Watershed Ecosystems Graduate Program, Trent University, 1600 West Bank Drive, Peterborough, ON, K9J 7B8, Canada.
Environ Monit Assess. 2012 Dec;184(12):7175-87. doi: 10.1007/s10661-011-2489-5. Epub 2011 Dec 23.
The Mann-Kendall test has been proposed as a nonparametric method to evaluate trends in long-term water quality datasets with missing values, serial correlation, and non-normality. However, this test has rarely been used to evaluate long-term trends in biological data. In this study, we used the Mann-Kendall test to evaluate trends in 15 years of data on benthic macroinvertebrate communities from 17 Precambrian Shield lakes. We also used the van Belle and Hughes test of trend homogeneity to assess whether common among-lake temporal trends existed. We assumed that evidence of a common regional trend among lakes would support the hypothesis of long-term biological recovery from past acidification. We found decreasing proportions of Chironomidae and increasing proportions of Ephemeroptera, Plecoptera, and Trichoptera (EPT) in both single-lake and multi-lake trend analysis. Moreover, six of the nine lakes with significant trends in more than one benthos metric displayed a significant decrease in Chironomidae and increase in EPT concurrently, indicating a shift towards more acid-sensitive taxa. Weak trends in several of the biological metrics indicated that recovery in these lakes has been impeded. Results of this study indicate that the Mann-Kendall and van Belle and Hughes trend tests are useful statistical tools to evaluate long-term patterns in biological data.
曼恩-肯德尔检验法已被提议作为一种非参数方法，用于评估具有缺失值、序列相关性和非正态性的长期水质数据集的趋势。然而，该检验法很少用于评估生物数据的长期趋势。在本研究中，我们使用曼恩-肯德尔检验法评估了来自 17 个前寒武纪盾形地段湖泊的 15 年底栖大型无脊椎动物群落数据的趋势。我们还使用了范贝尔和休斯趋势同质性检验来评估是否存在常见的湖泊间时间趋势。我们假设，湖泊间存在共同的区域趋势的证据将支持长期从过去酸化中恢复的假说。我们在单湖和多湖趋势分析中均发现，摇蚊科的比例下降，而蜉蝣目、蜻蜓目和襀翅目（EPT）的比例上升。此外，在多个底栖生物指标中具有显著趋势的九个湖泊中有六个湖泊同时显示摇蚊科的显著减少和 EPT 的增加，表明朝着更敏感的酸类生物的转变。几个生物指标的微弱趋势表明，这些湖泊的恢复受到阻碍。本研究的结果表明，曼恩-肯德尔和范贝尔和休斯趋势检验法是评估生物数据长期模式的有用统计工具。
