PROTECT BALTIC - Deliverable 3.6 - Spatial map layers on the biotic ecosystem components in the Baltic Sea

This deliverable presents the spatial map layers developed for biotic ecosystem components across the Baltic Sea and describes the methodology used the produce them. The map layers are available for species of benthic invertebrates, macrophytes and fish here, in HELCOM’s GitHub repository, and visually presented here. 

Other species groups, such as birds and marine mammals, could not be modelled because the available data were insufficient and spatially biased. Therefore, species distribution models (SDMs) for birds and marine mammals were harvested from external sources.

Bird distribution models used in PROTECT BALTIC were obtained from eBird (see Fink et al., 2024).

Habitat suitability maps for harbour porpoise were produced and shared by the OBAMA-NEXT project (van Beest et al., 2025). Model outputs were available for both winter (November–April) and summer (May–October) seasons and are also available through the EMODnet product catalogue.

Habitat suitability maps for grey seal and harbour seal were produced using a similar workflow and shared by the OBAMA-NEXT project (Galatius et al., in press). For use in PROTECT BALTIC, seasonal habitat suitability model outputs from OBAMA-NEXT were averaged across years and reprojected to the analysis grid using bilinear interpolation.