The HELCOM State of the Baltic Sea Report has built upon experience gained from the HELCOM initial holistic assessment in 2010. This initial assessment provided for the first time a coherent assessment of the Baltic Sea ecosystem and its pressures from a holistic perspective, based on available data and prevailing knowledge. The regional development of indicators and assessment methods has continued since then and made the improvements in the current report possible. Through the HELCOM coordinated work of hundreds of experts, 28 regionally agreed core indicators have been operationalised since the initial assessment, and are included in this assessment to reflect the status of the Baltic Sea environment, together with 4 indicators agreed to be used as test.
The HELCOM holistic assessment is a multi-layered product; this summary report is supported by supplementary reports, several supporting HELCOM assessment reports, core indicator reports and spatial data fact sheets (Figure 2.1). Ninety-six spatial data sets at regional scale have been collated using regular HELCOM processes or dedicated data calls, to evaluate the geographical distribution of human activities, pressures, species and habitats.
The foundation of the assessment is the core indicators, which are based on the HELCOM coordinated monitoring programme and regionally agreed threshold values. The core indicators were assessed according to defined assessment units representing different level of detail, in a regionally agreed nested system. Four assessment unit levels were used, from coastal water bodies to the entire region, to enable assessing each core indicator at its most relevant spatial scale and making comparisons across indicators and geographical areas. Assessment tools with the core indicators were used to produce thematic integrated assessment results on hazardous substances (CHASE), eutrophication (HEAT) and biodiversity (BEAT; see Box 2.1).
The current assessment focuses on the time period 2011–2015. In addition, data showing the temporal development have been provided in order to understand long-term trends and evaluate the direction of ongoing changes. The focus of the assessment has been to show results of relevance at the regional scale, and large-scale patterns between geographic areas.