This 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.
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) Seasonal succession of dominating phytoplankton groups. HELCOM core indicator report. Online. [Date Viewed], [Web link].
Result: Seasonal succession of dominating phytoplankton groups
Data: Seasonal succession of dominating phytoplankton groups
The methods of collection, counting and identification should be unified between all laboratories sharing the same assessment area. Data has been collected directly from the persons responsible for phytoplankton monitoring, no common database was currently used. Currently the HELCOM COMBINE database hosted by ICES does not contain biomass values of dominating groups and is thus unsuitable.
The indicator can be updated either annually or for specific periods (e.g. for certain 6-year assessment periods) to detect reliable trends in seasonal dynamics on dominant phytoplankton groups.