GIS-based mapping of benthic habitats

The aim of the work was to map and analyse benthic habitats in the Polish zone of the Baltic Sea using the Geographical Information Systems (GIS). The habitats definitions were analogous to those proposed in the HELCOM classification, which is based on two concepts—the euphotic zone has no clearly defined boundaries and the bottom sediments are defined on the basis of their fractions. The mapping was done using the theory of fuzzy sets. The fuzzy set map for each HELCOM category was created as a result of an intersection operation on two fuzzy set maps—the first showed bottom position relative to euphotic depth, and the second described the presence of a given sediment type on the bottom. The maps obtained were used to create a thematic map of habitats, which was generated at a pre-set significance level from the statistical analysis of a set of random realizations of habitat maps generated by stochastic simulation. The GIS-based analyses of the thematic map allowed a map of habitat groups to be developed and also allowed to find whether and to what extent the definitions proposed by HELCOM were applicable to the mapping of benthic habitats in the study area.