Hobson Keith A, Kuwae Tomohiro, Drever Mark C, Easton Wendy E, Elner Robert W
Environment and Climate Change Canada, 11 Innovation Blvd., Saskatoon, Saskatchewan, S7N 3H5, Canada.
Coastal and Estuarine Environment Research Group, 3-1-1, Nagase, Yokosuka 239-0826, Japan.
Conserv Physiol. 2022 Feb 18;10(1):coac006. doi: 10.1093/conphys/coac006. eCollection 2022 Jan 1.
Shorebirds use key migratory stopover habitats in spring and fall where body proteins are replenished and lipids stored as fuel for the remaining journey. The Fraser River estuary, British Columbia, Canada, is a critical spring stopover site for hundreds of thousands of migrating western sandpiper, , and dunlin, . Intertidal biofilm in spring is an important nutritional source for western sandpiper, with previous isotopic research predicting 45-59% of total diet and 50% of total energy needs. However, these studies relied on isotopic mixing models that did not consider metabolic routing of key dietary macromolecules. Complexity arises due to the mixed macromolecular composition of biofilm that is difficult to characterize isotopically. We expanded on these earlier findings by considering a protein pathway from diet to the body protein pool represented by liver tissue, using a Bayesian mixing model based on C and N. We used C measurements of adipose tissue and breath CO to provide an estimate of the carbohydrate and protein C values of microphytobenthos and used these derived values to better inform the isotopic mixing models. Our results reinforce earlier estimates of the importance of biofilm to staging shorebirds in predicting that assimilated nutrients from biofilm contribute ~35% of the protein budgets for staging western sandpipers ( = 13) and dunlin ( = 11) and at least 41% of the energy budget of western sandpiper ( = 69). Dunlin's ingestion of biofilm appeared higher than anticipated given their expected reliance on invertebrate prey compared to western sandpiper, a biofilm specialist. Isotopic analyses of bulk tissues that consider metabolic routing and that make use of breath CO and adipose lipid assays can provide new insights into avian physiology. We advocate further isotopic research to better understand biofilm use by migratory shorebirds in general and as a critical requirement for more effective conservation.
滨鸟在春秋季会利用关键的迁徙中途停歇栖息地，在那里补充身体蛋白质并储存脂质，作为剩余旅程的燃料。加拿大不列颠哥伦比亚省的弗雷泽河河口是成千上万只西部滨鹬和黑腹滨鹬重要的春季中途停歇地。春季的潮间带生物膜是西部滨鹬重要的营养来源，先前的同位素研究预测其占总食物量的45 - 59%以及总能量需求的50%。然而，这些研究依赖于同位素混合模型，该模型未考虑关键饮食大分子的代谢途径。由于生物膜的大分子组成复杂，难以通过同位素进行表征，从而产生了复杂性。我们通过考虑从饮食到以肝脏组织为代表的身体蛋白质库的蛋白质途径，扩展了这些早期发现，使用基于碳和氮的贝叶斯混合模型。我们利用脂肪组织的碳测量值和呼出的二氧化碳来估计微型底栖植物的碳水化合物和蛋白质的碳值，并使用这些推导值来更好地为同位素混合模型提供信息。我们的结果强化了早期对生物膜对停歇期滨鸟重要性的估计，预测来自生物膜的同化营养物质占停歇期西部滨鹬（n = 13）和黑腹滨鹬（n = 11）蛋白质预算的约35%，以及西部滨鹬（n = 69）能量预算的至少41%。与西部滨鹬（一种生物膜专家）相比，考虑到黑腹滨鹬预期对无脊椎动物猎物的依赖，它们对生物膜的摄取似乎高于预期。考虑代谢途径并利用呼出二氧化碳和脂肪脂质分析的整体组织同位素分析可以为鸟类生理学提供新的见解。我们主张进一步开展同位素研究，以更好地了解迁徙滨鸟对生物膜的利用情况，这通常是更有效保护的关键要求。
