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After ocean entry, juvenile Japanese chum salmon migrate northeastward to the Sea of Okhotsk. However, some juveniles originating in rivers along the Pacific coast of Hokkaido were reported to migrate in the opposite direction (westward). We compiled historical data to determine which river‐origin juveniles migrate westward and to what extent. Then, the ocean‐entry conditions and growth rates of 398 juveniles from two rivers along the Pacific coast of Hokkaido were estimated with otolith daily‐increment analysis. Many juveniles migrated >100 km westward from multiple natal river mouths. Juveniles collected to the west of their natal rivers tended to enter the ocean earlier than those collected to the east, and many did so before sea surface temperatures reached 5°C (the lower limit of the empirically favorable temperature range). In the west, many small juveniles were collected soon after ocean entry, suggesting that they migrated passively with the Coastal Oyashio, a westward cold current. By contrast, juveniles collected in the east tended to grow faster in length and have a lower body condition factor at capture, possibly due to growth‐dependent mortality during their migration against the flow of the Coastal Oyashio. Moreover, many juveniles in the west were exposed to temperatures near 13°C (the upper limit of favorable temperatures) at capture. In recent years, there has been a shortening of the favorable water‐temperature period and a drastic decline in adult chum returns in the region. There is hence concern that the likelihood of abortive migrations for juveniles transported westward will increase. [ABSTRACT FROM AUTHOR]

The first outbreak of rabbit haemorrhagic disease (RHD) in Nigeria was reported in 2020 after over three decades of its existence in several parts of the world. In this study, we traced the timeline of the 2020 outbreaks of RHD in Nigeria, assessed the knowledge and practices of farmers about RHD and other infectious diseases of rabbits. A structured questionnaire was administered using Google Forms shared through the rabbit farmers' social media groups and other professional livestock platforms. Responses were obtained from 114 rabbitries across 15 States in Nigeria. Our findings revealed that the 2020 RHDV outbreak started in February, though its earlier introduction into Nigeria is possible. The responses indicated that 85.6% (3007/3514) of the rabbit population in Kwara, Ogun, Oyo and Osun States was lost to RHD between February - November 2020. The cases were confirmed as RHD based on clinical signs, necropsy findings and or reverse transcriptase-polymerase chain reaction results. The major clinical signs observed include sudden death (89.6%), uncoordinated movement (31.3%), paralysis (27.1%), epistaxis (22.9%) and melena (2.8%). Additionally, some (27.1%) of the farmers reported they suspected that RHD was introduced to their farm mainly 'after a co-farmer visited the rabbitry', 'after the introduction of new rabbit stock' (20.8%), and 'after a visit to another rabbitry' (12.5%). Our findings indicated snuffles, myxomatosis, coccidiosis, helminthiasis, mange, hairball, bloat, uterine tumours, overgrown teeth and ear canker as the commonest disease conditions encountered. Continuous surveillance and maintenance of an active reporting system for known and novel/emerging rabbit diseases in Nigeria are imperative. [ABSTRACT FROM AUTHOR]

Every year, thousands of seabirds are cast ashore and are found dead along the coasts of North America and Western Europe. These massive mortality events called ‘winter wrecks’ have generally been attributed to harsh climatic conditions and prolonged storms which affect bird energy balance and impact their body condition. Nevertheless, additional stress factors, such as contaminant body burden, could potentially cumulate to energy constraints and actively contribute to winter wrecks. However, the role played by these additional factors in seabird massive winter mortality has received little attention to date. In February/March 2014, an unprecedented seabird wreck occurred along the Atlantic French coasts during which > 43,000 seabirds were found dead. By analyzing mercury (Hg) concentrations in various tissues collected on stranded birds, we tested the hypothesis that Hg played a significant role in this mortality. More specifically, we aimed to (1) describe Hg contamination in wintering seabirds found along the French coasts in 2014, and (2) determine if Hg concentrations measured in some vital organs such as kidney and brain reached toxicity thresholds that could have led to deleterious effects and to an enhanced mortality. We found some of the highest Hg levels ever reported in Atlantic puffins, common guillemots, razorbills and kittiwakes. Measured concentrations ranged from 0.8 to 3.6 μg·g − 1 of dry weight in brain, 1.3 to 7.2 μg·g − 1 in muscle, 2.5 to 13.5 μg·g − 1 in kidney, 2.9 to 18.6 μg·g − 1 in blood and from 3.1 to 19.5 μg·g − 1 in liver. Hg concentrations in liver and brain were generally below the estimated acute toxicity levels. However, kidney concentrations were not different than those measured in the liver, and above levels associated to renal sub-lethal effects, suggesting a potential Hg poisoning. We concluded that although Hg was not directly responsible for the high observed mortality, it has been a major aggravating stress factor for emaciated birds already on the edge. Importantly, this study also demonstrated that total blood, which can be non-lethally collected in seabirds, can be used as a predictor of Hg contamination in other tissues. [ABSTRACT FROM AUTHOR]

Abstract: Quantification of mRNA of genes related to metabolism, immunity and cellular stress was examined in relation to a massive mortality event during the culture of American oyster larvae, Crassostrea virginica which was probably, in regard to previous microbiological analysis, induced by Vibrio infection. To document molecular changes associated with the mortality event, mRNA levels were compared to biochemical and physiological data, previously described in a companion paper. Among the 18 genes studied, comparatively to the antibiotic control, 10 showed a lower relative gene expression when the massive mortality occurred. Six of them are presumed to be related to metabolism, corroborating the metabolic depression associated with the mortality event suggested by biochemical and physiological analyses. Relationships between the regulation of antioxidant enzyme activities, lipid peroxidation, and the mRNA abundance of genes linked to oxidative stress, cytoprotection, and immune response are also discussed. Finally, we observed an increase in the transcript abundance of two genes involved in apoptosis and cell regulation simultaneously with mortality, suggesting that these processes might be linked. [Copyright &y& Elsevier]

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. [ABSTRACT FROM PUBLISHER]

The article investigates the effects of coastal coseismic uplifts and the 2010 Chilean mega-earthquake on intertidal biomarker species. The mean coseismic uplift on the Gulf of Arauco, Santa Maria Island and the Bay of Concepción is measured. Intertidal rocky shore and shallow subtidal edible/commercial species that were found stranded at the uplifted areas include Concholepas concholepas, Fissurella spp, Pyura chilensis, Rhodymeniales Sarcothalia sp. and the Ceramiales Chondracanthus sp.