https://orcid.org/0000-0002-4573-9445
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ABSTRACT
Benthic diatoms are widely used as bio-indicators in water quality monitoring of rivers and streams, but less commonly in lentic waterbodies such as pools and lakes. Currently, a new method for assessing the ecological status of lakes is being tested in France to meet the requirements of the European Water Framework Directive (WFD) 2000/60/EC. This new method uses epilithic and epiphytic diatoms growing on stones and aquatic plants. Alternatively, freshwater turtles and the epizoic algae found on their carapaces may provide an excellent substrate for estimating water quality. Our study proposes an original diatom-based method for assessing the quality of water bodies in which turtles live. The main objective was to compare the Biological Diatom Index (BDI) values measured from epizoic diatom samples taken on the carapace of turtles with classical epilithic or epiphytic samples. Epizoic samples were taken from the carapaces of the turtle Emys orbicularis in two shallow French Mediterranean wetlands. Our results indicate that diatom assemblages differ slightly within the three substrates studied with limited variations in index value. However, some variability among epizoic samples from the same site suggests that several turtle individuals should be sampled for water quality biomonitoring.
Graphical abstract
Acknowledgments
We are indebted to the many people who participated in the turtle catches, in particular Maëlys Marage (Tour du Valat) and Rozen Rocher (CEN PACA) as well as to Sophie Guingand for her assistance in data processing. We thank the French Ministry of Environment for giving us the permission to capture European pond turtles in Esquineau and Charpines. We are grateful to the Association des Diatomistes de Langue Française (ADLaF) for allowing us to present this work at the conference held in Dijon (September 2017), and to the anonymous reviewers for their useful comments on the manuscript. This study was made possible thanks to the support of Séverine Lopez and the management of the Service Biodiversité Eau et Paysage of the DREAL PACA. We would like to express our sincere thanks to them.
Disclosure statement
No potential conflict of interest was reported by the authors.
Supplementary material
Supplemental data for this article can be accessed here.
Additional information
Notes on contributors
Véronique Vassal
Véronique Vassal: Coordination of the project, sample collection, LM pictures, plates and writing of the article.
Luc Ector
Luc Ector: Provision of literature, bibliographic research, help with identification of diatom species, discussion of results, revision and editing of the manuscript.
Bart Van de Vijver
Bart Van de Vijver: Discussion of results, revision and editing of the manuscript.
Vincent Roubeix
Vincent Roubeix: Data analysis, discussion of results and manuscript co-writing and edition.
Anthony Olivier
Anthony Olivier: Sample collection and help with the redaction of the manuscript.
Samuel Pauvert
Samuel Pauvert Discussion and revision of the manuscript.
Cédric Roy
Cédric Roy: Sample collection and revision of the manuscript.
Stéphanie Fayolle
Stéphanie Fayolle: Discussion of results and manuscript co-writing and revision.
