Current and proposed transcontinental pipelines for the transport of diluted bitumen (dilbit) from the Canadian oil sands traverse the coastal watersheds of British Columbia, habitat essential to Pacific salmonids. To determine the potential risks posed to these keystone species, juvenile sockeye (Oncorhynchus nerka; 1+ parr) were acutely (24-96 h) or subchronically (21-42 d) exposed to 4 concentrations of the water-soluble fraction (WSF) of unweathered Cold Lake Blend dilbit (initial total PAC concentrations: 0, 13.7, 34.7 and 124.5 μg/L) in a flow-through system. Dilbit effects on iono-osmoregulation, the physiological stress response, and the immune system were assessed by both biochemical and functional assays. Hydrocarbon bioavailability was evidenced by a significant induction of liver ethoxyresorufin-O-deethylase (EROD) activity in exposed fish. Acute and subchronic exposure significantly reduced gill Na+-K+-ATPase activity and resulted in lower plasma osmolality, Cl-, and Na+ concentrations. Acute exposure to dilbit resulted in a classic physiological stress response, however at 21 d of exposure, plasma cortisol remained elevated while other measured parameters had returned to baseline values. A compromised immune system was demonstrated by a 29.5 % higher mortality in fish challenged with Vibrio (Listonella) anguillarum following dilbit exposure compared to unexposed controls. Exposure of juvenile salmonids to the WSF of dilbit (at TPAC concentrations at the ppb level) resulted in sublethal effects that included a classic physiological stress response, and alterations in iono-osmoregulatory homeostasis and immunological performance.

中文翻译：

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暴露于水溶性沥青稀释液中的红鲑鱼（Oncorhynchus nerka）的生理失调。

目前和拟议中的用于从加拿大油砂中运输稀释沥青（莳萝）的横贯大陆管道穿越不列颠哥伦比亚省的沿海分水岭，这是太平洋鲑鱼必不可少的栖息地。为了确定对这些关键物种造成的潜在风险，将幼稚红眼鱼（Oncorhynchus nerka; 1+ parr）急性（24-96 h）或亚慢性（21-42 d）暴露于4个浓度的水溶性级分（WSF）流过系统中未风化的冷湖混合Dilbit（初始总PAC浓度：0、13.7、34.7和124.5μg/ L）。通过生化和功能分析评估了对电离渗透，生理应激反应和免疫系统的假阳作用。碳氢化合物的生物利用度可通过在裸露的鱼类中显着诱导肝脏乙氧基间苯二酚-O-脱乙基酶（EROD）活性来证明。急性和亚慢性暴露会大大降低g Na + -K + -ATPase的活性，并导致血浆渗透压，Cl-和Na +浓度降低。dilbit的急性暴露导致经典的生理应激反应，但是在暴露21 d时，血浆皮质醇仍升高，而其他测量参数已恢复至基线值。与未暴露的对照组相比，在暴露后的百日咳小肠弧菌感染的鱼类死亡率高29.5％，这证明了免疫系统受损。