Elevated seawater temperatures are linked to the development of harmful algal blooms (HABs), which pose a growing threat to marine birds and other wildlife. During late 2015 and early 2016, a massive die-off of Common Murres (Uria aalge; hereafter, murres) was observed in the Gulf of Alaska coincident with a strong marine heat wave. Previous studies have documented illness and death among seabirds resulting from exposure to the HAB neurotoxins saxitoxin (STX) and domoic acid (DA). Given the unusual mortality event, corresponding warm water anomalies, and recent detection of STX and DA throughout coastal Alaskan waters, HABs were identified as a possible factor of concern. To evaluate whether algal toxins may have contributed to murre deaths, we tested for STX and DA in a suite of tissues obtained from beach-cast murre carcasses associated with the die-off as well as from apparently healthy murres and Black-legged Kittiwakes (Rissa tridactyla; hereafter, kittiwakes) sampled in the preceding and following summers. We also tested forage fish and marine invertebrates collected in the Gulf of Alaska in 2015–2017 to evaluate potential sources of HAB toxin exposure for seabirds. Saxitoxin was present in multiple tissue types of both die-off (36.4 %) and healthy (41.7 %) murres and healthy kittiwakes (54.2 %). Among birds, we detected the highest concentrations of STX in liver tissues (range 1.4–10.8 μg 100 g⁻¹) of die-off murres. Saxitoxin was relatively common in forage fish (20.3 %) and invertebrates (53.8 %). No established toxicity limits currently exist for seabirds, but concentrations of STX in birds and forage fish in our study were lower than values reported from most other bird die-offs in which STX intoxication was causally linked. We detected low concentrations of DA in a single bird sample and in 33.3 % of invertebrates and 4.0 % of forage fish samples. Although these results do not support the hypothesis that acute exposure to STX or DA was a primary factor in the 2015–2016 mortality event, additional information about the sensitivity of murres to these toxins is needed before we can discount their potential role in the die-off. The widespread occurrence of STX in seabirds, forage fish, and invertebrates in the Gulf of Alaska indicates that algal toxins should be considered in future assessments of seabird health, especially given the potential for greater occurrence of HABs in the future.

海水温度升高与有害藻华（HAB）的发展有关，藻华对海洋鸟类和其他野生动植物构成了越来越大的威胁。在2015年末和2016年初，Commun Murres（Uria aalge; 此后，在阿拉斯加湾发现了海浪并伴有强烈的海洋热浪。先前的研究记录了由于暴露于HAB神经毒素，沙门毒素（STX）和海藻酸（DA）而导致的海鸟疾病和死亡。考虑到异常的死亡事件，相应的温水异常以及最近在整个阿拉斯加沿海水域检测到的STX和DA，HAB被确定为可能的关注因素。为了评估藻毒素是否可能导致了鼠尾草死亡，我们测试了一组组织中的STX和DA，这些组织是从与死者相关的沙滩cast鼠尸体以及显然健康的鼠尾草和黑脚Kittiwakes（Rissa）中获得的。木d; 此后，kittiwakes）在之前和之后的夏季进行了采样。我们还测试了2015-2017年在阿拉斯加湾采集的饲料鱼和海洋无脊椎动物，以评估海鸟暴露于HAB毒素的潜在来源。腐殖毒素存在于多种组织类型中，包括死亡（36.4％）和健康（41.7％）的小鼠，以及健康的kittiwakes（54.2％）。在鸟类中，我们检测到肝组织中STX的最高浓度（范围1.4–10.8μg100 g ^-1）死掉的泥潭。虎毒素在草料鱼（20.3％）和无脊椎动物（53.8％）中相对常见。目前尚无确定的海鸟毒性限值，但我们研究中的鸟类和饲料鱼中STX的浓度低于因其他原因导致STX中毒的大多数鸟类死亡所报告的值。我们在单个鸟类样本，33.3％的无脊椎动物和4.0％的饲料鱼样本中检测到了低浓度的DA。尽管这些结果不支持以下假设：急性暴露于STX或DA是2015-2016年死亡事件的主要因素，但在我们不考虑它们对模具中的潜在作用之前，还需要有关murre对这些毒素的敏感性的其他信息，离开。STX在海鸟，饲料鱼，