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Evidence of biological recovery from gross pollution in English and Welsh rivers over three decades

Pharaoh, Emma, Diamond, Mark, Ormerod, Steve J. ORCID:, Rutt, Graham and Vaughan, Ian P. ORCID: 2023. Evidence of biological recovery from gross pollution in English and Welsh rivers over three decades. Science of the Total Environment 878 , 163107. 10.1016/j.scitotenv.2023.163107

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Uncertainty around the changing ecological status of European rivers reflects an evolving array of anthropogenic stressors, including climate change. Although previous studies have revealed some recovery from historical pollution in the 1990s and early-2000s, there are contrasting trends among pollutants across Europe and recovery may have even stalled or been reversed. To provide more contemporary evidence on trends and status, here we investigate changes in English and Welsh river macroinvertebrate communities over almost 30 years (1991–2019) using a network of nearly 4000 survey locations. Analysis comprised: i) trends in taxonomic and functional richness, community composition and ecological traits, ii) gains, losses and turnover of taxa, and the overall homogeneity of macroinvertebrate communities nationally, and iii) an exploration of how temporal trends varied with catchment characteristics. Taxonomic richness increased, primarily in the 1990s, whilst a shift towards pollution-sensitive taxa continued throughout the study period, accompanied by a growing prevalence in traits such as preferences for fast-flowing conditions, coarser substrata, and ‘shredding’ or ‘scraping’ feeding strategies. Changes consistent with improvement occurred in both urbanised and agricultural catchments, but were more pronounced in urban rivers as they gained pollution sensitive taxa that were otherwise more prevalent in rural rivers. Overall, these results indicate continuing biological recovery from organic pollution, consistent with national scale trends in water quality. Results reemphasise the importance of looking at multiple facets of diversity, with periods of near-constant richness disguising changes in taxonomic and functional composition. Whilst this national-scale picture is broadly positive, we highlight the need to investigate more local variations or pollutants that depart from this aggregate picture.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Biosciences
Water Research Institute (WATER)
Publisher: Elsevier
ISSN: 0048-9697
Funders: NERC
Date of First Compliant Deposit: 28 March 2023
Date of Acceptance: 23 March 2023
Last Modified: 21 Jun 2023 17:48

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