Same same, but different: The response of diatoms to environmental gradients in Fennoscandian streams and lakes – barcodes, traits and microscope data compared

• Published in: Ecological Indicators
• Main Authors: Kahlert, Maria, Bailet, Bonnie, Chonova, Teofana, Karjalainen, Satu Maaria, Schneider, Susanne, Tapolczai, Kálmán
• Other Authors: Swedish University of Agricultural Sciences = Sveriges lantbruksuniversitet (SLU), Centre Alpin de Recherche sur les Réseaux Trophiques et Ecosystèmes Limniques (CARRTEL), Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Observatoire des Sciences de l'Univers de Grenoble (Fédération OSUG), Finnish Environment Institute (SYKE), Norwegian Institute for Water Research (NIVA), Hungarian Academy of Sciences (MTA), University of Pannonia
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2021
• Subjects: Amplicon Sequence Variants; Environmental assessment; IndexI; ndicator value; Eutrophication; Metabarcoding; [SDE]Environmental Sciences; Fennoscandia; Fennoscandian
• Online Access: https://hal.inrae.fr/hal-03480236; https://doi.org/10.1016/j.ecolind.2021.108088

International audience We developed and compared the performance of freshwater benthic diatom indices calculated from (i) traditional morphological species identification, (ii) Amplicon Sequence Variants (ASVs) obtained via DNA metabarcoding, and (iii) morphological traits to indicate eutrophication in rivers and lakes in Fennoscandia. Based on the results, we provided recommendations for the future routine use of diatom bioassessment tools in environmental monitoring and assessment. Our results show that ASVs are the most promising candidates to be used in environmental assessment. Indices based on ASVs correlated better with TotP concentrations than morphological taxa data, whereas the trait indices correlated least. We could see by studying the taxonomic assignments of the ASVs that traditional morphotaxa were divided up into several ASVs with different ecological profiles, which explained part of the better index performance and also encourages further studies on diatom diversity and ecological preferences. In general, ASV- and morphotaxon-specific optima differed slightly between streams and lakes, but were significantly correlated with each other. This means that it should be possible to develop a common index that is applicable in both streams and lakes, but boundary values with respect to TotP might need to be set separately for them. More knowledge on diatom traits is required to enable their use for environmental assessment.