title: Quantifying the responses of biological indices to rare macroinvertebrate taxa exclusion: Does excluding more rare taxa cause more error?
abstract: Including or excluding rare taxa in bioassessment is a controversial topic, which essentially affects the reliability and accuracy of the result. In the present paper, we hypothesize that biological indices such as Shannon-Wiener index, Simpson's index, Margalef index, evenness, BMWP (biological monitoring working party), and ASPT (Average Score Per Taxon) respond differently to rare taxa exclusion. To test this hypothesis, a benthic macroinvertebrate data set based on recent fifteen-year studies in China was built for suppositional plot analyses. A field research was conducted in the Nansi Lake to perform related analyses. The results of suppositional plot simulations showed that Simpson's index placed more weight on common taxa than any other studied indices, followed by Shannon-Wiener index which remained a high value with the exclusion of rare taxa. The results indicated that there was not much of effect on Simpson's index and Shannon-Wiener index when rare taxa were excluded. Rare taxa played an important role in Margalef index and BMWP than in other indices. Evenness showed an increase trend, while ASPT varied inconsistently with the exclusion of rare taxa. Results of the field study also indicated that rare taxa had few impacts on the Shannon-Wiener index. By examining the relationships between the rare taxa and biological indices in our study, it is suggested that including the rare taxa when using BMWP and excluding them in the proposed way (e.g., fixed-count subsampling) to calculate Shannon-Wiener index and Simpson's index could raise the efficiency and reduce the biases in the bioassessment of freshwater ecosystems.
authors.affiliation: Institute of Environmental Research Shandong University Jinan China.
authors.forename: Zhengda
authors.initials: Z
authors.lastname: Yu
authors.affiliation: Institute of Environmental Research Shandong University Jinan China.
authors.forename: Hui
authors.identifier: 0000-0003-2197-7075
authors.initials: H
authors.lastname: Wang
authors.affiliation: Institute of Environmental Research Shandong University Jinan China.
authors.forename: Jiao
authors.initials: J
authors.lastname: Meng
authors.affiliation: College of Life Science Shandong Normal University Jinan China.
authors.forename: Mingsheng
authors.initials: M
authors.lastname: Miao
authors.affiliation: College of Geography and Environment Shandong Normal University Jinan China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Kong
authors.affiliation: Institute of Environmental Research Shandong University Jinan China; School of Life Sciences Shandong University Jinan China.
authors.forename: Renqing
authors.initials: R
authors.lastname: Wang
authors.affiliation: Institute of Environmental Research Shandong University Jinan China.
authors.forename: Jian
authors.identifier: 0000-0003-1920-2641
authors.initials: J
authors.lastname: Liu
keywords: benthic macroinvertebrate; biological indices; rare taxa; subsampling; suppositional plot simulation