The risks to aquatic wildlife from spills of diluted bitumen (dilbit) into inland waters are poorly understood. In this paper, we describe the response of larval wood frogs (Rana sylvatica) to hydrocarbons and other compounds released from experimental spills of dilbit in a temperate boreal lake. To simulate a wide range of environmentally relevant oil spill scenarios, different volumes of Cold Lake Winter Blend dilbit (0, 1.5, 2.9, 5.5, 18, 42, 82, and 180 L) were added to 10 m diameter in-lake limnocorrals. Larvae (n = 360) were reared (from Gosner Stage (GS) 25 to ∼42) in land-based aquatic microcosms, where they were first exposed to clean water during a 2-week baseline phase, and then (at GS ∼30), to contaminated water withdrawn from the limnocorrals for 3 weeks. We observed no statistically significant trends in survival, growth, or development of larvae as a consequence of exposure to the chemical compounds released from naturally weathered dilbit. Likewise, neither cytochrome P450 1A biomarkers nor levels of thyroid hormones in wood frogs near metamorphic climax were significantly related to volume of the oil spills. However, there was a modest statistically significant decrease in larval activity (up to 8.7% relative to the control), but no change in other behavioral metrics (i.e., sociality or space use). Our work adds to the limited body of literature on the effects of unconventional oils on aquatic wildlife and helps to inform risk assessments regarding pipeline projects.

稀释沥青（dilbit）泄漏到内陆水域对水生野生动物的风险知之甚少。在本文中，我们描述了幼虫林蛙 ( Rana sylvatica ) 对温带北方湖泊中实验性稀释稀释剂泄漏所释放的碳氢化合物和其他化合物的反应。为了模拟各种与环境相关的溢油情景，将不同体积的冷湖冬季混合稀释液（0、1.5、2.9、5.5、18、42、82 和 180 L）添加到直径为 10 m 的湖内 limnocorrals。幼虫 ( n = 360）在陆地水生微观世界中饲养（从戈斯纳阶段（GS）25到~42），在两周的基线阶段，它们首先暴露在干净的水中，然后（在GS~30），到污染的水从 limnocorrals 中抽出 3 周。由于暴露于自然风化的稀释液中释放的化合物，我们没有观察到幼虫的存活、生长或发育有统计学意义的趋势。同样，在变质高潮附近的林蛙中，细胞色素 P450 1A 生物标志物和甲状腺激素水平都与溢油量没有显着相关。然而，幼虫活动在统计学上有适度的显着下降（相对于对照高达 8.7%），但其他行为指标（即社交或空间使用）没有变化。