排序方式: 共有95条查询结果,搜索用时 171 毫秒
11.
Paleodietary changes by penguins and seals in association with Antarctic climate and sea ice extent 总被引:1,自引:0,他引:1
Positioned near the top of the food web, the dietary composition of Antarctic penguins and seals can be an excellent indicator of the regional food web and thus the status of the marine ecosystem. The dietary composition of modern penguins and seals has been well investigated; a long-term time series of data on penguin and seal diets, however, are rare. Such data, especially any predating the initiation of human harvesting of fish, whales and seals in Antarctica, are crucial for understanding and predicting responses of regional marine food webs to natural climate changes. Here we review recent progress on research of paleodietary change in Antarctic penguins and seals, specifically the Adelie penguin (Pygoscelis adeliae) and Antarctic fur seal (Arctocephalus gazella). These studies indicate that the dietary changes of penguins correspond quite well with fluctuations in climate and sea ice extent during the Holocene. The depleted δ15N ratios found in modern Adelie penguins support the "krill surplus hypothesis" in relation to historic human depletion of krilleating fish, seals and whales. 相似文献
12.
13.
14.
15.
16.
17.
1993-11-1994-03对南极长城站地区的企鹅种群的数量和分布进行了调查,共记录到6种企鹅即阿德利企鹅巴布亚全鹅,南级企鹅,长冠企鹅,王企鹅和帝企鹅。其中前3种企鹅在本地区繁殖,后3种企鹅为本地区鸟类分布的新记录。在长城站地区繁殖的企鹅总数约为1.1万只,繁殖成功率为1.30-1.57只/对。 相似文献
18.
《河北经贸大学学报(综合版)》2017,(3):58-62
数字技术改变了信息传播方式,使出版企业需要调整发展战略以迅速适应出版环境的变化。但是究竟如何适应新市场、做好新角色仍是每个出版企业如今面临的重大难题,其中尤以大众出版企业最为突出。作为大众出版领域的佼佼者,企鹅兰登公司通过战略转型之后获得了长足的发展,通过分析该公司的发展模式,可对我国大众出版企业的发展方向提供思路。 相似文献