Clearance rates of jellyfish and their potential predation impact on zooplankton and fish larvae in a neritic ecosystem (Limfjorden, Denmark)
Clearance rates of jellyfish and their potential predation impact on zooplankton and fish larvae in a neritic ecosystem (Limfjorden, Denmark)
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DOI：
10.3354/meps304117
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发表时间：
2005-12
影响因子：
2.5
通讯作者：
L. Hansson;O. Moeslund;T. Kiørboe;H. U. Riisgård
中科院分区：
文献类型：
--
作者：
L. Hansson;O. Moeslund;T. Kiørboe;H. U. Riisgård
在实验室条件下测定了管花八叠梅、八点红珊瑚、三角梅和耳状钵水母奥雷利亚的清除率。肠内容物分析还原位收集了耳，随后用于估计清除率。A.耳虫与被捕食生物的差异很大。大型甲壳类猎物与低逃逸能力（卤虫无节幼体和蜈蚣幼虫）清除率高，而桡足类清除率较低，和清除率的小双壳类幼虫和桡足类无节幼体相对较低。这些数据被用来评估水母捕食对丹麦Limfjorden的浮游动物和鱼苗的影响。2003年上半年对浮游动物、鱼苗和水母进行了重复取样。水螅水母类9个分类群和钵水母类4个分类群。结合估计的个体水母的清除率来计算Limfjor- den中潜在的鱼类诱导的猎物死亡率。桡足类被用作模型猎物组估计集体捕食的影响，所有水母。具有未知清除潜力的美杜莎物种被假定为清除率瓦尔- ues，但这些物种的集体捕食潜力被评估为很小。水螅水母占主导地位的数字和最高的潜在清除春季的影响，但在此期间的桡足类的整体水母清除潜力低。从五月A。海蜇是最丰富的水母，潜在的水母捕食影响完全由这种scyphome-dusa主导。某些猎物的清除潜力在当地很高，A. aurita可能控制了Limfjorden的蔓足类幼虫和鱼类幼虫的丰度。对于这些猎物群体，半衰期预期在几个地点不到1天。
Clearance rates of the hydromedusae Sarsia tubulosa, Rathkea octopunctata and Bougainvillea superciliaris and the scyphomedusa Aurelia aurita were measured in the laboratory. Gut contents analyses of A. aurita were also collected in situ and subsequently used for estimation of clearance rate. The clearance rate of A. aurita varied widely with prey organisms. Large crustacean prey with low escape capabilities (Artemia salina nauplii and cirripede larvae) were cleared at high rates, whereas copepodites were cleared at lower rates, and clearance rates of small bivalve larvae and copepod nauplii were comparatively low. These data were used to assess the impact of jellyfish preda- tion upon zooplankton and fish larvae in Limfjorden, Denmark. Repeated sampling of zooplankton, fish larvae and medusae was undertaken during the first half of 2003. Nine taxa of hydromedusae and 4 taxa of scyphomedusae were identified. Abundance estimates were combined with estimated clear- ance rates of individual medusae to calculate potential jellyfish-induced mortality on prey in Limfjor- den. Copepoda was used as a model prey group to estimate the collective predation impact by all medusae. Medusa species with unknown clearance potential were given assumed clearance rate val- ues, but the collective predation potential by these species was evaluated to be small. Hydromedusae dominated numerically and had their highest potential clearance impact in spring, but overall jellyfish clearance potential on copepods was low during this period. From May A. aurita was the most abun- dant jellyfish and the potential jellyfish predation impact became totally dominated by this scyphome- dusa. Clearance potential was locally high on some prey, and predation by A. aurita probably con- trolled the abundance of cirripede larvae and fish larvae in Limfjorden. For these prey groups, half-life expectancy was less than 1 d at several locations.