How many is enough? Determining optimal count totals for ecological and palaeoecological studies of testate amoebae
How many is enough? Determining optimal count totals for ecological and palaeoecological studies of testate amoebae
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DOI：
10.1007/s10933-008-9299-y
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发表时间：
2009-12
影响因子：
2.1
通讯作者：
R. Payne;E. Mitchell
中科院分区：
文献类型：
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作者：
R. Payne;E. Mitchell
有壳变形虫越来越多地用于湿地生态学和古生态学研究。为了观察阿米巴群落，需要在显微镜下对一定数量的个体进行计数。迄今为止，大多数研究的目标是150人，但样本量并没有足够的证据。当有遗嘱阿米巴浓度低时，可能很难或不可能达到这个总数。更低的计数总数的影响从未被认真审查。我们调查的数量确定的类群，环境变量的定量推断和阿米巴和环境数据之间的联系，在预测深度的背景下，地下水位的强度计数大小的影响。通过从四个现有数据集中随机选择个体来模拟低计数。结果显示，随着计数大小从低数字增加到150个计数，所有标准的收益都逐渐递减。需要更高的计数来识别所有类群，而不是充分识别社区的传递函数推断。我们建议，在大多数情况下，将更多数量的样本计数到更低的计数将是更有效地利用时间。虽然50个个体的计数可能足以用于某些地点的某些样品，但我们建议100个个体的计数应足以用于大多数样品。计数只需要增加到150或更多，目的是确定相对较小，但仍然可能与生态有关的社区变化。这种方法将有助于减少缺乏复制和低分辨率，这是常见的限制，在有遗嘱的变形虫为基础的古生态和生态研究。
Testate amoebae are increasingly used in ecological and palaeoecological studies of wetlands. To characterise the amoeba community a certain number of individuals need to be counted under the microscope. To date, most studies have aimed for 150 individuals, but that sample size is not based on adequate evidence. When testate amoeba concentrations are low, it can be difficult or impossible to reach this total. The impacts of lower count totals have never been seriously scrutinised. We investigated the impact of count size on number of taxa identified, quantitative inferences of environmental variables and the strength of the links between amoebae and environmental data in the context of predicting depth to water table. Low counts were simulated by random selection of individuals from four existing datasets. Results show progressively diminishing returns by all criteria as count size increases from low numbers to counts of 150. A higher count is required to identify all taxa than to adequately characterise the community for transfer function inference. We suggest that in most cases, it will be a more efficient use of time to count a greater number of samples to a lower count. While a count of 50 individuals may be sufficient for some samples from some sites we recommend that counts of 100 individuals should be sufficient for most samples. Counts need only be increased to 150 or more where the aim is to identify relatively minor, but still potentially ecologically relevant community changes. This approach will help reduce lack of replication and low resolution, which are common limitations in testate amoeba-based palaeoecological and ecological studies.