Experimental evidence of a low‐oxygen refuge for large zooplankton
Experimental evidence of a low‐oxygen refuge for large zooplankton
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大型浮游动物低氧避难所的实验证据
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
W. Lampert
中科院分区：
文献类型：
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作者：
Petter Larsson;W. Lampert
我们验证了这样一种假设，即湖泊的金属和次生离子中的缺氧带可以为大型浮游动物提供一个避难所，以抵御鱼类的捕食。实验是在一个大型室内中游系统(普隆浮游生物塔)中进行的。我们比较了在缺氧性或缺氧性低氧状态下，由自由放养的鱼类引起的幼体幼虫的死亡率。在鱼的存在下，水蚤向温跃层下方移动。在低氧条件下，当O2浓度约为1mgO2时，其分布在上层膜中达到高峰，L−1。在氧饱和膜中，水蚤分布均匀。低氧处理的水蚤死亡率仅为好氧处理的1/3。低氧的栖息地提供了一个避难所，因为水蚤比鱼类耐受更低的氧气浓度。然而，在低氧条件下生活可能会产生人口成本。因此，在自然条件下，低氧避难所的重要性很可能取决于捕食风险和低氧水域生活成本之间的权衡。
We tested the hypothesis that hypoxic zones in the metalimnion and hypolimnion of lakes can provide a refuge against fish predation for large zooplankton. Experiments were run in a large indoor mesocosm system (Plön Plankton Towers). We compared mortality rates of Daphnia pulicaria due to free‐ranging fish in mesocosms with either oxic or hypoxic hypolimnia. In the presence of fish Daphnia moved down below the thermocline. Under hypoxic conditions their distribution peaked in the upper hypolimnion at a concentration of approximately 1 mg O2 L−1. In oxygen‐saturated hypolimnia Daphnia were distributed evenly. The mortality rate of Daphnia in the hypoxic treatment was only one third of that in the oxic treatment. The hypoxic habitat provided a refuge, as Daphnia tolerated lower oxygen concentrations than did fish. However, there may be demographic costs associated with living in low‐oxygen conditions. Hence, the importance of a hypoxic refuge under natural conditions will most likely depend on the trade‐off between predation risk and cost of living in hypoxic waters.