The 2019 version of the EUNIS marine habitat classification system includes ‘biogenic habitat’ at level 2 of the classification hierarchy, putting it on the same footing as other, grain-size-based substrate types such as ‘mud’ and ‘sand’.
Until now, the EUSeaMap seabed substrate data product1 has been primarily composed of grain-size based classes, plus rock and Posidonia oceanica meadows. The process was:
1. The EMODnet Geology consortium compiled a data product showing the extent of grain-size based sediment classes, plus rock.
2. The EMODnet Seabed Habitats consortium made some additional ad hoc changes, including:
a. Addition of data that did not make it into the EMODnet Geology product for various reasons,
b. Addition of Posidonia oceanica meadows polygons in the Mediterranean. This is the only biogenic substrate type that has been included in EUSeaMap to date.
The ad hoc changes previously made to the EMODnet Geology substrate layer by EMODnet Seabed Habitats are described in the EUSeaMap 2019 and EUSeaMap 2016 technical reports (Vasquez et al, 2020; Populus et al, 2017).
Therefore, in 2017, the EMODnet Seabed Habitats consortium agreed that they should create a new data product for ‘biogenic substrate’, which may be combined with the grain-size-based substrate data from EMODnet Geology to provide a more complete representation of all substrate types relevant to biological communities.
It is important to note that:
• biogenic substrates have not been mapped comprehensively in any region of Europe and therefore the final product is not representative of the full distribution.
• The purpose of this compilation is not to compile data on habitats of conservation interest, although several biogenic substrate types are also habitats of conservation interest.