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International audience; Free-living (FL) marine microbial communities differ from those attached to particles (PA). Likewise, biofilms (B) colonizing artificial surfaces, including plastics or ship hulls, hardly resemble their planktonic surroundings. However, few studies have examined the effect of the environment on these lifestyles and on the source of organisms colonizing marine surfaces. Using 16S rRNA gene metabarcoding, we identified specificities of marine prokaryotic community lifestyles (FL, PA or B) sampled in three coastal polluted locations with dissimilar environmental conditions: the North-Western Mediterranean Sea and the Atlantic and Indian Oceans. Biofilms developed over polyvinyl chloride (PVC) were found to be significantly different from FL or PA collected during the immersions. Alpha-diversity increased from FL to PA and to B, illustrating the integrative aspect of the latter, with little proportion of operational taxonomic units shared with the first two. Beta-diversity clustered first the lifestyles and then the sites. FL and PA were more affected by water quality, especially by trace metal contamination, whereas B were as sensitive to trace metals as to nutrients. Although biofilms should be supplied by the planktonic (ultra) rare biosphere, source tracking could only detect small contributions of FL or PA taxa to B communities.

International audience; We investigated seabird plastic ingestion in the western Indian Ocean by analyzing the stomach contents of 222 individuals belonging to nine seabird species (including two endangered species endemics to Reunion Island). The most affected species were tropical shearwaters (79%) and Barau's petrels (59%). The average number of plastic particles per contaminated bird was higher in Barau's petrels (6.10 ± 1.29) than in tropical shearwaters (3.84 ± 0.59). All other studied species also showed plastic presence in their stomach contents. The mass of plastic particles was significantly higher both in juvenile's Barau's petrels and tropical shearwaters than in adults. These results demonstrate the foraging areas of seabirds of the western Indian Ocean have a high level of plastic pollution. In Reunion Island, hundreds of tropical shearwaters and Barau's petrels are attracted by urban lights and die each year. We suggest taking advantage of this situation by using these species as long-term indicators of plastic marine pollution in the region.

International audience; We investigated the influence of freshwater discharges on biogeochemistry and benthic communities of La Saline fringing reef, the largest coral reef system of La Réunion Island (France, Indian Ocean). Sampling was conducted in February-March 2012 along a land-ocean continuum, including rivers, groundwater, reef waters, and oceanic waters. Our results indicated the discharges of basalt groundwater (enriched in nitrates) in the southern part of the reef, and the discharges of sand groundwater and river waters (enriched in organic matter) in sites located northward. These discharges mainly impacted fore reef surface waters, while groundwater resurgences were more diffuse and not clearly detected in depth. We highlighted the relationship Si(OH) 4 /NO 3 − to identify basalt groundwater discharges. We also put forward the relationships humic-like fluorescence/NH 4 + and tryptophan-like fluorescence/PO 4 3− to identify sand groundwater discharges and wastewater pollutions, respectively. We observed the eutrophication of the southern part of the reef through higher phytoplankton biomasses, a massive presence of fleshy algal formations and a low coral coverage. The spatial homogeneity of the benthic community structures onto the entire slope contrasted with the spatial heterogeneity of chemical variables in water. This reflected the different spatial and temporal scales involved in biological and chemical processes in coral reef ecosystems.

Marine microalgae and cyanobacteria have largely been studied for their biotechnological potential and proved their ability to produce a wide array of bioactive molecules. We investigated the antifouling potential of unexplored benthic tropical microalgae using anti-adhesion and toxicity bioassays against two major micro- and ma crobiofoulers, namely bacteria and barnacles. Fifty strains belonging to six phyla [Cyanobacteria, Miozoa (Dinoflagellata), Bacillariophyta, Cryptophyta, Rhodophyta and Haptophyta] were isolated from southwestern Islands of the Indian Ocean. They were chosen in order to represent as much as possible the huge biodiversity of such a rich tropical ecosystem. The associated chemodiversity was highlighted by both NMR- and LC-MS-based metabolomics. The screening of 84 algal fractions revealed that the anti-adhesion activity was concentrated in methanolic ones (i.e. 93% of all active fractions). Our results confirmed that microalgae constitute a promising source of natural antimicrofoulants as 17 out of the 30 active fractions showed high or very high capacity to inhibit the adhesion of three biofilm-forming marine bacteria. Dinoflagellate-derived fractions were the most active, both in terms of number and intensity. However, dinoflagellates were also more toxic and may not be suitable as a source of environmentally friendly antifouling compounds, in contrast to diatoms, e.g. Navicula mollis. The latter and two dinoflagellates of the genus Amphidinium also had interesting anti-settlement activities while being moderately toxic to barnacle larvae. Our approach, combining the bioprospecting of a large number of tropical microalgae for their anti-settlement potential and metabolomics analyses, constituted a first step towards the discovery of alternative ecofriendly antifoulants.

The marine benthic cyanobacteria of the Iles Eparses, Mozambique Channel, were surveyed for the first time. A total of 39 species are reported: 29 from Europa, 17 from Glorioso and 23 from Juan de Nova Islands. The higher biodiversity in Europa is explained by greater habitat diversity on this Island with unique ecosystems (mangroves, fossil reefs, pools). Average species richness varied between the geomorphological habitat types with higher diversity in shallow environments (fossil reef pools, mangroves, reef flats), which are characterized by high temperatures and high irradiances. The most common species observed on the three islands were Hydrocoleum coccineum , Hydrocoleum glutinosum , Hydrocoleum lyngbyaceum , Phormidium laysanense , Lyngbya sordida , and Symploca hydnoides ; which are also the dominant species observed in the Southwest Indian Ocean region. The most frequent species was Phormidium laysanense with extensive cover observed in the northwest of Juan de Nova Island. Our study provided a comparison between the cyanobacterial flora of Iles Eparses and the recorded surveys in the Southwest Indian Ocean region. The low similarity observed between these species lists could be explained by differences in sampling strategies and efforts, as well as by different taxonomic approaches employed in past regional studies.

The evolution of regulations concerning biocidal products aimed towards an increased protection of the environment (e.g., EU Regulation No 528/2012) requires the development of new non-toxic anti-fouling (AF) systems. As the marine environment is an important source of inspiration, such AF systems inhibiting the adhesion of organisms without any toxicity could be based on molecules of natural origin. In this context, the antibiofilm potential of tropical microalgal extracts was investigated. The tropics are particularly interesting in terms of solar energy and temperatures which provide a wide marine diversity and a high production of microalgae. Twenty microalgal strains isolated from the Indian Ocean were studied. Their extracts were characterized in terms of global chemical composition by high resolution magic angle spinning (HR-MAS) and nuclear magnetic resonance (NMR) spectroscopy, toxicity against marine bacteria (viability and growth) and anti-adhesion effect. The different observations made by confocal laser scanning microscopy (CLSM) showed a significant activity of three extracts from Dinoflagellate strains against the settlement of selected marine bacteria without any toxicity at a concentration of 50 &mu, g/mL. The Symbiodinium sp. (P-78) extract inhibited the adhesion of Bacillus sp. 4J6 (Atlantic Ocean), Shewanella sp. MVV1 (Indian Ocean) and Pseudoalteromonas lipolytica TC8 (Mediterranean Ocean) at 60, 76 and 52%, respectively. These results underlined the potential of using microalgal extracts to repel fouling organisms.

The monitoring of macroalgae is required by the Water Framework Directive (WFD) to achieve good ecological status for coastal waters and specific questions arise for tropical ecosystems belonging to the outermost European regions. To assess the suitability of macroalgae as a biological quality indicator for La Reunion reef flats (France), we performed multivariate analyses linking the abundance and composition of macroalgae to water physico-chemistry. Three hydrological groups of stations were identified according to dissolved inorganic nitrogen (DIN) concentrations and DIN/PO4 ratios. Some indicator species were found at the N-enriched stations (Bryopsis pennata, Caulerpa lamourouxii, Chaetomoropha vieillardii, Derbesia sp., Blennothrix lyngbyacea, Sphacelaria tribuloides), and others at the non-impacted stations (Anabaena sp1, Blennothrix glutinosa, Codium arabicum, Neomeris vanbosseae). Another key result was the significant increase in red algal cover at the most N-enriched station. Our findings are discussed in the context of the application of the WFD in the outermost French regions.

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 id...

Severe food poisoning events after the consumption of sharks have been reported since the 1940s; however, there has been no clear understanding of their cause. Herein, we report for the first time the presence of ciguatoxins (CTXs) in sharks. The identification by mass spectrometry of CTXs, including two new analogues, in a bull shark (Carcharhinus leucas) that was consumed by humans, causing the poisoning and death of 11 people in Madagascar in 2013 is described. Typical neurotoxic ciguatera symptoms were recorded in patients, and toxicological assays on extracts of the shark demonstrated CTX-like activity. These results confirm this episode as a ciguatera poisoning event and expand the range of pelagic fish species that are involved in ciguatera in the Indian Ocean. Additionally, gambieric acid D, a molecule originally described in CTX-producing microalgae, was identified for the first time in fish. This finding can contribute to a better understanding of trophic relations within food webs. The present work confirms that consumption of sharks from the Indian Ocean should be considered a ciguatera risk, and actions should be taken to evaluate its magnitude and risk in order to manage shark fisheries. © 2017 The Author(s)., We kindly acknowledge Dr. Bernard Reche, the veterinarian in charge of the shark autopsies in La Réunion and who confirmed the viscera sample was stomach, and also Erwan Lagadec (CRVOI) for performing the DNA extraction. We also thank the World Health Organization (WHO) for facilitating the transfer of samples from Madagascar to Reunion Island. The authors acknowledge Dr. Chris Rodgers for his critical review of the manuscript and Dr. Melissa Dunkle for assistance with the English. The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007–2013) under the ECsafeSEAFOOD project (grant agreement no. 311820) and from CERCA/Generalitat de Catalunya program.

International audience; Biofoulings are associated to colonization of artificial submerged structures by aquaticorganisms. This process induces adverse effects such as loss of hydrodynamism, weightincrease of equipments… Numerous toxic compounds (copper, arsenic) have been usedduring decades to avoid biofouling of ships, until organostatic substances were developed.According to their toxicity for marine environment and fauna, due to their non-specificity andnon-biodegradability, EU has banned them since 2008. For this reason, a new strategy,focusing on environmental friendly molecules is requested aiming to provide coatings thatrelease progressively active natural compounds, non-toxic for environment. In tropicalmarine environment, deterrent molecules are recognized as one of the most efficient way forprotection against predators or competition with other surfaces organisms (e.g corals,microalgae). Such active compounds are considered quite « infinite » (20,000 have beendescribed to date), so of them for their antifouling activity. As a significant component ofmarine organisms, microalgae are a promising source of active natural substances, withbiotechnological potential value. Growing microalgae is a worldwide project for variouspurposes actually e.g. biofuel. BIOPAINTROP project aims to develop antifouling coatingswith active biomolecules originating tropical marine resources (microalgae) from ReunionIsland. 2 main objectives have been designated: (i) identification of active molecules fromtropical microalgae and (ii) incorporation of these compounds in adequate coatings toconfirm the efficiency of these products in both temperate and tropical marine environment.To reach the targeted results, a pluridisciplinary group has been set up with 6 French teamswith complementary expertises: (i) HYDRÔ based on Reunion island and specialized intropical marine microalgae, (ii) 3 University laboratories: LCSNSA (Reunion) specialized innatural products valorisation, LBCM (Bretagne), specialized in marine biotechnologies;MAPIEM (Toulon) specialized in polymer materials engineering and marine biocompounds,(iii) Private partners: NAUTIX producing environmental friendly paints, expert in processingecological and antifouling coatings; BIOALGOSTRAL a start-up from Reunion specialized inproduction/valorisation of microalgae biomass.

In this study, we report the chemical characterization of 47 tropical microalgae and cyanobacteria by HR-MAS. The generated data confirm the interest of HR-MAS as a rapid screening technique with the major advantage of its easiness. The sample is used as powder of freeze-dried microalgae without any extraction process before acquisition. The spectral fingerprints of strains are then tested as variables for a chemotaxonomy study to discriminate cyanobacteria and dinoflagellates. The individual factor map generated by PCA analysis succeeds in separating the two groups, essentially thanks to the presence of specific carbohydrates. Furthermore, more resolved signals enable to identify many osmolytes. More precisely the characteristics δ of 2-O-alpha-D-glucosylglycerol (GG) are observed in all 21 h-MAS spectra of tropical cyanobacteria. After specific extraction, complementary analysis by 1D and 2D-NMR spectroscopies validates the identification of this osmolyte.

Chronic and subchronic toxicity following exposure to the DSP (Diarrhetic shellfish poisoning) toxin okadaic acid (OA) is receiving increasing attention as a public human health biohazard. However information on ecological impacts induced by proliferation of the OA producing dinoflagellate Prorocentrum is scarce. In order to analyse the toxicity of these substances, in vivo experiments were conducted on medaka fish (Oryzias latipes) embryos used as an experimental model. The study was focused on two strains of benthic Prorocentrum species, P. arenarium and P. emarginatum, naturally found in the Indian Ocean. Sample extracts (crude extracts, CE) were obtained from algal cultures and their toxic potential was explored. Their OA (and derivatives) content was evaluated by two methods: one based on chemical analysis using HPLC-MS, the other based on screening the inhibiting effect on protein phosphatase PP2A. P. arenarium extracts inhibit PP2A and the active toxin was confirmed as being OA by HPLC-MS. In contrast, P. emarginatum showed negative results regardless of the method used. The development of medaka fish embryos kept in medium containing pure OA or Prorocentrum CE was examined. Survival rates were reduced up to 100% depending on the concentrations used of both OA and CE of P. arenarium, while no effect was observed with CE of P. emarginatum. Anatomopathological studies of surviving embryos indicate that OA treatment resulted in significant increases in liver and digestive tract areas compared to controls. P. arenarium treated surviving embryos exhibited significant quantitative increases of global body and vitellus areas. Together, our results indicate that the toxic effects to medaka embryos development of pure OA and P. arenarium extracts containing OA are distinguishable. The differences may indicate the presence of additional toxic substance(s) (or molecules able to modulate OA impact) in the P. arenarium CE that probably are not present in P. emarginatum.

International audience; ABSTRACT: 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.

Lionfish (Pterois spp.) are invasive species that have recently spread throughout the Caribbean. Lionfish are available for purchase in local markets for human consumption in several islands of the region. We examined the prevalence of ciguatoxins (CTXs) in lionfish from the French Antilles, a ciguatera-endemic region. The neuroblastoma-2a (N2a) cell assay was used to assess composite cytotoxicity in 120 fish samples collected from the surrounding waters of Guadeloupe (n = 60), Saint Barthelemy Islands (n = 55) and Saint Martin (n = 5). Twenty-seven of these samples exhibited CTX-like activity by the N2a assay. Ciguatoxin (CTX) was confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in multiple samples that presented highest composite toxicity levels by N2a. Those fish found to contain CTXs were all from Saint Barthelemy. Lionfish from Guadeloupe and Saint Martin did not exhibit toxin activity, although the sample size from Saint Martin was insufficient to draw any conclusions as to the incidence of CTXs. In this study, we provide information about the potential hazard of ciguatera associated with the consumption of lionfish from known endemic areas. We also demonstrate the utility of the cell-based assay combined with LC-MS/MS to assess activity and to provide structural confirmation of CTXs respectively.

International audience; 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 dena-turing 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 phy-lum 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 biogeo-graphic structure.

Benthic dinoflagellates of the genus Ostreopsis Schmidt are common in tropical and subtropical water, and some species produce toxins potentially involved in human intoxication events. A benthic bloom of Ostreopsis mascarenensis Quod was observed near Rodrigues Island during a survey of benthic dinoflagellates in the southwestern Indian Ocean. The morphology of O. mascarenensis was studied by LM and SEM. Preliminary screening of a crude extract of an O. mascarenensis bloom revealed neurotoxicity in mice similar to that induced by palytoxin. After partition of the crude extract, the highest toxicity was retained in the butanol-soluble fraction, which retained hemolytic activity suggestive of palytoxin analogues. Two new toxins, mascarenotoxin-A and -B, were resolved from this fraction by HPLC coupled to a diode array detector. The closed mass spectrum profile and fragmentation pattern obtained by advanced nano-electrospray ionization quadrupole time-of-flight mass spectrometry between purified toxins and a reference palytoxin confirmed the mascarenotoxins as palytoxin analogues. These results were confirmed by tandem mass spectrometry with the identification of specific fragment ion m/z 327. An on-line liquid chromatography protocol coupled to tandem mass spectrometry was developed for detection of these palytoxin analogues. The present study describes the first purification, chemical, and toxicological characterization of new palytoxin analogues isolated from a benthic bloom of O. mascarenensis. These results suggest that O. mascarenensis, which is largely distributed in the southwestern Indian Ocean, could be a source of palytoxin poisoning in this tropical area.

Resume L'ichtyosarcotoxisme de type ciguatera regroupe le syndrome polymorphe associe a la consommation de chair de poissons de recifs coralliens. Ces poissons herbivores s'intoxiquent par ingestion de micro-algues (dinoflagelles), en particulier Gambierdiscus toxicus. Les toxines (ciguatoxine, maitotoxine, acide okadaique) contenues dans ces algues subissent une bioamplification dans la chaine trophique. L'intoxication se manifeste dans les heures suivant l'ingestion de poisson toxique, par des troubles digestifs, du prurit, des paresthesies de la langue et des extremites. L'evolution est habituellement favorable. Le diagnostic se fait sur l'anamnese en l'absence de test fiable. La prevention est basee sur l'interdiction de consommer certaines especes de poissons coralliens.

International audience; Many people around the world depend on the marine environment, for its nutritional, recreational, and general economic value. For many years, a notable increase has been observed in the number of cases of severe intoxication, through the consumption of contaminated seafood and through external exposure. While dinoflagellates and diatoms are considered the main source of marine biotoxins, there is also growing evidence that certain groups of marine cyanobacteria are likely to produce various toxins with potential harmful effects on humans, especially in cases of massive proliferation. Some of the recent findings that support this hypothesis are summarized in this chapter.

A new benthic dinoflagellate, Coolia areolata Ten-Hage, Turquet, Quod & Coute sp. nov., was isolated from sandy substrata in La Possession Bay, La Reunion, and at various other sites in the western Indian Ocean. This new species is described and illustrated by light and scanning electron micrographs and drawings. The plate formula of C. areolata is P03′7″ 6c 6?s 5′″ 2″″. Cell size ranges are 30–36.5 μm long and 28–36.5 μm wide. Cells are spherical, areolate, and covered with scattered round pores. The surface of the apical plate 1′ is smooth. The apical pore is 9–10 μm long. Cells of C. areolata are distinguished from C. monotis and C.tropicalis by thecal surface morphology, thecal plate size and shape, and apical pore length.

Okadaic acid was isolated from a strain of Prorocentrum arenarium Faust (Prorocentrales, Dinophyceae) collected from Europa Island (40 degrees 22'E, 22 degrees 20'S, SW Indian Ocean). The presence of okadaic acid in the algal extract was suspected after cytotoxicity and phosphatase 2A inhibition testing. It was confirmed by ADAM derivatization, immunoaffinity extraction and liquid chromatography with fluorimetric detection analysis as well as by liquid microchromatography with mass spectrometric detection. Results indicate that the P. arenarium strain was toxinogenic and could be potentially involved in the toxin production associated with the human diseases, diarrhetic shellfish poisoning and possibly ciguatera fish poisoning in the SW Indian Ocean area.

A new toxic benthic marine dinoflagellate, Prorocentrum borbonicum Ten-Hage, Turquet, Quod, Puiseux-Dao & Coute sp. nov., isolated from the fringing coral reef of St Leu from La Reunion Island (France, southwest Indian Ocean) is described from light and scanning micrographs. The species was identified based on shape, size, surface micromorphology, ornamentation of thecal plates, and architecture of the periflagellar area and intercalary band. Prorocentrum borbonicum is a small species (18–24 μm long and 16–20 μm wide) with a broadly ovate shape. Thecal depressions are numerous (950–1020 per valve). Two sizes of valve pores were recognized: large pores, which are scattered on the valve surface, except in the central area, and smaller pores, which are localized chiefly in the centre of the valve and at the periphery, along the intercalary band. The periflagellar area is V-shaped and accommodates a flagellar pore and an auxiliary pore, the latter being the smaller of the two. Prorocentrum borbonicum...

A new benthic marine dinoflagellate, Sinophysis canaliculata Quod, Ten-Hage, Turquet, Mascarell et Coute sp. nov., was isolated from coral and sediment samples from sites in the western Indian Ocean. This new species is described and illustrated by drawings and light and scanning electron micrographs. Members of Sinophysis Nie et Wang are generally laterally flattened with circular outlines. The new species differ from others of the genus in the following characters: cell shape and size and features of thecal plates (plate shapes, size and number of valve pores, presence of a narrow thecal cut in the left hypothecal plate). Sinophysis canaliculata is heterotrophic, lacking any chloroplasts.

A preliminary screening of toxins of the crude extract of Ostreopsis mascarenensis Quod, a benthic dinoflagellate from the south-western Indian Ocean, revealed a neurotoxicity in mice similar to that induced by palytoxin, one of the most potent marine toxins involved in seafood poisoning. The highest toxicity was retained in the butanol-soluble fraction, revealing a strong haemolytic activity, as found for palytoxin. Analyses using high-performance liquid chromatography with ultraviolet detection allowed the detection of two new toxins named mascarenotoxins (McTXs). Their mass spectrum profile and fragmentation pattern, obtained by advanced nano-ESI-Q-TOF mass spectrometry of purified McTXs, were similar to those of a reference palytoxin. They were identified as palytoxin analogues, with the characterisation of a specific fragment ion m/z 327. O. mascarenensis is a species not previously known to produce palytoxin analogues.

Environmental context Hydrocarbons are among the most widespread and harmful pollutants found in the aquatic media. Although they have been investigated in various temperate coastal environments, their dynamics in coral reef tropical ecosystems, which are under increasing human pressure, remain poorly understood. It was found that hydrocarbons had moderate to high concentrations, multiple origins (biogenic and anthropogenic) and could be used to track inland intrusions in fore reef waters of the eutrophicated La Saline reef ecosystem (La Reunion Island, Indian Ocean). Abstract The La Saline fringing reef, which is the most important coral reef complex of La Reunion Island, (south-western Indian Ocean), is subjected to anthropogenic pressures through river and groundwater inputs. Salinity and biogeochemical parameters (silicates, nitrates, dissolved organic carbon, chlorophyll-a), as well as aliphatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs) were analysed in particulate and dissolved material from groundwaters, rivers, harbour, back reef, fore reef and oceanic waters in the La Saline reef area during the rainy season (February-March 2012). Particulate and dissolved AH concentration ranges were 0.07-144 and 0.06-0.58 mu gL(-1) respectively. Particulate and dissolved PAH concentrations ranges were 4.3-326 and 28-350ng L-1 respectively. AHs, dominated by nC(15), nC(17), nC(18) compounds or nC(26), nC(27), nC(29), nC(31) compounds, were mainly of biogenic origin (phytoplankton, bacteria, higher-plant debris) although some anthropogenic (petroleum inputs) signatures were recorded in the dissolved phase from the harbour and fore reef areas. PAHs, dominated by two- to three-ring compounds and their alkylated homologues, reflected unburned petroleum inputs, but probably also biogenic sources. From the distribution of salinity, biogeochemical parameters and hydrocarbons, we found that inland waters flowed mainly in the surface and in the southern part of reef waters and that particulate PAHs allowed tracking these inland water intrusions in fore reef waters. Finally, this pilot study highlights the uncoupling between the dynamics of AHs and PAHs in tropical environments.

Ciguatera is a human food poisoning caused by consumption of tropical and subtropical fish that have, through their diet, accumulated ciguatoxins in their tissues. This study used laboratory mice to investigate the potential to apply blood collection cards to biomonitor ciguatoxin exposure. Quantitation by the neuroblastoma cytotoxicity assay of Caribbean ciguatoxin (C-CTX-1) spiked into mice blood was made with good precision and recovery. The blood collected from mice exposed to a sublethal dose of Caribbean ciguatoxic extract (0.59 ng/g C-CTX-1 equivalents) was analyzed and found to contain detectable toxin levels at least 12 h post-exposure. Calculated concentration varied from 0.25 ng/ml at 30 min post-exposure to 0.12 ng/ml at 12 h. A dose response mice exposure revealed a linear dose-dependent increase of ciguatoxin activity in mice blood, with more polar ciguatoxin congeners contributing to 89% of the total toxicity. Finally, the toxin measurement in mice blood exposed to toxic extracts from the Indian Ocean or from the Pacific Ocean showed that the blood collection card method could be extended to each of the three known ciguatoxin families (C-CTX, I-CTX and P-CTX). The low matrix effect of extracted dried-blood samples (used at 1:10 or 1:20 dilution) and the high sensitivity of the neuroblastoma assay (limit of detection 0.006 ng/ml C-CTX-1), determined that the blood collection card method is suitable to monitor ciguatoxin at sublethal doses in mice and opens the potential to be a useful procedure for fish screening, environmental risk assessment or clinical diagnosis of ciguatera fish poisoning in humans or marine mammals.

Benthic dinoflagellates of the genus Prorocentrum are common in tropical and subtropical water and several species produce phycotoxins potentially involved in human toxic outbreaks. The toxic dinoflagellate Prorocentrum borbonicum collected at La Reunion Island (France) was cultured in laboratory. A crude extract of the organism displayed significant toxicity in mice characterized by progressive limb paralysis, severe dyspnea, and death, and the toxicity was retained, after partition, in the extract's butanol-soluble fraction (BSF). Electrophysiological experiments characterizing the fraction's effect on isolated vertebrate neuromuscular preparations revealed that it depolarizes the muscle membrane and reduces the driving force for endplate potentials (EPPs) evoked by nerve stimulation, blocking directly- and indirectly-elicited muscle twitches. The depolarization induced by P. borbonicum BSF was not due to Na(+) influx through voltage-dependent Na(+) channels, since tetrodotoxin neither prevented nor suppressed the depolarization. However, ouabain, a specific ligand of the Na/K ATPase, reduced the depolarization. These results suggest the presence of palytoxin-like compounds in the fraction. HPLC-MS and MS/MS analysis showed the presence of several toxins having identical UV absorbance, among which two new isomeric toxins, borbotoxin-A and -B, of molecular mass of 1037.6 Da were isolated. The purified borbotoxin-A, had no effect on the resting membrane potential of muscle fibers and did not affect directly-elicited muscle twitches. However, the toxin reduced nerve-evoked muscle twitches, in a dose-dependent manner, reduced EPPs' amplitudes and completely blocked miniature endplate potentials. These observations suggest that the main action of borbotoxin-A is to block post-synaptic nicotinic ACh receptors.

A new benthic marine dino¯agellate, Bysmatrum granulosum Ten-Hage, Turquet, Quod & Couté, sp. nov., was obtained from sediment and coral samples from sites of La Réunion Island (SW Indian Ocean). This new species is described and illustrated by light and scanning electron micrographs. Cells are 40-50 µm long and 40-46 µm wide. The epitheca is conical and smaller than the hypotheca, which is trapezoidal with convex sides. Plate tabulation is typical for the genus (Pₒ, X, 4', 3a, 7'', 6c, 5s, 5''', 2''''); epithecal plates 3’ and 4’’ separate the intercalary plates 2a and 3a. Thecal plates are perforated by pores and covered by both small and minute wart-like projections, linearly arranged, radiating from the apical pore. This new species differs from the three others of the genus Bysmatrum in the following characters: cell shape and size, size of the apical pore complex and features of thecal plates (plate shapes and ornamentations)

One hundred and fifty-nine ichtyosarcotoxic outbreaks, including 477 people, were recorded in the island of Reunion (SW Indian ocean) between 1986 and 1994. Ciguatera outbreaks represented 78.6% of the total cases and its annual incidence rate was estimated to be 0.78/10,000 residents. Symptoms caused by ciguatera poisoning are not different from those reported in Pacific and Caribbean islands, except for the additional symptoms of hallucinatory poisoning in 16% of the patients. Serranidae fish, including species of great commercial value, were the most commonly incriminated, accounting for 50% of the outbreaks.