Centre de recherche en toxicologie de l'environnement (TOXEN), Département des sciences biologiques, Université du Québec à Montréal, P.O. Box 8888, Succursale Centre-ville, Montréal, QC, H3C 3P8, Canada.
Maurice Lamontagne Institute, Fisheries and Oceans Canada, P.O. Box 1000, 850 route de la Mer, Mont-Joli, QC, G5H 3Z4, Canada.
Environ Res. 2021 Jan;192:110272. doi: 10.1016/j.envres.2020.110272. Epub 2020 Oct 7.
The endangered St. Lawrence Estuary (SLE) beluga population is declining and has shown no sign of recovery over the past decades despite several protective measures. Changes in the availability of food resources and exposure to organohalogen contaminants have been suggested as potential factors limiting the recovery of this population. Studies on SLE belugas have suggested that contaminant exposure may perturb energy metabolism, however, whether this translates into changes in energy reserves (lipid composition) and body condition is unknown. The objective of this study was to investigate the relationships between body condition and concentrations of organohalogens (polychlorinated biphenyls, organochlorine pesticides, and flame retardants) and a range of lipid metabolites (fatty acids, acylcarnitines, lysophosphatidylcholines, phosphatidylcholines, and sphingomyelins) in blubber samples collected from 51 SLE beluga carcasses recovered between 1998 and 2016 for which the cause of mortality was documented. Blubber Σfatty acid concentrations in SLE belugas significantly decreased between 1998 and 2016, suggesting a decline in energy reserves over the past two decades. Concentrations of several phosphatidylcholine analogues were greater in blubber of beluga males and/or females that were in poor body condition compared to those in good body condition. Moreover, concentrations of phosphatidylcholine acyl-alkyl C32:2 were greater in females that died from primary starvation (poor body condition). Greater concentrations of Σemerging flame retardants were also found in blubber of SLE beluga females that were in poorer body condition. This study suggests that the use of membrane lipids including phosphatidylcholine concentrations may be a good indicator of body condition and energy reserve status in blubber of marine mammals.
圣劳伦斯河口（SLE）的濒危白鲸数量在过去几十年中一直呈下降趋势，且没有恢复的迹象，尽管采取了多项保护措施。食物资源的可利用性变化和接触有机卤代污染物被认为是限制该种群恢复的潜在因素。SLE 白鲸的研究表明，污染物暴露可能会扰乱能量代谢，但这是否会转化为能量储备（脂质组成）和身体状况的变化尚不清楚。本研究旨在调查身体状况与有机卤化物（多氯联苯、有机氯农药和阻燃剂）浓度以及一系列脂质代谢物（脂肪酸、酰基肉碱、溶血磷脂酰胆碱、磷脂酰胆碱和神经鞘磷脂）之间的关系，这些脂质代谢物是从 1998 年至 2016 年间回收的 51 具 SLE 白鲸尸体的鲸脂样本中检测到的，这些白鲸尸体的死因都有记录。SLE 白鲸的鲸脂总脂肪酸浓度在 1998 年至 2016 年间显著下降，这表明在过去二十年中能量储备有所下降。与身体状况良好的白鲸相比，身体状况较差的白鲸雄鲸和/或雌鲸的鲸脂中几种磷酯酰胆碱类似物的浓度更高。此外，在因原发性饥饿（身体状况不佳）而死亡的雌性白鲸的鲸脂中，磷酯酰基-烷基 C32:2 的浓度更高。在身体状况较差的 SLE 白鲸的鲸脂中，也发现了更多的Σ新兴阻燃剂。本研究表明，包括磷酯酰胆碱浓度在内的膜脂浓度的使用可能是海洋哺乳动物鲸脂身体状况和能量储备状态的良好指标。
