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.

Dataset represent urban land use (urban areas) around Baltic Sea coast. The resolution of the data is 250 m x 250 m. The dataset is constructed from CORINE Land Cover (CLC) 2006 for EU countries and from Open street map (OSM) open source data in Russia. Dataset is based on data collated for the HELCOM Second Holistic Assessment of the Ecosystem health of the Baltic Sea. The dataset covers the whole catchment area of the Baltic sea.

Data for Furcellaria harvesting presenting the amount of dredged tonnes per unit area per year. The data was made available by HELCOM Contracting Parties in response to data request. The data was received from Estonia. The activity was declared as not relevant in Denmark, Germany, Finland, Latvia, Lithuania, Poland, Russia and Sweden. Attribute specification and units: Dredged_ar: Furcellaria dredging area (km2, ND = no data available) Area: Area (fishing area) within dredging occurs (km2), area do not represent actual dredging area. 2011 - 2015: Amount of dredged Furcellaria (tonnes / year) Total: Amount (Sum) of dredged Furcellaria during 2011-2015 (tonnes) Average: Calculated annual average of the amount of dredged Furcellaria (tonnes/year)

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.

Locations of the coastal protection structures. The dataset contains information about the coastal defence structure type and for some the structure length (m) and the year of construction. The data was made available by HELCOM Contracting Parties in response to data request. The data was received from Denmark, Estonia, Germany, Finland, Poland and Sweden. The activity was declared as not relevant in Lithuanian area. From Latvia and Russia no data was reported. Attribute specification and units Country: Country Type: Modification structure type Const_year: Year of construction Estimated: Estimated date of completion if under construction (Estonia) or the year of environmental permit if year of construction is lacking (Finland) Out_of_use: Year when costal defence structure has been taken out of use Measure: Additional information about the modification structure Length: Length of the modified coastline (m) width: Width of the modification structure (m) Area: Area of the modification structure (km2) X_Lon: Original X (Longitude) coordinate point (Finland)

This dataset contains all heavy metal monitoring station locations, observed matrix, biota matrix and monitored species as reported to HELCOM secretariat by HELCOM Contracting Parties by 2016.

This dataset contains all PBDE 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 PCB in biota monitoring station locations, observed matrix, biota matrix and monitored species as 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.