The dataset reflects the spatial delineation of river catchments in the Baltic Sea drainage area. The data is based on the reporting by Contracting Parties within in the HELCOM Pollution Load Compilation (PLC) framework. The catchments consist of monitored river catchments and unmonitored coastal areas. The delineation of the catchments can be connected to the flow and nitrogen and phosphorous load information available in the PLC assessment data set (https://metadata.helcom.fi/geonetwork/srv/eng/catalog.search#/metadata/441f878f-67e7-4aa8-927e-8f5e073dc893). The river catchments consist of whole rivers, meaning that although a river would run through several countries or would be a border river between two countries, the catchment is not split into separate sub-catchments. The unmonitored areas are aggregated based on PLC subbasins and country areas, thus forming areas such as the unmonitored area of Finnish Gulf of Finland, Polish Baltic Proper or Danish Kattegat. Attribute information: SourceCode: Unique code for river catchment Name: Name of river catchment SubBasin: The PLC subbasin where the river meets the sea. Country: The Country on which territory the river mouth is located, for border rivers both are mentioned. Monitoring: The monitoring status of the river (M=monitored and U=unmonitored). Marked as monitored only if it’s been monitored for the whole time series. Transbound: Listing all countries that have the rivers drainage area on its territory. Area_km2: The total area of the catchment in square kilometers. flow_1995...flow_2022: The water flow of the river catchment for the whole time-series TN_1995...TN_2022: Total nitrogen load of the river catchment for the whole time-series TP_1995...TP_2022: Total phosphorus load of the river catchment for the whole time-series

This dataset represents the underlying data on core indicator Zooplankton mean size and total stock (MSTS). The core indicator evaluates zooplankton community structure to determine whether it reflects good environmental status. Quantitative thresholds are used to evaluate core indicators status in Achieve, Fail or Not assessed. As a rule, achieve status occur when large sized zooplankters occur abundantly in the plankton community. Due to strong environmental gradients, size distribution and total stock of the zooplankton corresponding to achieve status vary between the Baltic Sea sub-basins. This dataset displays the result of the indicator in HELCOM Assessment Scale 2 (Division of the Baltic Sea into 17 sub-basins). The dataset contains following attributes: DOME - output field Description CNTRY - Country that has reported the measurement (cf. CNTRY) CRUIS - Cruise identifier (unique for data submission) STNNO - Station identification (unique for each CRUIS within the same data submission) SMPNO - Sample identifier (unique for each CRUIS and STNNO within the same data submission) MPROG - Monitoring programme (cf. MPROG). Multiple programmes are possible separated by “~” (ascii 126) PURPM - Purpose of monitoring (cf. PURPM) . Multiple purposes possible separated by “~” (ascii 126) MYEAR - Monitoring year. Note that MYEAR may not always be identical to the year in date of sampling DATE - Date of sampling (DD/MM/YYYY) Latitude - Latitude of measurement (decimal degrees) Longitude - Longitude of measurement (decimal degrees) MNDEP - Minimum depth of sample (m) MXDEP - Maximum depth of sample (m) STATN - Station name as reported HELCOM_subbasin - HELCOM subbasin name (L2) HELCOM_L3 - HELCOM subbasin with coastal and offshore division – HELCOM_ID (L3) HELCOM_L4 - HELCOM subbasin with coastal WFD waterbodies or watertypes – HELCOM_ID (L4) OSPAR_region - OSPAR region ICES area - ICES Statistical Areas (cf. ICES statistical areas) RLABO - Reporting laboratory (cf. RLABO) ALABO - Analytical laboratory (cf. RLABO) SLABO - Sampling laboratory (cf. RLABO) RLIST - Reference code list used for species (cf RLIST) SPECI - Species/taxon code/name of examined specimen, as reported by submitter (according to reported reference list RLIST) SPECI_name - Species/taxon name of examined specimen, as reported by submitter (according to reported reference list RLIST) AphiaID - AphiaID (id) of species in World Registry of Marine Species (WoRMS) WoRMS_name - Taxon species/name of species in World Registry of Marine Species (WoRMS) AphiaID_accepted - Accepted AphiaID (id) of species in World Registry of Marine Species (WoRMS) WoRMS_accepted_name - Accepted species/taxon name of species in World Registry of Marine Species (WoRMS) SEXCO - Sex of specimen (cf. SEXCO) SFLAG - Species flag (cf. SFLAG) . Multiple purposes possible separated by “~” (ascii 126) SIZCL - Size class (value from reference in SIZRF) SIZRF - Size class reference list (cf. SIZRF) STAGE - Developmental stage of the species (cf. STAGE) CPORT - Number of portions counted from split sample NPORT -Number of portions in split sample (SMPNO) PARAM - Measured parameter (cf. PARAM) MUNIT - Measurement unit (cf. MUNIT) Value - Value measured Final_MUNIT - The unit of the final value (cf. MUNIT) Final_value - For values that are reported as a number only (eg. ‘nr’ or ‘g’) the final concentration (eg. ‘nr/l’ or ‘g/l’) is calculated as value*NPORT/(CPORT * SMVOL). If value is reported as a concentration, Final_value and Value are identical SMTYP - Sampler type (cf. SMTYP) SAREA - Sampler/swept area (cm2) METOA - Method of analysis (cf. METOA) MAGNI -Total magnification FLVOL - Calculated flow .volume of water (m3) CLMET MESHS - Mesh size of net or sieve (µm) CLMET - Calculation method for FLVOL (cf. CLMET) SMVOL - Total sampled volume (m3) METFP - Method of chemical fixation/preservation (cf. METFP) QFLAG - Qualifier flag for measured value, i.e. “<” (cf. QFLAG). Multiple flags possible separated by “~” (ascii 126) VFLAG - Validity flag, i.e. “S“ suspect value (cf. VFLAG). Multiple flags possible separated by “~” (ascii 126) FINFL - Factors potentially influencing guideline compliance and interpretation of data (cf. FINFL) Multiple factors possible separated by “~” (ascii 126) REFSK - Reference source or key (cf. REFSK) DCFLGs - Data conversion flags from ICES Data Centre (cf. DCFLG). Multiple flags possible separated by “~” (ascii 126) Reference to the uploaded submission (integer). Unique for a submission tblSpotID Reference to the sampling event (integer). Unique for a sampling event tblSampleID Reference to the sample (integer). Unique for a sample tblParamID Reference to the measurement (integer). Unique for the data table

This dataset represents the underlying data on the pre-core indicator Diatom/Dinoflagellate index for HOLAS 3. The core indicator evaluates phytoplankton community structure to determine whether it reflects good environmental status. Quantitative thresholds are used to evaluate if core indicators status is Good, Not good or Not assessed.

The dataset contains the extraction of one of the target species, cod, for the period 2016-2021. The extraction of cod data set is based on "Fish extraction - commercial fisheries HOLAS 3". Further information about how this dataset was collected and extracted can be found at: https://metadata.helcom.fi/geonetwork/srv/eng/catalog.search#/metadata/a0104cfd-d237-459b-84f8-8e9e21d2df9b Reported per ICES Rectangles, Russian data extracted from ICES annual reports, reported per ICES sub-divisions. Values are redistributed with fishing effort data c-squares (all gears) 2016-2021. Effort values missing from Russia and sub-basin average values given. Extraction of fish species (landings) per ICES c-squares, average of 2016-2020. Landings calculated per km2. Tons/km2 calculated for each species. For cod, recreational fisheries catches were added. Log-transformed and normalized.

Potential cumulative impacts of eutrophication and hazardous substances assesses the cumulative potential effect of eutrophication and hazardous substances over all ecosystem components. The evaluation is based on the pressure layer on eutrophication and hazardous substances, combined with information on all ecosystem components (57 layers) included in SPIA for HOLAS 3. The thematic analyses is calculated for each assessment unit (1 km2 grid cells) and the data set covers the time period 2016-2021. Spatial Pressure and Impact Assessment (SPIA) is the framework for assessing spatial and cumulative pressures and impacts in HOLAS 3, and this analyses present a thematic assessment including only a certain subset of layers. The framework also includes results for the Baltic Sea Impact Index (full cumulative impact assessment), Baltic Sea Pressure Index (full cumulative pressure assessment), and other thematic assessments where a subset of pressure and ecosystem layers are used. For more info please - visit the HOLAS 3 website (http://stateofthebalticsea.helcom.fi/) - download the report thematic assessment of spatial distribution of pressures and impacts 2016-2021 (https://helcom.fi/post_type_publ/holas3_spa) - or check out the HELCOM SPIA online tool to make calculations for any desired combination of pressures and ecosystem layers (https://maps.helcom.fi/website/bsii/). Please scroll down to "Lineage" for a more detailed description of the methodology.

This core indicator evaluates the status of the marine environment based on concentrations of heavy metal Lead (Pb) in biota. Quantitative thresholds are used to classify core indicators status in “Achieve”, “Fail” or “Not assessed”. Threshold values are based on Environmental quality standards (EQS), defined at EU level for substances included in the priority list under the Water Framework Directive. 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 specifications and units: "HELCOM_ID" = Code of the HELCOM scale 4 assessment unit "country": country in which the HELCOM assessment unit is located or a mention to an open sea area "level_2" = Name of the HELCOM assessment unit in scale 2 "Name" = Name of the HELCOM assessment unit in scale 4 "Open_sea" = Name of the HELCOM assessment unit in the open sea "F2_Name" = Name of the HELCOM assessment unit "determinan" = Determinat "est" = The estimated mean loge concentration in the assessment unit "se" = The standard error on the estimated mean log concentration in the assessment unit "fit" = The estimated mean concentration in the assessment unit "upper_cl" = Upper one-sided 95% confidence limit on the mean concentration: exp(est + qnorm(0.95) * see) "Status" = Overall Status of the indicator according to one-out-all-out

This dataset is built from following Human activities datasets: • https://metadata.helcom.fi/geonetwork/srv/eng/catalog.search#/metadata/3d6bd6f9-72d5-40cf-aaaa-b7c0c18878e3 • https://metadata.helcom.fi/geonetwork/srv/eng/catalog.search#/metadata/41da8e41-d907-419d-8841-f95062d002e7 The game hunting of seabirds data (see separate metadata): The total number of hunted seabirds were averaged over 2016-2021 (number of hunted seabirds / year). The area of the reporting unit was used to calculate the number of hunted seabirds / km2 and the data was converted to 1km x 1km grid. The predator control of seabirds data (see separate metadata): The total number of hunted cormorants were averaged over 2016-2021 (number of hunted cormorants / year). The area of the reporting unit was used to calculate the number of hunted cormorants / km2 and the data was converted to 1km x 1km grid. The two datasets were first separately log transformed and then summed, to get the total value for each grid cell. Zero values were given to all grid cells with no reported seabird hunting activity. The layer was normalized.

This core indicator evaluates the status of the marine environment based on concentrations of heavy metal Lead (Pb) in water. Quantitative thresholds are used to classify core indicators status in “Achieve”, “Fail” or “Not assessed”. Threshold values are based on Environmental quality standards (EQS), defined at EU level for substances included in the priority list under the Water Framework Directive. 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 specifications and units: "HELCOM_ID" = Code of the HELCOM scale 4 assessment unit "country": country in which the HELCOM assessment unit is located or a mention to an open sea area "level_2" = Name of the HELCOM assessment unit in scale 2 "Name" = Name of the HELCOM assessment unit in scale 4 "Open_sea" = Name of the HELCOM assessment unit in the open sea "F2_Name" = Name of the HELCOM assessment unit "determinan" = Determinat "est" = The estimated mean loge concentration in the assessment unit "se" = The standard error on the estimated mean log concentration in the assessment unit "fit" = The estimated mean concentration in the assessment unit "upper_cl" = Upper one-sided 95% confidence limit on the mean concentration: exp(est + qnorm(0.95) * see) "Status" = Overall Status of the indicator according to one-out-all-out

This core indicator evaluates the status of the marine environment based on the presence of hazardous substances in the bottom sediments. The rate of embryo malformations indicates reproductive toxicity due to the presence of hazardous substances in the bottom sediments. The threshold value has not been achieved on all stations within each basin indicating that toxic effects of contaminants may be present. The variability of the malformation rate is much greater within a basin than between the Bothnian Sea and the Baltic proper. This dataset displays the result of the indicator in HELCOM Assessment Scale 2 (Division of the Baltic Sea into 17 sub-basins). Attribute information: "HELCOM_ID" = Code of the HELCOM scale 4 assessment unit "level_2" = name of subbasin "Area (km2)" = Area of the HELCOM scale 2 assessment unit "L2" = ID for the HELCOM scale 2 assessment unit "AULEVEL" = Assessment unit level used for the indicator "STATUS" = Status of the indicator (“Achieve”, “Fail”, "Not assessed" or “Not applicable”)

The Diatom/Dinoflagellate index (Dia/Dino index) reflects the dominance patterns in the phytoplankton spring bloom. It has high relevance for the pathway of the food into the pelagic or benthic food web. In principle, the indicator is applicable in all coastal and open sea assessment units, except lagoons, large river plumes and the Bothnian Bay; however, thresholds for the good status are defined only for the southern and central Baltic Sea up to now. In this assessment unit, the average Dia/Dino index of the years 2016-2021 was just below the threshold value of 0.5 for good status. The confidence of the indicator evaluation depends on the data frequency. The data have to represent the diatom and dinoflagellate blooms adequately. If the diatom bloom is not sufficiently represented in the data, an alternative Dia/Dino index may be applied, based on silicate consumption data. This indicator is robust; its calculation is simple and traceable. The phytoplankton monitoring is operational in the whole Baltic Sea using methods prescribed in the COMBINE manual. Currently, a high quality of the data is assured by the experts of the HELCOM Phytoplankton Expert Group (PEG). The basic data are phytoplankton biomass data, determined as explained in the HELCOM COMBINE manual, originating from the depth of 0 – 10 m. Also silicate data were used that were taken parallel to the phytoplankton sampling. Diatom-dinoflagellate ratio dataset displays the result of the indicator in HELCOM Assessment Scale 2 (Division of the Baltic Sea into 17 sub-basins). Attribute information: "HELCOM_ID" = ID of the HELCOM scale 2 assessment unit "level_2" = Name of the HELCOM scale 2 assessment unit "Indicator_" = Name of the indicator "Period" = Interval of year of the sampling "AnnualSamp" = Assessment average sampling value "Unit" = Unit of the indicator "Type" = Type of indicator (1=monotonic, 2=unimodal, optimal range) "Threshold_" = Threshold value of indicator "Indicator1" = Result of the indicator "Status" = Status of the indicator (“Achieve”, “Fail” or “Not assessed”)