Introduction of radionuclides is based on HELCOM MORS discharge data (2016-2020) . Annual averages of CO60, CS137 and SR90 from the period 2016-2020 per nuclear power plant. Gradual buffer around outlet to 10km distance (Type B decline). 10 km buffer with linear decline composed of 5 rings from discharges of radioactive substances (Type B decline)12.

This core indicator evaluates the status of the marine environment based on concentrations of radioactive substances (Cs-137) in seawater and biota. Quantitative thresholds are used to evaluate if core indicators status is "Achieve", "Fail" or "Not assessed". Good status is achieved when concentrations reach levels measured before the Chernobyl accident in 1986. This dataset displays the result of the indicator in HELCOM Assessment Scale 2 (Division of the Baltic Sea into 17 sub-basins) for herring. Attribute information: "OBJECTID" = Object identification "HELCOM_ID" = Code of the HELCOM scale 2 assessment unit "Indicator" = Name of HELCOM Core indicator "Type" = Type of indicator "Threshold value" = Threshold value for specific assessment unit "Indicator value" = Value of indicator calculated for specific assessment unit "Status" = Status of the indicator (“Achieve”, “Fail” or “Not assessed”)

This pre-core indicator evaluates the eutrophication status of the Baltic Sea area based on cyanobacterial bloom index. The index is calculated using two types of data: biomass data and Earth observation data. More detailed description on methodology can be found at HELCOM pre-core indicator report and http://www.helcom.fi/Documents/Eutrophication%20assessment%20manual.pdf This dataset displays the result of the indicator in HELCOM Assessment Scale 4 (Division of the Baltic Sea into 17 open sea sub-basins and division of coastal areas to WFD water types or water bodies), but applicable only to certain open sea assessment units. Attribute information: "HELCOM_ID" = Code of the HELCOM scale 4 assessment unit "Country" = country/ opensea "level_2" = name of the subbasin "level_4" = Name of the HELCOM scale 4 assessment unit "Area (km2)" = Area of the HELCOM scale 2 assessment unit “Season” = Season of the indicator (Summer = June-September) “Period” = Assessment unit period start and end year (20162021 = 2016 – 2021) "Indicator value (ES)" = Indicator value calculated for the assessment unit "Standard deviation (STD)" = Standard deviation of data used for calculating ES "Number of samples " = Number of samples (not applicable for cyanobacterial bloom index) "Threshold value (ET)" = Commonly agreed threshold value "Ratio between ES and ET (ER)" = Ratio between ES and ET (in case of indicator with positive response to eutrophication) "ES_SCORE” = Confidence based on the data used for calculating ES "ET_SCORE” = Confidence of target-setting procedure "I_SCORE” = Confidence (%) = average of ES-Score and ET-Score "Indicator Weight" = Indicator Weight in integrated eutrophication assessment “Status” = Status of the indicator (“Achieve”, “Fail”, “Not assessed” or "Not applicable") "AULEVEL" = Assessment unit level used for the indicator "FID_12" = "Indicator" = Indicator name “CONFIDENCE” = Confidence of result based on I-SCORE (“High”, “Moderate”, “Low” or "Not assessed")

Observations of Fucus serratus were collected from the Baltic Sea area for HELCOM Red List species list. The HELCOM Red List of Baltic Sea species in danger of becoming extinct (2013) is the first threat assessment for Baltic Sea species that covers all marine mammals, fish, birds, macrophytes (aquatic plants), and benthic invertebrates, and follows the Red List criteria of the International Union for Conservation of Nature (IUCN). Almost 2800 species were considered in the Red List assessment and about 1750 were evaluated according to the IUCN Red List criteria. Fucus serratus has been placed to the Red List category of Least Concern (LC) species. Dataset for download contains spatial grid of the Baltic Sea. Distribution of the species can be found in corresponding name column. Values are coded: 0 = no observations 1 = present before year 1995 or in 1995 2 = present after year 1995 3 = present before and after year 1995

This dataset contains all HBCD stations by sub-basin in the Baltic Sea as reported to the HELCOM MORE project.

This dataset contains coastal fish key species and key functional group indicator data collected from national coastal fish monitoring programs as coordinated under HELCOM FISH PRO, FISH PRO II, FISH PRO III and EG Coastal Fish and used for HELCOM coastal fish indicator and thematic assessments. HELCOM Coastal fish core indicator database (COOL) contains updated data used in coastal fish core indicators for every current monitoring station in the Baltic Sea and information on the latest status assessment for the two coastal fish indicators: https://indicators.helcom.fi/indicator/coastal-fish-key-groups/ https://indicators.helcom.fi/indicator/coastal-fish-key-species/ The collection of monitoring data is described in the Monitoring guideline: https://helcom.fi/wp-content/uploads/2020/01/HELCOM-Guidelines-for-coastal-fish-monitoring-2019.pdf The database was originally developed in BalticBoost project (https://helcom.fi/helcom-at-work/projects/balticboost/) Theme 1: Biodiversity, which focused on creating a biodiversity assessment tool and improving data arrangements for the biodiversity elements where this is limited (e.g. coastal fish, birds and seals) so that a comprehensive assessment of biodiversity in the Baltic Sea can be carried out by 2018. The dataset is divided to pointwise observations where values are collected from one single location and polygon areas where values reflect larger area (ICES squares). The data is reported by national representatives of HELCOM EG Coastal Fish and validated annually in the group meeting and hosted by HELCOM Secretariat. Attributes: ID = Unique identifier of observation Country = Country of organization carrying out monitoring (in ISO 2-digit country codes) Organization = Organization carrying out monitoring AreaID = ID of monitoring areas AreaName = Name of monitored area Latitude = Latitude coordinate of monitoring site in WGS84 decimal degrees Longitude = Longitude coordinate of monitoring site in WGS84 decimal degrees L3_AssessmentUnit = HELCOM Level3 assessment unit Year = Year of observation IndicatorName = Indicator which the obsrevation value is related to IndicatorValue = Indicator value as in CPUE/WPUE Species = Key coastal fish species tthat indicator value applies to FunctionalGroup = Key coastal fish functional group that indicator value applies to Method = Monitoring method Geartype = Gear type used for monitoring Season = Season of monitoring RegistrationDate = Date when observation was included in the Coastal fish database

Summary Estimated observations of the biotope AA.I3L10, AA.J3L10, AB.I3L10 and AB.J3L10 were collected from the Baltic Sea area by expert judgements for HELCOM Red List of biotopes, habitats and biotope complexes. Description Baltic photic or aphotic coarse sediment or sand dominated by multiple infaunal bivalve species: Macoma calcarea, Mya truncata, Astarte spp., Spisula spp. The HELCOM Red List of Baltic Sea underwater biotopes, habitats and biotope complexes (2013) is an updated and improved version of the Red List assessment of marine and coastal biotopes and biotope complexes published in 1998. The classification of the report follows the proposed International Union for Conservation of Nature (IUCN) criteria and assessment principals but with some modifications for the Baltic Sea.Altogether, the HELCOM Underwater Biotope and habitat classification (HELCOM HUB) includes 209 biotopes of which 59 were red-listed. Many of the red-listed biotopes are located in deep areas of the Baltic Sea due to oxygen-free nature as well as in the southwestern Baltic Sea due to the salinity restricted distribution of species in certain biotope. The HELCOM assessment relies heavily on expert judgment and inference, and the questionnaire data represents the estimated presence-absence data not in-situ measured data. This must be taken in account when observing the map presentation. The biotopes are shown on the map using the EEA 100 km grid. This dataset displays estimated presence of AA.I3L10, AA.J3L10, AB.I3L10 andAB.J3L10according to HELCOM RED LIST assessment experts:Kiel bight to Isle of Fehmarn, might occasionally occur in Mecklenburg Bight to Darss sill, South-westernBaltic Sea. The distribution map indicates the area in the 100 x 100 km grid where biotope is known tooccur.AA.I3L10, AA.J3L10, AB.I3L10 andAB.J3L10have been placed in the Red List classification to the category of Near Threatened (NT) biotopes. (Data (expert judgements) collected in HELCOM RED LIST project, released in May 2013)

This dataset represents the underlying sediment data on core indicator Polyaromatic hydrocarbons (PAH) and their metabolites. The core indicator evaluates the status of the marine environment based on concentrations of Polyaromatic hydrocarbons (PAH) in sediment and biota. Quantitative threshold value is used to evaluate if core indicators status is Achieve, Fail or Not assessed. As There is no commonly agreed threshold value for measuring metabolites available, this report only considers concentrations of contaminants. This dataset displays the result of the indicator in HELCOM Assessment Scale 4 (Division of the Baltic Sea into 17 sub-basins and further division into coastal and off-shore areas and division of the coastal areas by WFD water types or water bodies). Attribute information: "region" = name of subbasin "country" = country "station" = Unique code for the station "stationNam" = name for the station "determinan" = determinant parameter (ANT = anthracene) "detGroup" = the grouping of determinands used to display the results "_shape" = shape used to map assessment results "colour" = colour used to map assessment results "l3area" = HELCOM assessment unit on scale 3 "l4area" = HELCOM assessment unit on scale 4 "nyall" = total number of years of data "nyfit" = number of years of data used in the assessment "nypos" = number of years with at least one measurement above the limit of detection "lastyear" = most recent year of data "prtrend" = the significance of the change over the most recent 20 years; for the assessment conducted in November 2017 and published in June 2018, this is the period 1996-2016 "rtrend" = annual ‘linear’ change over the most recent 20 years "meanLY" = fitted value in last monitoring year "clLY" = upper one-sided 95% confidence limit on fitted value in last monitoring year "EQS" = Threshold value "EQSdiff" = difference between clLY and EQS "EQSbelow" = whether the mean value in the last monitoring year is significantly below EQS

Observations of Entelurus aequoreus were collected from the Baltic Sea area for HELCOM Red List species list. The HELCOM Red List of Baltic Sea species in danger of becoming extinct (2013) is the first threat assessment for Baltic Sea species that covers all marine mammals, fish, birds, macrophytes (aquatic plants), and benthic invertebrates, and follows the Red List criteria of the International Union for Conservation of Nature (IUCN). Almost 2800 species were considered in the Red List assessment and about 1750 were evaluated according to the IUCN Red List criteria. Entelurus aequoreus has been placed to the Red List category of Least Concern (LC) species. The map shows the sub-basins in the HELCOM area where the species is known to occur regularly and to reproduce (HELCOM 2012).

Dataset description: This dataset displays spatial coverage of available data on riverine inputs of hazardous substances to the Baltic Sea. The data illustrates availability and where available contains values of annual average inputs of hazardous substances (the latest assessment period) from sub-catchments and coastal areas designated for the HELCOM PLC assessment. The sub-catchments are the smallest areas for which loads of nutrients and hazardous substances are assessed. Sub-catchments are always located within borders of a single country and drain into one Baltic Sea sub-basin. Sub-catchments may correspond to either monitored or unmonitored areas. Unmonitored sub-catchments may represent either unmonitored parts of river catchments or aggregated unmonitored areas (depending on the reporting format of each Contracting Party). The data is obtained through national monitoring programmes and annually reported by Contracting Parties to the HELCOM Pollution Load Compilation (PLC-water) database as an integral part of HELCOM Pollution Load Compilation process https://nest.su.se/helcom_plc/. However, the assessment of inputs and respective data updates are performed periodically in accordance with the workplan of respective PLC-projects. The data is produced, compiled and quality assured in accordance with the HELCOM Guidelines for the annual and periodical compilation and reporting of waterborne pollution inputs to the Baltic Sea (HELCOM PLC-Water Guideline). Dataset content: Polygonal feature class contains the following attributes: Source code (source_code): Unique code for river sub-catchments and unmonitored areas Source name (source_name): Name of river catchment or unmonitored area Sub-basin code (subb_code): Sub-basin of the Baltic Sea the sub-catchment drains to. Country code (c_code): The Country on which territory the river mouth is located, for border rivers both are mentioned. Area km2 (area_km2): Polygon area in sq.km. Cd_20XX: annual average input of cadmium in each year of the assessment period (tonnes/year) Cd_average: average input of cadmium in the assessment period (tonnes/year) Cr_20XX: annual average input of cadmium in each year of the assessment period (tonnes/year) Cr_average: average input of chromium in the assessment period (tonnes/year) Cu_20XX: annual average input of cadmium in each year of the assessment period (tonnes/year) Cu_average: average input of copper in the assessment period (tonnes/year) Hg_20XX:annual average input of cadmium in each year of the assessment period (tonnes/year) Hg_average: average input of mercury in the assessment period (tonnes/year) Ni_20XX: annual average input of cadmium in each year of the assessment period (tonnes/year) Ni_average: average input of nickel in the assessment period (tonnes/year) Pb_20XX: annual average input of cadmium in each year of the assessment period (tonnes/year) Pb_average: average input of lead in the assessment period (tonnes/year) Zn_20XX: annual average input of cadmium in each year of the assessment period (tonnes/year) Zn_average: average input of zinc in the assessment period (tonnes/year) Year: year of the assessment Visualization: The following maps visualize the data: Map of data coverage for zinc Map of data coverage for chromium Map of data coverage for copper Map of data coverage for nickel Map of data coverage for lead Map of data coverage for cadmium Map of data coverage for mercury Data update: Metadata is updated by HELCOM Secretariat periodically after adoption of PLC report on sources of nutrients. The dataset is updated by HELCOM Secretariat periodically after adoption of PLC report on sources of nutrients.