Macroinvertebrate data from Welsh and English rivers 1991-2019 for mapping changes in ecological condition through time and studying the underlying drivers of change

Two subsets of data derived from national data sets collected by the Environment Agency and Natural Resources Wales (© Environment Agency copyright and database right 2023; Natural Resources Wales information © Natural Resources Wales and Database Right. All rights Reserved) which were supplied under the Open Government Licence https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/ The full data sets can be accessed from the Environment Agency's Ecology and Fish Data Explorer (https://environment.data.gov.uk/ecology/explorer/) and NBNAtlas for Natural Resources Wales data (https://registry.nbnatlas.org/public/show/dr2116).

Data set 1: england_wales_t1_t2_t3.csv

Data set for creating maps of macroinvertebrate communities across England and Wales at three time points. Data comprise 13921 rows and seven columns:

1. time = time period when data were collected: t1 = 1991-3, t2 = 2004-6, t3 = 2017-19
2. site = site code, prefixed with 'S'.
3. easting = x-coordinate of each site on the British National Grid
4. northing = y-coordinates of each site on the British National Grid
5. Year = year the sample was collected
6. richness = number of macroinvertebrate families present in the sample
7. ca1.score = measure of macroinvertebrate community composition. Larger values indicate that a higher proportion of pollution-sensitive taxa are present.

Data set 2: england_wales_SEM_GWR.csv

Data set for running structural equation modelling and geographically-weighted regression analyses to explain macroinvertebrate community composition across England and Wales. Data comprise 3632 rows and 15 columns:

• Column 1: site = site code, prefixed with 'S'.
• Columns 2-3 (easting and northing) = x- and y-coordinates of each site on the British National Grid
• Column 4: year = year the macroinvertebrate sample was collected
• Columns 5-9 (pH, temperature, BOD, nitrate, phosphate) are median values in the 12 months prior to an invertebrate sample for: pH, water temperature (degrees Celsius), biochemical oxygen demand (mg l^-1), nitrate (mg l^-1) and orthophosphate (mg l^-1)
• Columns 10-12 (arable, imp.grass, urban) represent the percentage of the river's catchment covered by three different land cover types (arable agriculture, improved grassland, urban)
• Column 13 (scaled.med.discharge) is the annual median discharge at a site, divided by the catchment area; units = m³ s^-1 km^-2)
• Column 14: richness = number of macroinvertebrate families present in the sample
• Column 15: ca1.score = measure of macroinvertebrate community composition. Larger values indicate that a higher proportion of pollution-sensitive taxa are present.

Research results based upon these data are published at https://doi.org/10.1016/j.scitotenv.2024.174369