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Kelly MG, Mann DG, Taylor JD, Juggins S, Walsh K, Pitt JA, Read DS. Maximising environmental pressure-response relationship signals from diatom-based metabarcoding in rivers. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 914:169445. [PMID: 38159778 DOI: 10.1016/j.scitotenv.2023.169445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 11/28/2023] [Accepted: 12/15/2023] [Indexed: 01/03/2024]
Abstract
DNA metabarcoding has been performed on a large number of river phytobenthos samples collected from the UK, using rbcL primers optimised for diatoms. Within this dataset the composition of non-diatom sequence reads was studied and the effect of including these in models for evaluating the nutrient gradient was assessed. Whilst many non-diatom taxonomic groups were detected, few contained the full diversity expected in riverine environments. This may be due to the performance of the current primers in characterising the wider phytobenthic community and influenced by the sampling method employed, as both were developed specifically for diatoms. Nevertheless, the study identified considerable diversity in some groups, e.g. Eustigmatophyceae and a wider distribution than previously thought for freshwater Phaeophyceae. These results offer a strong case for the benefits of metabarcoding for expanding knowledge of aquatic biodiversity in the UK and elsewhere. Many of the ASVs associated with non-diatoms showed significant pressure responses; however, models that included non-diatoms had similar predictive strength to those based on diatoms alone. Whilst limitations of the primers for assessing non-diatoms may play a role in explaining these results, the diatoms provide a strong signal along the nutrient gradient and other algae, therefore, add little unique information. We recommend that future developments should use ASVs to calculate metrics, with links to reference databases made as a final step to generate lists of taxa to support interpretation. Any further exploration of the potential of non-diatoms would benefit from access to a well-curated reference database, similar to diat.barcode. Such a database does not yet exist, and we caution against the indiscriminate use of NCBI GenBank as a taxonomic resource as many rbcL sequences deposited have not been curated.
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Affiliation(s)
- Martyn G Kelly
- Bowburn Consultancy, 11 Monteigne Drive, Bowburn, Durham DH6 5QB, UK; School of Geography, Nottingham University, Nottingham NG7 2RD, UK.
| | - David G Mann
- Royal Botanic Garden Edinburgh, Edinburgh EH3 5LR, Scotland, UK; Marine and Continental Waters, Institute for Food and Agricultural Research and Technology (IRTA), Crta de Poble Nou Km 5.5, E-43540 La Ràpita, Catalunya, Spain
| | - Joe D Taylor
- UK Centre for Ecology & Hydrology (UKCEH), Wallingford, Oxfordshire OX10 8BB, UK
| | - Stephen Juggins
- School of Geography, Politics and Sociology, Newcastle University, Newcastle upon Tyne NE1 7RU, UK
| | - Kerry Walsh
- Chief Scientist's Group, Environment Agency, Deanery Road, Bristol BS1 5AH, UK
| | - Jo-Anne Pitt
- Chief Scientist's Group, Environment Agency, Deanery Road, Bristol BS1 5AH, UK
| | - Daniel S Read
- UK Centre for Ecology & Hydrology (UKCEH), Wallingford, Oxfordshire OX10 8BB, UK
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