Stephenson R
Department of Zoology, University of Toronto, Ont., Canada.
Respir Physiol. 1995 May;100(2):129-37. doi: 10.1016/0034-5687(94)00130-r.
Closed-circuit plethysmography and inert gas equilibration analysis were used to measure the volumes of gas in the respiratory system and plumage at the end of voluntary dives in unrestrained lesser scaup (Aythya affinis). Total (respiratory plus plumage) gas volumes were measured by helium dilution and estimated from body mass, body tissue density and buoyant force. These two techniques yielded results that differed by only 2.1 +/- 1.5%. Buoyancy decreased from a maximum of 3.46 +/- 0.16 N at immersion to a minimum of 2.65 +/- 0.16 N at 1.5 m depth at the end of the feeding phase of voluntary dives. At 0.193 +/- 0.013 L BTPS, the respiratory system contributed 52% of the initial buoyancy and 65% of the minimum value. The increasing relative influence of the respiratory system on buoyancy was due to the loss of 47 +/- 5% of the air in the plumage layer during the dive. These data differ significantly from estimates based on restrained ducks, and this has implications for modelling of mechanical costs of diving, oxygen storage capacity and thermal insulation in foraging ducks.
采用闭路体积描记法和惰性气体平衡分析法，对未受束缚的小潜鸭（Aythya affinis）在自主潜水结束时呼吸系统和羽毛中的气体体积进行了测量。通过氦气稀释法测量了总（呼吸加羽毛）气体体积，并根据体重、身体组织密度和浮力进行估算。这两种技术得出的结果仅相差2.1±1.5%。在自主潜水的摄食阶段结束时，浮力从浸入时的最大值3.46±0.16 N下降到1.5米深度时的最小值2.65±0.16 N。在0.193±0.013升体温、气压、饱和水蒸气条件下，呼吸系统贡献了初始浮力的52%和最小值的65%。呼吸系统对浮力的相对影响增加是由于潜水过程中羽毛层中47±5%的空气流失。这些数据与基于受束缚鸭子的估计值有显著差异，这对觅食鸭子潜水的机械成本、氧气储存能力和隔热的建模有影响。
