This study aimed at identifying potentially suitable foraging habitats for the North Atlantic right whale (NARW; Eubalaena glacialis) in the Gulf of St Lawrence (GSL), on the Scotian Shelf (SS) and in the Bay of Fundy (BoF), Canada, based on the distribution densities of their main prey, Calanus copepod species. More than 4800 historical Calanus spp. water column integrated samples as well as 221 vertically stratified sampling stations were used to create a 3D (latitude, longitude and vertical) climatology of Calanus spp. biomass densities for spring and summer–fall when NARW are feeding in Canadian waters. We then combined this 3D preyscape with bio-energetic considerations to highlight potentially suitable NARW foraging habitats in the region. Our 3D climatological approach successfully identified the known feeding areas of Grand Manan (BoF) and Roseway Basin (western SS), confirming its validity. Expanding our analyses to the GSL and other parts of the SS, we identified in both regions areas previously unknown where Calanus spp. biomass densities exceeded minimum levels suitable for foraging NARW. Our results represent a key contribution to the identification of important foraging areas for NARW in Canadian waters, especially in the context of climate change and the documented shift in NARW distribution.
The Saguenay-St. Lawrence Marine Park (SSLMP) is a region that sustains a high abundance of zooplankton. The connectivity between zooplankton populations within the SSLMP and the surrounding areas was investigated for Calanus finmarchicus and C. hyperboreus. Deepdwelling stage V copepodites (CVs) were collected in the Marine Park as well as in putative source regions in the St. Lawrence system in July 2009 (a time when they were entering into diapause). In May 2010, at the end of the overwintering period, diapausing CVs were sampled again in the Marine Park. To discriminate the origins and to predict the probable regions of origin of these deep-dwelling diapausing CVs in the SSLMP, a quadratic discriminant function analysis (QDFA) was performed. The classification algorithm was based on the carbon isotopic composition (δ 13 C) and percent carbon (%C) of individual copepods, as these variables are conservative when lipids are extracted prior to analysis. Our results suggest that about 23% of the Calanus spp. population sampled in SSLMP in late spring 2010 originated from the Saguenay Fjord (inside the SSLMP). The remainder of this population originated from regions outside the SSLMP, including the Lower St. Lawrence Estuary, and likely further east in the Gulf of St. Lawrence. Our results revealed high connectivity across the Saguenay and the St. Lawrence systems, as well as the potential for significant local production and recruitment of Calanus spp. within the Saguenay Fjord. This study also revealed the effectiveness of using δ 13 C as a marker in delineating the origin of Calanus spp., which has a relatively long non-feeding overwintering and diapausing period making it amenable to the conservation of isotopic signatures.
Des essais de réplication du virus de l’entérite hémorragique du dindon sur cultures cellulaires de rate de dindon sont décrits. L'observation en microscopie électronique des surnageants de cultures cellulaires ainsi que leur inoculation à des animaux sensibles, permettent d'affirmer que le virus s'est multiplié in vitro dans ce système. Cependant, aucun effet cytopathogène caractéristique n’a encore été observé.
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