No abstract

This study examines the effects of varying dietary lipids on growth, survival, lipid composition and behaviour in lobster Homarus americanus (Milne Edwards, 1837) postlarvae. Lobsters were fed one of 3 diets during their early ontogeny: (1) Artemac, a widely used Artemia replacement; (2) a ternary mixture consisting of Artemac, frozen Artemia adults and Artemia flakes; or (3) a mixture of live A. salina nauplii and adults. We evaluated the olfactory capacity (response to predator odour plume) and cryptic behaviour (ability to hide during settlement) of lobster postlarvae as a function of these diets and the lipid and the fatty acid composition of lobsters. Growth and survival of lobster postlarvae were highest in those fed live Artemia, followed by the ternary mix, then Artemac. The low performance of lobster postlarvae fed Artemac may be attributable to dietary deficiencies in phospholipids (PLs) or 20:4n-6 and coincided with low levels of endogenous triacylglycerols (TAG). Those lobsters fed live Artemia showed low levels of 22:6n-3 and 20:5n-3 compared to levels occurring in wild animals. Here we report the selective incorporation of 20:4n-6, 20:5n-3 and 22:6n-3 to polar lipids and, to a lesser extent, to neutral lipids in lobsters. Finally, lobster postlarvae fed the 3 experimental diets responded to a predator odour plume by reducing their activity levels and increasing the time spent swimming downstream. However, lobster settlement behaviour varied as a function of the diet: low-performing lobsters fed Artemac were less active than those fed the other diets, presumably due to low levels of endogenous TAG or changes in dietary long-chain PUFA.

Au Québec, les problèmes associés aux phénomènes d'érosion riveraine sont répandus et affectent de nombreux cours d'eau, en particulier ceux qui traversent les dépôts argileux d'origine marine. Les sédiments marins déposés lors de l'épisode de la Mer de Champlain (8000 ans BP) sont particulièrement sensibles à l'érosion riveraine et il n'est pas rare d'observer d'importants mouvements de masse le long des berges constituées de ces argiles marines. La rivière Saint-Maurice dans son cours inférieur circule dans ce type de dépôts et on peut y voir de nombreux glissements ou éboulements le long des pentes riveraines. Dans la partie aval de la rivière Saint-Maurice, entre les rapides Manigance et les rapides des Hêtres, on estime que plus de 65 % des berges sont actives et qu'elles sont affectées à divers degrés par l'érosion riveraine. Cette portion aval de la rivière Saint-Maurice est caractérisée par la prédominance des berges argileuses ou argilo-limoneuses très hautes (8-10 m) et fortement inclinées (>25°). La composition des matériaux et la géométrie des talus riverains expliquent en grande partie la vulnérabilité des berges à l'érosion riveraine dans ce secteur. 2 Phénomènes d'érosion fluviale et conditions hydrodynamiques de la rivière Sai...

Background: A cohort study was conducted to describe and compare the burden and characteristics of SARS-CoV-2 infection in hospitalized children in three countries. Methods: This was a retrospective cohort of consecutive children admitted to 15 hospitals (13 in Canada and one each in Iran and Costa Rica) up to November 16, 2020. Cases were included if they had SARS-CoV-2 infection or multi-system inflammatory syndrome in children (MIS-C) with molecular detection of SARS-CoV-2 or positive SARS-CoV-2 serology. Results: Of 211 included cases (Canada N=95; Costa Rica N=84; Iran N=32), 103 (49%) had a presumptive diagnosis of COVID-19 or MIS-C at admission while 108 (51%) were admitted with other diagnoses. Twenty-one (10%) of 211 met criteria for MIS-C. Eighty-seven (41%) had comorbidities. Children admitted in Canada were older than those admitted to non-Canadian sites (median 4.1 versus 2.2 years; p<0.001) and less likely to require mechanical ventilation (3/95 [3%] versus 15/116 [13%]; p<0.05). Requirement for oxygen or ICU occurred in 64 (30%) and death in four, three of whom. had malignancies. Age < 30 days, admission outside of Canada, presence of at least one comorbidity and chest imaging compatible with COVID-19 predicted severe disease. Conclusions: Approximately half of hospitalized children with confirmed SARS-CoV-2 infection or MIS-C were admitted with other suspected diagnoses. Disease was more severe at non-Canadian sites. Neonates, children with comorbidities and those with chest radiographs compatible with COVID-19 were at increased risk for severe disease.