Data and updating

This pre-core indicator and its threshold values are yet to be commonly agreed in HELCOM. 
The indictor is included as a test indicator for the purposes of the 'State of the Baltic Sea' report, and the results are to be considered as intermediate.

Access and use

The data and resulting data products (tables, figures and maps) available on the indicator web page can be used freely given that the source is cited. The indicator should be cited as following: 

HELCOM (2018) Diatom/Dinoflagellate index. HELCOM pre-core indicator report. Online. [Date Viewed], [Web link].

ISSN 2343-2543



Result: Diatom-Dinoflagellate index

Data: Diatom-Dinoflagellate index

Data source: The data of the HELCOM Contracting Parties are kept in the HELCOM COMBINE database, hosted by ICES ( However, it turned out that the data are incomplete. Therefore, the original data were directly received from the contributors (see below). The evaluation of the southern part of the Eastern Gotland data was supported by the National Marine Fisheries Research Institutes (NMFRI) statutory activity and Polish National Environmental Monitoring (PMŚ). Further data originated from the Leibniz Institute of Baltic Sea Research Warnemünde (IOW), Swedish Meteorological and Hydrological Institute, Västra Frölunda (SMHI), Estonian Marine Institute, University of Tartu (EMI), and Environmental Protection Agency, Department of Marine Research, Klaipeda.

Description of data: The basic data are phytoplankton biomass data, determined as explained in the HELCOM COMBINE manual, originating from the depth of 0 – 10 m. Also silicate data were used that were taken parallel to the phytoplankton sampling.

Temporal coverage: The assessment period comprised the years 2011-2016. From each year, spring data (March to May) were used. For silicate information, also data from February were considered.

Data aggregation: If original data were strongly skewed in temporal respect, monthly means were calculated first as a basis for seasonal means. The data from different stations were pooled.