NorBAF – The NORdic-Baltic network for Benthic Algae in Freshwater is currently performing the 6th Nordic-Baltic diatom intercalibration/harmonization exercise, organized jointly by NorBAF and the Department of Aquatic Sciences and Assessment, SLU (Swedish University of Agricultural Sciences).

NorBAF is a cooperation of people working with freshwater benthic algae in Scandinavia and countries around the Baltic Sea. Our objective is to establish and develop contacts between educational institutions, research institutions and non-governmental organisations in the field of education and lifelong learning. The network is open to anyone who shares our interest, we are also cooperating with other phycological networks. NorBAF started 2005 with financial help of Nordplus Neighbour and the Erken Laboratory, University of Uppsala, Sweden. Nordplus Neighbour was one of the Nordic Council of Ministers’ five mobility and network programs. Now, NorBAF is organized as informal cooperation of the participants.

We are convinced that it is important to harmonize diatom identification in order to improve comparisons between different studies (Kahlert et al. 2009), especially as diatom monitoring is now often standard in aquatic assessments following the Water Framework Directive, and diatom diversity is used in many research studies as an indicator of water quality. It is furthermore important to learn about and discuss recent developments in diatom taxonomy and ecological research. We are convinced that a practical exercise combined with a friendly discussion of the results is an effective way to find disagreements and to agree on solutions (Kahlert et al. 2016). Based on our experience from the activities in former years, the NorBAF participants agreed to continue with diatom intercalibrations every ~ 3rd to 4th year. SWEDAC (Swedish Board for Accreditation and Conformity Assessment), The Swedish Agency for Marine and Water Management (SwAM) and the Finnish Environment Institute (SYKE) are informed about our activities and the participation of Swedish and Finnish laboratories and consultants.

This year, we are counting diatom slides from three Nordic sites with different ecology. Slides had to be prepared by the participants from preserved material in ethanol. We are following the European Standard method for preparation, identification and enumeration of the diatoms, and the Swedish standard taxa list for reporting of the results. The counts will be evaluated according to Kelly (2001) by calculating a similarity index between participants and two auditors (Amelie Jarlman, Jarlman Konsult AB, Bart Van de Vijver, Botanic Garden Meise, Belgium). We will also calculate and compare several diatom indices. The results will be discussed during a workshop, planned in Sweden, but now changed to an online meeting. Hopefully next time we will meet again in place, because we are not many people in the Nordic countries who are enthusiastic in diatom identification, and it is always nice to meet a colleague.

Welcome to participate next time!
Please contact Maria Kahlert (maria.kahlert at for further information.

Results and discussions with solutions to problematic taxa, and how to deal with changed taxonomy for other taxa, will be published at the NorBAF webpage later this year.

warning of the vikings

Warning of the vikings – sign close to the Norr Malma field station in Sweden where the NorBAF intercalibration workshops usually are held.

Kahlert, M., et al. (2009). Harmonization is more important than experience-results of the first Nordic-Baltic diatom intercalibration exercise 2007 (stream monitoring). Journal of Applied Phycology, 21(4):471-482.
Kahlert, M., et al. (2016). Quality assurance of diatom counts in Europe: towards harmonized datasets. Hydrobiologia, 772(1):1-14.
Kelly, M. (2001): Use of similarity measures for quality control of benthic diatom samples. Wat. Res. Vol. 35 (11), 2784-2788