Drift diving in female northern elephant seals: Implications for food processing
Drift diving in female northern elephant seals: Implications for food processing
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DOI：
10.1139/z97-004
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发表时间：
1997-01-01
影响因子：
1.4
通讯作者：
Costa, DP
中科院分区：
文献类型：
--
作者：
Crocker, DE;LeBoeuf, BJ;Costa, DP
我们测试了一种假设的预测，即北象海豹（miounga angustirostris）在一些潜水（称为C级潜水）的底部漂移，利用减少运动所节省的氧气来处理食物。在加利福尼亚Ano Nuevo的13只成年雌性在妊娠早期或晚期每两年进行一次觅食旅行时，用微型潜水记录仪获得了16份自由放养的潜水记录；游泳速度记录在一个潜水记录中。在出海前和出海后测量身体成分。回合长度为2-10次，平均持续时间与其他潜水类别相似的C级潜水，占纪录潜水次数的6.3 +/- 1.9%。在这些潜水的第二个漂移段，游泳速度接近或低于记录失速速度（0.22米/秒）。漂流时的垂直深度变化率在几回合内变化不大，最初与出发时的脂肪与瘦体重比显著相关，并且随着海豹在海上进食而系统地变化。妊娠早期雌鼠体脂初始平均为24%，平均下降速率为0.31±0.04 m/s；妊娠后期雌鼠体脂平均值接近36%，平均上浮速率为0.17±0.05 m/s。漂移潜水的频率、持续时间和时间模式与觅食行为相关，支持了潜水时漂移与加工食物的代谢成本相关的假设。这项研究间接支持了一种假设，即海象在某些潜水中暂停积极游泳，在此期间，更大比例的氧气储存被分配给食物的加工，而不会中断海豹正常的连续潜水模式，使它们保持在有氧潜水极限内。
We tested predictions from the hypothesis that northern elephant seals, Mirounga angustirostris, drift during the bottom segment of some dives (called C dives) using oxygen saved from reduced locomotion to process food. Sixteen free-ranging dive records were obtained with microcomputer dive recorders attached to 13 adult females from Ano Nuevo, California, during biannual foraging trips when they were in early or late stages of gestation; swim speed was recorded throughout one dive record. Body composition was measured before and after trips to sea. C dives with a bout length of 2-10 dives and a mean duration similar to those of other dive types made up 6.3 +/- 1.9% of the dives recorded. Swim speed was near or below the recorder stall speed (0.22 m/s) during the second, drift segment of these dives. The rate of vertical depth change while drifting varied little within bouts, was initially significantly correlated with the ratio of fat to lean body mass at departure, and changed systematically as the seals fed while at sea. Females in early gestation, with initial mean body fat of 24%, drifted down at a mean rate of 0.31 +/- 0.04 m/s; females in late gestation, with mean body fat approaching 36%, drifted up at an average rate of 0.17 +/- 0.05 m/s. The frequency, duration, and temporal pattern of drift dives were correlated with foraging behavior, supporting the hypothesis that drifting while diving is associated with the metabolic cost of processing food. This study provides indirect support for the hypothesis that elephant seals suspend active swimming on certain dives, during which a greater proportion of oxygen stores is allocated to the processing of food, without interrupting the seals' normal pattern of continuous diving and allowing them to remain within their aerobic dive limit.