Diversity and distribution of benthic macrofauna in the Baltic Sea: Data inventory and its use for species distribution modelling and prediction

This study attempts to model the probability of occurrence of some characteristic macro-invertebrate species of the Baltic Sea from different functional groups (i.e. grazers, deposit and suspension feeders, and predators) in response to major environmental forcing factors (salinity, water depth and seabed substrate type). Analyses were based on the inventory data set compiled by revising the data on macrobenthic species for over 12,000 sampling events in the Baltic Sea. In addition, data on environmental variables are retrieved from the results of modelling and large-scale mapping efforts. A simple logistic regression based modelling technique was applied and the candidate model with highest discriminatory power was selected for habitat suitability mapping. Habitat suitability models allowed to satisfactorily predict the potential distribution of macrofaunal species based solely on modelled salinity, bathymetry and rough sediment class information. Our results indicated that salinity, depth and substrate type are all important in determining the distribution of most characteristic macrobenthic species on the large-scale of the whole Baltic Sea. The present exercise is only a first step. Implementation of other variables (e.g. characterizing oxygen and temperature fluctuations, total organic content, and nutrient supply) would obviously increase the model applicability. Information on the ecological potential of habitat suitability can serve as the utmost important basis for scientifically sound marine spatial planning.