Vincent Turpin

Influence of metal exposure on metallothionein synthesis and lipid peroxidation in two bivalve mollusks: the oyster (Crassostrea gigas) and the mussel (Mytilus edulis)

The impact of metals (silver, cadmium, copper, mercury and zinc) on metallothionein (MT) and malondialdehyde (MDA) levels of the oyster (Crassostrea gigas) and the mussel (Mytilus edulis) was studied after 4 or 21 days of metal exposure. Moreover, total protein levels were determined. After 4 days of metal exposure, although C. gigas and M. edulis accumulated cadmium and mercury concentrations in the gills and digestive gland, no significant variation of total protein level was occurred. After 21 days of exposure, metals were bioaccumulated in the gills and the digestive gland of both mollusks. A decrease of total protein concentrations in the gills of oysters and the digestive gland of mussels and an increase on metallothionein concentrations in the gills of both mollusks were observed. An increase of MDA levels was noticed for the gills and the digestive gland of mussels exposed for 21 days to either cadmium, silver or mercury whereas a decrease of MDA levels was observed in the gills of the oysters exposed for the same time to the same metals. The levels of proteins, MDA and MT were metal, species or organ dependent.

Alginate-entrapped Haslea ostrearia as inoculum for the greening of oysters

Entrapment in calcium alginate beads of the marine diatom, Haslea ostrearia, was successfully used for stock-culture managment and afterwards the sowing of ponds for the greening of oysters. After storage during almost 2 months, viable and cultivable cells were recovered from beads by dissolving alginate matrix but an original way lies in directly introducing beads in ponds and promoting natural cell leakage.

Utilisation of intertidal mudflats by the Dunlin Calidris alpina in relation to microphytobenthic biofilms

AbstractThe small-scale spatial distribution of Dunlin Calidris alpina staging and wintering in Bourgneuf Bay (France) was investigated on two different mudflats colonized by either epipsammic- or epipelic-dominated microphytobenthos assemblages. Shorebird counts were conducted monthly at ebb tide from October 2011 to May 2012 and from November 2012 to May 2013. Multiple linear regressions followed by hierarchical partitioning of variance showed that microphytobenthos biomass was not a significant factor to explain Dunlin densities. However, on epipelic-dominated mudflats, Dunlins did not show their typical “tide follower” behaviour and instead significantly selected the highest microphytobenthos biomass zones. The biomass of a gastropod predator of an important local Dunlin prey, Retusa obtusa, was negatively correlated with Dunlin densities. This paper provides new suggestions in the ways that biofilms on mudflats affect small shorebird foraging.ZusammenfassungDie Nutzung von Wattflächen durch AlpenstrandläuferCalidris alpina im Hinblick auf mikrophytobenthische Biofilme Die kleinräumige Verteilung von Alpenstrandläufern Calidris alpina, die in der Bucht von Bourgneuf (Frankreich) rasten und überwintern, wurde auf zwei verschiedenen Wattflächen untersucht, die von Mikrophytobenthosgemeinschaften besiedelt wurden, welche entweder von epipsammischen oder epipelischen Arten dominiert wurden. Watvogelzählungen wurden monatlich bei Ebbe von Oktober 2011 bis Mai 2012 durchgeführt. Multiple lineare Regressionen, gefolgt von der hierarchischen Partitionierung der Varianz, zeigten, dass die Biomasse des Mikrophytobenthos keinen signifikanten Einfluss auf die Dichte der Alpenstrandläufer hatte. Auf von epipelischen Arten dominierten Wattflächen zeigten Alpenstrandläufer jedoch nicht ihr typisches “Gezeitenfolgeverhalten”, sondern wählten stattdessen die Zonen mit der höchsten Mikrophytobenthosbiomasse. Die Biomasse einer Schnecke, die eine wichtige lokale Beute des Alpenstrandläufers frisst (Retusa obtusa), zeigte eine negative Korrelation mit der Alpenstrandläuferdichte. Diese Studie liefert neue Hinweise, dass Biofilme auf Wattflächen das Nahrungsverhalten kleiner Watvögel beeinflussen.

Optimizing metamorphosis in Paracentrotus lividus aquaculture using alternative macroalgae species to Corallina sp.

Metamorphosis induction cues (by chemical mediation or direct contact) were tested in Paracentrotus lividus using three different macroalgae treatments: Corallina sp., Palmaria palmata, and Laminaria digitata. Higher percentages of metamorphosis were reached in Paracentrotus lividus larvae by direct contact with a Palmaria palmata substrate.

A FAST COLORIMETRIC ASSAY TO CONTROL GROWTH OF ALGAL STRAINS: APPLICATION TO NUMERATION OF MARINE DIATOM CELLS

The suitability of the oxidation-reduction indicator MTT [3-(4,5-dimethyl-thiazol-2yl)-2,5-diphenyl-tetrazolium bromide] to measure viability of marine diatoms is evaluated. This tetrazolium salt is reduced to form bluish violet formazan derivative in living cells while it is not reduced in dead cells. Using a contact time of three hours the formazan is spectrophotometrically quantified. Culture conditions were standardised in 24-multiwell microculture plates using four marine diatom species, some of which are currently grown in aquaculture, to determine the minimal cell concentration for detecting of formazan metabolisation. Our results demonstrate that the absorbance due to the reduction of MTT is strictly related to the diatom cellular activity. This simple colorimetric assay permits rapid cell numeration of a great number of samples in comparison to the classic haematimetric method, notably for in vitro bioassays in ecological and physiological diatom investigations. This method is only applicable to unicellular algal strains (monospecific and axenic culture). For that reason, this method is suitable for algal bioassay (e.g. water fertility tests, allelopathic studies).