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Seguin-Heine M.-O.,University of Quebec at Montreal | Lachance A.-A.,University of Quebec at Rimouski | Genard B.,University of Quebec at Rimouski | Myrand B.,Merinov | And 3 more authors.
Aquaculture | Year: 2014

Offshore and open sea suspension-culture of mussels is largely in development but, in this particular environment, sleeved mussels are submitted to high-energy oceanographic conditions which could increase fall-offs. In this study, we compared the performance of open sea mussel culture to that of culture in a lagoon environment. Byssus attachment strength, condition index, mechanical properties of individual byssal threads, metal content of the filaments for mussels from both the open sea and the semi-closed lagoon sites were monitored as well as the environmental characteristics of these sites. The spawning event occurred approximately one month earlier for mussels in the open sea than in the lagoon, probably due to a difference in temperature and food availability. The attachment strength of the mussels was weaker in the open sea, even if individual threads were bigger and stronger than in the lagoon. This lower attachment strength seems related to a lower production of byssal threads. © 2014 Elsevier B.V.

Picard R.,Institute des Sciences de la Mer de Rimouski | Myrand B.,Merinov | Tremblay R.,Institute des Sciences de la Mer de Rimouski
Aquatic Living Resources | Year: 2014

Blue mussels (Mytilus edulis) and soft-shell clams (Mya arenaria) are both aquaculture species in east coast of Canada and US shellfish farmers take advantage of the byssal threads production of mussels for suspension culture and the burrowing behaviour of soft-shell clams for enhancement practices. It is important that these animals attach and burrow efficiently to minimize losses during rearing. The aim of this work was to study two potential vitality indices on mussels (23.6±0.1 mm) and clams (22.6±0.1 mm) seeds following various periods of emersion: attachment strength of Mytilus edulis and burrowing ability of Mya arenaria. The effect of emersion on energy content (proteins, lipids, glycogen) was also examined. We observed no significant decrease in the attachment strength of mussels after air exposure for 78 h or in the burrowing efficiency of soft-shell clams after 54 h. Air exposure had no effect on different lipid classes, proteins, or glycogen content in either mussel or clam tissues. The stressful emersion event induced in our study may not have been high enough to induce detectable behavioural responses. This can be explained by the bivalves' ability to adapt their metabolism to minimize activity during air exposure. In doing so, they do not consume their energy reserves, which are then still available when specimens are reimmersed. Thus mussels are able to efficiently produce byssal threads and clams to burrow into sediments as soon as they are back in the water. © EDP Sciences, IFREMER, IRD 2014.

Guderley H.E.,Laval University | Himmelman J.H.,Laval University | Nadeau M.,Merinov | Cortes H.P.,Laval University | And 3 more authors.
Marine Biology | Year: 2015

To assess whether giant scallops, Placopecten magellanicus use distinct escape strategies to respond to their seastar and crustacean predators, escape responses to two major seastar predators, Asterias vulgaris and Leptasterias polaris, two seastars with little predatory impact, Crossaster papposus and Solaster endeca, and two crustacean predators, Cancer irroratus and Hyas araneus were compared. A glass rod served as a mechanical control. The responses of juvenile [2+ year (y), ~36-mm shell height (SH)] and adult (6+ y, ~100-mm SH) scallops from the Magdalen Islands, Quebec, Canada, were assessed in early summer 2005. The predatory seastars evoked the strongest response, in terms of both response latency and minimum interval between phasic contractions and numbers of phasic contractions, particularly early in the escape response. Both the minor seastar predators and crabs stimulated stronger responses than the mechanical control. Juvenile scallops were livelier than adult scallops. As P. magellanicus consistently responded to predators with an initial flurry of phasic contractions that tapered off to spaced phasic contractions separated by increasingly long tonic contractions, only the intensity of the escape response seems to have been modified by selection. © Springer-Verlag Berlin Heidelberg 2015

Cherif M.,Umea University | Granados M.,McGill University | Duffy S.,McGill University | Robert P.,Institute des Sciences de la Mer de Rimouski | And 10 more authors.
PLoS ONE | Year: 2016

Mussel aquaculture has expanded worldwide and it is important to assess its impact on the water column and the planktonic food web to determine the sustainability of farming practices. Mussel farming may affect the planktonic food web indirectly by excreting bioavailable nutrients in the water column (a short-term effect) or by increasing nutrient effluxes from biodeposit-enriched sediments (a long-term effect). We tested both of these indirect effects in a lagoon by using plankton-enclosing benthocosms that were placed on the bottom of a shallow lagoon either inside of a mussel farm or at reference sites with no history of aquaculture. At each site, half of the benthocosms were enriched with seawater that had held mussels (excretion treatment), the other half received non-enriched seawater as a control treatment. We monitored nutrients ([PO4 3-] and [NH4 +]), dissolved oxygen and plankton components (bacteria, the phytoplankton and the zooplankton) over 5 days. We found a significant relationship between long-term accumulation of mussel biodeposits in sediments, water-column nutrient concentrations and plankton growth. Effects of mussel excretion were not detected, too weak to be significant given the spatial and temporal variability observed in the lagoon. Effects of mussels on the water column are thus likely to be coupled to benthic processes in such semi-enclosed water bodies. © 2016 Cherif et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

The lithium-ion battery is a very popular energy storage device that provides power for our laptops, cellphones, hover boards, etc. However, there are serious safety problems with lithium-ion batteries, including serious fires caused by dendrite growth during charging. There are also cost issues. To overcome these problems, research has turned toward alternative batteries using other alkali metals such as sodium or alkaline-earth metals like magnesium as the active cation. Among these, sodium-ion batteries are most extensively studied. However, a longstanding puzzle is why sodium leads to a lower storage capacity in graphite than lithium. A paper published on Proceedings of the National Academy of Science reports the solution to this mystery by Caltech scientists: Dr. Yuanyue Liu, Dr. Boris Merinov and Professor William A. Goddard III of the Materials and Process Simulation Center at Caltech. "We used quantum-mechanical (QM) calculations (solving the Schrodinger Equation) to show that the sodium capacity in graphite is, indeed, smaller than for lithium, but we discovered that it is also weaker than for potassium, rubidium, and caesium," said Liu. Previously, it was suggested that the sodium has too large a radius to intercalate into graphite. However, Liu says this couldn't be the correct explanation since potassium, rubidium and caesium have a larger radius than sodium, but also lead to higher battery capacity. "Normally, there are periodic trends leading to monotonic behavior going down a column of the periodic table. More interestingly, we considered many other possible substrates with structures and chemistry that differ from graphite and find that sodium has a weaker binding than lithium, potassium, rubidium and caesium for all cases," said Merinov. "Moreover, we predict that magnesium also has the weakest binding compared with other elements in the same column of the periodic table (beryllium, caesium, strontium, barium)." This raises the important question: Why do sodium and magnesium have the weakest binding? The QM results showed that it is because of the competition between trends in the ionization energy and the ion-substrate bonding, down the columns of the periodic table. "As one moves down a column of the periodic table, it becomes easier to lose an electron, which enhances the binding; but the ion also becomes larger, forcing it to be farther from the substrate, which weakens the ion-substrate binding. This competition gives rise to the weakest binding at sodium and magnesium," said Liu. "In addition to identifying the origin of weak sodium capacity in graphite," said Professor Goddard, "we now have a conceptual a basis for analyzing the binding of alkali and alkaline-earth metal atoms over a broad range of systems. These concepts can now be used by experimentalists as they consider new materials for designing a better battery." More information: Yuanyue Liu et al. Origin of low sodium capacity in graphite and generally weak substrate binding of Na and Mg among alkali and alkaline earth metals, Proceedings of the National Academy of Sciences (2016). DOI: 10.1073/pnas.1602473113

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