Broad-scale habitat maps for the Baltic Sea have been produced in the EUSeaMap project in 2016. For German and Estonian marine areas, national (more accurate) datasets were used. German data included both substrate and light information (division into infralittoral/circalittoral). Estonian data included only substrate and the division into light regimes was obtained from the EuSeaMap data. Here, the habitat class “circalittoral sand includes classes “Sand” and “Muddy sand” of the original data, in the circalittoral zone. The original polygon maps have been converted to 1 km x 1km grid. The scale of the substrate data used in broad-scale habitat maps varies from 1:250 000 to 1:1M (data from EMODnet Geology). Coarser resolution data has been used in areas, where 1: 250 000 substrate data has not been available. Due to different scales used, the habitat classes may show different sized patterns in different areas.

This dataset contains all PAH in sediment monitoring station locationsas reported to HELCOM secretariat by HELCOM Contracting Parties by 2016.

This dataset contains all PCB in sediment monitoring station locations as reported to HELCOM secretariat by HELCOM Contracting Parties by 2016.

The amount of collected mussels with dredging. Data is presented from the Danish mussel areas within the HELCOM marine areas. The data was made available by HELCOM Contracting Parties in response to data request. The data was received from Denmark. The activity was declared as not relevant in Estonia, Finland, Latvia, Lithuania, Poland, Russia and Sweden. Germany indicated that data is not available. Attribute specification and units: Nr: Identification number of the mussel area Name: Name of the mussel area BluMusl05 – BluMusl15: Amount of Blue mussel (kg) collected per year ComCockl05 – ComCockl15: Amount of Common Cockle (kg) collected per year Sum_BMus: Total amount of collected Blue mussel in 2005 to 2015 (kg) AVG_BMus: A calculated average of the collected blue mussels in 2005 – 2015 (kg/year) AVG_2_BM: A calculated average of the collected blue mussels in HOLAS2 period 2011 – 2015 (kg/year) Sum_ComC: Total amount of the collected common cockles in 2005 – 2015 (kg) AVG_ComC: a calculated average of the collected common cockles in 2005 – 2015 (kg/year) AVG_2_ComC: A calculated average of the collected common cockles in HOLAS2 period 2011 – 2015 (kg/year) Area: The mussel area within the dredging occurs (km2)

This dataset contains all heavy metal monitoring station locations where seawater samples are analysed. The information is based on data reported to HELCOM secretariat by HELCOM Contracting Parties by 2016.

The occurrence of suitable nursery habitats is crucial for maintaining fish populations (Sundblad et al. 2013). Species distribution modelling studies have shown the importance of suitable environmental conditions for pikeperch recruitment. Due to lack of coherent data on pikeperch spawning and nursery areas across the Baltic Sea countries, environmental variables were used in delineating potential recruitment areas for pikeperch. The pikeperch recruitment area presented on the map is mainly delineated by selecting areas where depth < 5 m, logged exposure < 5, salinity < 7 PSU, Secchi depth < 2 m and distance to deep (10m) water < 4km. The threshold values have been obtained from literature (Veneranta et al. 2011, Bergström et al. 2013, Sundblad et al. 2013, Kallasvuo et al. 2016). Temperature, although important for pikeperch, was left out due to high variation in timing of suitable spawning temperatures across the Baltic Sea. In Finnish coastal waters, a national pikeperch model (Kallasvuo et al. 2016) has been used, with very suitable areas for pikeperch generalized to 1 km grid. In Sweden, the areas delineated by environmental variables have been complemented with information from national interview survey (Gunnartz et al. 2011) as well as expert opinion.

Distribution of Fucus sp. based on data submission by HELCOM contracting parties. Mainly pointwise occurrences of Fucus were submitted, originally gathered in national mapping and monitoring campaigns, or for scientific research purposes. From Estonian waters, a predictive model was used (200m resolution), that was converted to presence/absence using minimized difference threshold (MDT) criteria. All data (Fucus points and the raster presenting predicted presence of Fucus) were generalized to 5km x 5km grid cells.

This dataset contains all PAH in seawater station locationsas reported to HELCOM secretariat by HELCOM Contracting Parties by 2016.

Introduction of radionuclides is based on HELCOM MORS Discharge data from 2011 to 2014. The isotopes taken into account were: Cesium-137, Strontium-90, and Cobalt-60. The decay-corrected annual average of the sum of the radionuclide discharges (in Bq) were calculated for the pressure. 10 km buffer with linear decreasing function was used to represent the impact distance from the nuclear power plant outlets.

Estuaries (according to Habitats Directive Annex I) are coastal inlets that are strongly influenced by freshwater. The distribution map is based on data submission by HELCOM contracting parties. Most of the submitted data is based on modelling, GIS analysis and/or aerial photos. Data coverage, accuracy and the methods in obtaining the data vary between countries.