Saint-Denis, Reunion
Saint-Denis, Reunion

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Mattio L.,University of Cape Town | Mattio L.,Institute Of Recherche Pour Le Developpement | Zubia M.,ARVAM | Loveday B.,University of Cape Town | And 6 more authors.
Phycologia | Year: 2013

Mauritius and Réunion are part of the Mascarene Islands situated in the southwestern Indian Ocean, c. 800 km east of Madagascar. A total of 44 different Sargassum species and subspecific taxa was listed in the literature for these islands. This was a remarkable number for such isolated and small islands, and was more than have been recorded from Madagascar or other East African countries. The first aim of our study was to revise these species lists using newly collected specimens to provide a reliable and illustrated tool for the identification of the Mauritian and Réunion Sargassum. On the basis of morphological and molecular analyses, a total of six taxa was identified as S. cymosum f. borbonicum, S. obovatum, S. pfeifferae (reinstated), S. polycystum, S. portierianum and S. robillardii (stat. nov.). A seventh taxon, S. scopula, was identified from a herbarium collection but not re-collected. As a result of our taxonomic revision, we concluded that most of the species listed in the literature for both Mauritius and Réunion were misidentifications or synonyms, and we proposed three new taxonomic synonyms. The biogeography of the six Sargassum taxa was further investigated using local and regional hydrodynamic dispersal models. Results underlined the isolated position of the Mascarene Islands with (1) unlikely import of Sargassum in present-day conditions, (2) likely dispersal/exchanges within the archipelago and (3) a two-pronged export of Sargassum to the east coast of Madagascar and the Seychelles with a major stream northwestward and a weaker stream southwestward. These oceanic conditions had probably shaped the Sargassum diversity of the Mascarene Islands and in particular explained the endemicity of S. cymosum f. borbonicum and restricted distribution of S. obovatum, S. pfeifferae, S. robillardii and S. scopula.


Echenique-Subiabre I.,Institute Pasteur Paris | Echenique-Subiabre I.,University Pierre and Marie Curie | Villeneuve A.,Institute Pasteur Paris | Golubic S.,Boston University | And 3 more authors.
Microbial Ecology | Year: 2014

Cyanobacteria-dominated microbial mat communities thrive widely and year round in coral reefs and tropical lagoons, with periodic massive development of benthic blooms. We studied the diversity and spatiotemporal variation of the cyanobacterial dominance in mats of the shallow lagoon of La Réunion Island in the Indian Ocean by means of denaturing gradient gel electrophoresis and cloning-sequencing approaches targeting the 16S rRNA gene, combined with macromorphological and micromorphological characterization of corresponding phenotypes. The mat-forming cyanobacteria were highly diversified with at least 67 distinct operational taxonomic units identified in the lagoon, encompassing the entire morphological spectrum of the phylum Cyanobacteria, but with striking dominance of Oscillatoriales and Nostocales. It appeared also that selective pressures acting at different geographical scales have an influence on the structure and composition of these mats dominated by cyanobacteria. First, large changes were observed in their diversity and composition in relation to local changes occurring in their environment. Second, from the data obtained on the richness and composition of the mats and from the comparison with similar studies in the world, tropical mats seem to display wider cyanobacterial richness than in temperate and cold areas. Moreover, these tropical mats share more species with mats in other tropical regions than with those in temperate and cold climatic regions, suggesting that marine cyanobacteria in biofilms and mats display a biogeographic structure. © 2014, Springer Science+Business Media New York.


Bollard S.,ARVAM | Pinault M.,Pareto Ecoconsult | Pinault M.,CNRS Insular Research Center and Environment Observatory | Quodi J.-P.,ARVAM | And 5 more authors.
Cahiers de Biologie Marine | Year: 2013

Echinodernis from Reunion Island have been studied mostly from west coast reefs. A recent faunal inventory (BIOLAVE) was conducted on the underwater lava flows of Piton de La Fournaise and constitutes the first submarine survey on the south-east side of the island. The aim of the present study was to evaluate the species richness in the different echinoderm classes and assess their potential as indicator of the colonisation of lava with different ages. During 8 days, 9 sites with different habitats defined by depth and substrate homogeneity were explored using a stratified sampling. Description of echinoderms and comparison of the taxonomic composition between sites of different ages and depths were presented. 45 species of the 5 classes were identified, belonging to 23 families and 32 genera. Ophiuroid was the most diverse class (22 species), followed by echinoids (13 species), asteroids and holothuroids (6 species each), and crinoids (2 species). Species number increased with lava flow's age, except for echinoids, which showed a higher species number on recent sites, but ophiuroids only showed a significantly higher species number on the oldest sites. On the contrary, species number tended to decrease with depth, but echinoids only showed a significantly higher species number on shallow water. Some asteroid, echinoid and holothuroid species, such as Aquilonastra richmondi, Asthenosoma varium, Echinothrix spp., Echinometra mathaei and Euapta godeffroyi, were observed on the most recent sites only, while some ophiuroid species were observed in deeper sites only. These characteristic species could be seen as bioindicators of disturbed environment or have a distribution restricted to deeper areas.


Carnicer O.,IRTA - Institute of Agricultural-Alimentary Research and Technology | Tunin-Ley A.,ARVAM | Andree K.B.,IRTA - Institute of Agricultural-Alimentary Research and Technology | Turquet J.,ARVAM | And 2 more authors.
Cryptogamie, Algologie | Year: 2015

The toxic epi-benthic dinoflagellate Ostreopsis is distributed worldwide in coral reef ecosystems and temperate regions. There are nine species described to date based on morphological features. Some of them have been proved to be producers of palytoxin-like compounds, representing a threat to coastal marine organisms and human health. The taxonomy of the genus is currently under revision due to morphological similarities among species. The present study aims to provide additional information on morphology, 5.8S and ITS data and toxin content from thirty three strains isolated along the west coast of Reunion Island, in the Indian Ocean. Two morphotypes, non overlapping in size, were distinguishable: the small morphotype (DV = 53.5 ± 6.9 μm; W = 37.7 ± 5.6 μm) with a typical tear-drop shape and the large morphotype (DV = 103.9 ± 5.1 μm; W = 85.3 ± 6.9 μm) with a rounded shape. Phylogenetic analysis revealed the presence of three genotypes. Within the small morphotype, two different species were identifided, O. cf. ovata and a cryptic species not previously characterized. The larger cells constituted a genetically homogeneous clade. Nucleotide divergence between this species and the one qualified by Sato et al., 2011 of Ostreopsis sp. 5 was relatively low (p < 0.088) and those two strains are likely to be the same species. Haemolytic analysis resulted in no palytoxin-like activity in any of the three species. © 2015 Adac. Tous droits réservés.


Sere M.G.,ARVAM | Sere M.G.,CEA DAM Ile-de-France | Sere M.G.,Oceanographic Research Institute ORI | Sere M.G.,Center Reunion | And 4 more authors.
Diseases of Aquatic Organisms | Year: 2015

Coral diseases have caused a substantial decline in the biodiversity and abundance of reef-building corals. To date, more than 30 distinct diseases of scleractinian corals have been reported, which cause progressive tissue loss and/or affect coral growth, reproductive capacity, recruitment, species diversity and the abundance of reef-associated organisms. While coral disease research has increased over the last 4 decades, very little is known about coral diseases in the Western Indian Ocean. Surveys conducted at multiple sites in Reunion, South Africa and Mayotte between August 2010 and June 2012 revealed the presence of 6 main coral diseases: black band disease (BBD), white syndrome (WS), pink line syndrome (PLS), growth anomalies (GA), skeleton eroding band (SEB) and Porites white patch syndrome (PWPS). Overall, disease prevalence was higher in Reunion (7.5 ± 2.2%; mean ± SE) compared to South Africa (3.9 ± 0.8%) and Mayotte (2.7 ± 0.3%). Across locations, Acropora and Porites were the genera most susceptible to disease. Spatial variability was detected in both Reunion and South Africa, with BBD and WS more prevalent on shallow than deep reefs. There was also evidence of seasonality in 2 diseases: the prevalence of BBD and WS was higher in summer than winter. This was the first study to investigate the ecology of coral diseases, providing both qualitative and quantitative data, on Western Indian Ocean reefs, and surveys should be expanded to confirm these patterns. © Inter-Research 2015.


Sweet M.J.,University of Derby | Sere M.G.,ARVAM | Sere M.G.,Oceanographic Research Institute ORI | Sere M.G.,Center Reunion
Journal of Sea Research | Year: 2015

Incidences of coral disease are increasing. Most studies which focus on diseases in these organisms routinely assess variations in bacterial associates. However, other microorganism groups such as viruses, fungi and protozoa are only recently starting to receive attention. This study aimed at assessing the diversity of ciliates associated with coral diseases over a wide geographical range. Here we show that a wide variety of ciliates are associated with all nine coral diseases assessed. Many of these ciliates such as Trochilia petrani and Glauconema trihymene feed on the bacteria which are likely colonizing the bare skeleton exposed by the advancing disease lesion or the necrotic tissue itself. Others such as Pseudokeronopsis and Licnophora macfarlandi are common predators of other protozoans and will be attracted by the increase in other ciliate species to the lesion interface. However, a few ciliate species (namely Varistrombidium kielum, Philaster lucinda, Philaster guamense, a Euplotes sp., a Trachelotractus sp. and a Condylostoma sp.) appear to harbor symbiotic algae, potentially from the coral themselves, a result which may indicate that they play some role in the disease pathology at the very least. Although, from this study alone we are not able to discern what roles any of these ciliates play in disease causation, the consistent presence of such communities with disease lesion interfaces warrants further investigation. © 2015.


PubMed | ARVAM
Type: Journal Article | Journal: Diseases of aquatic organisms | Year: 2015

Coral diseases have caused a substantial decline in the biodiversity and abundance of reef-building corals. To date, more than 30 distinct diseases of scleractinian corals have been reported, which cause progressive tissue loss and/or affect coral growth, reproductive capacity, recruitment, species diversity and the abundance of reef-associated organisms. While coral disease research has increased over the last 4 decades, very little is known about coral diseases in the Western Indian Ocean. Surveys conducted at multiple sites in Reunion, South Africa and Mayotte between August 2010 and June 2012 revealed the presence of 6 main coral diseases: black band disease (BBD), white syndrome (WS), pink line syndrome (PLS), growth anomalies (GA), skeleton eroding band (SEB) and Porites white patch syndrome (PWPS). Overall, disease prevalence was higher in Reunion (7.5 2.2%; mean SE) compared to South Africa (3.9 0.8%) and Mayotte (2.7 0.3%). Across locations, Acropora and Porites were the genera most susceptible to disease. Spatial variability was detected in both Reunion and South Africa, with BBD and WS more prevalent on shallow than deep reefs. There was also evidence of seasonality in 2 diseases: the prevalence of BBD and WS was higher in summer than winter. This was the first study to investigate the ecology of coral diseases, providing both qualitative and quantitative data, on Western Indian Ocean reefs, and surveys should be expanded to confirm these patterns.

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