Wild CRU, Zoology, University of Oxford, The Recanati-Kaplan Centre Tubney House, Abingdon Road, Tubney, Abingdon, OX13 5QL, U.K.
APEM Limited, Riverview A17 Embankment Business Park Heaton Mersey, Stockport, SK4 3GN, U.K.
Ecol Evol. 2014 Feb;4(4):494-504. doi: 10.1002/ece3.903. Epub 2014 Jan 23.
Invasive species are a major cause of species extinction in freshwater ecosystems, and crayfish species are particularly pervasive. The invasive American signal crayfish Pacifastacus leniusculus has impacts over a range of trophic levels, but particularly on benthic aquatic macroinvertebrates. Our study examined the effect on the macroinvertebrate community of removal trapping of signal crayfish from UK rivers. Crayfish were intensively trapped and removed from two tributaries of the River Thames to test the hypothesis that lowering signal crayfish densities would result in increases in macroinvertebrate numbers and taxon richness. We removed 6181 crayfish over four sessions, resulting in crayfish densities that decreased toward the center of the removal sections. Conversely in control sections (where crayfish were trapped and returned), crayfish density increased toward the center of the section. Macroinvertebrate numbers and taxon richness were inversely correlated with crayfish densities. Multivariate analysis of the abundance of each taxon yielded similar results and indicated that crayfish removals had positive impacts on macroinvertebrate numbers and taxon richness but did not alter the composition of the wider macroinvertebrate community. Synthesis and applications: Our results demonstrate that non-eradication-oriented crayfish removal programmes may lead to increases in the total number of macroinvertebrates living in the benthos. This represents the first evidence that removing signal crayfish from riparian systems, at intensities feasible during control attempts or commercial crayfishing, may be beneficial for a range of sympatric aquatic macroinvertebrates.
入侵物种是淡水生态系统物种灭绝的主要原因，而螯虾物种尤其普遍。入侵的美洲红点螯虾（Pacifastacus leniusculus）对一系列营养层次都有影响，但对底栖水生大型无脊椎动物的影响尤其大。我们的研究考察了从英国河流中移除诱捕红点螯虾对大型无脊椎动物群落的影响。我们对泰晤士河的两条支流进行了密集的诱捕和移除，以检验降低红点螯虾密度会导致大型无脊椎动物数量和分类丰富度增加的假设。我们在四个阶段共移除了 6181 只螯虾，导致移除区中心的螯虾密度降低。相反，在对照区（诱捕并放回螯虾的区域），螯虾密度向中心区域增加。大型无脊椎动物数量和分类丰富度与螯虾密度呈反比。对每个分类群丰度的多元分析得出了类似的结果，并表明螯虾的移除对大型无脊椎动物的数量和分类丰富度有积极影响，但没有改变更广泛的大型无脊椎动物群落的组成。综合与应用：我们的结果表明，非根除导向的螯虾移除计划可能导致底栖生物中生活的大型无脊椎动物总数增加。这是首次证明，从河岸系统中移除红点螯虾（在控制尝试或商业捕捞期间可行的强度下）可能对一系列同域水生大型无脊椎动物有益。
