Harmful algal blooms produce toxins that bioaccumulate in the food web and adversely affect humans, animals, and entire marine ecosystems. Blooms of the diatom Pseudo-nitzschia can produce domoic acid (DA), a toxin that most commonly causes neurological disease in endothermic animals, with cardiovascular effects that were first recognized in southern sea otters. Over the last 20 years, DA toxicosis has caused significant morbidity and mortality in marine mammals and seabirds along the west coast of the USA. Identifying DA exposure has been limited to toxin detection in biological fluids using biochemical assays, yet measurement of systemic toxin levels is an unreliable indicator of exposure dose or timing. Furthermore, there is little information regarding repeated DA exposure in marine wildlife. Here, the association between long-term environmental DA exposure and fatal cardiac disease was investigated in a longitudinal study of 186 free-ranging sea otters in California from 2001 – 2017, highlighting the chronic health effects of a marine toxin. A novel Bayesian spatiotemporal approach was used to characterize environmental DA exposure by combining several DA surveillance datasets and integrating this with life history data from radio-tagged otters in a time-dependent survival model. In this study, a sea otter with high DA exposure had a 1.7-fold increased hazard of fatal cardiomyopathy compared to an otter with low exposure. Otters that consumed a high proportion of crab and clam had a 2.5- and 1.2-times greater hazard of death due to cardiomyopathy than otters that consumed low proportions. Increasing age is a well-established predictor of cardiac disease, but this study is the first to identify that DA exposure affects the risk of cardiomyopathy more substantially in prime-age adults than aged adults. A 4-year-old otter with high DA exposure had 2.3 times greater risk of fatal cardiomyopathy than an otter with low exposure, while a 10-year old otter with high DA exposure had just 1.2 times greater risk. High Toxoplasma gondii titers also increased the hazard of death due to heart disease 2.4-fold. Domoic acid exposure was most detrimental for prime-age adults, whose survival and reproduction are vital for population growth, suggesting that persistent DA exposure will likely impact long-term viability of this threatened species. These results offer insight into the pervasiveness of DA in the food web and raise awareness of under-recognized chronic health effects of DA for wildlife at a time when toxic blooms are on the rise.

有害的藻华会产生毒素，这些毒素会在食物网中生物蓄积，并对人类，动物和整个海洋生态系统产生不利影响。硅藻假奈茨卡亚的花朵可以产生多摩酸（DA），这是一种最常在吸热动物中引起神经系统疾病的毒素，其心血管作用最早在南部水獭中被发现。在过去的20年中，DA中毒在美国西海岸的海洋哺乳动物和海鸟中引起了极大的发病率和死亡率。鉴定DA暴露仅限于使用生化测定法检测生物液体中的毒素，而全身毒素水平的测量是暴露剂量或时间的不可靠指标。此外，关于海洋野生生物中反复暴露于DA的信息很少。在此，一项长期的环境DA暴露与致命性心脏病之间的关系在2001年至2017年间对加利福尼亚州的186只自由放养的水獭进行了一项纵向研究，强调了海洋毒素对健康的长期影响。一种新颖的贝叶斯时空方法被用来表征环境DA的暴露，方法是将几个DA监测数据集结合起来，并与时间依赖的生存模型中的放射性标记水獭的生活史数据进行整合。在这项研究中，与低暴露的水獭相比，高DA暴露的水獭的致命性心肌病危险增加了1.7倍。食用比例较高的螃蟹和蛤的水獭比食用比例低的水獭有2.5倍和1.2倍的因心肌病导致的死亡危险。年龄的增长是确定的心脏病的预示因素，但这项研究是首次发现暴露于DA的年龄比成年成年人对心脏病风险的影响更大。高暴露水平的4岁水獭致命性心肌病的风险是低暴露水平的水獭2.3倍，而高DA暴露的10岁水獭的高风险仅1.2倍。高弓形虫滴度也使心脏病引起的死亡危险增加了2.4倍。藻酸暴露对成年成年人最有害，其存活和繁殖对人口增长至关重要，这表明持续暴露于DA可能会影响这一受威胁物种的长期生存能力。这些结果提供了对DA在食物网中的普遍性的洞察力，并提高了人们对有毒的花开增多之时DA对野生生物的长期健康影响的认识不足。