Data from: Effect of canal lock presence on macroinvertebrate diversity and community composition

We assessed the influence of canal lock presence on macroinvertebrate diversity and community composition by comparing two stretches of the Leeds-Liverpool canal using a cost-effective, replicable method. Specifically, our investigation sought to: (1) assess whether the diversity of aquatic macroinvertebrates is linked to the presence of canal locks and to differences in biophysical conditions; (2) assess differences in water pollution using biotic indices across the lock and control areas; (3) examine how macroinvertebrate community structure varies between a lock-dominated and lock-lacking (‘control’) area. Methods We sampled two areas of the Leeds-Liverpool canal in Lancashire: an area with high lock density in Lathom (53.590°N 2.820°W) and a control area without locks in Halsall (53.584°N 2.953°W). Six sites were sampled per area, with each site spaced ~400m apart along a 2.5 km transect route (Fig. 1). See "Context_of_twelve_sampling_sites" for characteristics on each sampling site. Distance from urban settlement was measured by canal length from the closest sampling site to an urban source. Urban settlements were defined using the Major Towns and Cities boundaries dataset (Office for National Statistics, 2015). Each site was visited three times between June and August 2022, on the same day and within a four hour window. Salinity, temperature and pH were measured using a Hanna Waterproof Salinity Tester (model HI-98319) and Preciva pH Meter (model 2011). Invertebrate samples were collected using sweep sampling: a pond net attached to an extendable pole was used to sweep along the bottom of the canal to disturb the canal bed at ~1.5 m distance from the canal edge, then was moved in figure-of-eight motion six times before being removed. Invertebrates were identified ex situ to family level on the same day as collection to minimise the likelihood of predation within samples. See "Macroinvertebrate_data_raw.csv" for this data. Taxonomic diversity was calculated using Hill numbers (q = 0, 1, 2: corresponding to species richness, Hill-Shannon and Hill-Simpson) from abundance data using the “hillR” package (Li, 2018) R (v. 4.3.3; R Core Team, 2024). Abundance counts were summed by site, then were used to derive three Hill diversity values per site. Three biotic indices were calculated to assess water quality using the “biotic” R package (Briers, 2016): the British Monitoring Working Party score (BMWP) and Average Score Per Taxon (ASPT) were calculated using the [biotic::calcBMWP] fuction, then the Walley Hawkes Paisley Trigg score ASPT (WHPT-ASPT) index using [biotic::calcWHPT]. The Enchytraeidae and Lumbriculidae families were merged into an Oligochaetes subclass to allow for these counts to be included in the indices. See "Hill_diversity_and_biotic_indices_scores_per_site.csv" for this data. Funding No funding was recieved for this research, which was initially conducted at Liverpool Hope University for CBR's Masters of Science dissertation in summer 2022.我们通过比较利兹-利物浦运河（Leeds-Liverpool canal）的两段水域，采用低成本且可重复的研究方法，评估了运河船闸（canal lock）对大型无脊椎动物（macroinvertebrate）多样性及群落组成的影响。本研究旨在达成以下三项目标：(1) 探究水生大型无脊椎动物多样性是否与运河船闸的存在及生物物理环境差异相关；(2) 利用生物指数（biotic index）对比船闸区域与对照区域的水污染程度差异；(3) 分析以船闸为主的区域与无船闸（对照）区域之间，大型无脊椎动物群落结构的变化差异。 研究方法 本研究在兰开夏郡的利兹-利物浦运河设置两处采样区域：一处是位于兰索姆（Lathom，53.590°N 2.820°W）的高船闸密度区域，另一处是位于哈尔萨尔（Halsall，53.584°N 2.953°W）的无船闸对照区域。每个区域设置6个采样点，各采样点沿2.5公里样线间隔约400米布设（见图1）。各采样点的具体特征详见"Context_of_twelve_sampling_sites"文档。采样点距城镇聚落的距离以最近采样点到城镇源地的运河航道长度测算，城镇聚落边界采用《主要城镇和城市边界数据集》（Office for National Statistics，2015）进行界定。 2022年6月至8月期间，每个采样点均进行3次采样，且所有采样均在同一天的4小时窗口期内完成。盐度、温度及pH值采用哈纳防水盐度测试仪（型号HI-98319）和Preciva pH计（型号2011）进行测定。无脊椎动物样本采用扫网采样法采集：将附着于可伸缩杆上的捕虫网沿运河底部拖拽，在距运河岸线约1.5米处扰动河床，随后以8字形运动方式扫网6次后收起。样本采集当日即于现场外完成科级分类单元的物种鉴定，以降低样本内捕食现象的发生概率。相关原始数据详见"Macroinvertebrate_data_raw.csv"文件。 分类多样性采用Hill数（Hill numbers）进行计算，其中q=0、1、2分别对应物种丰富度、Hill-Shannon指数与Hill-Simpson指数，基于丰度数据通过R语言的"hillR"包（Li，2018）完成分析（R版本4.3.3；R核心团队，2024）。首先将各采样点的丰度计数汇总，随后为每个采样点生成3项Hill多样性指数值。本研究采用"biotic"R包（Briers，2016）计算3项生物指数以评估水质：通过[biotic::calcBMWP]函数计算英国监测工作组评分（British Monitoring Working Party score，BMWP）及平均分类单元评分（Average Score Per Taxon，ASPT），再通过[biotic::calcWHPT]函数计算Walley-Hawkes-Paisley-Trigg评分的平均分类单元指数（WHPT-ASPT）。为将颤蚓科（Enchytraeidae）与仙女蚓科（Lumbriculidae）纳入指数计算，将二者合并为寡毛纲（Oligochaetes）子类群。相关数据详见"Hill_diversity_and_biotic_indices_scores_per_site.csv"文件。 资助说明 本研究未获得任何资助，最初于2022年夏季在利物浦希望大学完成，作为CBR的理学硕士学位论文研究内容。