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This data products displays seagrass, macroalgae and live coral from the existing library of habitat maps on the EMODnet Seabed Habitats map viewer.
These layers present the first attempt to map the areal extent of three Essential Ocean Variables (EOVs) in Europe
Introduction - Essential Ocean Variables from Seabed Habitats
The Global Ocean Observing System (GOOS) aims to promote common standards for data collection around the world. As part of this it has identified a series of variables that it hopes will lead to consistency and cost-effective marine monitoring, globally; these are known as 'Essential
Ocean Variables' (EOVs).
Of the ten EOVs in the 'Biology and Ecosystems' category there are three that relate to European seabed habitats, and within each EOV there are several sub-variables (specific variables that may be measured), one of which can be directly informed by habitat maps (Table 1).
EOV | Relevant sub-variable |
---|---|
Hard coral cover and composition | Live hard coral cover and extent |
Seagrass cover and composition | Areal extent of seagrass meadows |
Macroalgal canopy cover and composition | Areal extent |
At the time of writing, the specification sheets for these habitats were still under development; therefore, the 3 EOV layers produced should also be seen as a “work in progress”.
EMODnet Seabed Habitats Map Viewer
EMODnet Seabed Habitats (ESBH) collates habitat maps, habitat models and habitat point data (Figure 1). It also produces a broadscale predictive map – EUSeaMap – which displays EUNIS marine habitats in European waters. A library of over 750 habitat maps have been collated to date. These maps span the extent of the Northeast Atlantic Ocean, Baltic Sea, Mediterranean Sea and Black Sea. The maps are in themed categories: EUNIS, Habitats Directive Annex 1, Composite Data Products and broad-scale predictive maps. (The maps are fully INSPIRE compliant. All maps can be freely downloaded from the ESBH portal along with metadata and confidence scores for each map).
Figure 1. Categories of maps available for download from the EBSH map viewer.
The resources on this web viewer were used in the compilation of composite layers displaying the areal extent of the three EOVs listed above.
Generating EOV layers
A list of habitats was prepared for each EOV with input from all ESBH project partners. These are presented in Appendix 1. After agreeing on the habitat lists, the relevant data for each EOV were extracted from the library of habitat maps on the portal. An R script was used to extract the data from all EUNIS habitat maps. Data from other maps types were extracted manually. The data were merged into standardised, non-overlapping polygon shapefiles and published as web mapping service (WMS) layers from the ESBH viewer.
Seagrasses provide essential habitat and nursery areas for many marine fauna. There are approximately 72 seagrass species that belong to four major groups: Zosteraceae, Hydrocharitaceae, Posidoniaceae and Cymodoceaceae. Zostera beds and Cymodecea meadows
are named on the OSPAR Threatened or Declining Habitats list (Appendix 2). Posidonia beds are protected under Annex I of the EU Habitats Directive (Appendix 3).
Seagrass habitat data have been collated from the following map categories from the ESBH
portal (order reflects the priority):
Decision rules when dealing with overlaps
Layers (1), (2) and (3) are high resolution vector data. The EUSeaMap layer is a vectorised polygon layer converted from a 250 m model of predicted habitats. It was given the least priority on account of its course resolution (Figure 2a). OSPAR data was given priority over any overlapping data from EUNIS or non-EUNIS maps. In areas where 2 EUNIS maps overlapped, the map with the highest confidence was given priority (Figure 2b). In areas where there was a mosaic of live Posidonia and dead Posidonia, the
polygons displaying live Posidonia were selected for input into the final layer.
Figure 2. (a) Overlap between EUNIS habitat maps and EUSeaMap. (b) Overlaps between 2 EUNIS habitat maps with difference confidence assessment scores.
The final layer shows extent of seagrass collated by ESBH in European waters (Figure 3).
Figure 3. Collated seagrass polygon data from the ESBH map viewer used in the generation of the Seagrass EOV layer.
Kelp and fucoid brown algae are the dominant species that comprise macroalgal forests.Although not on any list of protected habitats, they provide many important functions including provision of nursery areas and protection from coastal erosion.
Macroalgal forest data have been collated from the following map categories from the ESBH portal (order reflects the priority):
In areas where 2 EUNIS maps overlapped, the map with the highest confidence score was given
priority.
The final layer shows extent of macroalgal forests collated by ESBH in European waters (Figure 4).
Figure 4. Collated kelp and fucoid polygon data from the ESBH map viewer used in the generation of the Macroalgal Canopy Cover EOV layer.
The health and areal extent of the hard coral community within a reef are direct indicators of the ability of a system to sustain the diversity of associated species. Lophelia pertusa and Coral gardens are both on the OSPAR List of threatened and/or declining species and habitats.
Live coral habitat data have been collated from the following map categories from the ESBH portal (order reflects the priority):
The final layer shows extent of hard coral collated by ESBH in European waters (Figure 5).
Figure 5. Collated coral polygon data from the ESBH map viewer used in the generation of the Live Coral EOV layer.
Limitations and future improvements
There are a few key limitations with these products that are important to highlight.
The composite maps are the most comprehensive collection of maps related to these EOVs in Europe. However, they cannot be assumed to show the true extent of the habitats, and likewise areas that are not mapped do not necessarily imply that the habitat is absent.
This is due to multiple reasons including:
Using the current method, if a single site has been mapped repeatedly over time, all instances of the habitat will be included from all the maps. This would lead to an overestimate of the extent of the habitat within the site if the extent had decreased over time.
It may be useful for a user to know whether a habitat is not mapped somewhere because the area hasn't been surveyed, or because it was surveyed and another habitat was present. For future versions of these composite products we recommend to:
More Information
References
European Seabed Habitats portal: http://www.emodnet-seabedhabitats.eu/
Products in product mapper
Seagrass cover: http://www.emodnet-biology.eu/geoviewer/?active_layer_ids=11992#!/
Macroalgal canopy cover: http://www.emodnet-biology.eu/geoviewer/?active_layer_ids=11991#!/
Live Coral: http://www.emodnet-biology.eu/geoviewer/?active_layer_ids=11990#!/
Authors
Eimear O’Keeffe (Marine Institute, Ireland) & Helen Lillis (Joint Nature Conservation Committee, England)
Appendix 1: Habitat lists for EOVs
Table 2 displays a list of habitat types from the EUNIS habitat classification system that the ESBH partners determined relate to
the seagrass EOV. These were used to extract the relevant polygons from the individual EUNIS habitats maps and EUSeaMap.
Also included are columns indicating with which Annex I and OSPAR habitats these habitat types might correspond.
Table 3 displays a list of habitat types from the EUNIS habitat classification system that the ESBH partners determined relate to
macroalgal cover EOV. These were used to extract the relevant polygons from the individual EUNIS habitat maps and
EUSeaMap. Also included is a column entitled “Other Habitat Maps” which lists two habitat types identified from non-EUNIS
habitat maps.
Table 4 displays a list of habitat types from the EUNIS habitat classification system that the ESBH partners determined relate to
the live coral EOV. These were used to extract the relevant polygons from the individual EUNIS habitats maps and EUSeaMap.
Also included are columns indicating with which Annex I and OSPAR habitats these habitat types might correspond.
Appendix 2: OSPAR List of Threatened and/or Declining Habitats
Table 5: Habitats selected from the OSPAR List for inclusion in the EOV layers.
Appendix 3: Marine habitats listed in Annex I of the EU Habitats Directive.
Table 6: Habitats selected from the Annex I List for inclusion in the EOV layers.