Ecologically or Biologically Significant Marine Areas (EBSA) are special areas in world's oceans that serve important purposes, in one way or another, to support the healthy functioning of oceans and the many services that they provide. Following the voluntary commitment from HELCOM Contracting Parties at the United Nations Oceans Conference in June 2017, HELCOM started the process of identifying EBSAs in the Baltic Sea. The February 2018 EBSA workshop resulted in a proposal for areas for the Convention on Biological Diversity (CBD) to consider during the later half of 2018. Nine Baltic marine areas were described by the workshop participants as ecologically or biologically significant, including five transboundary areas covering waters of two or more countries. The described EBSAs extend into 14 of the 17 Baltic Sea sub-basins. Altogether, they cover 23% of the Baltic Sea, slightly higher than the 19% the average in other areas of the world. The described EBSAs are: - Northern Bothnian Bay - Kvarken Archipelago - Åland Sea, Åland Islands and the Archipelago Sea of Finland - Eastern Gulf of Finland - Inner Sea of West Estonian Archipelago - Southeastern Baltic Sea Shallows - Southern Gotland Harbour Porpoise Area - Fehmarn Belt - Fladen and Stora and Lilla Middelgrund. This dataset contains borders of these 9 areas and related attribute information.

The aim of HELCOM Biodiversity database is to collate all available species observation data made available by HELCOM Contracting Parties from a single entry point. The database contains +1M species observations and applies World Register of Marine Species (WoRMS) taxonomy. The data model used is based on Darwin Core format, with required extensions added. Species observations are mostly pointwise observations, but also gridded observations are included for some species. The database can be searched, viewed and downloaded using a specific web application. The whole database can be downloaded as a zipped ESRI File geodatabase. Disclaimer: Data in the database is stemming from various sources. While there has been considerable quality assurance efforts, the accuracy of data can not be quaranteed.

This online application serves as a joint regional tool to identify low risk routes for IMO Ballast Water Convention exemptions (A-4) for HELCOM and OSPAR marine areas. Data are provided following the port survey protocol described in the HELCOM/OSPAR Joint Harmonised Procedure. https://helcom.fi/wp-content/uploads/2021/01/HELCOM-OSPAR-Joint-Harmonized-Procedure-for-BWMC-A-4-exemptions_2020.pdf The database contains environmental data recorded from OSPAR and HELCOM ports as well as species observations and applies World Register of Marine Species (WoRMS) taxonomy. The data model used is based on Darwin Core format, with required extensions added. The database can be searched, viewed and downloaded using a specific web application. The whole database can be downloaded as a zipped ESRI File geodatabase. The HELCOM/OSPAR Ballast Water Exemptions Decision Support Tool was further developed in the EU INTERREG Baltic Sea Region project COMPLETE, following work developed with funding through the HELCOM ALIENS 2 and 3 and BALSAM projects by the HELCOM Secretariat and Germany (BSH/Brockmann consult). The data contained in the database are resulting from various sources and contains also historical legacy data from old projects. Main sources are listed below: - HELCOM and OSPAR countries national projects - HELCOM ALIENS 2 - HELCOM ALIENS 3 - HELCOM BALSAM

This dataset contains all indicator and assessment results and data for the State of the Baltic Sea (HOLAS II) 2017 version. Final 2018 versions are included separately in HELCOM Map and Data service and metadata catalogue. All datasets for HOLAS II and associated metadata were here compiled. The datasets are: Abundance of coastal fish key functional group cyprinids Abundance of coastal fish key functional group piscivores Abundance of coastal fish species Abundance of salmon spawners and smolt Abundance of waterbirds in the breeding season Abundance of waterbirds in the wintering season Chlorophyll a status Cyanobacterial bloom Dissolved inorganic nitrogen Dissolved inorganic phosphorous Distribution of grey seals Distribution of harbour seals Distribution of ringed seals Eutrophication assessment insitu data Heavy metals – Cadmium (Cd) levels Heavy metals – Lead (Pb) levels Heavy metals – Mercury (Hg) levels Hexabromocyclododecane (HBCDD) levels Integrated biodiversity status assessment for benthic habitats Integrated biodiversity status assessment for fish Integrated biodiversity status assessment for grey seals Integrated biodiversity status assessment for harbour porpoises Integrated biodiversity status assessment for pelagichabitats Integrated biodiversity status assessment for ringed seals Integrated biodiversity status assessment for seals Integrated contamination status assessment Integrated eutrophication status assessment Oxygen det PCB dioxin and furan Perfluorooctane sulphonate (PFOS) Polyaromatic hydrocarbons (PAH) and their metabolites Polybrominated diphenyl ethers Cesium-137 in fish Cesium-137 in flatfish Cesium-137 in herring Cesium-137 in seawater Malformed embryos of amphipods State of the soft bottom macrofauna community TBT and imposex Total nitrogen Total phosphorous Trend in arrival of new non-indigenous species Water clarity Zooplankton mean size and total stock MSTS

In 2010, HELCOM completed the initial assessment (HOLAS I) of the ecosystem health of the Baltic Sea – including the associated costs and benefits to the society. The assessment was based on data from 2003 to 2007. The summary report can be found at: https://helcom.fi/wp-content/uploads/2019/08/BSEP122.pdf and more information about HOLAS I at: https://helcom.fi/baltic-sea-trends/holistic-assessments/2010-initial-holistic-assessment/ All datasets for HOLAS I and associated metadata were here compiled. The datasets are: BaP in mussel BaP in sediment BDE47 Status Benzo[b]fluoranthene status BghiP in mussels BghiP in sediment Bisphenol A in biota Cadmium in fish liver Cadmium in fish muscle Cadmium in mussels CB118 in fish CB118 in mussels CB118 in sediment Chlorophyll a status 2007-2011 Chlorophyll a status confidence 2007-2011 Chlorophyll a status distance to target 2007-2011 Coastal areas chl-a Coastal areas nitrogen Coastal areas overall eutrophication status Coastal areas phosphorus Coastal areas secchi DDE in herring DDE in mussels DDE in sediment DEHP in biota DEHP in sediment Dioxin and PCB in herring Dioxin and PCB in perch Dioxin in herring Dioxin in mussels Dioxin in perch Eutrophication status 2007-2011 Eutrophication status confidence 2007-2011 HCH in sediment HCH in water Interpolated benthic invertebrate status classification Interpolated chemical status Interpolated Chlorophyll a status classification Interpolated DIN status classification Interpolated DIP status classification Interpolated ecosystem health status Interpolated ecosystem health status Interpolated eutrophication status classification Interpolated secchi depth status classification Mercury in fish muscle Mercury in mussels Nitrogen status 2007-2011 Nitrogen status confidence 2007-2011 Nitrogen status distance to target 2007-2011 Nonylphenols Octylphenols Open sea areas benthic invertebrates Open sea areas chl-a Open sea areas nitrogen Open sea areas overall eutrophication status Open sea areas phosphorus Open sea areas secchi Overall biodiversity status coastal area Overall biodiversity status open sea Overall chemical status coastal areas Overall chemical status open sea Overall ecosystem health status coastal area Overall ecosystem health status open sea Oxygen status 2007-2011 Oxygen status confidence 2007-2011 Oxygen status distance to target 2007-2011 PFOS in herring liver PFOS in seal liver Phosphorus status 2007-2011 Phosphorus status confidence 2007-2011 Phosphorus status distance to target 2007-2011 SCCP in fish TBT in fish TBT in mussels TBT in sediment Water clarity status 2007-2011 Water clarity status confidence 2007-2011 Water clarity status distance to target 2007-2011 More information about the HELCOM holistic assessments can be found here: https://helcom.fi/baltic-sea-trends/holistic-assessments/