Stable isotopes in southern right whale (Eubalaena australis) baleen as indicators of seasonal movements, feeding and growth
Stable isotopes in southern right whale (Eubalaena australis) baleen as indicators of seasonal movements, feeding and growth
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DOI：
10.1007/bf00351030
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发表时间：
1996-02-01
期刊：
影响因子：
2.4
通讯作者：
Schell, DM
中科院分区：
文献类型：
--
作者：
Best, PB;Schell, DM
对来自南非的11头南露脊鲸鲸须的稳定碳氮同位素进行了测定，其中包括1头新生鲸、6头幼鲸和4头成年鲸。碳同位素比值的振荡是显着的，并表示喂养北或在副热带辐合区（STC）与喂养南的STC交替。有一个成反比的关系，在青少年之间的周期性的振荡和须鲸板的长度，表明减少须鲸的增长随着年龄的增长。预测的最小的少年板的周期性的大小相当于在1岁的年龄从鲸须的增长率估计在小牛的鲸须的长度，这表明碳同位素比值的振荡是年度事件。根据这一假设：根据前一年的死亡日期和鲸须生长速度，可以计算出每个个体最近碳富集峰形成的时间;形成发生在1月至4月的100天内（平均在2月）。一个类似的分析表明，在氮同位素比值的谷形成1月和6月（平均在4月），和富集峰之间的8月和5月（平均在12月）。这些模式与以前南露脊鲸迁徙的情景并不矛盾，如果碳同位素的富集峰被认为代表在STC北部觅食，随后的富集水平下降代表秋季在STC南部觅食，以及整个冬季和早春高纬度浮游生物的同位素特征的持续存在，表明当北方迁移开始了，直到南方迁移开始时才恢复。氮同位素比值的振荡将支持这一解释，如果他们被假定为代表饥饿和恢复的循环。与露脊鲸的须鲸生长速度进行比较，可以评估六个少年的年龄。他们在年龄的大小，相比的长度和生长速度的小牛测量摄影，建议南露脊鲸的体长增长显着放缓断奶和1岁之间，从1到4岁的年龄几乎可以忽略不计。
Ratios of stable carbon and nitrogen isotopes were examined in the baleen of 11 southern right whales originating from South Africa, including one neonate, six juveniles and four adults. Oscillations in carbon isotope ratios were marked, and indicated feeding north of or at the Subtropical Convergence (STC) alternating with feeding south of the STC. There was an inverse relationship in juveniles between the periodicity of the oscillations and the length of the baleen plate, indicating a reduction in baleen growth with age. The size of the periodicity predicted for the smallest juvenile plate was equivalent to the length of the baleen at 1 yr of age as estimated from the rate of baleen growth in calves, suggesting that the oscillations in carbon isotope ratios were annual events. On this assumption: the timing of the formation of the most recent carbon enrichment peak could be calculated for each individual, given the date of death and the rate of baleen growth in the preceding year; formation occurred over a period of 100 d from January to April (mean in February). A similar analysis indicated that valleys in the nitrogen isotope ratios were formed between January and June (mean in April), and enrichment peaks between August and May (mean in December). These patterns were not inconsistent with previous scenarios of southern right whale migration, if the enrichment peaks in carbon isotopes were taken to represent feeding just north of the STC, the subsequent decline in enrichment levels to represent feeding south of the STC in autumn, and the persistence of an isotopic signature characteristic of high latitude plankton throughout the winter and early spring to indicate that feeding essentially ceased when the northern migration began, and did not resume until the southern migration was under way. The oscillations in nitrogen isotope ratios would support this interpretation, if they were assumed to represent cycles of starvation and recovery. A comparison with baleen growth rates for bowhead whales allowed the ages of the six juveniles to be assessed. Their size at age, when compared to the lengths and growth rates of calves measured photogrammetrically, suggested that growth in body length of southern right whales slows markedly between weaning and 1 yr, and may be almost negligible from 1 to 4 yr of age.