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Genard B.,University of Quebec at Rimouski | Pernet F.,Institute Of Recherche Sur Les Zones Cotieres | Pernet F.,French Research Institute for Exploitation of the Sea | Lemarchand K.,University of Quebec at Rimouski | And 3 more authors.
Aquatic Living Resources | Year: 2011

In this paper, biochemical and physiological analyses were used to characterize changes associated with mortality event occurred during veliger development of American oyster, Crassostrea virginica. Biochemical analyses included the evaluation of lipid classes, fatty acid composition and total protein content. Larval physiology was evaluated by studying feeding activity, enzymes related to energy metabolism, oxidative stress levels and enzymatic antioxidant defenses. These analyses were complemented by bacterial community analyses as well as by measuring larval oyster performance. We observed that mortality events coincided with (1) strong changes in the surrounding bacterial community; (2) a progressive decrease in feeding activity; (3) higher levels of some lipid classes (free fatty acids, diglycerides, and acetone mobile phospholipids); (4) lower levels of phospholipids and protein; (5) higher contents of non-methylene interrupted dienoic fatty acids (22:2 NMI); (6) a decrease in energy metabolism activity (citrate synthase and cytochrome oxidase activities); (7) a higher oxidative stress (lipid peroxidation level); and (8) an activation of antioxidant defences before mortality (glutathione peroxidase and superoxide dismutase). We hypothesized that mortality emergence was related to higher energy consumption coupled with the progressive decline in feeding activity, lowered energy reserves and a decrease in energy metabolism activity. Thus, the low energy availability limited the efficiency of antioxidant defenses, resulting in a higher oxidative stress. © EDP Sciences, IFREMER, IRD 2011. Source


Rotifers and Artemia are generally used as first foods in marine finfish aquaculture. Because of their poor nutritional value and the incapacity of marine fish to elongate or desaturate 18-carbon of longer polyunsaturated fatty acids (PUFA), it is a common practice to enrich live foods with commercial products. Since live foods represent a significant vector for transmitting bacterial contaminants, this study describes the impact of using different enrichment strategies for rotifers and Artemia on bacterial load, in addition to fatty acid profiles. Rotifers were reared in continuous culture while Artemia were obtained from cysts; both were enriched for 24h. Total bacterial counts were obtained after a 7-d incubation on marine agar. Docosahexaenoic acid (DHA) levels varied from 9.8 to 34.4% and from 8.3 to 23.2% respectively, for rotifers and Artemia. Eicosapentaenoic acid (EPA) levels ranged from 3.2 to 7.3% for rotifers and from 5.1 to 9.0% for Artemia, while arachidonic acid (ARA) levels varied, respectively, from 0.7 to 2.9 and from 1.4 to 3.7. Total bacterial counts varied from 0.9×108 to 56.6×108 for rotifers and from 0.2×109 to 11.7×109 for Artemia. These results demonstrate the importance of the enrichment strategy on the fatty acid composition and the bacterial contamination of live food. © 2010 Elsevier B.V. Source


Benoit H.P.,Gulf | Benoit H.P.,Dalhousie University | Plante S.,Institute Of Recherche Sur Les Zones Cotieres | Plante S.,University of Moncton | And 2 more authors.
ICES Journal of Marine Science | Year: 2013

Determining the sustainability of fishing mortality for discards requires information on discard amounts as well as capture and release mortality rates. Formal estimates of these rates are costly and only available for a limited number of species and fisheries. In their absence, proxies for discard mortality could inform risk assessments of fishing mortality sustainability for discarded species. Here, time-to-mortality (TM) was assessed for 48 marine fish species exposed to air following capture during an annual multi-species bottom-trawl survey. Species-specific estimates of TM were related qualitatively to more formal estimates of discard mortality from commercial fisheries, confirming the use of TM as a proxy. The effects on TM of species and individual traits, phylogenetic similarity (proxy for traits not explicitly included in the analysis) and environmental factors related to capture were also assessed. Much of the observed individual variability was explained by intraspecific and interspecific positive relationships between body size and TM. Sedentary species and those lacking a gas bladder or deciduous scales had greater TM. Effects of phylogeny and capture depth and temperature were also found. This study demonstrates how reliable proxies of discard mortality rate can be readily obtained in the field or estimated from relevant covariates. © 2012 International Council for the Exploration of the Sea. Source


Hache R.,Institute Of Recherche Sur Les Zones Cotieres | Mallet M.D.,Homarus Inc. | Mallet M.D.,EcoNov Inc. | Dumas A.,Institute Of Recherche Sur Les Zones Cotieres
Aquaculture | Year: 2015

Throughout the world, several efforts currently exist for restocking clawed lobster (. Homarus sp.) by releasing mass amounts of postlarvae in the wild. Therefore, optimization of hatchery techniques and evaluation of their influence on lobster postlarvae behavior at release time are of interest. This study looked at the effects of light regime (photoperiod and light intensity) on growth, survival, and behavior of American lobster postlarvae (stage IV) at release time. Results showed that photophase length did not induce any significant differences in growth and survival at 100. lx. Light intensity did not affect larval development at 16. h photophase. Results showed a significant interaction between the two factors (photoperiod and light intensity) on larval survival, but not on growth. When compared to other studies, our results indicate that the feeding time (night vs. day) may be of importance for optimizing growth and survival of early larvae. Behavior results clearly demonstrated that the age of the lobster at postlarvae stage IV had more influence than the day length or light intensity, and that the light intensity induced more variability than the day length. The results suggest that a light regime of 16. h photophase at 1000. lx light intensity, both survival and settling behavior at release time. © 2015 Elsevier B.V. Source


Hache R.,Institute Of Recherche Sur Les Zones Cotieres | Lanteigne C.,Ministere de lAgriculture | Hebert Y.,Institute Of Recherche Sur Les Zones Cotieres
Aquaculture | Year: 2016

Live food represents one of the major sources of bacterial contamination in larval culture. Since Artemia are widely used as live food, this approach has been thoroughly studied. Several techniques using antibiotics, ozone, chemical compounds, algae, and probiotics, have been tested to reduce bacterial load in Artemia. This research looked at the potential of salt to reduce bacterial contamination. Two salt treatments, consisting of 1 - a dip in a 200gL-1 salt solution, and 2 - a 24h enrichment in a 60gL-1 salt solution, were compared to a commercial antimicrobial enrichment product (A1 DHA Selco), a mix of commercial antibacterial products and a non-antimicrobial enrichment product (AlgaMac) as well as a control (enriched with AlgaMac). All treatments induced a reduction of the bacterial count of over 99.999983%. It was expected that different enrichment products would induce variations in the nutrient profiles, but the levels of DHA were higher in the Artemia treated with either of the salt treatments, when compared to the control. The salt treatment did not affect EPA and ARA levels, neither did it affect the levels of vitamins C and E. Therefore, salt allows for a comparable or higher reduction of the bacterial load in Artemia nauplii, than that obtained with other techniques, with a limited effect on nutrient profiles. Even more, the use of salt does not limit the choice of the enrichment product used, since it can be used in combination with a non-antibacterial enrichment product. Statement of relevance: Utilization of salt allows for a comparable or higher reduction of the bacterial load in Artemia nauplii than the ones obtained with more complicated or less durable techniques such as antibiotics, formaldehyde and ozone. As demonstrated in the present study, commercial enrichment products exist that allow for an achievement of similar results, but the use of salt does not limit the choice to enrichment products containing antimicrobial compounds, and produces minimal variations in the nutritional profiles of the Artemia. Therefore this new technique could be useful for all fish culture using Artemia. © 2015 Elsevier B.V. Source

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