Significant improvement in freshwater invertebrate biodiversity in all types of English rivers over the past 30 years

Yueming Qu, Virginie Keller, Nuria Bachiller-Jareno, Michael Eastman, Francois Edwards, Monika D. Jürgens, John P. Sumpter, Andrew C. Johnson

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Abstract

There remains a persistent concern that freshwater biodiversity is in decline and being threatened by pollution. As the UK, and particularly England, is a densely populated nation with rivers of modest dilution capacity, this location is very suitable to examine how freshwater biodiversity has responded to human pressures over the past 30 years. A long-term dataset of 223,325 freshwater macroinvertebrate records from 1989 to 2018 for England was retrieved and examined. A sub-set of approximately 200 sites per English Region (1515 sites in total with 62,514 samples), with the longest and most consistent records were matched with predicted wastewater exposure, upstream land cover and terrain characteristics (latitude, altitude, slope gradient and flow discharge). To understand changes in macroinvertebrate diversity and sensitivity with respect to these parameters, the biotic indices of (i) overall family richness, (ii) Ephemeroptera, Plecoptera, Trichoptera (EPT) family richness, and (iii) the Biological Monitoring Working Party (BMWP) scores of NTAXA (number of scoring taxa) and (iv) ASPT (average score per taxon) were selected. A review of how close the BMWP scores come to those expected at minimally impacted reference sites was included. For all latitudes, altitudes, channel slope, river size, wastewater exposure levels, and differing proportions of upstream woodland, seminatural, arable and urban land cover, all diversity or sensitivity indices examined improved over this period, although this improvement has slowed in some cases post 2003. Mean overall family richness has increased from 15 to 25 family groups, a 66 % improvement. The improvement in mean EPT family richness (3 to 10 families, >300 % improvement), which are considered to be particularly sensitive to pollution, implies macroinvertebrate diversity has benefited from a national improvement in critical components of water quality.
Original languageEnglish
Article number167144
Number of pages13
JournalScience of the Total Environment
Volume905
Early online date22 Sept 2023
DOIs
Publication statusPublished - 20 Dec 2023

Keywords

  • Freshwater invertebrates
  • Biodiversity increase
  • Land cover
  • Wastewater exposure
  • English rivers
  • Long-term trends
  • UKRI
  • NERC
  • NE/S000100/1

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