Empirical correspondence between trophic transfer efficiency in freshwater food webs and the slope of their size spectra.
Empirical correspondence between trophic transfer efficiency in freshwater food webs and the slope of their size spectra.
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DOI：
10.1002/ecy.2347
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发表时间：
2018-06
期刊：
影响因子：
4.8
通讯作者：
T. Mehner;B. Lischke;K. Scharnweber;K. Attermeyer;S. Brothers;U. Gaedke;S. Hilt;S. Brucet
中科院分区：
文献类型：
--
作者：
T. Mehner;B. Lischke;K. Scharnweber;K. Attermeyer;S. Brothers;U. Gaedke;S. Hilt;S. Brucet
生物体的密度随着体积的增大而减小，因为较大的生物体比较小的生物体需要更多的能量，当较大的生物体以较小的生物体为食时，就会发生能量损失。密度-尺寸分布的一个潜在表达是归一化生物量尺寸谱（NBSS），它绘制了对数生物体尺寸箱内独立于分类的生物量的对数，除以箱宽。理论上，当营养转移效率（TTE，相邻营养级之间的生产率之比）为10%，捕食者-被捕食者质量比（PPMR）为104时，多营养群落的NBSS斜率正好为-1.0。在这里，我们提供的证据，从四个多营养湖泊食物网的经验估计TTE对应于经验估计的斜率各自的社会NBSS。每一个国家生物抽样调查都考虑了浮游生物和底栖生物，从细菌到鱼类，所有样本都在一年内的三个季节中取样。4个NBSS斜率显著陡于-1.0（范围-1.14至-1.19，95%CI不包括-1）。相应的平均TTE在四个食物网中均显著低于10%（范围1.0%至3.6%，平均1.85%）。合并来自四个系统的所有生物量-大小数据对的总体斜率（-1.17）几乎与假设PPMR为104的恒定值，从四个食物网的算术平均TTE预测的斜率（-1.18）相同。因此，我们的经验数据证实了理论预测的TTE和生物量大小分布的斜率之间的定量关系。此外，我们表明，底栖生物和浮游生物可以合并成一个社区NBSS，但未来的研究还没有探索栖息地特定的TTE和PPMR的潜在差异。我们认为，社区NBSS可以提供有价值的信息，食物网的结构和充满活力的途径，并可以提高TTE估计的准确性。
The density of organisms declines with size, because larger organisms need more energy than smaller ones and energetic losses occur when larger organisms feed on smaller ones. A potential expression of density-size distributions are Normalized Biomass Size Spectra (NBSS), which plot the logarithm of biomass independent of taxonomy within bins of logarithmic organismal size, divided by the bin width. Theoretically, the NBSS slope of multi-trophic communities is exactly -1.0 if the trophic transfer efficiency (TTE, ratio of production rates between adjacent trophic levels) is 10% and the predator-prey mass ratio (PPMR) is fixed at 104 . Here we provide evidence from four multi-trophic lake food webs that empirically estimated TTEs correspond to empirically estimated slopes of the respective community NBSS. Each of the NBSS considered pelagic and benthic organisms spanning size ranges from bacteria to fish, all sampled over three seasons in 1 yr. The four NBSS slopes were significantly steeper than -1.0 (range -1.14 to -1.19, with 95% CIs excluding -1). The corresponding average TTEs were substantially lower than 10% in each of the four food webs (range 1.0% to 3.6%, mean 1.85%). The overall slope merging all biomass-size data pairs from the four systems (-1.17) was almost identical to the slope predicted from the arithmetic mean TTE of the four food webs (-1.18) assuming a constant PPMR of 104 . Accordingly, our empirical data confirm the theoretically predicted quantitative relationship between TTE and the slope of the biomass-size distribution. Furthermore, we show that benthic and pelagic organisms can be merged into a community NBSS, but future studies have yet to explore potential differences in habitat-specific TTEs and PPMRs. We suggest that community NBSS may provide valuable information on the structure of food webs and their energetic pathways, and can result in improved accuracy of TTE-estimates.