Summary Estimated observations of the biotope AB.B1E4 were collected from the Baltic Sea area by expert judgements for HELCOM Red List of biotopes, habitats and biotope complexes. Description Baltic aphotic hard clay dominated by Astarte 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 AB.B1E4 according to HELCOM RED LIST assessment experts:Known from German and Polish waters in the Baltic Sea. Aphotic hard clay dominated by Astarte spp. occurs on the sills (thresholds) of the Slupsk Furrow that connects the Bornholm Deep with the Gotland Deep and Gdansk Deep. Distribution map indicates the area in the 100 x 100 km grid where biotope is known to occur.(Data (expert judgements) collected in HELCOM RED LIST project, released in May 2013)

Summary Estimated observations of the biotope AA.I3L11, AB.I3L11, AA.J3L11 and AB.J3L11 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 dominated by multiple infaunal polychaete species including Ophelia spp Baltic photic or aphotic sand dominated by multiple infaunal polychaete species including Ophelia spp. and Travisia forbesii 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.I3L11, AB.I3L11, AA.J3L11 andAB.J3L11according to HELCOM RED LIST assessment experts: The biotope occurs mainly in the southern and western parts of the Baltic Sea area, but is very rare. They are found in exposed abrasion areas (sandbanks, near-shore wave exposed shallow sublittoral). Kiel bight to Darss sill. The distribution map indicates the area in the 100 x 100 km grid where biotope is known to occur. AA.I3L11, AB.I3L11, AA.J3L11 andAB.J3L11have 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)

Summary Estimated observations of the biotope AE.O5 were collected from the Baltic Sea area by expert judgements for HELCOM Red List of biotopes, habitats and biotope complexes. Description Baltic Sea aphotic pelagic below halocline oxicThe 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 AE.O5 according to HELCOM RED LIST assessment experts:The distribution map indicates the area in the 100 x 100 km grid where biotope is known to occur. The habitat only makes up a section of the pelagic water mass in the area indicated by the map. The map is created based on the bathymetric data of the Baltic Proper. According to the depth contours, the grid indicated on the map include areas deeper than 60-80m.(Data (expert judgements) collected in HELCOM RED LIST project, released in May 2013)

Summary Estimated observations of the biotope AA.H1B4, AA.I1B4, AA.J1B4 and AA.M1B4 were collected from the Baltic Sea area by expert judgements for HELCOM Red List of biotopes, habitats and biotope complexes. Description Baltic photic muddy or coarse sediment, sand or mixed substrate dominated by Charales 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.H1B4, AA.I1B4, AA.J1B4 andAA.M1B4according to HELCOM RED LIST assessment experts:The Charales biotopes are distributed along the whole Baltic Sea coastline. The biotope covers largeareas in the comparatively large, shallow and sheltered erman Bodden areas, the Polish and LithuanianLagoons, the Latvian Bay ofRiga and Estonian, and along the coasts of Finland and Sweden especially inflads. The higher the salinities, the higher the diversity of the biotope withrespect to accompanyingplant species and inhabiting invertebrate and fishcommunities. The diversity of Charales and relatedgenera can howeverincrease with decreasing salinity, as the charophytes are brackish andfreshwatermacrophytes. The distribution map indicates the area in the 100 x100 km grid where biotope is knownto occur.AA.H1B4, AA.I1B4, AA.J1B4 andAA.M1B4have 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)

Summary Estimated observations of the biotope AC were collected from the Baltic Sea area by expert judgements for HELCOM Red List of biotopes, habitats and biotope complexes. Description Baltic Sea seasonal sea iceThe 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 AC according to HELCOM RED LIST assessment experts:The distribution of the biotope covers the whole Baltic Sea, but is most common in the northern regions. From a time series of the maximum annual ice extent of sea ice, a declining trend can be detected. During the last two decades all ice winters of the Baltic Sea have been between average and extremely mild. The length of the ice season shows a decreasing trend by 14–44 days in the latest century (Vihma & Haapala 2009). The distribution area in the 100 x 100 km grid where the biotope occurs during an average ice winter when the ice covers approximately 200 000 km2.(Data (expert judgements) collected in HELCOM RED LIST project, released in May 2013)

Summary Estimated observations of the biotope AA.H3L6 were collected from the Baltic Sea area by expert judgements for HELCOM Red List of biotopes, habitats and biotope complexes. Description Baltic photic muddy sediment dominated by UnionidaeThe 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.H3L6according to HELCOM RED LIST assessment experts:The biotope is known to occur in the eastern parts of the Curonian lagoon in Lithuania. Mussel species of the family Unionidae occur in the whole Baltic Sea region and can occur in densities high enough to be habitat forming in estuaries. The distribution map indicates the area in the 100 x 100 km grid where biotope is known to occur.(Data (expert judgements) collected in HELCOM RED LIST project, released in May 2013)

Summary Estimated observations of the biotope AA.M1Q2, AA.H1Q2, AA.I1Q2 and AA.J1Q2 were collected from the Baltic Sea area by expert judgements for HELCOM Red List of biotopes, habitats and biotope complexes. Description Baltic photic mixed substrate, mud, coarse sediment or sand dominated by stable aggregations of unattached Fucus spp. (dwarf form) 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.M1Q2, AA.H1Q2, AA.I1Q2 andAA.J1Q2according to HELCOM RED LIST assessment experts:The Fucus spp. dwarf form is known from Sweden, Finland, Germany andEstonia. In all countries plusPoland also unattached Fucus spp. occurswidespread in sheltered areas. But it is not clear for each ofthose countries, ifthese unattached forms are built of the typical F. vesiculosus morphology, thedwarfform or both forms. In Poland the unattached Fucus biotope hasdisappeared from the Puck Lagoon, soit might be difficult to clear this question.Presently this biotope is only known to occur in Sweden andGermany. InGermany it exists only in very few coastal lagoons with low to moderateeutrophicationpressures and salinities of around 7–10 psu (Vitter Bodden,Kubitzer Bodden, Wieker Bodden.Distribution map indicates the area in the 100 x 100 km grid where biotope is known to occur.AA.M1Q2, AA.H1Q2, AA.I1Q2 andAA.J1Q2have been placed in the Red List classification to the category of Critically Endangered (CR) biotopes. (Data (expert judgements) collected in HELCOM RED LIST project, released in May 2013)

Summary Estimated observations of the biotope AB.H3L3 were collected from the Baltic Sea area by expert judgements for HELCOM Red List of biotopes, habitats and biotope complexes. Description Baltic aphotic muddy sediment dominated by ocean quahog (Arctica islandica)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 AB.H3L3 according to HELCOM RED LIST assessment experts:The distribution map indicates the area in the 100 x 100 km grid where biotope is believed to occur based on environmental conditions and the availability of the muddy substrate. The biotope has declined severely in the indicated area.(Data (expert judgements) collected in HELCOM RED LIST project, released in May 2013)

Summary Estimated observations of the biotope AA.H1B5 and AA.J1B5 were collected from the Baltic Sea area by expert judgements for HELCOM Red List of biotopes, habitats and biotope complexes. Description Baltic photic muddy sediment or sand dominated by spiny naiad (Najas marina)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.H1B5 and AA.J1B5 according to HELCOM RED LIST assessment experts:The Najas biotopes are distributed along the whole Baltic Sea coastline. Especially some very sheltered, oligohaline German Boddens, the Puck, Vistula and Curonian Lagoon, as well as Finnish and Swedish flads and glo-flads are typical localities where the biotopes occur. The distribution map indicates the area in the 100 x 100 km grid where biotopes are known to occur.(Data (expert judgements) collected in HELCOM RED LIST project, released in May 2013)

Summary Estimated observations of the biotope AB.J3L3 were collected from the Baltic Sea area by expert judgements for HELCOM Red List of biotopes, habitats and biotope complexes. Description Baltic aphotic sand dominated by ocean quahog (Arctica islandica)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 AB.J3L3 according to HELCOM RED LIST assessment experts:The main distribution area of this biotope is the western Baltic Sea. The largest populations of A. islandica are found in Kiel and Mecklenburg Bights (Zettler et al. 2001). The distribution map indicates the area in the 100 x 100 km grid where biotope is believed to occur based on the suitability of the environmental conditions.(Data (expert judgements) collected in HELCOM RED LIST project, released in May 2013)