 1982) and 2003 (with a 95% HPD ranging from 2002 to 2003). While we inferred that MSV-A variants are spreading at an average rate of 38.9 km/year (with a 95% highest posterior density interval of 34.0–44.4) across their geographical range. Since their arrival in Madagascar, MSV-A variants have been migrating at an average rate of 47.6 km/year (with a 95% highest posterior density interval of 36.05–61.70). Human influences are likely significant contributors to both sporadic long-range movements of MSV-A between mainland Africa and Madagascar, as well as shorter to medium range movements within the island.

A review and analysis of the nomenclature and taxonomy of the genus-rank synonyms of Kalanchoe (Crassulaceae subfam. Kalanchooideae) published between 1763 and 1956

The genus name Kalanchoe, which is in use for about 200 tetramerous-flowered infrageneric taxa, species, and infraspecific taxa of Crassulaceae subfam. Kalanchooideae that are indigenous to Madagascar, some Indian Ocean islands off the African east coast, most of sub-Saharan Africa, and the Near, Middle, and Far East, was validly published in 1763 by Michel Adanson (1727–1806) and is legitimate. Genus names that are included in the synonymy of Kalanchoe are assessed and assigned to the appropriate subgenera recognised in the genus, and their nomenclature is reviewed. In chronological sequence the genus names in question are: (1) Vereia (1798), (2) Physocalycium (1820), (3) Baumgartenia (1821), (4) Meristostylus (1861), and (5) Geaya (1908); and (6) Bryophyllum (1805) is the basionym of K. subg. Bryophyllum (1919), and (7) Kitchingia (1881) is the basionym of K. subg. Kitchingia (2018). When Bryophyllum is treated as a synonym of Kalanchoe—a view followed here—the nothogenus name (8) ×Bryokalanchoe (1956) is a synonym of Kalanchoe.

Past fire dynamics in sub-Saharan Africa during the last 25,000 years: Climate change and increasing human impacts

The aim of this study is to provide the drivers of long-term fire dynamics in various regions of Sub-Saharan Africa using a synthesis of updated sedimentary charcoal records, from 25,000 years ago to the present. We used the charcoal data currently available in the Global Paleofire Database, updated with the most recent published charcoal data, to reconstruct past biomass burning across the continent. We analyzed standardized charcoal data grouped by region (central Africa, eastern Africa, southern Africa, and Indian Ocean) and by vegetation type (forest, savanna, and shrubland). Within this framework, we found that quality data were lacking to reconstruct a robust trend in biomass burning before 5000 years at the continental scale. This large spatial scale was indeed masking regional peculiarities. Our results suggest that past changes in biomass burning were nuanced and cannot be simply attributed to either climate- or humans, and that they varied from each sub-regions and vegetation type history. In central Africa, biomass burning increased after the end of the African Humid Period and the first wave of Bantu-speaking people migration, whereas in East Africa and the Indian Ocean islands, it seems that human population growth was the main driver of fire activity. In South Africa, reduced rainfall seemed to offset fire activity due to population growth by reducing potentially flammable biomass. While the diversity of methodological techniques used to produce charcoal quantification made comparisons difficult, regional patterns still emerged from these data. This synthesis thus highlights the need to increase the number of sites with charcoal data and to harmonize charcoal extraction and quantification methods across Africa to improve regional to continental assessments of fire histories.

Small island but great diversity: thirty six species of Parmotrema (Parmeliaceae, lichenized Ascomycota), including sixteen new species, on Réunion (Mascarenes), with additional data from the Western Indian Ocean

This work is part of our taxonomical and phylogenetic studies on the lichen flora of Réunion (Mascarene Archipelago, Indian Ocean). Thirty-six species belonging to the conspicuous genus Parmotrema are recognized on the island, sixteen being new to science: P. aurantioreagens, P. brachyblepharum, P. crossotum, P. eleonomum, P. intonsum (also found in Madagascar), P. mezierii, P. mascarenense (also found in Mauritius), P. mirum, P. nemorum, P. nephophilum, P. occultum, P. orarium, P. paramascarenense (also found in Madagascar), P. reunionicum, P. subdeflectens (also found in Madagascar) and P. udisilvestre (also found in Madagascar). Parmotrema mwaliense is a further new species found on the island of Mohéli (Comoros). Three new combinations are introduced: Parmotrema inexspectatum, P. meiospermum and P. odontatum. We propose synonymization of P. acrotrychum with P. subcorallinum. The following species are confirmed or reported as new to Réunion: P. austrosinense, P. cetratum, P. cf. clavuliferum, P. cooperi, P. crinitum, P. cristiferum, P. cf. deflectens, P. dilatatum, P. mellissii, P. cf. negrosorientale, P. praesorediosum, P. reticulatum, P. robustum, P. subcorallinum, P. subisidiosum, and P. tinctorum. Parmotrema appendiculatum and P. thomsonii are only known to Réunion from single reports, poorly documented, dating back to the 19th century; detailed descriptions with photographs, distribution maps and ecological data are provided for the other species. An identification key for the 36 species is provided. Parmotrema austrosinense and P. cf. negrosorientale are newly reported, and P. meiospermum confirmed, for Mauritius; the Papuan P. menyamyaense is newly reported for Mohéli (Comoros). One hundred and seventy-four new sequences for the barcode ITS loci have been produced, an increase of ca. one third for Parmotrema on GenBank. LSU, mtSSU and EF1-α loci have been added for subgroups. The molecular data highlight the existence of two pairs of ‘nearly’ cryptic species (P. crinitum/P. occultum, P. brachyblepharum/P. eleonomum), high variability in the production of vegetative propagules in two of the new species described (P. nephophilum, P. orarium), and two strongly supported clades including potential endemics to Réunion or the MIOI (Madagascar and the Indian Ocean Islands) biodiversity hotspot. One clade comprises 10 species (P. brachyblepharum, P. crossotum, P. eleonomum, P. intonsum, P. mezierii, P. cf. negrosorientale, P. nemorum, P. subcorallinum, P. subdeflectens and P. udisilvestre), eight described as new for science, the other five species (P. aurantioreagens, P. mascarenense, P. meiospermum, P. odontatum and P. orarium), three of them new for science.

Dynamics of emergence and genetic diversity of dengue virus in Reunion Island from 2012 to 2022.

Dengue is a major public health concern in Reunion Island, marked by recurrent epidemics, including successive outbreaks of dengue virus serotypes 1 and 2 (DENV1 and DENV2) with over 70,000 cases confirmed since 2017. In this study, we used Oxford Nanopore NGS technology for sequencing virologically-confirmed samples and clinical isolates collected between 2012 and 2022 to investigate the molecular epidemiology and evolution of DENV in Reunion Island. Here, we generated and analyzed a total of 499 DENV1, 360 DENV2, and 18 DENV3 sequences. By phylogenetic analysis, we show that different genotypes and variants of DENV have circulated in the past decade that likely originated from Seychelles, Mayotte and Southeast Asia and highly affected areas in Asia and Africa. DENV sequences from Reunion Island exhibit a high genetic diversity which suggests regular introductions of new viral lineages from various Indian Ocean islands. The insights from our phylogenetic analysis may inform local health authorities about the endemicity of DENV variants circulating in Reunion Island and may improve dengue management and surveillance. This work emphasizes the importance of strong local coordination and collaboration to inform public health stakeholders in Reunion Island, neighboring areas, and mainland France.

Archaeology in the Fourth Dimension: Studying Landscapes with Multitemporal PlanetScope Satellite Data

For the last seven years, PlanetScope satellites have started near-daily imaging of parts of the Earth’s surface, making high-density multitemporal, multispectral, 3-m pixel imagery accessible to researchers. Multitemporal satellite data enables landscape archaeologists to examine changes in environmental conditions at time scales ranging from daily to decadal. This kind of temporal resolution can accentuate landscape features on the ground by de-emphasizing non-permanent signatures caused by seasonal or even daily changes in vegetation. We argue that the availability of high spatial and temporal resolution multispectral imagery from Planet Inc. will enable new approaches to studying archaeological visibility in landscapes. While palimpsests are discrete overlapping layers of material accumulation, multitemporal composites capture cyclical and seasonal time and can be used to interpret past landscape histories at multiple scales. To illustrate this perspective, we present three case studies using PlanetScope imagery in tropical environments on the Indian Ocean islands of Madagascar, Mauritius, and Zanzibar.

Environmental DNA recovers fish composition turnover of the coral reefs of West Indian Ocean islands.

Islands have been used as model systems to study ecological and evolutionary processes, and they provide an ideal set-up for validating new biodiversity monitoring methods. The application of environmental DNA metabarcoding for monitoring marine biodiversity requires an understanding of the spatial scale of the eDNA signal, which is best tested in island systems. Here, we investigated the variation in Actinopterygii and Elasmobranchii species composition recovered from eDNA metabarcoding along a gradient of distance-to-reef in four of the five French Scattered Islands in the Western Indian Ocean. We collected surface water samples at an increasing distance from reefs (0 m, 250 m, 500 m, 750 m). We used a metabarcoding protocol based on the 'teleo' primers to target marine reef fishes and classified taxa according to their habitat types (benthic or pelagic). We investigated the effect of distance-to-reef on β diversity variation using generalised linear mixed models and estimated species-specific distance-to-reef effects using a model-based approach for community data. Environmental DNA metabarcoding analyses recovered distinct fish species compositions across the four inventoried islands and variations along the distance-to-reef gradient. The analysis of β-diversity variation showed significant taxa turnover between the eDNA samples on and away from the reefs. In agreement with a spatially localised signal from eDNA, benthic species were distributed closer to the reef than pelagic ones. Our findings demonstrate that the combination of eDNA inventories and spatial modelling can provide insights into species habitat preferences related to distance-to-reef gradients at a small scale. As such, eDNA can not only recover large compositional differences among islands but also help understand habitat selection and distribution of marine species at a finer spatial scale.

Puddles, creeks, and drainage: connected histories of water and malaria in Zanzibar, 1910–2021

This article draws on a combination of archival and oral sources in order to highlight the connected histories of water and malaria on the Indian Ocean island of Zanzibar (Unguja) over the past century. We argue that in both the past and the present, water and malaria have been deeply connected, through the lifecycle of the disease, through control measures enacted, and in how Zanzibari residents continue to talk about the relationship between rain, puddles, stagnant water, and disease. Archival sources show that between roughly 1913 and 1957, the British colonial government managed malaria by managing water. That entailed a focus on watery breeding sites that included attention to both the micro: cattle hoofprints, and the macro: a multi-decade drainage of the tidal creek and surrounding swamp. These water-based malaria control efforts were limited in their efficacy by being geographically restricted to urban Zanzibar Town, and often limited to just the Stone Town area. 98 interviews conducted with Zanzibaris about malaria indicate that people continue to draw strong connections between malaria and the environment (mazingira), and that they most commonly discuss water’s relationship with malaria in terms of puddles (dimbwi/madimbwi), small puddles (kidimbwi/vidimbwi) and stagnant water (maji yaliyotuama).

Notes on the nomenclature of the genus name Vereia, the earliest-published synonym of Kalanchoe, and the species published in Vereia (Crassulaceae subfam. Kalanchooideae)

At the rank of genus, at least seven names have been published for taxa that are today included in Kalanchoe (Crassulaceae subfam. Kalanchooideae). Kalanchoe is the earliest validly published and legitimate name that must be used for the ca. 200 tetramerous-flowered taxa recognised in the genus. Kalanchoe has a wide natural geographical distribution range that stretches from Madagascar and some of the nearby Indian Ocean islands, through most of sub-Saharan Africa and the northern parts of North Africa to the Middle, Near, and Far East, more or less south of the latitude of 35⁰ N. The nomenclature of the genus name Vereia, for which five different spellings have been recorded, is reviewed here. Vereia is the earliest synonym of Kalanchoe. Notes are provided on the natural geographical distribution range of K. crenata, the accepted name of the type, V. crenata, of the genus Vereia. The species names published in Vereia are assigned to species in Kalanchoe.

Mycorrhizal communities of Vanilla planifolia in an introduction area (La Réunion) under varying cultivation practices

Societal Impact StatementVanilla is one of the most valuable spices in the world. In Madagascar and La Réunion, the world's leading producers, vanilla is of great economic and cultural importance. Like all orchids, vanilla plants associate with mycorrhizal fungi in their roots forming mutualistic associations that allow them to grow and thrive. Understanding the diversity of mycorrhizal fungi adapted to vanilla cultivation, particularly in the Indian Ocean islands where they have never previously been studied, is becoming a necessity for maintaining vanilla crops in these regions in the face of climate change and the emergence of new pathogens.Summary The vanilla orchid (Vanilla spp.) is one of the most valuable cultivated plants worldwide. As with all orchids, vanillas form mycorrhizal associations with fungi in their roots, but their fungal partners have not been investigated outside their native geographic range in Central America. We investigated the whole fungal and mycorrhizal associations in cultivated vanilla (Vanilla planifolia) by sequencing the fungal ITS‐2 marker in the terrestrial and aerial roots using a metabarcoding approach. We selected plants cultivated in three conditions (i.e., cultivation under shade house, in openfield, or in the understory) in one locality of La Réunion island (Indian Ocean) and tested for a possible effect of cultivation practices on fungal communities. Cultivated vanillas in La Réunion mainly associate with Tulasnellaceae (75 OTUs) and Ceratobasidiaceae (8 OTUs). Among the seven most abundant Tulasnellaceae, six are similar to fungi detected in the roots of cultivated vanillas in Central America or in the roots of native orchids in La Réunion. Cultivation practices impacted both total fungal and mycorrhizal community compositions with no clear effect on fungal richness. Notably, Tulasnellaceae and Ceratobasidiaceae were scarce in aerial roots, except in the traditional cultivation in the forest understory. These results shed light on the geographical origins of mycorrhizal fungi of cultivated vanillas in La Réunion and show that they form a pool of both locally and globally distributed fungal partners. These mycorrhizal communities vary according to cultivation practices, and their potential roles in plant nutrition and resistance against pathogens await further attention.

The evolutionary history of three Baracoffea species from western Madagascar revealed by chloroplast and nuclear genomes.

The wild species of the Coffea genus present a very wide morphological, genetic, and biochemical diversity. Wild species are recognized more resistant to diseases, pests, and environmental variations than the two species currently cultivated worldwide: C. arabica (Arabica) and C. canephora (Robusta). Consequently, wild species are now considered as a crucial resource for adapting cultivated coffee trees to climate change. Within the Coffea genus, 79 wild species are native to the Indian Ocean islands of Comoros, Mayotte, Mauritius, Réunion and Madagascar, out of a total of 141 taxa worldwide. Among them, a group of 9 species called "Baracoffea" are particularly atypical in their morphology and adaptation to the sandy soils of the dry deciduous forests of western Madagascar. Here, we have attempted to shed light on the evolutionary history of three Baracoffea species: C. ambongensis, C. boinensis and C. bissetiae by analyzing their chloroplast and nuclear genomes. We assembled the complete chloroplast genomes de novo and extracted 28,800 SNP (Single Nucleotide Polymorphism) markers from the nuclear genomes. These data were used for phylogenetic analysis of Baracoffea with Coffea species from Madagascar and Africa. Our new data support the monophyletic origin of Baracoffea within the Coffea of Madagascar, but also reveal a divergence with a sister clade of four species: C. augagneurii, C. ratsimamangae, C. pervilleana and C. Mcphersonii (also called C. vohemarensis), belonging to the Subterminal botanical series and living in dry or humid forests of northern Madagascar. Based on a bioclimatic analysis, our work suggests that Baracoffea may have diverged from a group of Malagasy Coffea from northern Madagascar and adapted to the specific dry climate and low rainfall of western Madagascar. The genomic data generated in the course of this work will contribute to the understanding of the adaptation mechanisms of these particularly singular species.

The Ties That Bind: Protection and Projection in France’s Indian Ocean Islands of Mayotte and Réunion

ABSTRACT The article addresses a two-fold question: first, why does the French state invest so much time and resources in its Indian Ocean islands, Mayotte and Réunion? And why do these ultra-marine regions remain wedded to the French Republic? The high degree of insular buy-in both regions involves a two-level game, connecting state and island actors. Such turning to mainland France represents a form of African agency, however dependent on the mainland these islands appear to be. The causal mechanisms of the integration of the French Indian Ocean territories combine historical legacy (choosing France), institutional evolution (departmentalisation), common economic and military security challenges, the cost calculus of mainland France’s readiness to govern ultramarine territories and a widely shared set of beliefs in the value of remaining French. The islands are acting like rational actors, whose insular and isolated status pushes in the direction of seeking protection in an unstable environment.

Chemical, Bioactive and antioxidant properties of Alhydwan (Boerhavia elegana Choisy) Seeds- A review

In recent years, consumers have turned to natural foods, but this is not the case. Since synthetic preservatives are harmful to health, consumers demand partial or complete replacement of synthetic preservatives. Because of this, there is an increasing demand for the development of more natural alternatives to improve food shelf life and safety. Strategies for natural protection are gaining popularity in food mapping. New preservation methods focus on using environmentally friendly organic plants with antioxidant and antimicrobial properties to extend the safety and shelf-life of food. Since ancient times, medicinal plants have been used in almost all cultures to treat many ailments around the world. The genus Boerhavia is found around the world in tropical, subtropical in nature and temperate climates, including Mexico, as well as the United States, Africa, Asia, Indian Ocean islands, Pacific islands, and Australia. Boerhavia plants are widely used by locals and physicians to treat hepatitis, urinary tract disorders, gastrointestinal disorders, inflammation, skin problems, infectious diseases and asthma. This review focuses on the bioactive compounds of Boerhavia elegana Choisy.

Microplastics in the insular marine environment of the Southwest Indian Ocean carry a microbiome including antimicrobial resistant (AMR) bacteria: A case study from Reunion Island

The increasing threats to ecosystems and humans from marine plastic pollution require a comprehensive assessment. We present a plastisphere case study from Reunion Island, a remote oceanic island located in the Southwest Indian Ocean, polluted by plastics. We characterized the plastic pollution on the island's coastal waters, described the associated microbiome, explored viable bacterial flora and the presence of antimicrobial resistant (AMR) bacteria. Reunion Island faces plastic pollution with up to 10,000 items/km2 in coastal water. These plastics host microbiomes dominated by Proteobacteria (80 %), including dominant genera such as Psychrobacter, Photobacterium, Pseudoalteromonas and Vibrio. Culturable microbiomes reach 107 CFU/g of microplastics, with dominance of Exiguobacterium and Pseudomonas. Plastics also carry AMR bacteria including β-lactam resistance. Thus, Southwest Indian Ocean islands are facing serious plastic pollution. This pollution requires vigilant monitoring as it harbors a plastisphere including AMR, that threatens pristine ecosystems and potentially human health through the marine food chain.

North Atlantic forcing of Indian Winter Monsoon intensification: Evidence from Holocene sediments from the tropical Indian Ocean Island of Sri Lanka

The teleconnection between the Asian monsoon system and North Atlantic forcing is an enduring prospect of the Earth’s climate. During the Holocene interstadial, the Indian summer monsoon showed asynchronous weakening links to ice rafting events documented in the North Atlantic region. However, the sensitivity of the Indian Winter Monsoon in response to North Atlantic cold spells is unclear due to a lack of compelling evidence. This study aims to extract the deglacial Indian Winter Monsoon signals using lithogenic tracers in coastal sediments and explore its association with the North Atlantic cooling episodes. A 5.1 m sediment core was retrieved from Pottuvil Lagoon in the southeastern coast of Sri Lanka, and the concentrations of K, Rb, Mg, Al, and Ti in 101 sub-sections were analysed using ICP-MS. The core- chronology was established by Bacon 2.2 age-depth modelling based on calibrated AMS 14C dates. The monsoon signal was reconstructed using element proxies and compared with the drift ice indices from the North Atlantic deep-sea sediments. Results revealed distinct phases of intense monsoon activity at 2553–2984 years BP, 3899–5021 years BP, and 5244–5507 years BP intervals with intermittent weak phases during 2253–2553, 2984–3899, and 5021–5244 years BP. The episodes of the intensified Indian Winter Monsoon coincided with Bond Events 2, 3, and 4, showing a strong coherence with the North Atlantic’s deglacial climate. Thus, on a millennial scale, North-Atlantic cooling has triggered intense winter monsoon conditions over the tropical Indian Ocean region from the mid to late Holocene. In comparison with regional monsoon archives, the Pottuvil winter monsoon record exhibits an anti-phase association with the Indian Summer Monsoon during Holocene ice-rafted debris events. The geochemical approach executed in this study could provide new insight into the millennial-scale pacing of the winter counterpart of the Indian monsoon links to climate extremes of high northern latitudes.

On the report of a new world millipede (Rhinotus purpureus) from India

The Indian millipede fauna is diverse with many families and genera but remains seriously underexplored. Among the families of the order polyzoniida, Siphonotidae is the only family to have reports from the southern hemisphere. The tropical tramp species of this family, Rhinotus purpureus (Pocock, 1894) shows a cosmopolitan distribution. It has been repeatedly described as a new species leading to more than a dozen synonyms. It is designated as a common tramp species as it is frequently found in green houses and other synanthropic habitats from many different parts of the world including Kew Gardens in England, green houses in Germany, Central America and Southern USA, Comoro Islands, Madagascar and Indian Ocean Islands. The present study provides the first record of R. purpureus, from the Indian subcontinent.