Hubert Grossel

Factors determining the distribution of foraminiferal assemblages in Port Joinville Harbor (Ile d'Yeu, France): the influence of pollution

Port Joinville harbor is located on an island. Thus, it receives only a few freshwater inputs, contrary to most of the areas where the influence of pollution on foraminiferal assemblages has been studied. The pollution in the harbor mainly results from the boats, including cleaning, painting and outfall of oil and motor-fuel. A total of 59 sediment samples was collected at three sampling periods (November–December 1997, May 1998 and September 1998). These samplings were supplemented by the study of algal flora and macrobenthos and by the study of water circulation by means of six stations where water was collected every hour during a tide cycle. Contaminants were analyzed in the last series of 17 samples. Total assemblages were used for this study. This choice is explained and discussed. This study shows that the main factor that determines the distribution of foraminiferal species in Port Joinville harbor is the geographical position. The correlation that occurs between heavy metals and the silt and clay fraction makes it difficult to determine whether sediment characteristics or pollution have the stronger influence on foraminiferal assemblages, except in areas heavily affected by pollution. Polluted sediments, near the careening areas, are indicated by the tolerant pioneer species Cribroelphidium excavatum and Haynesina germanica. The growth of epiphytic species depends on the presence of algae and their distribution may be favored by local conditions such as the constant immersion of the supports in the wet dock.

Trends in Ostreopsis proliferation along the Northern Mediterranean coasts

Harmful benthic microalgae blooms represent an emergent phenomenon in temperate zones, causing health, ecological and economic concern. The main goal of this work was to compile records of Ostreopsis at large temporal and spatial scales, in order to study the relationship between cell abundances, the periodicity and intensity of the blooms and the role of sea water temperature in 14 Spanish, French, Monegasque and Italian sites located along the northern limits of the Mediterranean Sea. General trends were observed in the two considered basins: the north-western Mediterranean Sea, in which higher cell abundances were mostly recorded in mid-summer (end of July), and the northern Adriatic Sea where they occur in early fall (end of September). The sea-water temperature does not seem to be a primary driver, and the maximal abundance periods were site and year specific. Such results represent an important step in the understanding of harmful benthic microalgae blooms in temperate areas, and provide a good base for policy makers and managers in the attempt to monitor and forecast benthic harmful microalgae blooms.

Health impact of unicellular algae of the Ostreopsis genus blooms in the Mediterranean Sea: experience of the French Mediterranean coast surveillance network from 2006 to 2009

Objective. Ostreopsis ovata and Ostreopsis siamensis are tropical unicellular algae that have been found recently in the Mediterranean. Both of these dinoflagellates produce palytoxin (PTX)-like toxins that are powerful vasoconstrictors in mammals. Since 2003, Ostreopsis blooms in Italy and Spain have been accompanied by reports of respiratory problems and skin/mucosa irritation in persons in contact with toxic microalgal cells (epiphytes, plankton, or sea spray) or associated toxins. Methods. In France, a surveillance network has been set up to monitor water conditions and to protect swimmers from contamination due to Ostreopsis. Results. Between 2006 and 2009, a total of nine blooms were observed on the French Mediterranean coast including five that led to manifestations in divers, swimmers, and shoreline inhabitants. A total of 47 patients presented symptoms of involving benign or mild skin, mucosal, and/or respiratory irritation that regressed spontaneously without treatment within 12–72 h (4–12 h with nonsteroidal anti-inflammatory drugs). During the study period, five beaches were temporarily closed. Discussion. In the Mediterranean, Ostreopsis blooms induce skin and respiratory disorders when human beings are exposed to saltwater with a high concentration of algal cells. However, palytoxin dosages carried out on the food chain (urchins, mussels) indicate that this risk of toxins accumulation in seafood must be taken into account and that the surveillance network should be upgraded accordingly.

Ovatoxin-a and Palytoxin Accumulation in Seafood in Relation to Ostreopsis cf. ovata Blooms on the French Mediterranean Coast

Dinoflagellates of the genus Ostreopsis are known to cause (often fatal) food poisoning in tropical coastal areas following the accumulation of palytoxin (PLTX) and/or its analogues (PLTX group) in crabs, sea urchins or fish. Ostreopsis spp. occurrence is presently increasing in the northern to north western Mediterranean Sea (Italy, Spain, Greece and France), probably in response to climate change. In France, Ostreopsis. cf. ovata has been associated with toxic events during summer 2006, at Morgiret, off the coast of Marseille, and a specific monitoring has been designed and implemented since 2007. Results from 2008 and 2009 showed that there is a real danger of human poisoning, as these demonstrated bioaccumulation of the PLTX group (PLTX and ovatoxin-a) in both filter-feeding bivalve molluscs (mussels) and herbivorous echinoderms (sea urchins). The total content accumulated in urchins reached 450 µg PLTX eq/kg total flesh (summer 2008). In mussels, the maximum was 230 µg eq PLTX/kg (summer 2009) compared with a maximum of 360 µg found in sea urchins during the same period at the same site. This publication brings together scientific knowledge obtained about the summer development of Ostreopsis spp. in France during 2007, 2008 and 2009.

Interactions between scientists, managers and policy makers in the framework of the French MediOs project on Ostreopsis (2008-2010)

Abstract The main goal of the multidisciplinary MediOs project was to acquire and analyze pertinent scientific knowledge in fields as diverse as ecology, biology, chemistry, epidemiology or socio-economics concerning the occurrence of species belonging to genus Ostreopsis (toxic benthic dinoflagellates) in the Mediterranean. The economic impact of Ostreopsis was estimated, based on the intensity and frequency of blooms. Results obtained allowed science-based recommendations concerning the management of risk, with suggestions to optimize environmental surveys, to initiate a food risk survey, and to structure actions at the national level.

Ostreopsis cf. ovata in the French Mediterranean Coast: Molecular Characterisation and Toxin Profile

Abstract The presence of dinoflagellates of the genus Ostreopsis along Mediterranean coasts was first observed in 1972, in the bay of Villefranche-sur-Mer. However, over the past ten years, harmful events related to this benthic dinoflagellate have been reported in Italian, Spanish, Greek, French, Tunisian and Algerian coastal areas. In France, during a hot period in August 2006, cases of dermatitis and respiratory problems were registered in Marseille area. At that time, a link to the proliferation of Ostreopsis was highlighted for the first time in that area. A specific monitoring was designed and implemented in the summer 2007. Two strains of Ostreopsis cf. ovata, collected in 2008 from Villefranche-sur-Mer and Morgiret coastal waters and grown in culture, were identified by molecular analysis and studied to characterise their growth and toxin profile. Liquid chromatography-mass spectrometry (LC-MS/MS) indicated that both strains produced ovatoxin-a (OVTX-a) as the major component (ca. 90%), and traces of palytoxin (PLTX). Toxin content was determined at the end of the exponential growth phase with highest concentration of 55 pg.cell-1 of OVTX-a and 2.5 pg.cell-1 of PLTX.

Distribution and abundance of Ostreopsis spp. and associated species (Dinophyceae) in the northwestern Mediterranean: the region and the macroalgal substrate matter

The range of Ostreopsis (Dinophyceae), a taxon harmful to both human health and ecosystems, has spread from a tropical and subtropical range of distribution to temperate areas, such as the Mediterranean Sea. This study has evidenced widespread summer occurrence in the northwestern Mediterranean, from French Catalonia to the French Riviera and Corsica. Ostreopsis spp. are usually associated with two other dinophycean taxa, Prorocentrum lima and Coolia spp. No obvious correlation (indicative of competition and/or facilitation) between the abundance of the three taxa was evidenced. In addition to local variability, we observed regional variability, with low abundance and local absence in French Catalonia and Languedoc, which contrasted with overall abundance and blooms in Provence, the French Riviera and Corsica, especially in late summer. Possible causes for this regional variability are discussed. Furthermore, the three taxa can grow on a variety of macroalgal substrates: 34 taxa belonging to the fleshy, bushy, flat and erect morpho-functional groups. Some macroalgal species were correlated with either high or low abundance of the studied dinophycean taxa and could therefore enhance or hinder their blooming.