Rodrigues Island Research Articles

<p><strong>Diatom phenotypic plasticity: <em>Olifantiella gorandiana</em> epizoic on ‘G5-Manahere’ (Society Archipelago, South Pacific), a case study</strong></p>

First described from the Mascarenes (Rodrigues Island, Indian Ocean), Olifantiella gorandiana Riaux-Gobin was later observed from several other oceanic basins. We here examine the morphology of this taxon from a scraping of a juvenile green turtle Chelonia mydas Linnaeus, named ‘G5-Manahere’, from Moorea Island (Society Archipelago, South Pacific). In this sample, a great range of morphologies, not previously described for the species, were encountered, demonstrating a high degree of polymorphism with regard to valve shape and also stria pattern. These morphological differences appear to be associated with size, as smaller cells become more rounded. The fine structure (e.g., stria density and pattern) may also be associated with changes in shape. These specimens may all belong to the same and unique taxon: Olifantiella gorandiana. This high degree of polymorphism is described, and put into the context of the constraining epizoic conditions. This study permits furthers the description of the fine structure of O. gorandiana, using focused ion beam (FIB) and scanning electron microscopy (SEM) techniques.

Ethnozoological practices in Rodrigues island of the Mascarene archipelago

Ethnopharmacological relevanceRodrigues, is an autonomous island that forms part of the Republic of Mauritius. It is a component of the Mascarene archipelago alongside Mauritius and Reunion island. Despite their relative geographical proximity, each island has its own unique biodiversity and indigenous knowledge. Nonetheless, there is no documentation of the use of animal-based remedies (ABR) in Rodrigues. This study was therefore designed to gather and compare primary traditional knowledge on the different ABR used by Rodriguans.Aim of the study: To collect, analyse, document, compare, and disseminate the use of ABR against common human ailments in Rodrigues island. MethodsData was collected following interviews from key informants (n = 150). Primary data collected in the present study was compared with those reported from the nearest island, Mauritius. Three quantitative indices including (i) the frequency of citation, (ii) the similarity ratio and the percentage of shared uses among the two islands and (iii) new uses and percentage of new uses recorded in Rodrigues for each animal species mentioned were calculated. ResultsA total of 32 animal species belonging to 13 taxonomic groups among which 55% were vertebrates and 45% invertebrates were reported to treat 38 different ailment conditions. Altogether, 73 distinct medicinal preparations employing 22 different animal parts and by-products were concocted from the different animal species reported. Most used animal parts were meat (21%) followed by the whole body (14%). The preparations were either administered orally (78%) or topically (22%). Interestingly, resources such as the Rodriguan bat (Pteropus rodricensis) and honey are unique to the island and have never been studied before. Pteropus rodricensis is an endangered species while Carcharodon carcharias is a vulnerable one. The shared medicinal uses of the species among the 2 islands ranged from 0 to 50% with the most similar uses (50%) being for Columba livia and Donax Spp. respectively. The proportion of new uses of animal species recorded in Rodrigues was higher (NUR ≥ 30%) for Panulirus penicillatus, Ovis aries, Gallus gallus domesticus, Scutigera coleoptrata, Apis mellifera, Bos taurus and Capra aegagrus hircus. ConclusionRodriguans were found to possess valuable knowledge on a plethora of ABR. It is believed that the present documentation will serve to record and present this vanishing knowledge to the scientific community before it is further eroded from the island. Given the dearth of primary published information on zootherapeutic practices in Rodrigues, this study opens new avenues for biomedicine development in an attempt to develop alternative therapies or complement existing ones.

Hydro-climatic variability in the southwestern Indian Ocean between 6000 and 3000 years ago

Abstract. The “4.2 ka event” is frequently described as a major global climate anomaly between 4.2 and 3.9 ka, which defines the beginning of the current Meghalayan age in the Holocene epoch. The “event” has been disproportionately reported from proxy records from the Northern Hemisphere, but its climatic manifestation remains much less clear in the Southern Hemisphere. Here, we present highly resolved and chronologically well-constrained speleothem oxygen and carbon isotopes records between ∼6 and 3 ka from Rodrigues Island in the southwestern subtropical Indian Ocean, located ∼600 km east of Mauritius. Our records show that the 4.2 ka event did not manifest itself as a period of major climate change at Rodrigues Island in the context of our record's length. Instead, we find evidence for a multi-centennial drought that occurred near-continuously between 3.9 and 3.5 ka and temporally coincided with climate change throughout the Southern Hemisphere.

Ancient DNA reveals the origins, colonization histories, and evolutionary pathways of two recently extinct species of giant scops owl from Mauritius and Rodrigues Islands (Mascarene Islands, south‐western Indian Ocean)

AbstractAimThe islands of the south‐western Indian Ocean region are home to many endemic bird species, with their closest relatives occurring in Africa and Madagascar, Eurasia, the Sunda Islands, and the Australasian region. Among owls, the extant endemic scops owls (genus Otus) from Madagascar, Comoros, Seychelles, and Socotra are related to the Southeast Asian species, O. sunia, the Oriental scops owl. Three owl species, presumably Otus derivatives, twice the size of standard scops owls and now extinct, once inhabited the Mascarene Islands, and have been placed in a separate genus, Mascarenotus. Insular apomorphies have made their precise relationships difficult to determine. Here we investigate the phylogenetic position of these enigmatic owls.LocationThe Mascarene Islands (Réunion, Mauritius, Rodrigues) in the south‐western Indian Ocean.MethodsPhylogenetic relationships were reconstructed using ancient DNA extracted from subfossil remains. Fragments of cytochrome b gene were amplified and sequenced. The ancient sequences were analysed with modern sequences of 19 ingroup Otus taxa using Bayesian and Maximum Likelihood methods.ResultsThe Mauritian extinct species M. sauzieri was reconstructed as the sister to both O. pauliani (Grand Comoro) and O. rutilus (Madagascar). The Rodrigues extinct species M. murivorus was the sister, in a star‐like differentiation, to the preceding clade as well as the remaining Comorian species and a clade formed by O. insularis (Seychelles) and O. sunia.Main conclusionsThe ancestor of O. sunia simultaneously colonized Rodrigues Island (evolving into Otus murivorus), Madagascar, and part of the Comoros Islands around 3 million years ago. Later, presumably from Madagascar, new lineages colonized Grand Comoro and Mauritius (O. sauzieri). Independently, a more recent O. sunia ancestor colonized the Seychelles Islands and Socotra. These colonizations were probably favoured by Pliocene cyclonic events, stronger and more frequent than today. Several features, including giantism, wing reduction, and a relative decrease in skull and orbit size evolved convergently in the polyphyletic species O. sauzieri and O. murivorus.

Cocconeis scutellum var. parva (Bacillariophyceae) re-examination and typification

Electron microscope (EM) is essential for the morphological description of small taxa, but also reveals taxa hitherto grouped under the same name although presenting marked ultrastructural differences: e.g., Cocconeis scutellum var. parva. The latter taxon has been interpreted differently by authors, while no type has been examined since the original description. A slide from the Grunow’s collection in W, annotated by Albert Grunow as containing C. scutellum var. parva was examined and detailed for the first time. This slide allowed for a more precise definition of C. scutellum var. parva and is here designated as lectotype. This paper analyzes the history of C. scutellum var. parva and attempts to exclude definitions that are too far from the original drawings and from the lectotype illustration. A tropical–population from Rodrigues Island (Indian Ocean) composed of small specimens with stria densities significantly denser than observed on the nominate variety, is here described as an epitype of C. scutellum var. parva and is illustrated with SEM. A small taxon from Tahiti Island (South Pacific Ocean), seemingly close to C. scutellum var. parva, has unique raphe valve valvocopula with cupuliform papillae. The latter specificity is considered a simple variation and may illustrate the range of morphological variability admitted for a taxon.

Reintroduction or natural colonization? Using cost‐distance analysis to inform decisions about Rodrigues Island Fody and Warbler reintroductions

AbstractWhen making decisions about reintroducing a species, practitioners need to consider whether the release site contains habitat suitable for those species, whether past extinction drivers have been remedied and whether reintroduction is the best option for the species to recolonize the release site. These concerns are captured within two paradigms; the habitat and metapopulation paradigms. We use cost‐distance analysis to assess the need for reintroduction of two bird species, Rodrigues Fody and Rodrigues Warbler, to Anse Quitor reserve on Rodrigues Island, testing hypotheses based on these underlying paradigms. Given a lack of detailed field studies of dispersal across the landscape on either species we rely on expert judgment. Our results show that experts believe Rodrigues Fody will naturally colonize Anse Quitor but that Rodrigues Warbler may not, at least within a time frame of 10 years. This information and treatment of expert judgment allows greater justification in reintroduction planning. Our method shows one way to assist in reintroduction decision making in poorly studied systems.

First Report of Ralstonia pseudosolanacearum Phylotype I Causing Bacterial Wilt on Rodrigues Island, Indian Ocean

The Ralstonia solanacearum species complex (Rssc) encompasses strains that are highly destructive on a wide host range, and some are listed as quarantine organisms in Europe, the United States, and many other countries. This soil-borne bacterial plant pathogen invades the roots and colonizes the xylem vessels, causing a bacterial wilt (BW) disease. Strains are distributed into four phylogenetic groups (phylotypes) linked to their geographical origin of evolution: phylotype I (Asia), phylotype II (America), phylotype III (Africa), and phylotype IV (Australia - Indonesia - Japan). Phylotypes are subdivided into sequevars, encompassing strains that share high homology on the endoglucanase gene partial sequence (750 bp) (Fegan and Prior 2005). Rodrigues is part of the Mascarene Islands in the Southwest Indian Ocean. In February 2016, a survey was conducted to identify the causal agent of BW, encountered for years on this island. Typical BW disease symptoms, including leaf epinasty and browning vessels, were observed on tomato (Solanum lycopersicum L.) in Terre Rouge and on chili pepper (Capsicum frutescens L.) in Nouvelle Decouverte and Montagne Malgache. Seventy-eight stem sections were collected, surface disinfected with 70% ethanol, and crushed into 2 ml of Tris-buffer, then processed for bacterial isolation by plating 50 µl on SM-1 medium (Granada and Sequeira 1983). Among all of the collected stems, typical Ralstonia pseudosolanacearum colonies grew on the semiselective medium from 51 of the 78 samples. Corresponding strains were subcultured and typed as R. pseudosolanacearum phylotype I (Safni et al. 2014), based on the PMX-PCR (Fegan and Prior 2005). A subset of six strains, two from each location, was selected for sequevar identification (Fegan et al. 1998). Strains CFBP8472 and CFBP8465 (Terre Rouge) were identified as sequevar I-31 (GenBank KX242311 and KX242312), but strains CFBP8467 and CFBP8468 (Montagne Malgache) along with CFBP8469 and CFBP8466 (Nouvelle Decouverte) were identified as sequevar I-33 (KX242313 to KX242316). This subset of strains was inoculated on five plants per strain by soil drenching on the susceptible tomato cultivar L390 (Lebeau et al. 2011) with 5 ml of a calibrated suspension (108 CFU/ml in Tris-buffer). Plants were grown in a fully controlled environment at day/night temperatures of 30/25°C ± 1°C under high relative humidity (∼90%). Sterile Tris-buffer inoculated negative controls were grown with the same parameters. Typical BW symptoms were observed within 6 days postinoculation and strains were reisolated and characterized using the same protocol as for the strains that were inoculated, fulfilling Koch's postulates. No symptoms were observed and no Rssc strains could be isolated from negative controls. To our knowledge, this is the first report of R. pseudosolanacearum phylotype I strains causing bacterial wilt on tomato and pepper on Rodrigues. Further studies need to be conducted on the prevalence and diversity of the Rssc strains causing the BW disease, in order to implement adapted control measures, such as the use of local and adapted resistant cultivars. Further surveys on other Southwest Indian Ocean islands such as Mauritius, Reunion, and Seychelles should be achieved to determine the potential origin of the R. pseudosolanacearum phylotype I strains isolated on Rodrigues island. (Texte integral)

Ethnopharmacological appraisal of culturally important medicinal plants and polyherbal formulas used against communicable diseases in Rodrigues Island

Ethnopharmacological relevanceThe tropical island of Rodrigues is one of three islands that constitute the Mascarene archipelago in the Indian Ocean. Currently considered as a biodiversity hotspot, the island has also a resilient history in the use of traditional medicine. However, there has been no ethnopharmacological study to document quantitatively such traditional practice against communicable diseases (CD), which currently accounts for 6.61% annual death and 30.7% attendances in public hospitals. The aim of the present study was to collect, analyse, and document traditionally used medicinal plants (MP) and polyherbal formulas from key informants and traditional medicine practitioners (TMP) in Rodrigues to treat and/or manage common CD. Materials and methodsData was collected via face-to-face interviews with MP users (n=113) and TMP (n=9) from 17 key sites. Seven quantitative ethnopharmacological indices, namely family use value (FUV), use value (UV), informant agreement ratio (IAR), relative frequency of citation (RFC), fidelity level (FL), relative importance (RI), and ethnobotanicity index (EI) were calculated. ResultsNinety-seven plants belonging to 49 families were recorded to be in common use as monotherapy (80 plants) and/or as part of polyherbal preparation (23 plants) for the treatment and/or management of 16 different CD. Thirteen MPs were found to have a maximum FL of 100% for CD. The highest IAR (0.98) was observed for diseases of the eye and adnexa and skin and subcutaneous tissue. The highest FUV was for Arecaceae. Ayapana triplinervis (Vahl) R.M. king et H.Rob. scored the highest UV (UV=2.72). Seven endemic medicinal plants have been recorded to be employed in cultural rituals for the management of common CDs, whereas 14 polyherbal preparations were used to treat and/or manage 6 different types of CDs. Side effects were also reported following use of some these medicinal plants. ConclusionGiven the dearth of updated information on traditional medicine from Rodrigues, this work has provided an opportunity to establish valuable primary information on the different MP used by the local people. Further research is needed to probe into the possible active constituents that could open new perspectives for further pharmacological research and hence be the basis of an evidence-based investigation to discover new drugs.

A sea surface temperature reconstruction for the southern Indian Ocean trade wind belt from corals in Rodrigues Island (19° S, 63° E)

Abstract. The western Indian Ocean has been warming rapidly over recent decades, causing a greater number of extreme climatic events. It is therefore of paramount importance to improve our understanding of links between Indian Ocean sea surface temperature (SST) variability, climate change and sustainability of tropical coral reef ecosystems. Here we present monthly resolved coral Sr ∕ Ca records from two different locations from Rodrigues Island (63° E, 19° S) in the south-central Indian Ocean trade wind belt. We reconstruct SST based on a linear relationship with the Sr ∕ Ca proxy with records starting from 1781 and 1945, respectively. We assess relationships between the observed long-term SST and climate fluctuations related to the El Niño–Southern Oscillation (ENSO), the Subtropical Indian Ocean Dipole Mode (SIOD) and the Pacific Decadal Oscillation (PDO) between 1945 and 2006, respectively. The reproducibility of the Sr ∕ Ca records is assessed as are the potential impacts of diagenesis and corallite orientation on Sr ∕ Ca–SST reconstructions. We calibrate individual robust Sr ∕ Ca records with in situ SST and various gridded SST products. The results show that the SST record from Cabri provides the first Indian Ocean coral proxy time series that records the SST signature of the PDO in the south-central Indian Ocean since 1945. We suggest that additional records from Rodrigues Island can provide excellent records of SST variations in the southern Indian Ocean trade wind belt to unravel teleconnections with the SIOD/ENSO/PDO on longer timescales.

Drift simulation of MH370 debris using superensemble techniques

Abstract. On 7 March 2014 (UTC), Malaysia Airlines flight 370 vanished without a trace. The aircraft is believed to have crashed in the southern Indian Ocean, but despite extensive search operations the location of the wreckage is still unknown. The first tangible evidence of the accident was discovered almost 17 months after the disappearance. On 29 July 2015, a small piece of the right wing of the aircraft was found washed up on the island of Réunion, approximately 4000 km from the assumed crash site. Since then a number of other parts have been found in Mozambique, South Africa and on Rodrigues Island. This paper presents a numerical simulation using high-resolution oceanographic and meteorological data to predict the movement of floating debris from the accident. Multiple model realisations are used with different starting locations and wind drag parameters. The model realisations are combined into a superensemble, adjusting the model weights to best represent the discovered debris. The superensemble is then used to predict the distribution of marine debris at various moments in time. This approach can be easily generalised to other drift simulations where observations are available to constrain unknown input parameters. The distribution at the time of the accident shows that the discovered debris most likely originated from the wide search area between 28 and 35° S. This partially overlaps with the current underwater search area, but extends further towards the north. Results at later times show that the most probable locations to discover washed-up debris are along the African east coast, especially in the area around Madagascar. The debris remaining at sea in 2016 is spread out over a wide area and its distribution changes only slowly.

Marine systematic conservation planning for Rodrigues Island, western Indian Ocean

There is a growing number of Marine Protected Areas (MPAs) that have been selected and designed through participatory processes, following the recognition of the need to increase the involvement of local communities likely to be affected by such developments. In parallel with this shift has been the development of systematic conservation planning (SCP) tools that have increased our capacity to design MPAs to maximise biodiversity outcomes and to scale-up community-based initiatives into more comprehensive MPA networks. In Rodrigues, four Marine Reserves (no-take zones) in the north of the island were identified through participatory processes. A Marine Protected Area (multi-use), South East Marine Protected Area (SEMPA), has also been gazetted in the south of the island through a community-based approach. In order to verify and assess gaps in the stakeholder-based design, a Marine Reserve network was designed using the SCP tool Marxan using available spatial data on marine biotopes and fishing effort (FE) to achieve fisheries benefits and marine biodiversity protection. The Marxan analysis identified that only two of the four marine reserves achieve partly the objectives set and SEMPA contains planning units which can be considered as no take zones. This study shows the importance of using both stakeholder’s knowledge and scientific input for a better design of MPAs. The results from the analyses can be used by decision makers to inform decisions in a scientific way by providing a set of scenarios from the Marxan analysis.

Rodrigues Island: carbonate deposition and karst processes as indicators of platform stability

Rodrigues Island is located in the western Indian Ocean ~600 km east of Mauritius, at 19°42′S and 63°24′E, a volcanic island with a small overlay of Quaternary eolian limestones, an area of 108 km2, elongated ENE to WSW, 18 km long and 6.5 km wide, maximum elevation of 396 m. The last volcanic activity was 1.3 ma, and only one lava tube is known. The eolian calcarenites are restricted to a narrow segmented band on the east coast, and two larger patches, Plaine Caverne and Plaine Corail, on the south coast. No subtidal carbonate facies are known, and no flank margin caves are known, indicating that platform subsidence has been in excess of 5 m/100 ka to bring such features from the MIS 5e +6 m sea-level highstand below modern sea level. The eastern eolianite outcrops contain rectangular incisions similar to the bokas found in the Netherlands Antilles, as a large volcanic rock watershed traverses a thin coastal limestone outcrop. The southern calcarenite exposures each contain large epigene cave passages developed by surface catchment from volcanic rocks. The Plaine Corail caves are abandoned by streams today, are segmented and modified by collapse and contain massive calcite speleothems, evidence of an eolianite age of perhaps 1 ma or more. Plaine Caverne contains two long, linear stream caves, mostly intact. Mauritius has flank margin caves, subtidal facies above modern sea level, and abundant lava tubes (volcanic activity as recent as 26 ka), consistent with thermal inflation now long ended on subsiding Rodrigues.

A new subfossil bulbul (Aves: Passerines: Pycnonotidae) from Rodrigues Island, Mascarenes, south-western Indian Ocean

The Hypsipetes bulbuls (Pycnonotidae) occur on Madagascar and oceanic islands throughout the Indian Ocean, as well as continental Asia. Endemic species are found on the Mascarene Islands of Mauritius and Réunion, but the genus was purportedly never reported from Rodrigues, the smallest and most isolated of the Mascarene group, which was somewhat anomalous considering present avian biogeography. Based on recently discovered subfossil remains, this paper describes a new Hypsipetes bulbul from Rodrigues Island, which presumably became extinct historically, thus filling in the biogeographical gap. This discovery further emphasises the need for palaeontological surveys in situations in which unexpected bird species distribution patterns occur, before robust biogeographical conclusions can be ascertained.http://zoobank.org/urn:lsid:zoobank.org:pub:D979AC29-B662-4A39-B4CA-984E04EB6B65

Microbiological and physico-chemical characterization of the Rodriguan chinese sausage

Rodrigues Island is a dependency of the Republic of Mauritius and is located at about 653 km northeast of it. Pig fattening is an important livestock activity in Rodrigues and pork is the most widely consumed meat (1). It is reported that Rodriguan pork has special sensorial attributes, firstly because pigs are fed with traditional starchy crops such as cassava, banana and sweet potato, and kitchen wastes, and secondly because of the rearing method which is mainly an outdoor system. In a previous study (2), the range of processed products made from pork and their processing techniques were described. The Rodriguan chinese sausage, a traditional dry-cured pork-based product, is one of the most popular products and is considered as an authentic product of Rodrigues (Figure 1). It could be eventually promoted and marketed with an appellation such as the geographical indi­cation label. However, from a food safety standpoint, there is a lack of information on the microbiological and physico-chemical characteristics of the finished product.The main objective of this work was to determine the microbio­logical and physico-chemical characteristics of the Rodriguan chinese sausage with a view to establish the standard profile of the product. The study also aimed to identify weaknesses and make recommendations to improve safety, quality and shelf life of the product.Sausages were sampled thrice from ten random family-owned processing units in seven villages and retail outlets of Rodrigues from November 2013 to January 2014. At each outlet, two sau­sages were taken and air-transported in sealed plastic bags within two days to the Faculty of Agriculture laboratory for analysis. All analyses were carried out using ISO (International Organization for Standardization) protocols.The total viable count and lactic acid bacteria count ranged from 7.8 to 8.11 and from 7.08 to 7.50 log10 CFUg-1, respectively (Table I). The total coliform and Staphylococcus spp. counts were about 3 log10 CFUg-1 each. Neither Escherichia coli nor Salmonella spp. were detected in the samples analyzed. The water activity, pH and lactic acid content of the sausages fell within the range of values typical of dry-fermented sausages (Table II). However, significant variations between samples were noted with regard moisture, protein, fat and ash contents. Similarly, water activity and pH values showed marked varia­tions between the sausages. In contrast, no significant differences were noted in the L*, a* and b* color attributes as defined by the Commission internationale de l’éclairage (CIE).Results confirmed that the Rodriguan chinese sausage satisfies the criteria of dry-cured raw meat products (3) and is overall a fairly safe and stable product. However, significant variations exist in its physico-chemical and microbiological characteristics probably due to variations in processing by the different artisans. There is thus a need to standardize the processing steps so as to improve the microbiological quality and safety of the sausage.

Ethnopharmacological analysis of medicinal plants used against non-communicable diseases in Rodrigues Island, Indian Ocean

Ethnopharmacological relevanceRodrigues is an autonomous outer island that form part of the Republic of Mauritius and one of three islands that constitute the Mascarene archipelago in the Indian Ocean. Though herbal medicine is in common use in Rodrigues, there has been no ethnopharmacological study to document quantitatively such traditional practise particularly against non-communicable diseases (NCD) which is currently a growing major health issue on the island. The aim of the present study was to collect, analyse and document traditionally used medicinal plants (MP) from key informants and traditional medicine practitioners (TMP) in the tropical island of Rodrigues to treat and/or manage common NCD. Materials and methodsData was collected via face-to-face interviews with MP users (n=113) and TMP (n=9). Seven quantitative ethnopharmacological indices, namely family use value (FUV), use value (UV), informant agreement ratio (IAR), relative frequency of citation (RFC), fidelity level (FL), relative importance (RI) and ethnobotanicity index (EI) were calculated. ResultsHundred and three plants belonging to 55 families were recorded for the treatment and/or management of 27 different NCD. Three of the MP (Terminalia bentzoë (L.) L.F, Sarcostemma cf. adontolepis Balf.f. and Clerodendrum laciniatum Balf.f.) recorded are endemic to Rodrigues and 2 (Carissa xylopicron Thouars., Phyllanthus casticum Willemet f.) endemic to the Mascarene Islands. The most solicited MP family was Asteraceae with a total of 8 species. Citrus aurantifolia (Christm.) Swingle scored the highest RFC (RFC=1.02) value. Ten plants were found to score 100% FL and the highest IAR (0.98) was observed for the disease category of certain conditions originating in the perinatal period. Arecaceae scored the highest FUV value and Ayapana triplinervis (Vahl) R.M. King et H.Rob highest UV (UV= 2.72). ConclusionGiven the dearth of updated information on traditional medicine of Rodrigues, this study can provide an opportunity to establish valuable primary information on the different MP used by the local people and hence can open new perspectives for further pharmacological research.

Ecotourism as a Means of Conservation of the Landscape of Rodrigues Island

Abstract The Indian Ocean island of Rodrigues provides an interesting landscape case study. It offers a characteristic example of a small island territory whose natural and environmental resources have been overexploited by human activity and whose inhabitants are now clinging to the remains of its symbolic heritage in an attempt to implement conservation and sustainable reconstruction. From this perspective, rurality, with its attendant agricultural practices, its traditional gardens and its natural or humanized landscapes, has become an essential asset; one which the island is trying to promote by means of a tourist strategy based on the enhancement of economic and identity-focused parameters.

The elusive genus Olifantiella (Bacillariophyta): South Pacific assemblage and Indo-Pacific biogeography

Abstract The biraphid genus Olifantiella (Bacillariophyta), which was recently discovered from the Mascarene Islands (Indian Ocean), is also present in coral reef environments of the islands of Tahiti and Moorea (South Pacific) as an epiphyte on the mangrove Rhizophora stylosa. The genus Olifantiella may be considered elusive because all of its currently known species are very small and difficult to identify under a light microscope. Several Olifantiella taxa first described from Rodrigues Island are also present in the South Pacific, along with three new taxa: O. societatis sp. nov., O. sp., and O. pilosella var. rhizophorae var. nov. Olifantiella societatis resembles O. paucistriata but the buciniportula opening of the former is oblong and faces one stria only. Olifantiella societatis and O. sp. show distinctive features of the genus Olifantiella but are very rare. A description of the buciniportula in O. pilosella is given. Although it is still unclear, the role of the buciniportula may be related to the excretion of mucilaginous material. The diversity of Olifantiella taxa between the Mascarene and Society archipelagos is similar with 6–7 species, five of which are common to both. Olifantiella mascarenica and O. pilosella are the most common members of the genus in the Mascarene Islands and the South Pacific, respectively. Olifantiella has only been previously described from the Indo-Pacific Basin, but it may be a widespread tropical genus. This genus has probably been overlooked in the past or misidentified as Navicula because of its overall naviculoid shape and small size. Electron microscopy remains essential in determining the identity of very small diatoms such as Olifantiella.

Stratigraphy and Chronology of Karst Features on Rodriguez Island, Southwestern Indian Ocean

6 Abstract: The remote Indian Ocean island of Rodrigues, while largely of volcanic origin, also contains a large body of eolian calcarenite with over thirty surveyed caves and many other karst features. Little is known, however, regarding the age and stratigraphy of the clastic deposits in the caves and the associated fossils of the highly endemic, now mostly extinct, fauna. On the Plaine Caverne and Plaine Corail of the southwestern part of the island, we obtained sediment cores up to 10 m in length and excavated bones of the extinct fauna from caves in the vicinity. Stratigraphic description and radiocarbon dating revealed that sediments in Canyon Tiyel, a collapsed-cave feature, primarily accumulated during the early and middle Holocene. Sedimentation in the canyon and adjacent caves has slowed in recent millennia, with the result that many bones of fauna that went extinct after human arrival in recent centuries are on or near the surface. The chemistry of the sediments and the alternate wet and dry regime of the cave and canyon surfaces are often not conducive to preservation of bone collagen and plant microfossils. Grotte Fougere, with an apparently unique anchialine pond inside a collapsing cave, however, contains over one meter of highly organic sediment with excellent preservation of plant and animal remains.

Genetic characterization of the honeybee (Apis mellifera) population of Rodrigues Island, based on microsatellite and mitochondrial DNA

Apis mellifera is present in Rodrigues, an island in the South-West Indian Ocean. The history of the established honeybee population is poorly known, and its biodiversity has never been studied. In this study, maternal origins of A. mellifera in Rodrigues have been assessed with the DraI test and sequencing of the mitochondrial COI-COII region. Nuclear genetic diversity was investigated with 18 microsatellite markers. A total of 524 colonies were sampled from 16 beekeepers in 20 sites. The Rodrigues population was characterized by the absence of the African lineage and presence of three European haplotypes from the C lineage. C1 haplotype was the most frequent (81.3 %), followed by C2 (18.0 %) (characteristics of A. m. ligustica and carnica, respectively) and a new haplotype, C1-Rod (0.7 %). No genetic structure was detected, and genetic diversity was comparable to continental populations. According to approximate Bayesian computation (ABC) analyses, bottleneck scenarios are most likely to have occurred.

Digital reconstruction of Rodrigues Solitaire (Pezophaps solitaria) (Aves: Columbidae) physical appearance based on early descriptive observation and other evidence

Rodrigues Solitaire (Pezophapssolitaria) is an extinct (eighteenth century) flightless bird endemic to Rodrigues Island (Mascarene Islands) and a sister taxon of iconic extinct Mauritian Dodo (Raphuscucullatus) (Columbiformes, Raphinae). Although numerous sub-fossilised bones have been recovered, no soft-tissue samples or taxidermically prepared specimens of Pezophaps solitaria are known to exist. The objective of this study was to produce accurate detailed digital reconstructions of Pezophapssolitaria based on early descriptions, contemporary and post-contemporary paintings, academic literature and images of mounted skeletons. Reconstructed images of Pezophaps solitaria generated illustrate the use of an established approach to visualise the appearance of this bird just before human influence and extinction. Digital simulation of photographic quality of males, females, juveniles and eggs of Pezophaps solitaria was obtained for the first time in this study. Inferred plumage crypsis in the Solitaire can be suggested to be superfluous in that their habitat was free of predators. There were a relatively large number of birds seen on the island by contemporary visitors, and thus it can be suggested cryptic colouration might be part of an adaptive strategy for intraspecific competition.