Evaluating the precision of kick-sampling in upland streams for assessments of long-term change: the effects of sampling effort, habitat and rarity
Evaluating the precision of kick-sampling in upland streams for assessments of long-term change: the effects of sampling effort, habitat and rarity
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评估高地溪流踢采样的精度以评估长期变化：采样工作、栖息地和稀有性的影响
DOI：
10.1127/archiv-hydrobiol/155/2002/199
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
S. Ormerod
中科院分区：
文献类型：
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作者：
D. Bradley;S. Ormerod
踢踢取样作为一种标准方法被广泛用于底栖大型无脊椎动物的定性研究，但其精度仅在有限范围的地点和分类群中进行了评估。在现有的数据中，高地流的表现尤其差。根据《水框架指令》，生物监测现已扩大到包括保护评价，并评估更广泛的水体的生态状况，现在是时候进行更全面的评估了。在这里，我们评估了在威尔士中部高地蒸汽的河床（2分钟）和边缘（1分钟）对不同丰度分类群进行定时踢踢采样的效率。从同时从5条河流中提取的重复样本中，我们评估了单个样本是否能够可靠地检测地点、栖息地和年份之间的差异。我们还考虑了稀有分类群（在5个样本重复中总个体数小于4个的分类群）的影响。从1990年到2001年的调查比较了年份、季节和运营商之间的差异。在1990年和2001年，平均每5个样本中，有69.4%和66.2%的分类群被捕获。单缘标本在5个重复中所占的分类群比例（54.1%和61.6%）普遍低于淡纹标本（71.5%和61.8%）。这些数据说明了采样多个溪流栖息地的重要性。在分类群积累过程中，对连续较少丰度的分类需要增加采样努力。结果表明，最稀有的类群（5个样本重复中少于4个个体）是样本重复中抽样误差的主要来源。使用预测函数的外推表明，在编制分类单元清单时，最多需要10个样本重复才能充分地普查里脊和边缘的稀有分类单元。然而，在栖息地和溪流内的样本重复比在它们之间的样本组成更相似，因此即使是单个样本也能区分地点和栖息地。无论从分析中是否删除了稀有分类群，来自裂谷和边缘的复合样本，以及单独来自裂谷的样本都能充分检测到站点内每年的动物变化。我们的结论是，在欧洲西北部典型的高地溪流中，单脚取样提供了可靠和可重复的样品，能够检测地点和年份之间的组合差异。这些结果与其他评估结果相当，为踢腿采样方法在大型无脊椎动物生物监测研究中的广泛应用提供了进一步的支持。但是，保护评价和分类单元清单的编制将需要在生境内和生境间进行更详尽的抽样。我们建议，那些为满足《水框架指令》而制定采样计划的人应该仔细研究采样工作对涉及稀有类群的任何措施的影响。
Kick-sampling is widely used as a standard method in qualitative studies of benthic macroinvertebrates, but its precision has been evaluated only for a limited range of sites and taxa. Upland streams are particularly poorly represented among the available data. With biomonitoring now expanding under the Water Framework Directive to encompass conservation evaluation, and also to assess the ecological status of a wider range of water bodies, fuller assessment is now timely. Here we appraise the efficiency of timed kick-sampling in riffles (2 minute) and margins (1 minute) of upland steams in mid-Wales for different abundance classes of taxa. From replicate samples drawn simultaneously from 5 streams, we assessed whether individual samples could reliably detect differences between sites, habitats, and years. We considered also the effect of rare taxa (taxa with <4 individuals in total over five sample replicates). Surveys from 1990 and 2001 were compared to account for differences between years, seasons, and operators. On average, 69.4 % and 66.2 % of taxa were captured in one combined riffle and margin sample replicate out of five in 1990 and 2001, respectively. Single margin samples generally contained a lower proportion of the taxa collected in total over five sample replicates (54.1 % and 61.6 %) than riffle samples (71.5 % and 61.8 %). These data illustrate the importance of sampling more than one stream habitat. Taxon accumulation required increased sampling effort for successively rarer abundance classes. As a result, the rarest taxa (<4 individuals in total over five sample replicates) were a large source of sampling error in sample replicates. Extrapolation using a predictive function suggested that up to ten sample replicates would be required to adequately census rare taxa in riffles and margins if compiling taxon inventories. Sample replicates were, nevertheless, more similar in composition within habitats and streams than between them so that even individual samples differentiate sites and habitats. Composite samples from riffles and margins, and samples from riffles alone, adequately detected year-to-year faunal changes within sites, irrespective of whether rare taxa were deleted from analyses. We conclude that in upland streams typical of NW Europe, single kick-samples provide reliable and reproducible samples capable of detecting differences in assemblages between sites and years. These results are comparable to other assessments, providing further support for the widespread application of the kick-sampling method in biomonitoring studies of lotic macroinvertebrates. However, conservation evaluation and compilation of taxon inventories will require more exhaustive sampling within and across habitats. We suggest that those developing sampling programmes to satisfy the Water Framework Directive should look carefully at the effects of sampling effort on any measure where rare taxa are involved.