Use constraints: Data can be used freely given that the source is cited (following creative commons license CC-BY). The source should be cited as: “HELCOM HOLAS 3 Dataset (2023)".

The dataset was created in order to update the information regarding underwater cables in the Baltic Sea Region for the HELCOM Assessments. Data was collected by the HELCOM Secretariat during 2022. Data were reported by Denmark, Germany, Estonia and Finland.

National remarks:

Denmark:

Original data on the spatial distribution of Habitats Directive Annex 1 habitat types (Marine and coastal). The marine habitat types have been mapped in the period 2004-2018. The marine habitats are currently mapped once or twice and the work is still in progress.

The habitat types Estuaries (1130), Mudflats and sandflats (1140), Coastal lagoons (1150) and Large shallow inlets and bays (1160) have mainly been mapped from existing map material including nautical charts.

The habitat types reefs (1170), submarine structures made by leaking gas (1180) and sandbanks (1110) are mainly mapped by a geological acoustic survey of the area. This is done by collecting sailing data in the area with so-called side-scan sonar, which gives a picture of the roughness of the seabed. This is compared with orthophoto, satellite photos as well as previous data from geological wells and other sailing data. Subsequently, the geological mapping is verified with video surveys at selected locations and possibly by diving, where flora and fauna are simultaneously registered and compared with any previous data from the Danish National Monitoring Programme (NOVANA).

The marine habitats are currently mapped once or twice and the work is still in progress. In some areas, the habitat types are mapped from existing map material including nautical charts.

The original nationwide dataset is quality-assured by the Danish Environmental Protection Agency.

Estonia:

Original data was compiled using field sampling, remote sensing, GIS analysis, predictive modeling, and expert judgment, depending on the habitat type and project where a specific polygon was produced. Conforms to Estonian national monitoring requirements and/or HELCOM recommendations. Biological laboratory of Estonian Marine Institute, the University of Tartu certified by Estonian Accreditation Centre (certificate No L179, http://www.eak.ee/dokumendid/ pdf/kasitlusala/L179.pdf).

For the type Boreal Baltic islets and small islands (1620), from the provided shapefile, 925 features are from the dataset which holds the EU habitat types of Estonia (latest inventory). However, for 1620 Estonia does not have a complete inventory of habitats. The database of islands is obsolete to some extent and will be replaced or updated by the Estonian topographic database (Estonian Land Board) in the next data calls. Therefore, all coastal islets that are less than 10 ha in size are included in the Database of islands (Estonian Environment Information System, EELIS). The inventory of EU habitat type 1620: mostly 2014-2015.

Data for "Baltic Esker islands" and "Submarine structures made by leaking gas" were classified as not relevant in national waters.

Finland:

The original dataset contains the most recent compilation of the N2000 habitats in Finland, used for the 2019 Article 18 reporting. The data has been aggregated to 1x1km grids for sensitivity reasons.

The dataset was gathered for the 2019 Article 17 reporting. The data for specific habitats have been produced by either spatial modeling (reefs and sandbanks) or delineations using e.g. satellite/aerial images and species data. The data production has spanned over several years from ca 2000-2019, but this is the most accurate picture of the occurrence and distribution at the moment. The database has been produced by several organizations: Metsähallitus, The Geological Survey of Finland, Åbo Akademi University, The Finnish Environment Insititute, and Ålands Landskapsrgering. Several of the occurrences have also been verified in the field.

Germany:

The original dataset for the Mecklenburg-Vorpommern region was compiled from 3 different sources:

1. within the FFH area, data from the management plans were used, if the data was available and not older than 2011, it’s modeled data with ground truthing. 2. outside the FFH areas if available data from the ATLAS-Project (3 focus areas: Plantagenetgrund, Wismarbucht, Darßer Schwelle) – using the new “Leitfaden zur großflächigen Abgrenzung und Kartierung des Lebensraumtyps „Riffe“ in der deutschen Ostsee (EU-Code 1170; Untertyp: geogene Riffe)“ BfN (Hrsg.) 2021 from the EEZ to define reefs. 3. modeled data from 2011 with potential areas of the Natura2000 habitats.

The dataset from the management plans was collected and quality assured by regional monitoring institutes and accepted by the State Agencies for Agriculture and Environment "StALU". The data from the ATLAS Project were collected and quality assured, as far as possible if the included data is stemming from others sources, from the Leibniz Institute for Baltic Sea Research, Warnemünde. The modeled potential areas for the NATURA2000 habitats are not validated nor quality assured. The LUNG MV has merged the 3 datasets as a national dataset.

The original dataset for the Mecklenburg-Vorpommern region for reefs was compiled from 3 different sources: 1. inside FFH areas, if data from the EEZ-Project 6 “Overall distribution of sediment types” were available (completed: Fehmarn Belt, Kadet Trench, Western Roenne Bank; almost completed: Adler Ground) – using the new “Leitfaden zur großflächigen Abgrenzung und Kartierung des Lebensraumtyps „Riffe“ in der deutschen Ostsee (EU-Code 1170; Untertyp: geogene Riffe)“, Heinicke et al. 2021 (Link: https://www.bfn.de/sites/default/files/2021-11/Skript612.pdf). In all other areas of the EEZ: 2. data as reported to the EU Commission in 2019 and already used in HOLAS II (in marine protected areas transferred to a 50 x 50 m grid). 3. data collected by project developers in the context of approval procedures (e.g. for offshore wind power) and accepted by BfN.

All datasets were collected and quality assured by the German Federal Agency for Nature Conservation.

The data from the EEZ-Project 6 “Overall distribution of sediment types” were collected and quality assured by the Federal Maritime and Hydrographic Agency and used by the BfN to map reefs with a new, Grid based method which is described in Heinicke et al. 2021. This data has the best quality status 3.

The data which are already reported to the EU Commission in 2019 are based on a method described in Boedeker et al. (2006): Interpretation, identification and ecological assessment of the Natura 2000 habitats „sandbank“ and „reef“ (In v. Nordheim et al. (Eds.): Progress in Marine Conservation in Europe: Natura 2000 sites in German Offshore waters). This data has for sandbanks the best quality status 3 and for reefs the quality status 2.

The data collected by project developers in the context of approval procedures could only partly be quality assured by BfN. This data has the lowest quality status 1.

The BfN has merged the 3 datasets as a national dataset for the German EEZ.

The original dataset for the Mecklenburg-Vorpommern region for sandbank was compiled from 2 different sources: 1. data as reported to the EU Commission in 2019 and already used in HOLAS II (transferred to a 50 x 50 m grid and intersected with the new reef data). 2. data collected by project developer Fermern A/S 2013 in the context of an approval procedure in the Natura 2000 site Fehmarn Belt. Both datasets were collected and quality assured by the German Federal Agency for Nature Conservation.

The data which are already reported to the EU Commission in 2019 are based on a method described in Boedeker et al. (2006): Interpretation, identification and ecological assessment of the Natura 2000 habitats „sandbank“ and „reef“ (In v. Nordheim et al. (Eds.): Progress in Marine Conservation in Europe: Natura 2000 sites in German Offshore waters). The update of this sandbank area was adjusted to match the newly delineated reef areas as far as finished.

All sandbank areas were transferred to a 50 x 50 m grid. All sandbank data have the best quality status 3. The BfN has merged the datasets as a national dataset for the German EEZ.

Metadata for the Germany Schleswig-Holstein region can be found at: https://opendata.schleswig-holstein.de/dataset/maritime-daten-ostsee-lrt-1110-und-1170

Data for "Baltic Esker islands", "Submarine structures made by leaking gas", and "Boreal Baltic islets and small islands" were classified as not relevant in national waters.

Data sources:

State Agency for Environment, Nature Conservation and Geology Mecklenburg-Vorpommern (LUNG MV)

State Office for Agriculture, Environment and Rural Areas (Schleswig-Holstein)

The Danish Environmental Protection Agency

Estonian Marine Institute, University of Tartu

Environmental Agency of Estonia (for Baltic islets and small islands)

Metsähallitus

The use of HOLAS 2 data was applied to Sweden, Latvia, Lithuania, and Poland.