Trends in Crabeater Seal Age at Maturity: An Insight into Antarctic Marine Interactions
Trends in Crabeater Seal Age at Maturity: An Insight into Antarctic Marine Interactions
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食蟹海豹成熟年龄的趋势：深入了解南极海洋相互作用
DOI：
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发表时间：
1985
期刊：
影响因子：
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通讯作者：
R. Laws
中科院分区：
文献类型：
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作者：
J. Bengtson;R. Laws
食蟹海豹 (Lobodon carcinophagus) 达到性成熟的年龄是一个可能反映南极磷虾 (Euphausia superba) 丰度变化的参数。随着身体生长的加速，性成熟的年龄也更早。据推测，须鲸种群的减少会导致磷虾供应量的增加，从而导致食蟹海豹的成熟年龄下降。随着捕鲸活动的减少，以及磷虾其他消费者的数量可能因猎物丰富而增加，磷虾对个人的可用性将会减少；随着身体生长放缓，食蟹海豹的成熟年龄预计会上升。从牙骨质过渡区可以明显看出，成熟度的明显下降与人口趋势无关。相反，成熟度的下降似乎与群体内的死亡率差异有关。那些成熟较早的人显然死得较早。因此，牙齿反算不是评估过去性成熟趋势的合适方法。卵巢体计数表明在预测期间（1962 年之后）成熟度有所增加。不幸的是，由于缺乏 1962 年之前的卵巢样本，无法对该时期进行完整的评估。然而，可用的 1 个样本（反映 1958-1962 年队列中的个体）确实落在预测范围内。因此，食蟹海豹的性成熟年龄似乎随着磷虾供应量的变化而下降或上升。这些过去的成熟趋势反映了海洋群落内营养关系的变化，表明食蟹海豹的性成熟年龄可能是未来监测的有用参数。正如过去捕鲸改变了磷虾的供应一样，商业磷虾捕捞可能会再次影响捕食者对磷虾的供应。监测食蟹海豹的性成熟年龄可能有助于了解未来对南极海洋生态系统的干扰程度。
The age at which Crabeater Seals, Lobodon carcinophagus, reach sexual maturity is a parameter that might reflect changes in the abundance of Antarctic Krill, Euphausia superba. With accelerated body-growth, sexual maturity is reached at an earlier age. It was hypothesized that the decrease in Baleen Whale stocks would have resulted in an increase in Krill availability, and a subsequent decrease in the age of maturity of Crabeater Seals. As whaling decreased and populations of other consumers of Krill presumably increased in response to abundant prey, Krill availability to individuals would have decreased; age at maturity in Crabeater Seals would have been expected to rise as body-growth slowed. An apparent decrease in maturity, as evident from the transition zone of tooth cementum, was found to be unrelated to population trends. Instead, the decrease in maturity appears to be related to a differential mortality within cohorts; those individuals maturing earlier apparently die sooner. Hence, tooth back-calculation is an unsuitable method to assess past trends in sexual maturity. Counts of ovarian corpora indicated an increase in maturity during the predicted period (post 1962). Unfortunately, lack of ovarian samples from years prior to 1962 does not allow a complete evaluation during that time. However, the 1 sample available (reflecting individuals from the 1958–1962 cohorts) does fall within the range predicted. Hence, it appears that age of sexual maturity in Crabeater Seals fell and rose in response to a presumed changing availability of Krill. These past trends in maturity, reflecting changing trophic relationships within the marine community, indicate that the age of sexual maturity in Crabeater Seals might be a useful parameter to monitor in the future. Just as whaling altered Krill availability in the past, commercial Krill harvests may again affect the availability of Krill to predators. Monitoring the age at sexual maturity in Crabeater Seals may provide insight into the extent of these future perturbations on the Antarctic marine ecosystem.