DataSheet_2_Scaled mass index derived from aerial photogrammetry associated with predicted metabolic pathway disruptions in free-ranging St. Lawrence Estuary belugas.pdf

The St. Lawrence Estuary (SLE) belugas (Quebec, Canada) are an endangered population whose numbers remain low despite ongoing conservation efforts. Multiple anthropogenic factors and changing environmental conditions are thought to have contributed to the recent 20-year decline in blubber fatty acid concentrations reported in stranded SLE belugas. Despite this evidence that energy reserves within the population are declining, there is currently no method for estimating the body condition of free-ranging animals. The potential metabolic consequences of declining fat reserves have also yet to be explored. The objectives of this study were to use unmanned aerial vehicle (UAV)-based photogrammetry to estimate the scaled mass index (SMI) of free-ranging SLE belugas, and to compare this proxy of body condition to the lipidome of outer-layer blubber samples collected from the same individuals via remote biopsy darting. Morphometric analysis of aerial images (n = 44 SLE belugas), combined with data collected from animals under professional human care, produced SMI estimates (females: 807 ± 98 kg, males: 743 ± 39 kg) similar in range to those previously calculated for SLE beluga carcasses of known weight. A non-targeted lipidomic analysis followed by pathway enrichment analysis, identified metabolic pathways predicted to show altered activity in association with SMI in the blubber of free-ranging male SLE belugas (n = 27). Mapping of enriched pathways compared to the Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathways maps, revealed that enriched pathways pertained to the metabolism of multiple lipid classes including fatty acyls and glycerophospholipids. Vitamin A, Vitamin E, and tyrosine metabolism pathways were also enriched in correlation with SMI. This study provides the basis for the development of a non-invasive technique for estimating the body condition of free-ranging SLE belugas and identifies metabolic pathways that merit further exploration to improve our understanding of the potential metabolic impacts of energy loss in cetaceans.

圣劳伦斯河口（St. Lawrence Estuary，缩写SLE）白鲸（加拿大魁北克种群）是濒危种群，尽管持续开展保护工作，其种群数量仍处于低位。多项人为活动因素与不断变化的环境条件，被认为是导致搁浅的SLE白鲸鲸脂脂肪酸浓度近20年来持续下降的原因。尽管已有证据表明该种群的能量储备正在减少，但目前尚无针对自由活动个体身体状况的评估方法，脂肪储备减少可能带来的代谢影响也尚未得到研究。本研究旨在基于无人机（unmanned aerial vehicle, UAV）摄影测量技术，评估自由活动的SLE白鲸的体重指数校正值（scaled mass index, SMI），并将这一体况替代指标与通过远程活检镖从同一批个体采集的外层鲸脂样本的脂质组（lipidome）进行对比。研究对航拍图像（样本量n=44头SLE白鲸）进行形态计量分析，并结合人工圈养个体的采集数据，得到的SMI估算值为：雌性807±98 kg，雄性743±39 kg，该数值范围与此前针对已知体重的SLE白鲸尸体计算得到的结果相近。通过非靶向脂质组学分析及通路富集分析，本研究确定了与自由活动的雄性SLE白鲸（n=27）鲸脂中SMI相关的、活性发生改变的预测代谢通路。将富集通路与京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）代谢通路图谱进行比对后发现，富集通路涉及多种脂质类别的代谢，包括脂肪酰类与甘油磷脂类。维生素A、维生素E以及酪氨酸代谢通路也与SMI呈显著相关且得到富集。本研究为开发用于评估自由活动SLE白鲸身体状况的非侵入性技术提供了基础，并确定了值得进一步探索的代谢通路，以加深我们对鲸类能量流失潜在代谢影响的理解。