Macroecology of the European soft sediment benthos: insights from the MacroBen database.

Macroecology provides a novel conceptual framework for analysis of the distribution and abundance of organisms at very large scales. Its rapid development in recent years has been driven primarily by studies of terrestrial taxa; the vast potential of marine systems to contribute to the macroecological research effort remains largely untapped. International collaborative efforts such as MarBEF have provided fresh impetus to the collation of regional databases of species occurrences, such as the newly available MacroBen database of the European soft sediment benthic fauna. Here, we provide a first macroecological summary of this unique database. We show that in common with almost all previously analysed assemblages, the frequency distribution of regional site occupancies across species in the MacroBen database is strongly right-skewed. More unusually, this right skew remains under logarithmic ransformation. There is little evidence for any major differences between higher taxa in this frequency distribution (based on the 8 animal classes for which we have sufficien tdata). Indeed, considerable variation in occupancy persisted across the taxonomic hierarchy, such that most variation occurred between species within genera. There was a weak positive relationship between local population density and regional occupancy across species, but this abundance–occupancy relationship varied considerably between higher taxa and between geographical areas. Our results highlight the potential of databases such as MacroBen to consolidate macroecological generalities and to test emerging theory.