EUNIS Combined Map: full-coverage EUNIS level 3 layer integrating maps from surveys and broad-scale models

In some cases, a full-coverage map displaying the best available data everywhere at the expense of consistency is required. The production of such a product showing EUNIS level 3 habitats requires integrating EUNIS level 3 seabed habitat data from fine and broad-scale habitat maps. The product aims to create a complete map that presents the best available information on the distribution of EUNIS level 3 habitats at any locations in UK waters. This data product is required for, among other things, assessments of progress towards networks of marine protected areas (MPAs) and marine spatial planning in the UK.

The aim was to produce a single map layer displaying the best quality EUNIS level 3 data for any given location. Furthermore, the process for producing the layer needed to be:

• Repeatable; • Transparent; • Easy to explain and understand; • Objective; • Fully documented; • Appropriate for EUNIS level 3 habitats; and, • Appropriate for the UK intertidal and subtidal areas

Any location would show only a single value describing the habitat at EUNIS level 3, i.e. no overlapping polygons leading to multiple possible values at a location. The data at any location should be the best available to describe the EUNIS level 3 habitat type (i.e. the most likely to be correct). EUNIS level 3 habitats (Appendix 1) describe physical habitats classified using biologically meaningful parameters – substrate type, and additionally for rock: energy and biological zone. Therefore, a method was created to choose data based on their ability to describe these physical variables.