Non-size-selective predation on fish larvae by moon jellyfish Aurelia aurita under low oxygen concentrations
Non-size-selective predation on fish larvae by moon jellyfish Aurelia aurita under low oxygen concentrations
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DOI：
10.3800/pbr.3.114
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发表时间：
2008-05
影响因子：
0.6
通讯作者：
J. Shoji
中科院分区：
文献类型：
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作者：
J. Shoji
近几十年来，日本沿海沃茨的月亮水母奥雷利亚奥瑞塔数量增加。由于月亮水母是高度耐受低溶解氧浓度，捕食的影响月亮水母对浮游动物可以增加夏季缺氧期间在沿海沃茨，这往往是由人为的影响，如增加营养负荷从土地。实验室实验进行，以测试的假设，夏季缺氧导致质的变化，捕食者-猎物之间的相互作用的月亮水母和仔鱼。本实验选用普通沿海鱼类真鲷（Pagrus major）的仔鱼（标准体长分别为2.9、4.1、6.2和8.6mm）。捕食率（每10分钟被月亮水母捕食的幼虫百分比）在10 L的培养箱中，分别在1、2、4和5.8 mg·L ~（-1）4种氧浓度下进行4次重复试验。在两个最高氧浓度（4和5.8 mg L-1）下观察到大小选择性捕食：大约一半的6.2和8.6 mm幼虫在10分钟的试验中存活，而超过85%的2.9和4.1 mm幼虫被捕获。在两个最低的氧浓度（1和2毫克L-1），幼虫的身体大小并不影响捕食率：超过90%的幼虫在所有大小的类被抓获。这些结果表明，夏季沿海沃茨缺氧期间，从鱼类浮游生物到月水母的营养流增加，捕食者-猎物相互作用发生质的变化，即，从大小选择性到非大小选择性捕食的转变发生在氧浓度为2 mg·L-1时。
The moon jellyfish Aurelia aurita has increased in abundance in coastal waters around Japan during recent decades. Since the moon jellyfish is highly tolerant of low dissolved oxygen concentrations, predation impacts by moon jellyfish on zooplankton can increase during summer hypoxia in coastal waters, which is often caused by anthropogenic effects such as an increase in nutritional loading from the land. Laboratory experiments were conducted in order to test the hypothesis that summer hypoxia leads to qualitative changes in predator-prey interactions between moon jellyfish and larval fish. Larvae of a common coastal fish, red sea bream Pagrus major (2.9, 4.1, 6.2 and 8.6 mm in standard length), were used for the experiments. Predation rates (% of larvae preyed on by a moon jellyfish per 10 min.) were ex- amined at four oxygen concentrations (1, 2, 4 and 5.8 mg L � 1 ) in 10 L tanks (4 replicates). Size-selective predation was observed at the two highest oxygen concentrations (4 and 5.8 mg L � 1 ): about half of the 6.2 and 8.6 mm larvae survived the 10 min. trials while more than 85% of the 2.9 and 4.1 mm larvae were captured. Larval body size did not affect the predation rates at the two lowest oxygen concentrations (1 and 2 mg L � 1 ): more than 90% of larvae in all size classes were caught. These results indicate that trophic flow from ichthyoplankton to moon jellyfish increases during summer hypoxia in coastal waters and a qualitative change in predator-prey interaction, i.e., shift from size-selective to non-size- selective predation occurs at oxygen concentrations � 2m g L � 1 .