Inter-lake comparisons indicate that fish predation, rather than high temperature, is the major driver of summer decline in Daphnia and other changes among cladoceran zooplankton in subtropical Florida lakes
Inter-lake comparisons indicate that fish predation, rather than high temperature, is the major driver of summer decline in Daphnia and other changes among cladoceran zooplankton in subtropical Florida lakes
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DOI：
10.1007/s10750-015-2177-5
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发表时间：
2015-05-01
期刊：
影响因子：
2.6
通讯作者：
East, Therese L.
中科院分区：
文献类型：
--
作者：
Havens, Karl E.;Beaver, John R.;East, Therese L.
盛夏时节，亚热带湖泊中的水蚤消失和枝角类小体型被解释为高水温引起的现象。最近的实验和观察研究表明，鱼的捕食可能是原因。在本研究中，我们通过比较夏季出现的水蚤和其他枝角类在亚热带湖泊中的季节性来评估温度和鱼类捕食的影响，在亚热带湖泊中，有(A)植被和高丰度和多样性的浮游鱼类；和(B)没有植被、浑浊的水，主要是底栖和食鱼鱼类。水蚤从盛夏所有有植被的浮游生物样本中消失，但在浑浊的无植被地点，尽管水温相同(所有湖泊都是浅水和等温的)，它仍然全年存在。总体而言，在植被覆盖的地方，枝角类的身体尺寸要小两倍，生物量要低三倍。在有植被的地方，尤其是在夏季，较小的物种占主导地位。我们的结果表明，在亚热带湖泊中，水蚤能够耐受夏季的高温，并表明对于枝角类的大小、生物量和分类结构，鱼类捕食可能是比温度更重要的调节因素。
The mid-summer disappearance of Daphnia and the small size of cladocerans in subtropical lakes have been explained as phenomena caused by high water temperature. Recent experimental and observational studies suggest that instead, fish predation could be the cause. In the present study, we evaluated effects of temperature and fish predation by comparing summer occurrence of Daphnia and seasonality of other cladocerans in subtropical lakes where there was (a) vegetation and a high abundance and diversity of planktivorous fish; versus (b) no vegetation, turbid water, and primarily benthivorous and piscivorous fish. Daphnia disappeared from mid-summer plankton samples at all locations with vegetation, yet it persisted year-round at the turbid vegetation-free location despite identical water temperatures (all lakes were shallow and isothermal). Body size of cladocerans, in general, was twofold lower at vegetated locations, and biomass was threefold lower. Smaller species dominated at the locations with vegetation, especially in summer. Our results demonstrate that in subtropical lakes Daphnia is able to tolerate high summer water temperatures, and suggest that fish predation may be a more important regulator than temperature for cladoceran size, biomass and taxonomic structure.