Abundance-occupancy patterns in British estuarine macroinvertebrates

Macroecology is essentially concerned with understanding the large-scale patterns in organisms' abundance and distribution, and determining how these patterns arise. Whilst macroecological studies abound in terrestrial and freshwater ecology, few comparable studies have ever been conducted using marine data. We examined the relationships between mean organismal abundance and the extent of site occupancy of 95 species of estuarine macroinvertebrates, censused over 143 grid squares of 1 km spread across the UK. A significant positive relationship between abundance and occupancy was revealed, with the slope of this relationship not differing significantly between taxonomic groups. Taxa with planktonic/lecithotrophic larvae showed no significant difference in abundance-occupancy slope compared to taxa with other reproductive/dispersal biologies. The patterns observed are consistent with those reported in many studies of terrestrial and freshwater taxa.