The detection of differences among assemblages of marine benthic species based on an assessment of dominance and diversity

Summary A criterion for comparing diversity is offered based on dominance patterns involving all the proportional species abundances. The method is applied by plotting percentage cumulative abundance curves. This can reveal that some assemblages cannot be compared in terms of diversity or equitability and that intrinsic diversity indices cannot under these circumstances be relied upon. The behaviour and interpretation of these dominance curves under different circumstances is explored using examples from macrobenthic and marine nematode studies. Dominance curves are also compared with Sanders' rarefaction curves and the relative advantages discussed. It is recommended that these graphical methods be routinely applied to marine biological data before calculating more complex diversity or equitability indices.