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The hydrothermal deep-sea vent fauna is naturally exposed to a highly specific environment enriched in potentially toxic species such as sulfides, metals and natural radionuclides due to the convective seawater circulation inside the oceanic crust and its interaction with basaltic or ultramafic host rocks. However, data on radionuclides in biota from such environment are very limited. An investigation was carried out on tissue partitioning of Po-210 and Pb-210, two natural radionuclides within the U-238 decay chain, in Bathymodiolus azoricus specimens from the Mid-Atlantic Ridge (Menez Gwen field). These two elements showed different distributions with high Pb-210 levels in gills and high Po-210 levels in both gills and especially in the remaining parts of the body tissue (including the digestive gland). Various factors that may explain such partitioning are discussed. However, Po-210 levels encountered in B. azoricus were not exceptionally high, leading to weighted internal dose rate in the range 3 to 4 mu Gy h(-1). These levels are slightly higher than levels characterizing coastal mussels (similar to 1 mu Gy h(-1)). (C) 2010 Elsevier B.V. All rights reserved.

Breast feathers were used to estimate mercury levels in six marine birds nesting in the tropical western Indian Ocean, i.e. Sooty Tern (Sterna fuscata), Brown Noddy (Anous stolidus), Lesser Noddy (Anous tenuirostris), Audubon Shearwater (Puffinus lherminieri bailloni), Barau's Petrel (Pterodroma baraui) and the White-tailed Tropicbird (Phaethon lepturus). Juveniles consistently showed lower plumage mercury than adults. The lowest mean level was noted in juvenile Sooty Terns from the Glorioso Archipelago (0.05 mu g g(-1)). The highest levels were obtained for adult Barau's Petrels from Reunion Island (0.96 mu g g(-1)). An inter-site analysis of Sooty Tern showed higher mercury levels in birds nesting on Juan de Nova Island. Levels were low in comparison with values reported in the plumage of seabirds worldwide. The potential impacts of the size, the type (fish/ cephalopod) and the origin (epi-/meso-pelagic) of prey on mercury intake in birds are discussed. Although the diet composition of individuals within a species appeared to be quite variable, combining results on mercury levels with common knowledge of each species allowed additional information on their dietary and foraging habits to be unraveled. (C) 2007 Elsevier B.V. All rights reserved.

Artificial media are used in physiological studies of microalgae to maintain consistent conditions from one experiment to another and these media must be adapted to the needs of the organism studied. The artificial medium, in this case named diatom artificial medium (DAM), was designed to maintain long-term cultures of Haslea ostrearia and 19 other planktonic microalgae, and to allow physiological studies related to metal metabolism. The biomass and biochemical composition of H. ostrearia grown in the DAM and in a modified Provasoli medium were compared to assess the suitability of this new artificial medium for the culture of this diatom. The DAM provided sufficient nutrients to allow H. ostrearia to grow as efficiently as in the enriched seawater medium, without negative impact on metabolism. The DAM was tested with 19 other microalgae in order to widen its potential use, and 18 of the 19 showed a good adaptation to this medium. The chemical speciation of metals (Cd, Cu, Pb, Zn) was assessed using a speciation mathematical model. The presence of EDTA resulted in the total complexation of the trace metals implying that they were present in a sole chemical species in the DAM.

Trace elements were analyzed in fish of commercial interest to determine their importance in marine systems of the Western Indian Ocean and their bioaccumulation patterns. The results are equivalent or lower than levels reported in ichthyofauna worldwide. Certain values of muscular Cd, Hg, Pb and Zn were, however, above thresholds for human consumption. Levels varied among tissues, species and fish length, but were seldom influenced by the nutritional condition of the fish, its gender and its reproductive status. Correlations between hepatic Hg and Se levels in Swordfish (r(2) = 0.747) and Yellowfin Tunas (r(2) = 0.226), and among metallothionein linking metals imply the existence of detoxification processes in these species. Level differences between fish from the Mozambique Channel and Reunion Island reflect differences of diets rather than differences of elemental availability in both environments. (c) 2006 Elsevier Ltd. All rights reserved.

The Bay of Bourgneuf, France, is a main site of shellfish production. In the marshes along the bay, oyster intensive rearing and fattening need the mass production of microalgae. Salt groundwaters, available in this region, support a large part of this production for aquaculture. Studies carried out by local authorities have brought to the fore the accumulation of lead (Pb) in several samples of algal pastes derived from cultures using salt groundwater. The aim of this study was to compare growth, nutritional value and metal (Cd, Cu, Pb and Zn) uptake of four microalgae grown in two salt groundwaters or in enriched coastal seawater. Cultures of microalgae used in aquaculture (Haslea ostrearia, Phaeodactylum tricornutum, Skeletonema costatum and Tetraselmis suecica) were realised at the laboratory under controlled experimental conditions. Results indicated that salt groundwaters provided cultures with, at least, an equal biomass and a nutritional value similar to cultures grown in enriched seawater. There was no difference regarding metal accumulation whatever the culture medium, except when S. costatum was grown in one of the salt groundwater in which case its cadmium levels were higher and could be above the French guideline level. These observations questioned on the bioavailability of metals in salt groundwaters. It also underlines the specificity of metal uptake and accumulation by microalgae., La baie de Bourgneuf (France) est un important site de production conchylicole. Dans les marais littoraux, la culture intensive et l'affinage d'huîtres nécessitent la production en masse de microalgues. Les eaux souterraines salées, facilement exploitables dans cette région, sont majoritairement utilisées dans la production des microalgues pour l'aquaculture en baie de Bourgneuf. Des études ont été menées sur les cultures de microalgues sur ces eaux souterraines salées et ont mis en évidence une accumulation de plomb (Pb) supérieure à la norme alimentaire en vigueur dans différents échantillons de pâte d'algue d'Haslea ostrearia issus de ces cultures. L'objectif de cette étude est de comparer la croissance, la composition biochimique globale et l'accumulation des métaux (Cd, Cu, Pb, Zn) pour quatre microalgues, utilisées en aquaculture, cultivées sur des eaux souterraines salées provenant de deux forages différents et sur un milieu enrichi à base d'eau de mer. Les cultures sont réalisées au laboratoire dans des conditions expérimentales contrôlées. Les eaux souterraines salées permettent la production de cultures d'une biomasse et d'une qualité biochimique au moins équivalentes à celles réalisées sur le milieu enrichi à base d'eau de mer. Les teneurs en métaux dans les microalgues ne sont pas différentes pour les algues cultivées sur les différents milieux, à l'exception de Skeletonema costatum qui, cultivée sur une des eaux souterraines, peut présenter des teneurs supérieures à la norme alimentaire en vigueur. Ces observations soulèvent des questions sur la biodisponibilité des métaux dans les eaux souterraines salées et soulignent la spécificité de l'accumulation des métaux dans les microalgues.